Journal Logo

Reviews

Cognitive Complaints in Motor Functional Neurological (Conversion) Disorders: A Focused Review and Clinical Perspective

Alluri, Priyanka R. BA*; Solit, Juliet*; Leveroni, Catherine L. PhD; Goldberg, Katherine BS; Vehar, Julia V. BS; Pollak, Lauren E. PhD; Colvin, Mary K. PhD; Perez, David L. MD, MMSc*

Author Information
Cognitive and Behavioral Neurology: June 2020 - Volume 33 - Issue 2 - p 77-89
doi: 10.1097/WNN.0000000000000218

Abstract

Functional neurological (conversion) disorder (FND) is a common neuropsychiatric condition associated with significant disability and substantial health care expenses (Barsky et al, 2005; Espay et al, 2018). Patients with motor FND (mFND) display clinical features of limb weakness, psychogenic nonepileptic (dissociative) seizures (PNES), and/or abnormal movements that are incompatible with other identifiable neurologic, psychiatric, or systemic disorders (Espay et al, 2018). In the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 2013), a “rule-in” mFND diagnosis is based on the presence of neurologic examination signs, such as a Hoover’s sign or tremor entrainment (Daum et al, 2014). Although the cardinal features of mFND relate to motor abnormalities, many individuals with the disorder report cognitive concerns, including clouded thinking, memory trouble, poor concentration, and/or word-finding difficulties (Stone et al, 2015; Teodoro et al, 2018). Cognitive complaints, in turn, can limit individuals’ engagement in evidence-based treatments (such as cognitive behavioral therapy) and negatively impact their health-related quality of life (Věchetová et al, 2018). These observations underscore the importance of evaluating cognition in this population.

Among the first 100 consecutive mFND patients evaluated in our outpatient FND clinical program at Massachusetts General Hospital, 54 reported cognitive complaints during their initial clinical interview (Matin et al, 2017). From a diagnostic perspective, similar to the observation that motor inconsistency is a clinical feature that can help guide a diagnosis of functional limb weakness, inconsistencies in cognitive performance and/or major discrepancies between subjective cognitive complaints and objective cognitive performance can help support the presence of functional cognitive symptoms (Stone et al, 2015). For example, individuals with mFND may complain of poor memory and general cognitive difficulties but may also drive unaccompanied to the clinic, recount recent events well, and express their concerns in an articulate manner. In our clinical program, we conduct adjunctive neuropsychological testing of mFND individuals with prominent cognitive complaints in an effort to not only define their neurocognitive strengths and weaknesses, but also to obtain objective data to aid the “rule-in” of concurrent functional cognitive symptoms.

In this article, we first briefly review the literature assessing the neuropsychological testing profiles of individuals with mFND—specifically across the spectrum of PNES, functional movement disorders, and functional limb weakness. When conducting the review, we used a transdiagnostic approach across the motor spectrum of FND, given that many individuals present with mixed symptoms or develop new symptoms over the course of their illness (Matin et al, 2017; McKenzie et al, 2011).

Following our literature review, we then report on three cases of mFND that illustrate discrepancies between cognitive complaints and objective cognitive performance, and highlight the relevance of functional somatic syndromes (eg, chronic fatigue syndrome, fibromyalgia), mild traumatic brain injury (TBI), and health anxiety, among other factors. These case examples underscore the potential utility of conducting adjunctive neuropsychological testing when triaging the severity and nature of cognitive complaints in individuals with mFND (Matin et al, 2017; Perez et al, 2016). Last, we outline work-in-progress suggestions for a potential adjunctive neuropsychological test battery that may be useful in assessing cognitive complaints in some individuals with mFND.

APPROACH TO LITERATURE REVIEW

We searched PubMed for original research articles, written in English and published from inception through December 31st, 2018, on the topic of neuropsychological testing in PNES, functional movement disorders, and functional limb weakness in adult patient populations. Search terms included “psychogenic” OR “conversion disorder” OR “functional neurological disorder” OR “functional neurological symptom disorder” OR “psychogenic nonepileptic seizures” OR “dissociative seizures” OR “nonepileptic attack disorder” OR “pseudoseizures” OR “functional movement disorder” OR “psychogenic movement disorder” OR “functional weakness” OR “functional paresis” OR “psychogenic weakness” OR “psychogenic paresis” AND “neuropsychology” OR “neuropsychologic” OR “attention” OR “memory” OR “language” OR “visual spatial” OR “executive” OR “cognitive complaints.”

Reviews and original articles on isolated functional cognitive, speech, and language disorders, and functional somatic disorders, were excluded because these topics have already been reviewed elsewhere (Chung et al, 2018; McWhirter et al, 2019a, 2019b; Mendez, 2018; Pennington et al, 2015, 2019; Stone et al, 2015; Teodoro et al, 2018). We did not conduct a systematic review or quantitative analysis given that investigations at the intersection of mFND and cognition remain in their early stages, particularly in individuals with functional movement disorders and functional limb weakness.

LITERATURE REVIEW FINDINGS

Validity Measures

Performance validity tests (PVTs) such as the Word Memory Test (Green et al, 1996) and the Test of Memory Malingering (Tombaugh, 1996) are commonly included in a neuropsychological evaluation to determine whether the individual being tested is putting forth consistent and adequate effort (Heilbronner et al, 2009). Poor performance on these tests is generally unexpected, as individuals who have severe cognitive disabilities (eg, severe TBI, intellectual disability, and mild dementia) pass PVTs in >90% of cases (Heilbronner et al, 2009; Williamson et al, 2012). In prior studies of individuals with mFND, PVT failure rates varied, ranging from 5% to 50% (Cragar et al, 2006; Dodrill, 2008; Drane et al, 2006; Hill et al, 2003; van Beilen et al, 2009; Williamson et al, 2012), although most reports showed that only a minority of individuals with mFND failed PVTs (Kemp et al, 2008).

For individuals with mFND, associations have been found between PVT failure and both adverse life event burden and other psychological factors. Williamson et al (2012) found that failure on the Word Memory Test was associated with a history of psychological abuse and not financial incentives. These authors also found that reports of psychological abuse in individuals with PNES more than doubled their likelihood of Word Memory Test failure compared to individuals with PNES who did not report similar adverse life events (Williamson et al, 2012). This finding suggests that adverse life events, which are known to be a predisposing vulnerability for the development of mFND (Ludwig et al, 2018), may be relevant when considering potential reasons for PVT failure in individuals with mFND. In support of associations between psychopathology and PVT results, PVT failure has correlated with psychological distress in both mFND and neurologic populations (van Beilen et al, 2009).

In addition to PVTs, self-report measures of highly atypical symptom complaints, termed symptom validity tests (SVTs), are also commonly included in neuropsychological evaluations. These tests include the Structured Inventory of Malingered Symptomatology (Widows and Smith, 2005) and embedded tests within the Personality Assessment Inventory (PAI) (Morey, 2007) and the Minnesota Multiphasic Personality Inventory—2—Restructured Form (MMPI–2–RF; Ben-Porath and Tellegen, 2008; Butcher, 2001; Dahlstrom and Welsh, 1960). Individuals with mFND often experience atypical symptoms; therefore, SVTs can capture these findings (Benge et al, 2012; Peck et al, 2013).

Cognitive Performance

Several studies of individuals with mFND have found minimal, if any, neurocognitive impairment compared to healthy controls (HCs) (Drane et al, 2006; Heintz et al, 2013; Strutt et al, 2011; Turner et al, 2011; Voon et al, 2013). Although much of this literature focused on individuals with PNES, two studies examining cognitive performance in individuals with functional movement disorders did not observe any differences in performance compared to HCs (Heintz et al, 2013; Voon et al, 2013). Heintz and colleagues (2013) found that a cohort of individuals with functional jerky movements reported more cognitive complaints than HCs; however, no group-level differences for cognitive performance were found on the neuropsychological tests (Heintz et al, 2013). Similarly, individuals with PNES overestimated word-finding difficulties by self-report yet performed better on the Boston Naming Test (Kaplan et al, 1983) compared to individuals with epileptic seizures (Prigatano and Kirlin, 2009).

