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
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).
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.
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).
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).
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.
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).
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).
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 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.
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.
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]).
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.
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