Co-Occurring Autism Spectrum and Borderline Personality Disorder: An Emerging Clinical Challenge Seeking Informed Interventions : Harvard Review of Psychiatry

Journal Logo

Clinical Challenge

Co-Occurring Autism Spectrum and Borderline Personality Disorder: An Emerging Clinical Challenge Seeking Informed Interventions

Cheney, Lukas MBBS, MPH, MP, FRANZCP; Dudas, Robert B. MD; Traynor, Jenna M. PhD; Beatson, Josephine A. MBBS, FRANZCP; Rao, Sathya MBBS, MD, DPM, DNB, FRANZCP; Choi-Kain, Lois W. MD, MED

Editor(s): Ribeiro, Monique MD

Author Information
Harvard Review of Psychiatry 31(2):p 83-91, 3/4 2023. | DOI: 10.1097/HRP.0000000000000361
  • Open


Brittany, a 21-year-old woman with borderline personality disorder (BPD), was referred to our specialist personality disorder service, with a presentation distinguished by high-lethality suicidal behaviors including ingestion of toxic substances and dangerous objects. She frequently ran to train stations and bridges. Brittany also engaged in daily cutting. Due to her high level of risk, she was increasingly restricted within her family home. She was not allowed into the backyard for fear that she would elope and engage in high lethality behavior.

Brittany is an only child, conceived via in vitro fertilization. Diagnosed with Asperger’s Syndrome at age six, Brittany displayed early restricted interests, desire for routine, and sensory difficulties, accompanied by a high level of social interest. Multi-disciplinary assessments showed pragmatic language impairment and social difficulties that included inflexibility and egocentricity in her play. Brittany demonstrated difficulty with sharing, losing in games, and when not able to take first turn. High levels of emotional distress were reported when she did not get what she wanted.

Brittany worked with a speech pathologist during this childhood period. She was subsequently diagnosed with obsessive compulsive disorder (OCD) and generalized anxiety. Restricted eating and self-injurious behaviors began in her early teen years. Brittany reported experiencing traumatic bullying from her peers during this period of her life. She reported that she began to cut herself after reading online about people using cutting to regulate emotions.

Her first admission to a psychiatric unit occurred at age 15. Following poor oral intake while in the unit, she was transferred to the pediatric ward for nutrition replacement during an extended admission of six weeks. She was then referred for case management.

Brittany continued to struggle with severe eating disorder symptoms until age 17, when she transferred to a small Christian school to escape bullying and receive additional support. For the next two years, she experienced relative stability with reduced admissions despite ongoing suicidal thoughts.

After graduating from school, her suicide attempts rapidly escalated, both in frequency and lethality. Despite extensive intervention from public services, this pattern of risk continued to escalate leading up to referral to our service in late 2019.

Assessments of Cognitive Domains

A neuropsychological assessment indicated relative strengths in processing verbal information, vocabulary, and short-term memory. Brittany displayed below age abilities in verbal abstract reasoning and speed of information processing; the assessing neuropsychologist reported that “she is overwhelmed by lengthy, detailed verbal information presented only once.” The report also noted “the most striking feature … was her executive difficulties. She demonstrated significant difficulty with planning and organization of information as well as problem solving and flexible thinking.”

Additional screening measures were administered to investigate the need for further neuropsychological assessment due to Brittany’s apparent difficulty with concepts in psychotherapy.

Montreal Cognitive Assessment (MOCA)

The MOCA is a rapid and generalized screening test of multiple cognitive domains.

  • Outcome:
  • – Brittany scored below normative averages at 20 out of a possible 30. A score of 26 or higher on the MOCA is considered within normal range.
  • – Consistent with previous neuropsychological testing, her most significant deficits were found in visuo-spatial and executive functioning.

The Awareness of Social Inference Test (TASIT) - Short

The TASIT-S comprises short video clips of actors displaying particular emotions and having brief social interactions. The test assesses naming of emotions and understanding of subtext during social interactions that may involve lying or sarcasm.

  • Outcome
  • – Emotion Evaluation – positive emotions 0/5, negative emotions 1/5
  • – Social Inference – minimal: Sincere 16/16, Sarcasm 6/16
  • – Social Inference – enriched: Lie 10/16, Sarcasm 7/20

These findings suggested performance below the 2nd percentile in emotion recognition and understanding complexity within social interactions. Brittany’s performance on evaluating emotions was in the extreme low range. Importantly, she displayed normal range performance in understanding sincere social interactions. This raised the concern that this relatively intact function of understanding straightforward social interactions may hide significant underlying deficits in her understanding of more nuanced social interactions.

Autism Quotient (AQ), Empathy Quotient (EQ)

The AQ is a self-report focusing on the common features of autism. The questions in the EQ assess a person’s own impression of their capacity for empathy.