Discrepancies between cognitive complaints and objective neuropsychological test performance highlight the presence of cognitive-perceptual incongruity in some individuals with mFND. Fargo et al (2004) found that individuals with PNES accurately rated their attentional abilities but underestimated their memory functioning (as evaluated by the Quality of Life in Epilepsy Inventory–89 [Vickrey et al, 1993]) and overestimated their language skills. These authors also observed that negative mood correlated with a greater tendency to underestimate cognitive functioning (Fargo et al, 2004).

In addition to these studies reporting generally normal cognitive performance in several mFND cohorts, other studies (summarized in the following pages) have identified specific domains of cognitive impairment in individuals with mFND.

Attention

Several studies have identified attentional deficits in individuals with mFND (Bendefeldt et al, 1976; O’Brien et al, 2015; Özer Çelik et al, 2015). After excluding those individuals who failed validity testing, one study found impaired attention in individuals with PNES compared to HCs (O’Brien et al, 2015). While frank attentional deficiencies (defined by <2nd percentile) were not found, attentional performance in women with PNES fell in the below average range (9th–24th percentile) compared to normative data (Strutt et al, 2011). Individuals with PNES also exhibited lower attentional performance compared to individuals with epilepsy (Özer Çelik et al, 2015; Strutt et al, 2011).

Memory

Several studies found memory deficits in individuals with mFND, including lower scores on tests of verbal memory (Brown et al, 2014; Özer Çelik et al, 2015), working memory (Heintz et al, 2013; Strutt et al, 2011), and spatial working memory (O’Brien et al, 2015). Compared to a psychiatric control group, individuals with mixed mFND exhibited deficits in memory retrieval (Bendefeldt et al, 1976).

Language

A few studies observed mild language-based deficits in individuals with PNES. In one study, individuals with PNES scored lower on tests of verbal categorical fluency than HCs (Özer Çelik et al, 2015). Although the PNES sample in the study by Strutt et al (2011) did not exhibit definitive language deficiencies compared to normative data, the PNES sample did score within the below average range (9th–24th percentiles) on two-thirds of the included language measures.

Visuospatial

One study identified impaired spatial memory in individuals with PNES compared to normative data (Kalogjera-Sackellares and Sackellares, 1999). Another study showed that visuospatial deficits correlated with the magnitude of reported psychopathology in individuals with PNES (Locke et al, 2006).

Executive Functioning

Several studies found executive functioning deficits in individuals with mFND (Black et al, 2010; Brown et al, 2014; Özer Çelik et al, 2015; Kalogjera-Sackellares and Sackellares, 1999; O’Brien et al, 2015; Strutt et al, 2011). One study identified impaired planning, task-switching, cognitive flexibility, and processing speed in individuals with functional limb weakness compared to HCs; however, between-group differences in IQ, anxiety, and mood primarily explained these findings (Brown et al, 2014). Other studies, of individuals with PNES, found impaired planning and organization (O’Brien et al, 2015), deficits in mental flexibility and problem-solving (Kalogjera-Sackellares and Sackellares, 1999), slow response inhibition (Özer Çelik et al, 2015), and below average information processing speed (Strutt et al, 2011) compared to HCs. In another study, lifetime seizure burden negatively correlated with executive function performance in a PNES cohort (Black et al, 2010). Additionally, when compared to individuals with epilepsy, individuals with PNES exhibited lower executive functioning (ie, worse Stroop Test interference times) (Özer Çelik et al, 2015), set shifting, and mental flexibility abilities (Strutt et al, 2011).

Motor Performance

A few neuropsychological studies obtained motor performance data from individuals with mFND. Of these, one study found impaired motor speed and coordination in individuals with PNES compared to HCs (Sackellares and Sackellares, 2001). Another study used a Go/No-go task to probe motor control and observed that individuals with functional movement disorders showed increased commission errors compared to HCs; this motor disinhibition occurred in the context of otherwise intact multidomain cognitive performance (Voon et al, 2013). In yet another study, individuals with PNES performed similarly to those with epilepsy on measures of perceptual motor functioning (Binder et al, 1998).

Personality

Personality and psychopathology profiles are commonly assessed using different versions of the MMPI and the PAI. Several studies compared the personality profiles of individuals with PNES to HC and epileptic seizure populations (Binder et al, 1998; Fargo et al, 2004; O’Brien et al, 2015). One study found that compared to HCs, individuals with PNES reported significantly greater health concerns and somatic symptoms of depression on the PAI (O’Brien et al, 2015). Another study found that, although their epilepsy and PNES groups performed similarly on neurocognitive measures, the two groups could be distinguished based on their MMPI/MMPI–2 profiles (Binder et al, 1998).

A few studies examined the relationship between personality profiles and cognition in individuals with mFND. One study identified three clusters of personality traits within individuals with PNES: (a) very high neuroticism, low extraversion, low openness, high agreeableness, and low conscientiousness; (b) average across domains; and (c) very high neuroticism, average extraversion, low openness, low agreeableness, and average conscientiousness (Cragar et al, 2005). Notably, in comparison to cluster 2, clusters 1 and 3 were associated with more severe psychopathology (as measured by the MMPI–2) as well as impaired neurocognitive performance, including lower scores on tests of intellectual functioning. Cluster 1 was also associated with poorer memory, language, and visual spatial functioning than clusters 2 and 3 (Cragar et al, 2005).

Several groups suggested that the PAI and MMPI–2 may be useful adjunctive tools for distinguishing between PNES and epileptic seizures (Gale and Hill, 2012; Hill and Gale, 2011; Locke et al, 2006; Wagner et al, 2005). On the PAI, individuals with PNES reported more somatic concerns and more symptoms of both anxiety and depression than HCs, as well as more somatic symptoms of anxiety and depression than individuals with epileptic seizures (Testa et al, 2011). On the MMPI/MMPI–2, individuals with PNES often exhibited abnormal scores on the following subscales: Hysteria (Bodde et al, 2011; Kalogjera-Sackellares and Sackellares, 1997; Testa et al, 2007), Hypochondriasis (Testa et al, 2007), Schizophrenia (Bodde et al, 2011; Kalogjera-Sackellares and Sackellares, 1997), and Depression (Cragar et al, 2005; Kalogjera-Sackellares and Sackellares, 1997). These personality profiles tend to yield a “Conversion V” pattern (ie, elevations in the Hysteria and Hypochondriasis subscales relative to the Depression subscale) (Bodde et al, 2011; Cragar et al, 2005; Drake et al, 1992). Compared to individuals with epilepsy, those with PNES exhibited higher scores on the Hysteria and Hypochondriasis subscales (Testa et al, 2007). Examinations of contributors to MMPI–2 profiles found that, in individuals with PNES, scores were not explained by medical comorbidities (Russell et al, 2009) but did correlate with an adverse life event burden (Myers et al, 2013).

Emotion Processing and Other Psychiatric Considerations

In individuals with PNES, mood symptoms were identified as stronger predictors of subjective cognitive ratings than objective neuropsychological test performances (Fargo et al, 2004). Additionally, Özer Çelik et al (2015) found that mood negatively impacted cognition in individuals with PNES. For example, verbal memory performance and response inhibition were both negatively correlated with depression severity in individuals with PNES but not in those with epilepsy (Özer Çelik et al, 2015). Psychopathology (as measured by the MMPI–2) has been linked to lower scores on tests of intelligence, memory, visuospatial skills, and motor functioning in individuals with PNES (Locke et al, 2006). When examining working memory performance in individuals with PNES, one study found that working memory improved after stress induction in HCs but not in individuals with PNES (Bakvis et al, 2010). Higher cortisol responses were also found to correlate with impaired working memory after stress induction in individuals with PNES (Bakvis et al, 2010).