AQ—26/50 (cut-off for a diagnosis of autism is a score > 32)

EQ—37/80 (cut-off for a clinically significant deficit in empathy is a score < 30)

For both measures, Brittany’s responses put her below the thresholds which would suggest autism spectrum disorder (ASD). The AQ and EQ are self-report measures, therefore these results suggested that Brittany lacks insight into the difficulty she has in social understanding as identified in the TASIT.

McLean Screening Instrument for BPD (MSI-BPD)

The MSI-BPD is a 10-item yes or no questionnaire based on the DSM 5 criteria for BPD.

  • – Brittany self-reported in the affirmative for 10 out of a possible 10 questions. A score of 8 or more is indicative of a diagnosis of BPD. Clinical assessment confirmed that Brittany met criteria for BPD according to DSM 5.

Differential Diagnoses

Brittany’s diagnosis of ASD was established; she had also previously been diagnosed and treated for generalized anxiety and major depressive disorders. A DSM-5 diagnosis of BPD was confirmed, better explaining features of her presentation including high risk of self-injury, suicidal behaviors, impulsivity, severe emotion dysregulation, intense anger, unstable relationships, and persistently unstable self-image. However, there was concern that differentiating the relative contribution of ASD or BPD to the clinical presentation was difficult and that an emphasis on a BPD formulation may overlook the importance of her neurodevelopmental history in her recovery plan.

Clinical Course Following Initial Presentation: Treatment Attempts

Brittany commenced a comprehensive dialectical behavioral therapy (DBT) program. Brittany engaged actively, completed all homework, and attempted to use DBT skills, but she reported that skills did not help her in crisis. She struggled with the abstract concepts in DBT and had even greater difficulty implementing the skills when distressed.

In the early stages, the overall treatment approach was based on principles for supporting a person with BPD. These principles include a treatment plan that encourages the autonomy and independent decision-making capacity of the person receiving support. Brittany’s relatively strong language function may give the impression that her cognitive function is higher than it truly is when objectively measured. An inaccurate understanding of Brittany’s neurocognitive abilities may lead expectations of her behavior and decision-making that are unrealistic and potentially counter-therapeutic. Treatment plans were subsequently reconsidered to emphasize the primacy of her neurodiversity, with BPD as a secondary consideration.

Over time, the focus shifted from psychotherapy as the primary intervention toward an emphasis on providing disability services in response. Brittany continued to receive psychotherapy sessions in order to maximize her reflective capacity, but also required around-the-clock support to help her absorb and apply behavioral and psychological interventions. At the time of writing, she was in the process of transitioning from her parents’ home to disability accommodation with 24-hour support. A guardian was appointed by the Office of the Public Advocate, as it was increasingly apparent that her executive impairment affected her decision-making capacity. Support services included medical, mental health, disability, housing, neuropsychology, and behavioral specialists to comprehensively address Brittany’s multiple areas of need.


As Brittany’s parents, we have always said “If only our daughter had come with an instruction manual” life for all of us might have been much easier.

Brittany was a much-wanted baby and we had never been happier in those first five years of her life. At 5 years old, she went to school, and, within a term, she was referred to an occupational therapist for dyspraxia. Soon after, she was diagnosed with Asperger’s syndrome. So began the journey of appointments, social skills classes, reading about ASD, and extra support at school.

Brittany found school challenging in many ways. Her teachers were fantastic, knowledgeable and nurturing for the first three years, but Brittany had difficulties with her motor skills, schoolwork, and the complicated world of socializing. As my friend described, “Your daughter never seems comfortable in her own skin.”

Brittany was eight years old when we explained that she had Asperger's. We are not sure she understood, but we know she hated being different from the other children. She still considers it a curse. She is quite rigid in her thinking and behavior and is not willing to learn things or do things unless she wants to.

Her anxiety levels grew as her resilience to teasing and being excluded was very low. She struggled with her academic work. At the end of year 5 we decided to have her repeat year 5 at a new school where she would get specialist support and smaller classes.

Unfortunately, our daughter struggled with the transition to the new school; she was taller and more developed physically than the other children. With her lack of sporting ability and organizational skills, difficulty with comprehension, lack of confidence, being aware she was different, and hitting puberty, the next few years were challenging. She felt bullied and excluded.

She started cutting and then developed a serious eating disorder. There were times when she was held down by security staff six times a day to have the nasogastric tube put down to feed her. It was a very distressing time. She missed out on two years of schooling. When she finally started eating again, she went to a new school which she attended only intermittently, missing out on more years of normal socializing and schoolwork.

Brittany spent a lot of time on social media talking to people she met in eating disorder programs and psychiatric units, which was good for working on social interactions. However, one person she met in the psychiatric unit killed herself and this experience caused Brittany terrible grief and guilt because she had not acted on a message this girl had sent out before she died. To this day, Brittany is terrified that acquaintances, whom she calls friends, will kill themselves. She compulsively checks in on a number of people every day and alerts their relatives or the police if she believes they are in danger. She is a caring person who hates to see people in mental distress.