Psychiatric comorbidities in individuals with mFND, such as anxiety and depression, are themselves associated with cognitive dysfunction (Castaneda et al, 2008; Mantella et al, 2007). Other factors, such as childhood maltreatment and posttraumatic stress disorder (PTSD), also tend to correlate with neurocognitive deficits, including intellectual, verbal, visuospatial, information processing, learning and memory, and executive function impairments (Malarbi et al, 2017). In addition to psychiatric and psychosocial factors, anti-epileptic drugs and psychotropic medications can negatively impact cognitive and motor functioning (Locke et al, 2006).

In summary, although the neuropsychologic literature regarding individuals with mFND identifies considerable heterogeneity among study findings (eg, some reports of normal neuropsychological test performances and other reports of specific cognitive impairments), it appears that only a subset of individuals with mFND reporting cognitive difficulties demonstrate evidence of cognitive impairment on neuropsychological tests. (A table of the studies reviewed is provided as Supplemental Digital Content, http://links.lww.com/CBN/A76.)

The next section presents three cases from the Massachusetts General Hospital outpatient FND clinical program that highlight the role of neuropsychological testing in identifying relative mismatches between subjective cognitive complaints and objective cognitive performance. For this retrospective chart review case report, institutional review board approval was obtained from the Partners Human Research Committee; individual informed consent was not required. All three patients passed the PVTs and the embedded symptom validity measures within the PAI (Figures 1 and 2); however, not surprisingly, on the Structured Inventory of Malingered Symptomatology, all three patients failed the Neurological Impairment subscale, and two failed the Amnestic Disorders subscale, indicating a high degree of atypical neurologic and memory symptoms.

FIGURE 1
FIGURE 1:
Performance validity testing results of three individuals with a motor functional neurological disorder and cognitive complaints. All three individuals passed the performance validity tests. The measures included in the test were the Forced-Choice subtest as an embedded validity measure within the California Verbal Learning Test—II (CVLT–II), the Test of Memory Malingering, and the Reliable Digit Span subtest as an embedded validity measure within the Wechsler Adult Intelligence Scale—IV (WAIS–IV).
FIGURE 2
FIGURE 2:
Symptom validity testing results of three individuals with a motor functional neurological disorder and cognitive complaints. All three individuals passed embedded symptom validity measures within the Personality Assessment Inventory. Not surprisingly, on the Structured Inventory of Malingered Symptomatology, all three individuals failed the Neurological Impairment subscale, and two of the individuals also failed the Amnestic Disorders subscale. These findings indicate a high endorsement of atypical neurologic and memory symptoms.

CASE REPORTS

Case 1, Complaint: “Clouded Thinking”

A 31-year-old, right-handed, married, college-educated woman on leave from graduate school, with a medical history notable for chronic fatigue syndrome and anxiety, presented to the neurology clinic for evaluation of cognitive difficulties, paroxysmal jerking limb movements, gait abnormalities, and fatigue. The individual’s symptoms began after she traveled abroad and subsequently developed gastrointestinal upset, fatigue, and joint pain. Despite negative infectious, autoimmune, and gastrointestinal evaluations, her symptoms progressed, and she developed intermittent, bilateral hand and foot numbness.

Two years later, the patient experienced abrupt-onset paroxysmal full body jerking movements accompanied by cognitive clouding. Between symptomatic episodes, she continued to experience clouded thinking. She was prescribed low-dose lorazepam as needed. She had a personal history of childhood maltreatment and a family history of anxiety and depression. She had no personal history of alcohol and/or substance misuse. Neurologic examination showed bilateral shoulder twitching induced when the tuning fork was applied to her upper face, and collapsing/give-way weakness on left hip extension testing. Her brain MRI was normal, and an ambulatory EEG capturing a full body convulsion with clouded thinking was negative for epileptiform activity. Regarding cognition, her mental status testing was notable for preserved orientation, attention, 3/3-word recall after 5 minutes, and clock drawing, although her overall processing speed was slow. Subsequent neuropsychological testing demonstrated that the individual had superior intellectual ability with subtle relative weaknesses on tasks that required simple attention and response speed (ie, low average Forward Digit Span and modestly slow response times on a visual continuous performance test). Her PAI showed an elevation in the Somatization subscale. The patient exhibited minimal anxiety (Beck Anxiety Inventory [Beck et al, 1988]=3 of 63) and minimal depression (Beck Depression Inventory—II [Beck et al, 1996]=5 of 63).

mFND, Other Functional Somatic Symptoms and Cognition

This case illustrates the intersection of mFND with mixed symptoms, a functional somatic disorder, and cognitive complaints. Notably, this individual was also diagnosed with chronic fatigue syndrome, which, along with other functional somatic disorders (eg, fibromyalgia, irritable bowel syndrome), can be comorbid with FND (Benbadis, 2005; Dixit et al, 2013). Individuals with fibromyalgia and chronic fatigue syndrome commonly report concentration, memory, language, and/or word-finding difficulties (Teodoro et al, 2018). Studies have shown that individuals with functional somatic disorders may disproportionately experience subjective memory and word-finding symptoms in relation to objective neuropsychological performance (Cope et al, 1995; Grace et al, 1999; Kane et al, 1997; Suhr, 2003). Notably, most studies examining cognition in patients with fibromyalgia and chronic fatigue syndrome did not include PVTs. Those studies that did include PVTs found that most of the individuals performed within normal limits (Busichio et al, 2004; Constant et al, 2011; Gervais et al, 2001; Iverson et al, 2007; Suhr, 2003).

Similar maladaptive cognitive processes have been described across mFND and functional somatic disorders (Pick et al, 2018, 2019; Teodoro et al, 2018). For example, a recent review of cognition in individuals with irritable bowel syndrome found that these individuals displayed an attentional bias toward words associated with gastrointestinal sensation as well as emotionally negative words (Lam et al, 2019). Another study found that on a face categorization task, individuals with PNES had difficulty switching from an emotional (happy vs angry) to a nonemotional face processing task (Gul and Ahmad, 2014). The attentional bias of the PNES group was interpreted to suggest that emotional categorization consumed more cognitive resources in individuals with PNES relative to HCs. Individuals with functional tremor also overestimated the frequency of their abnormal movements compared to actigraphy data (Pareés et al, 2012). Teodoro et al (2018) speculated that negative attentional biases may be a shared trait of individuals with mFND and functional somatic disorders with cognitive complaints.

Case 2, Complaint: “Memory Trouble”

A 47-year-old, right-handed, divorced man on short-term disability with a medical history of several concussions (including a motor vehicle accident with brief loss of consciousness), migraines, and well-controlled epileptic seizures presented for a treatment evaluation regarding video-EEG-documented psychogenic nonepileptic seizures and memory trouble. The individual reported new-onset seizures described as preserved wakefulness, jerking limb movements, and rapid breathing. He exhibited agoraphobia, avoiding public spaces for fear of having recurrent seizures, as well as complaints of forgetfulness for recently experienced events. The individual was on lamotrigine daily and lorazepam as needed. He denied other psychiatric symptoms and described a family history of epilepsy, suicide, and alcoholism. He had completed 2 years of college, had a remote history of alcohol misuse, and denied childhood maltreatment. His elemental neurologic examination was nonfocal, and clinic-based cognitive testing showed intact basic orientation, naming months of the year backwards, 4-word recall in 5 minutes, object naming, and clock drawing. His brain MRI was unremarkable.

Neuropsychological testing revealed average intellectual ability and generally intact functioning across most cognitive domains. Strengths included a superior general knowledge base; superior phonemic fluency; and high average color naming, psychomotor speed, set-shifting, visuospatial, and visual working memory abilities. He evidenced mild relative weaknesses on the initial encoding of noncontextual verbal information and source memory (characterized by many semantic intrusions). Mildly atypical inhibitory cognitive control (commission) errors, low average performance on working memory arithmetic, and impaired performance on grooved pegboard motor testing were also noted. His PAI showed elevated somatization scores, and his Beck Depression Inventory—II score was 9 of 63, indicating minimal depression.

PNES, Head Trauma, and Cognition

This case illustrates the intersection of PNES, mild TBI, and cognitive complaints. Although TBI (particularly moderate and severe forms) is a risk factor for epileptic seizures (Wilson et al, 2017), individuals with PNES commonly have a history of mild TBI (LaFrance et al, 2013; Popkirov et al, 2018; Salinsky et al, 2015). Individuals with mild TBI often display processing speed deficits on neuropsychological testing (Frencham et al, 2005)—a finding that is also present in some individuals with mFND (Kalogjera-Sackellares and Sackellares, 1999; Strutt et al, 2011). Commonly observed deficits immediately following a mild TBI include verbal and visual memory impairments that generally resolve by 3 months post-injury (Rohling et al, 2011).

Although mild TBI symptoms tend to be transient, a history of minor head trauma and other physical injuries are predisposing vulnerabilities for the development of mFND (Pareés et al, 2014; Stone et al, 2009). Of clinical relevance, in a study by LaFrance et al (2013), individuals with PNES and head trauma exhibited a worse prognosis than individuals with PNES and no head trauma. In a recent review examining the link between head injury and PNES, Popkirov and colleagues (2018) considered several possible etiological factors: patient recall bias and etiological misattribution, the emotional consequences of suffering a head injury, maladaptive emotional learning after acute postconcussive symptoms, and axonal injury and network connectivity alterations related to the brain injury.

Case 3, Complaint: “I Can’t Concentrate”

A 45-year-old, right-handed, single, college-educated woman on disability, with a medical history notable for whiplash 10 years ago following a motor vehicle accident, presented to the clinic with gait trouble, somatic complaints, and health anxiety. The individual reported dizziness, intermittent arm stiffness, episodes of burning sensations in her limbs, concentration difficulties, and a sense that at times her legs buckled. Some of her symptoms worsened with stress or anxiety. The individual reported worrying about her health and family members as well as feeling “overwhelmed.” She exhibited past panic attacks, PTSD symptoms related to childhood maltreatment, and a remote history of alcohol misuse. She did not have a current mental health provider. Her medical history was notable for migraines, and she was on nortriptyline and topiramate daily, as well as sumatriptan on an as-needed basis. She had a family history of Alzheimer disease and substance abuse.

Neurologic examination showed noneconomical compensatory movements on tandem gait (astasia-abasia) but was otherwise unremarkable. Her brain MRI was notable only for an incidental finding of a developmental venous malformation. On neuropsychological testing, she had average intelligence with modest weaknesses in sustained attention, registration of new information, and working memory. Her PAI profile showed elevated somatization scores, and she reported moderate anxiety (Beck Anxiety Inventory=20 of 63) and minimal depression (Beck Depression Inventory—II=9 of 63).

Health Anxiety and mFND

Health anxiety and somatic hypervigilance can perpetuate functional neurologic symptoms, with one study showing that one quarter of individuals with mixed FND experienced distressing health worries (Reuber et al, 2007). Therefore, it is important to understand the relationship between health anxiety and cognitive concerns. Studies have reported cognitive biases in individuals with health anxiety, including a memory bias for health-related words (Ferguson et al, 2007; Pauli and Alpers, 2002). In these two studies, the memory bias was mediated by the emotional valence of the health-related words, and it was stronger in individuals with high health anxiety (Ferguson et al, 2007). Another study found that individuals with health anxiety displayed a stronger attentional bias toward health-threat-related words compared to individuals with a DSM–IV (American Psychiatric Association, 1994) somatic symptom disorder or panic disorder (Gropalis et al, 2013). Notably, the individuals with health anxiety also demonstrated an attentional bias toward panic-related words, suggesting a more generalized negative attentional bias.

Interestingly, cognitive behavioral therapy can therapeutically modulate attentional biases in individuals with health anxiety (Gropalis et al, 2013). One study examined the relationship between health anxiety, fear of having dementia, and subjective and objective cognitive difficulties (Kinzer and Suhr, 2016). For individuals who had objective cognitive impairment, dementia worry did not relate to their subjective memory concerns. However, for individuals without objective cognitive impairment, greater dementia worry correlated with greater subjective memory concerns. Individuals with higher dementia worry with or without objective cognitive impairments were found to have the same levels of subjective cognitive complaints (Kinzer and Suhr, 2016).

Although somewhat less related to the third case example, the intersection of negative mood, anxiety, and cognition is also generally relevant in this patient population. The neuropsychological testing literature regarding individuals with major depression consistently shows impaired executive and psychomotor function (Porter et al, 2007). Moreover, neurocognitive deficits in verbal learning, information processing speed, attention, working memory, and verbal memory have been described in individuals with PTSD (Scott et al, 2015), which is another common disorder in mFND (Bowman and Markand, 1996; Roelofs et al, 2002). Individuals with PNES and comorbid PTSD exhibit lower episodic verbal memory performance as compared to individuals with PNES without PTSD (Myers et al, 2014). This finding is supported by evidence of greater cognitive impairment in individuals with PTSD compared to individuals with trauma exposure without PTSD (Qureshi et al, 2011). Overall, the literature detailed here underscores the need to consider the intersection of psychiatric comorbidities (categorically and dimensionally) when contextualizing cognitive difficulties in individuals with mFND.

Figures 3 and 4 display the neuropsychological testing results for the individuals in the three cases.

FIGURE 3
FIGURE 3:
Neuropsychological testing results of three individuals with a motor functional neurological disorder and cognitive complaints. Note, apart from an abnormality in motor performance observed for Case 3, all of the individuals performed generally in the normal range across the cognitive domains tested. The following measures were averaged for the z-score of each cognitive domain: Lower level executive function (EF) measures included the Coding and Digit Span Forward subtests of the Wechsler Adult Intelligence Scale—IV (WAIS–IV), and Trails A or Delis-Kaplan Executive Frontal System (D–KEFS) Trail Making Test Condition 1; higher level EF measures included WAIS–IV Digit Span Backwards, Trails B or D–KEFS Trail Making Test Condition 4, D–KEFS Verbal Fluency Total Letter, and WAIS–IV Similarities; language measures included D–KEFS Verbal Fluency Total Category and Boston Naming Test; memory encoding measures included California Verbal Learning Test—II (CVLT–II) Trials 1 to 5 Total, Semantic Clustering, and Learning Slope Trials 1 to 5; memory retrieval measures included CVLT–II Long Delay Free Recall—Short Delay Free Recall; and motor measures included a grooved pegboard (dominant and nondominant hands).
FIGURE 4
FIGURE 4:
Personality Assessment Inventory results of three individuals with a motor functional neurological disorder and cognitive complaints. Note that all three individuals exhibited an elevated score on the Somatic Concerns (SOM) subscale. The subscales included in the Personality Assessment Inventory (and listed on the x-axis) are the following: Infrequency (INF), Negative Impression (NIM), Positive Impression (PIM), Somatic Concerns (SOM), Anxiety (ANX), Anxiety Related Disorder (ARD), Depression (DEP), Mania (MAN), Paranoia (PAR), Schizophrenia (SCZ), Borderline Features (BOR), Antisocial Features (ANT), Alcohol Problems (ALC), Drug Problems (DRG), Aggression (AGG), Suicidal Ideation (SUI), Stress (STR), Nonsupport (NON), Treatment Rejection (RXR), Dominance (DOM), and Warmth (WRM).

DISCUSSION AND FUTURE DIRECTIONS

Table 1 details the neuropsychological testing battery that we have started using in some patients with (or suspected of having) mFND, who also report prominent cognitive complaints. Lessons learned regarding the potential utility of neuropsychological testing as part of the adjunctive assessment of individuals with mFND reporting prominent cognitive complaints are summarized in the paragraphs that follow.

  • The neuropsychological literature suggests that cognitive complaints in individuals with mFND are common, with only a subset of individuals exhibiting objective deficits on neuropsychological testing. Reasons for objective deficits in cognitive performance are multifactorial and include negative impact of psychiatric and medical comorbidities, medication side effects, and intrinsic mFND mechanisms, among others. From a neurobiologic perspective, prefrontal brain areas have been implicated in convergent affective, cognitive, nociceptive, and viscerosomatic information processing (eg, dorsal anterior cingulate cortex, anterior insula) and reveal functional and structural alterations in mFND and related conditions (Bègue et al, 2019; Perez et al, 2015; Voon et al, 2016). These findings provide a neural substrate for the “hijacking” of cognitive abilities by anxious cognitions and negative rumination.
  • Current neuropsychological practice guidelines recommend that PVTs be administered throughout the evaluation process to ensure consistent effort and engagement (Boone, 2009; Heilbronner et al, 2009). Notably, while failing PVTs should give pause to the interpretation of neuropsychological testing results as they may not accurately reflect the individual’s maximal abilities, it does not imply that the individual should necessarily be suspected of malingering (Heilbronner et al, 2009). Instead, PVT failure denotes inconsistent cognitive responses (akin to motor inconsistency on the physical examination) and may be linked to psychological phenomenon and predisposing vulnerabilities in mFND populations (Willment et al, 2015). If individuals fail PVTs, the neuropsychologist should shorten the assessment battery and focus on identifying intact (preserved) cognitive abilities, given that low scores on cognitive tests will be difficult to interpret (Boone, 2009). Similarly, SVTs index elevated rates of highly atypical complaints. Of note, the term “validity” is suboptimal in the context of mFND populations because the intrinsic validity of their symptoms is not in question; rather, the concern is how best to interpret their neuropsychological test results. A related point is that direct patient observation can also provide important information regarding effort and affective states that can be used as additional data points. The inclusion of personality and psychopathology measures aids the differential diagnosis of, and screening for, psychiatric comorbidities that may themselves be associated with cognitive deficits.
  • For individuals reporting significant cognitive concerns without marked cognitive impairment on formal neuropsychological testing, this mismatch may partly reflect a negative attentional bias that has been previously described in individuals with mFND (Pareés et al, 2012; Pick et al, 2018).
  • Although more work is needed to quantify clinically meaningful discrepancies between subjective and objective cognitive performance in individuals with mFND, this is a potentially promising research pursuit that may help calculate a neuropsychological “rule-in” sign for functional cognitive complaints.
  • The relationship between predisposing vulnerabilities for the development of mFND and cognitive complaints requires further inquiry (McKee et al, 2018). In addition, the relationship between psychological dissociation (eg, depersonalization, dissociative amnesia) and functional cognitive symptoms warrants more research. Research is also needed to understand the similarities and differences between cognitive profiles in individuals with mFND and those with isolated functional cognitive symptoms without mFND symptoms (McWhirter et al, 2019b).
  • Our experience is that some patients with mFND report that their cognitive symptoms impede their ability to engage in evidence-based treatments, such as cognitive behavioral therapy (LaFrance et al, 2014; Sharpe et al, 2011). We have also observed that several patients have found it helpful to learn of their largely intact neurocognitive test results while concurrently having their cognitive concerns validated. This is analogous to sharing with patients their functional motor signs on examination as a way of increasing diagnostic buy-in (Stone and Edwards, 2012). In addition, akin to models of motor retraining for functional motor symptoms, cognitive retraining through speech and language or occupational therapy also warrants more research in mFND populations with cognitive complaints (Gardiner et al, 2018; Ranford et al, 2018).
  • In our center, adjunctive neuropsychological testing has been valuable in both the diagnostic assessment and treatment planning phases of care for individuals with FND, including the identification of cognitive concerns that may warrant rehabilitation. However, we recognize that the availability of neuropsychological testing can be limited in some settings due to limited availability of providers and long wait times for scheduling. The cases described here help provide a starting point for research questions that will identify (a) the subset of mFND individuals for whom neuropsychological testing adds the most clinical value and (b) a targeted set of cognitive measures (incorporating PVTs) that can be administered quickly and routinely for the assessment of possible functional cognitive symptoms. The latter effort would aid the development of an instrument similar to specialized cognitive and emotional screening measures (“bedside tests”) that have been identified for other neuropsychiatric populations (eg, Montreal Cognitive Assessment [Nasreddine et al, 2005] for dementia and a recently developed screening tool for the cognitive-affective-cerebellar syndrome [Hoche et al, 2018]).

TABLE 1
TABLE 1:
Preliminary Suggestions for a Neuropsychological Test Battery for Patients With Motor Functional Neurological Disorders and Prominent Cognitive Symptoms

CONCLUSION

Cognitive complaints are common in individuals with mFND, and the behavioral neurology-neuropsychiatry perspective is primed to evaluate these concerns from a multiplicity of different perspectives. Adjunct neuropsychological testing can be useful in the assessment of individuals with mFND and prominent cognitive complaints. For mFND individuals with cognitive concerns, with or without objective cognitive deficits, future research should investigate the utility of cognitive retraining as a treatment option for this population.

REFERENCES

American Psychiatric Association. 1994. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. Washington, DC: American Psychiatric Association.
American Psychiatric Association. 2013. Diagnostic and Statistical Manual of Mental Disorders (DSM5), 5th ed. Washington, DC: American Psychiatric Association.
Bakvis P, Spinhoven P, Putman P, et al. 2010. The effect of stress induction on working memory in patients with psychogenic nonepileptic seizures. Epilepsy Behav. 19:448–454.
Barsky AJ, Orav EJ, Bates DW. 2005. Somatization increases medical utilization and costs independent of psychiatric and medical comorbidity. Arch Gen Psychiatry. 62:903–910.
Beck AT, Epstein N, Brown G, et al. 1988. An inventory for measuring clinical anxiety: psychometric properties. J Consult Clin Psychol. 56:893–897.
Beck AT, Steer RA, Brown GK. 1996. Manual for the Beck Depression Inventory—II. San Antonio, Texas: The Psychological Corporation.
Beery KE, Buktenica NA, Beery NA. 2004. The Beery-Buktenica Developmental Test of Visual-motor Integration: Administration, Scoring and Teaching Manual. Minneapolis, Minnesota: Pearson.
Bègue I, Adams C, Stone J, et al. 2019. Structural alterations in functional neurological disorder and related conditions: a software and hardware problem? Neuroimage Clin. 22:101798. doi:10.1016/j.nicl.2019.101798
Ben-Porath YS, Tellegen A. 2008. Minnesota Multiphasic Personality Inventory—2—Restructured Form. Minneapolis, Minnesota: University of Minnesota Press.
Benbadis SR. 2005. A spell in the epilepsy clinic and a history of “chronic pain” or “fibromyalgia” independently predict a diagnosis of psychogenic seizures. Epilepsy Behav. 6:264–265.
Bendefeldt F, Miller LL, Ludwig AM. 1976. Cognitive performance in conversion hysteria. Arch Gen Psychiatry. 33:1250–1254.
Benedict RHB. 1997. Brief Visuospatial Memory Test—Revised. Odessa, Florida: Psychological Assessment Resources.
Benge JF, Wisdom NM, Collins RL, et al. 2012. Diagnostic utility of the Structured Inventory of Malingered Symptomatology for identifying psychogenic non-epileptic events. Epilepsy Behav. 24:439–444.
Benton AL, de Hamsher KS, Rey G, et al. 1994. Multilingual Aphasia Examination, 3rd ed. Iowa City, Iowa: AJA Associates.
    Binder LM, Kindermann SS, Heaton RK, et al. 1998. Neuropsychologic impairment in patients with nonepileptic seizures. Arch Clin Neuropsychol. 13:513–522.
    Black LC, Schefft BK, Howe SR, et al. 2010. The effect of seizures on working memory and executive functioning performance. Epilepsy Behav. 17:412–419.
    Bodde NM, Bartelet DC, Ploegmakers M, et al. 2011. MMPI–II personality profiles of patients with psychogenic nonepileptic seizures. Epilepsy Behav. 20:674–680.
    Boone KB. 2009. The need for continuous and comprehensive sampling of effort/response bias during neuropsychological examinations. Clin Neuropsychol. 23:729–741.
    Bowman ES, Markand ON. 1996. Psychodynamics and psychiatric diagnoses of pseudoseizure subjects. Am J Psychiatry. 153:57–63.
    Brown LB, Nicholson TR, Aybek S, et al. 2014. Neuropsychological function and memory suppression in conversion disorder. J Neuropsychol. 8:171–185.
    Busichio K, Tiersky LA, Deluca J, et al. 2004. Neuropsychological deficits in patients with chronic fatigue syndrome. J Int Neuropsychol Soc. 10:278–285.
    Butcher JN. 2001. Minnesota Multiphasic Personality Inventory—2: Manual for Administration, Scoring, and Interpretation. Minneapolis, Minnesota: University of Minnesota Press.
    Castaneda AE, Tuulio-Henriksson A, Marttunen M, et al. 2008. A review on cognitive impairments in depressive and anxiety disorders with a focus on young adults. J Affect Disord. 106:1–27.
    Chung DS, Wettroth C, Hallett M, et al. 2018. Functional speech and voice disorders: case series and literature review. Mov Disord Clin Pract. 5:312–316.
    Conners CK, MHS Staff. 2014. Conners’ Continuous Performance Test 3rd Edition (Conners CPT 3): Computer Program for Windows Technical Guide and Software Manual. North Tonawanda, New York: Multi-Health Systems.
      Constant EL, Adam S, Gillain B, et al. 2011. Cognitive deficits in patients with chronic fatigue syndrome compared to those with major depressive disorder and healthy controls. Clin Neurol Neurosurg. 113:295–302.
      Cope H, Pernet A, Kendall B, et al. 1995. Cognitive functioning and magnetic resonance imaging in chronic fatigue. Br J Psychiatry. 167:86–94.
      Cragar DE, Berry DT, Fakhoury TA, et al. 2006. Performance of patients with epilepsy or psychogenic non-epileptic seizures on four measures of effort. Clin Neuropsychol. 20:552–566.
      Cragar DE, Berry DT, Schmitt FA, et al. 2005. Cluster analysis of normal personality traits in patients with psychogenic nonepileptic seizures. Epilepsy Behav. 6:593–600.
      Dahlstrom WG, Welsh GS. 1960. An MMPI Handbook: A Guide to Use in Clinical Practice and Research. Minneapolis, Minnesota: University of Minnesota Press.
      Daum C, Hubschmid M, Aybek S. 2014. The value of ‘positive’ clinical signs for weakness, sensory and gait disorders in conversion disorder: a systematic and narrative review. J Neurol Neurosurg Psychiatry. 85:180–190.
      Delis DC, Kaplan E, Kramer JH. 2001. Delis–Kaplan Executive Function System (D-KEFS) Examiner’s Manual. San Antonio, Texas: The Psychological Corporation.
        Delis DC, Kramer JH, Kaplan E, et al. 2017. California Verbal Learning Test, Third Edition (CVLT–3). Minneapolis, Minnesota: Pearson.
          Dixit R, Popescu A, Bagić A, et al. 2013. Medical comorbidities in patients with psychogenic nonepileptic spells (PNES) referred for video-EEG monitoring. Epilepsy Behav. 28:137–140.
          Dodrill CB. 2008. Do patients with psychogenic nonepileptic seizures produce trustworthy findings on neuropsychological tests? Epilepsia. 49:691–695.
          Drake ME Jr, Pakalnis A, Phillips BB. 1992. Neuropsychological and psychiatric correlates of intractable pseudoseizures. Seizure. 1:11–13.
          Drane DL, Williamson DJ, Stroup ES, et al. 2006. Cognitive impairment is not equal in patients with epileptic and psychogenic nonepileptic seizures. Epilepsia. 47:1879–1886.
          Espay AJ, Aybek S, Carson A, et al. 2018. Current concepts in diagnosis and treatment of functional neurological disorders. JAMA Neurol. 75:1132–1141.
          Fargo JD, Schefft BK, Szaflarski JP, et al. 2004. Accuracy of self-reported neuropsychological functioning in individuals with epileptic or psychogenic nonepileptic seizures. Epilepsy Behav. 5:143–150.
          Ferguson E, Moghaddam NG, Bibby PA. 2007. Memory bias in health anxiety is related to the emotional valence of health-related words. J Psychosom Res. 62:263–274.
          Frencham KA, Fox AM, Maybery MT. 2005. Neuropsychological studies of mild traumatic brain injury: a meta-analytic review of research since 1995. J Clin Exp Neuropsychol. 27:334–351.
          Gale SD, Hill SW. 2012. Concurrent administration of the MMPI–2 and PAI in a sample of patients with epileptic or non-epileptic seizures: implications for an inpatient epilepsy monitoring unit. Epilepsy Behav. 25:181–184.
          Gardiner P, MacGregor L, Carson A, et al. 2018. Occupational therapy for functional neurological disorders: a scoping review and agenda for research. CNS Spectr. 23:205–212.
          Gervais RO, Russell AS, Green P, et al. 2001. Effort testing in patients with fibromyalgia and disability incentives. J Rheumatol. 28:1892–1899.
          Golden CJ. 1978. Stroop Color and Word Test: A Manual for Clinical and Experimental Uses. Wood Dale, Illinois: Stoelting.
            Grace GM, Nielson WR, Hopkins M, et al. 1999. Concentration and memory deficits in patients with fibromyalgia syndrome. J Clin Exp Neuropsychol. 21:477–487.
            Green P. 2004. Medical Symptom Validity Test for Windows: User’s Manual and Program. Edmonton, Canada: Green’s.
              Green P, Allen LM, Astner K. 1996. The Word Memory Test: A User’s Guide to the Oral and Computer-administered Forms, US Version 11. Durham, North Carolina: Cognisyst.
              Gropalis M, Bleichhardt G, Hiller W, et al. 2013. Specificity and modifiability of cognitive biases in hypochondriasis. J Consult Clin Psychol. 81:558–565.
              Gul A, Ahmad H. 2014. Cognitive deficits and emotion regulation strategies in patients with psychogenic nonepileptic seizures: a task-switching study. Epilepsy Behav. 32:108–113.
              Heilbronner RL, Sweet JJ, Morgan JE, et al. 2009. American Academy of Clinical Neuropsychology Consensus Conference Statement on the neuropsychological assessment of effort, response bias, and malingering. Clin Neuropsychol. 23:1093–1129.
              Heintz CE, van Tricht MJ, van der Salm SM, et al. 2013. Neuropsychological profile of psychogenic jerky movement disorders: importance of evaluating non-credible cognitive performance and psychopathology. J Neurol Neurosurg Psychiatry. 84:862–867.
              Hill KS, Ryan LM, Kennedy CH, et al. 2003. The relationship between measures of declarative memory and the Test of Memory Malingering in patients with and without temporal lobe dysfunction. J Forensic Neuropsychol. 3:1–18.
              Hill SW, Gale SD. 2011. Predicting psychogenic nonepileptic seizures with the Personality Assessment Inventory and seizure variables. Epilepsy Behav. 22:505–510.
              Hoche F, Guell X, Vangel MG, et al. 2018. The cerebellar cognitive affective/Schmahmann syndrome scale. Brain. 141:248–270.
              Iverson GL, Le Page J, Koehler BE, et al. 2007. Test of Memory Malingering (TOMM) scores are not affected by chronic pain or depression in patients with fibromyalgia. Clin Neuropsychol. 21:532–546.
              Kalogjera-Sackellares D, Sackellares JC. 1997. Personality profiles of patients with pseudoseizures. Seizure. 6:1–7.
              Kalogjera-Sackellares D, Sackellares JC. 1999. Intellectual and neuropsychological features of patients with psychogenic pseudoseizures. Psychiatry Res. 86:73–84.
              Kane RL, Gantz NM, DiPino RK. 1997. Neuropsychological and psychological functioning in chronic fatigue syndrome. Neuropsychiatry Neuropsychol Behav Neurol. 10:25–31.
              Kaplan E, Goodglass H, Weintraub S. 1983. The Boston Naming Test. Philadelphia, Pennsylvania: Lea & Febiger.
              Kemp S, Coughlan AK, Rowbottom C, et al. 2008. The base rate of effort test failure in patients with medically unexplained symptoms. J Psychosom Res. 65:319–325.
              Kinzer A, Suhr JA. 2016. Dementia worry and its relationship to dementia exposure, psychological factors, and subjective memory concerns. Appl Neuropsychol Adult. 23:196–204.
              LaFrance WC Jr, Baird GL, Barry JJ, et al. 2014. Multicenter pilot treatment trial for psychogenic nonepileptic seizures: a randomized clinical trial. JAMA Psychiatry. 71:997–1005.
              LaFrance WC Jr, Deluca M, Machan JT, et al. 2013. Traumatic brain injury and psychogenic nonepileptic seizures yield worse outcomes. Epilepsia. 54:718–725.
              Lam NCY, Yeung HY, Li WK, et al. 2019. Cognitive impairment in irritable bowel syndrome (IBS): a systematic review. Brain Res. 1719:274–284.
              Lezak MD. 1995. Neuropsychological Assessment, 3rd ed. New York, New York: Oxford University Press.
                Locke DE, Berry DT, Fakhoury TA, et al. 2006. Relationship of indicators of neuropathology, psychopathology, and effort to neuropsychological results in patients with epilepsy or psychogenic non-epileptic seizures. J Clin Exp Neuropsychol. 28:325–340.
                Ludwig L, Pasman JA, Nicholson T, et al. 2018. Stressful life events and maltreatment in conversion (functional neurological) disorder: systematic review and meta-analysis of case-control studies. Lancet Psychiatry. 5:307–320.
                Malarbi S, Abu-Rayya HM, Muscara F, et al. 2017. Neuropsychological functioning of childhood trauma and post-traumatic stress disorder: a meta-analysis. Neurosci Biobehav Rev. 72:68–86.
                Mantella RC, Butters MA, Dew MA, et al. 2007. Cognitive impairment in late-life generalized anxiety disorder. Am J Geriatr Psychiatry. 15:673–679.
                Matin N, Young SS, Williams B, et al. 2017. Neuropsychiatric associations with gender, illness duration, work disability, and motor subtype in a US functional neurological disorders clinic population. J Neuropsychiatry Clin Neurosci. 29:375–382.
                McKee K, Glass S, Adams C, et al. 2018. The inpatient assessment and management of motor functional neurological disorders: an interdisciplinary perspective. Psychosomatics. 59:358–368.
                McKenzie PS, Oto M, Graham CD, et al. 2011. Do patients whose psychogenic non-epileptic seizures resolve, ‘replace’ them with other medically unexplained symptoms? Medically unexplained symptoms arising after a diagnosis of psychogenic non-epileptic seizures. J Neurol Neurosurg Psychiatry. 82:967–969.
                McWhirter L, Miller N, Campbell C, et al. 2019a. Understanding foreign accent syndrome. J Neurol Neurosurg Psychiatry. 90:1265–1269.
                McWhirter L, Ritchie C, Stone J, et al. 2019b. Functional cognitive disorders: a systematic review. Lancet Psychiatry. pii:S2215-0366. doi:10.1016/S2215-0366
                Mendez MF. 2018. Non-neurogenic language disorders: a preliminary classification. Psychosomatics. 59:28–35.
                Morey LC. 2007. Personality Assessment Inventory (PAI): Professional Manual. Lutz, Florida: Psychological Assessment Resources.
                Myers L, Perrine K, Lancman M, et al. 2013. Psychological trauma in patients with psychogenic nonepileptic seizures: trauma characteristics and those who develop PTSD. Epilepsy Behav. 28:121–126.
                Myers L, Zeng R, Perrine K, et al. 2014. Cognitive differences between patients who have psychogenic nonepileptic seizures (PNESs) and posttraumatic stress disorder (PTSD) and patients who have PNESs without PTSD. Epilepsy Behav. 37:82–86.
                Nasreddine ZS, Phillips NA, Bédirian V, et al. 2005. The Montreal Cognitive Assessment, MoCA: a brief screening tool for mild cognitive impairment. J Am Geriatr Soc. 53:695–699.
                O’Brien FM, Fortune GM, Dicker P, et al. 2015. Psychiatric and neuropsychological profiles of people with psychogenic nonepileptic seizures. Epilepsy Behav. 43:39–45.
                Özer Çelik A, Kurt P, Yener G, et al. 2015. Comparison of cognitive impairment between patients having epilepsy and psychogenic nonepileptic seizures. Nöro Psikiyatri Arş. 52:163–168.
                Pareés I, Kojovic M, Pires C, et al. 2014. Physical precipitating factors in functional movement disorders. J Neurol Sci. 338:174–177.
                Pareés I, Saifee TA, Kassavetis P, et al. 2012. Believing is perceiving: mismatch between self-report and actigraphy in psychogenic tremor. Brain. 135(pt 1):117–123.
                Pauli P, Alpers GW. 2002. Memory bias in patients with hypochondriasis and somatoform pain disorder. J Psychosom Res. 52:45–53.
                Peck CP, Schroeder RW, Heinrichs RJ, et al. 2013. Differences in MMPI–2 FBS and RBS scores in brain injury, probable malingering, and conversion disorder groups: a preliminary study. Clin Neuropsychol. 27:693–707.
                Pennington C, Ball H, Swirski M. 2019. Functional cognitive disorder: diagnostic challenges and future directions. Diagnostics (Basel). 9:E131. doi:10.3390/diagnostics9040131
                Pennington C, Newson M, Hayre A, et al. 2015. Functional cognitive disorder: what is it and what to do about it? Pract Neurol. 15:436–444.
                Perez DL, Barsky AJ, Vago DR, et al. 2015. A neural circuit framework for somatosensory amplification in somatoform disorders. J Neuropsychiatry Clin Neurosci. 27:e40–e50.
                Perez DL, Young SS, King JN, et al. 2016. Preliminary predictors of initial attendance, symptom burden, and motor subtype in a US functional neurological disorders clinic population. Cogn Behav Neurol. 29:197–205.
                Pick S, Goldstein LH, Perez DL, et al. 2019. Emotional processing in functional neurological disorder: a review, biopsychosocial model and research agenda. J Neurol Neurosurg Psychiatry. 90:704–711.
                Pick S, Mellers JDC, Goldstein LH. 2018. Implicit attentional bias for facial emotion in dissociative seizures: additional evidence. Epilepsy Behav. 80:296–302.
                Popkirov S, Carson AJ, Stone J. 2018. Scared or scarred: could “dissociogenic” lesions predispose to nonepileptic seizures after head trauma? Seizure. 58:127–132.
                Porter RJ, Bourke C, Gallagher P. 2007. Neuropsychological impairment in major depression: its nature, origin and clinical significance. Aust N Z J Psychiatry. 41:115–128.
                Prigatano GP, Kirlin KA. 2009. Self-appraisal and objective assessment of cognitive and affective functioning in persons with epileptic and nonepileptic seizures. Epilepsy Behav. 14:387–392.
                Qureshi SU, Long ME, Bradshaw MR, et al. 2011. Does PTSD impair cognition beyond the effect of trauma? J Neuropsychiatry Clin Neurosci. 23:16–28.
                Ranford J, Perez DL, MacLean J. 2018. Additional occupational therapy considerations for functional neurological disorders: a potential role for sensory processing. CNS Spectr. 23:194–195.
                Reuber M, Howlett S, Khan A, et al. 2007. Non-epileptic seizures and other functional neurological symptoms: predisposing, precipitating, and perpetuating factors. Psychosomatics. 48:230–238.
                Roelofs K, Keijsers GP, Hoogduin KA, et al. 2002. Childhood abuse in patients with conversion disorder. Am J Psychiatry. 159:1908–1913.
                Rohling ML, Binder LM, Demakis GJ, et al. 2011. A meta-analysis of neuropsychological outcome after mild traumatic brain injury: re-analyses and reconsiderations of Binder et al (1997), Frencham et al (2005), and Pertab et al (2009). Clin Neuropsychol. 25:608–623.
                Russell H, Coady EL, Chaytor N. 2009. The impact of seizure-related items and comorbid medical conditions on the MMPI–2 profiles of patients with epilepsy and psychogenic nonepileptic seizures. Epilepsy Behav. 15:325–329.
                Sackellares DK, Sackellares JC. 2001. Impaired motor function in patients with psychogenic pseudoseizures. Epilepsia. 42:1600–1606.
                Salinsky M, Storzbach D, Goy E, et al. 2015. Traumatic brain injury and psychogenic seizures in veterans. J Head Trauma Rehabil. 30:E65–E70.
                Scott JC, Matt GE, Wrocklage KM, et al. 2015. A quantitative meta-analysis of neurocognitive functioning in posttraumatic stress disorder. Psychol Bull. 141:105–140.
                Sharpe M, Walker J, Williams C, et al. 2011. Guided self-help for functional (psychogenic) symptoms: a randomized controlled efficacy trial. Neurology. 77:564–572.
                Smith GP, Burger GK. 1997. Detection of malingering: validation of the Structured Inventory of Malingered Symptomatology (SIMS). J Am Acad Psychiatry Law. 25:183–189.
                Spielberger CD. 1983. Manual for the State-Trait-Anxiety Inventory: STAI. Palo Alto, California: Consulting Psychologists Press.
                  Stone J, Carson A, Aditya H, et al. 2009. The role of physical injury in motor and sensory conversion symptoms: a systematic and narrative review. J Psychosom Res. 66:383–390.
                  Stone J, Edwards M. 2012. Trick or treat? showing patients with functional (psychogenic) motor symptoms their physical signs. Neurology. 79:282–284.
                  Stone J, Pal S, Blackburn D, et al. 2015. Functional (psychogenic) cognitive disorders: a perspective from the neurology clinic. J Alzheimers Dis. 48(suppl 1):S5–S17.
                  Strutt AM, Hill SW, Scott BM, et al. 2011. A comprehensive neuropsychological profile of women with psychogenic nonepileptic seizures. Epilepsy Behav. 20:24–28.
                  Suhr JA. 2003. Neuropsychological impairment in fibromyalgia: relation to depression, fatigue, and pain. J Psychosom Res. 55:321–329.
                  Teodoro T, Edwards MJ, Isaacs JD. 2018. A unifying theory for cognitive abnormalities in functional neurological disorders, fibromyalgia and chronic fatigue syndrome: systematic review. J Neurol Neurosurg Psychiatry. 89:1308–1319.
                  Testa SM, Lesser RP, Krauss GL, et al. 2011. Personality Assessment Inventory among patients with psychogenic seizures and those with epilepsy. Epilepsia. 52:e84–e88.
                  Testa SM, Schefft BK, Szaflarski JP, et al. 2007. Mood, personality, and health-related quality of life in epileptic and psychogenic seizure disorders. Epilepsia. 48:973–982.
                  Tombaugh TN. 1996. Test of Memory Malingering: TOMM. North Tonawanda, New York: Multi-Health Systems.
                  Tulsky D, Zhu J, Ledbetter M. 1997. WAIS–III/WMS–III Technical Manual. San Antonio, Texas: Harcourt Brace.
                    Turner K, Piazzini A, Chiesa V, et al. 2011. Patients with epilepsy and patients with psychogenic non-epileptic seizures: video-EEG, clinical and neuropsychological evaluation. Seizure. 20:706–710.
                    van Beilen M, Griffioen BT, Gross A, et al. 2009. Psychological assessment of malingering in psychogenic neurological disorders and non‐psychogenic neurological disorders: relationship to psychopathology levels. Eur J Neurol. 16:1118–1123.
                    Věchetová G, Slovák M, Kemlink D, et al. 2018. The impact of non-motor symptoms on the health-related quality of life in patients with functional movement disorders. J Psychosom Res. 115:32–37.
                    Vickrey BG, Perrine KR, Hays RD, et al. 1993. Quality of Life in Epilepsy QOLIE—31 (Version 10): Scoring Manual and Patient Inventory. Santa Monica, California: Rand.
                    Voon V, Cavanna AE, Coburn K, et al. 2016. Functional neuroanatomy and neurophysiology of functional neurological disorders (conversion disorder). J Neuropsychiatry Clin Neurosci. 28:168–190.
                    Voon V, Ekanayake V, Wiggs E, et al. 2013. Response inhibition in motor conversion disorder. Mov Disord. 28:612–618.
                    Wagner MT, Wymer JH, Topping KB, et al. 2005. Use of the Personality Assessment Inventory as an efficacious and cost-effective diagnostic tool for nonepileptic seizures. Epilepsy Behav. 7:301–304.
                    Wechsler D. 2008. Wechsler Adult Intelligence Scale, 4th ed. San Antonio, Texas: Psychological Corporation.
                      Wechsler D. 2009. Test of Premorbid Functioning. San Antonio, Texas: Psychological Corporation.
                        Widows MR, Smith GP. 2005. SIMS: Structured Inventory of Malingered Symptomatology: Professional Manual. Lutz, Florida: Psychological Assessment Resources.
                        Williamson DJ, Holsman M, Chaytor N, et al. 2012. Abuse, not financial incentive, predicts non-credible cognitive performance in patients with psychogenic non-epileptic seizures. Clin Neuropsychol. 26:588–598.
                        Willment K, Hill M, Baslet G, et al. 2015. Cognitive impairment and evaluation in psychogenic nonepileptic seizures: an integrated cognitive-emotional approach. Clin EEG Neurosci. 46:42–53.
                        Wilson L, Stewart W, Dams-O’Connor K, et al. 2017. The chronic and evolving neurological consequences of traumatic brain injury. Lancet Neurol. 16:813–825.
                        Keywords:

                        conversion disorder; psychogenic; neuropsychology; dissociative seizures; functional movement disorder

                        Supplemental Digital Content

                        Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.