In her last year at school, she had a primary teacher whose expectations of our daughter were unrealistic. Brittany also went to a local occupational training institute for cooking classes as part of her school training. The trainer there belittled her in front of her classmates and failed her. In the last term of Brittany’s schooling, a girl she had met at an eating disorders group died of suicide. Brittany was devastated and began trying to hang herself and walk onto a freeway.

After leaving school, she did an animal studies course at a protective college for students who were struggling. She ended up on the train tracks again, and we then had to escort her to and from college. After that course, Brittany has been at home and has found it very difficult to find another course, to work, or find direction in her life. She did finally join a bowling group for young people on the autism spectrum and has enjoyed that for two years. Nonetheless her mental health has deteriorated and despite accessing all the help we could find Brittany just wants to die. She jumped from a bridge in 2019 and broke her back. After a 5-hour operation, she is fortunately still able to walk. In 2020, she overdosed four times with poisonous substances and was in intensive care each time. After all the toxins and other objects she has swallowed, she has developed debilitating gastric problems. She struggles with continual bouts of diarrhea, pain, and nausea despite attempts at medical intervention.

For the past few years, we have kept all the doors to the outside of our house locked to ensure her safety. We have had no other choice as every time we take our daughter out she attempts to take her life. Our daughter has lost all hope and she does not trust anyone—police, hospital staff, therapists, and her parents. She is desperate to feel better and to end her suffering. She would really love to be like her other friends with partners, a job, a driver’s license, freedom, and confidence to go out and be happy. She just wants to be “normal.”

We will never give up on our daughter. She is stuck in a repetitive cycle, and she will need expert professionals to help her regain hope and to be given opportunities to improve her life. This is a complex puzzle, but we really want it solved.


  • – How does BPD emerge for an autistic person?
  • – How can the common features of cognition in autistic people contribute to the etiology of BPD and/or higher risk presentations?
  • – How can treatment accommodate these differences?
  • – How does neurocognitive function vary in autistic people and can it be improved with support?

Lois W. Choi-Kain, MD

BPD is an outcome and an engine for adversity. Therefore, complex comorbidity is a rule rather than exception.1 Like other psychiatric disorders, BPD is the result of the convergence of innate endowments and environmental risk factors. It is both a marker of low resilience as well as a generator of maladaptation. Biological processes such as genetics, chronic stress effects, developmental deprivation, impaired support systems, and sometimes trauma result in frontolimbic dysfunction in many diagnostic entities.2 In BPD, interpersonal and emotional hypersensitivity interferes with higher order cognitive processes that enable humans to appraise situations realistically and comprehensively, as well as respond in probabilistic ways toward achieving desired outcomes.3 This broad source of impairment is aggravated in the combination of BPD and autism, as shown in Brittany’s case. Her case is a common one. Having encountered this set of co-occurring disorders on several occasions in the tertiary care setting, it is a challenge to stabilize patients reliably even in well-resourced programs designed to treat BPD.

Part of the conundrum is that when BPD and ASD co-occur, the conjunction of their individual social disabilities further intensifies the isolation and loneliness which the patient suffers. Their impulsivity, compulsivity, and understandable existential pain drive a more serious form of suicidality and self-harm than is the case for individuals with either disorder alone. While not empirically documented, it seems that the lethality and mortal risk of the self-destructive behaviors of those with BPD and ASD are arguably of a different order of magnitude. The situation is made more unresolvable by the inability to sustain collaborative relationships that both diagnoses bring into the therapeutic space. ASD manifests earlier than BPD and reflects a neurodevelopmental etiology that results in increased emotional instability, impaired social cognition, and limited psychological capacities to conceptualize internal problems abstractly. For those with ASD, BPD is likely a secondary outcome of a distinct cognitive profile as well as imbalanced levels of emotional and social skill compared to demand. Providing formal guidelines for managing this co-morbidity requires more research, but in the meantime, we need to clarify what we already know and use it to inform best practices.

Good psychiatric management (GPM) is a pragmatic medicalized approach that relies on the procedures most clinicians already know and use for other disorders.4 Diagnosis and its disclosure, health literacy with education, and case management of life difficulties are bedrock for all medical illnesses. Mental illness is broadly stigmatized, and BPD is among the most stigmatized illness in psychiatry, with the result that the good care we otherwise generally provide becomes destabilized, inconsistent, and somehow more elusive. Reviewing what we know and making sense of these diagnoses is a starting point. Part of the difficulty lies in the heterogeneity of our professional views on both BPD and ASD.

In GPM, BPD is conceptualized as a problem of interpersonal hypersensitivity. Because of an inability to feel secure and navigate the world predictably, those with BPD have an over-reliance on others. When they feel connected, they may remain anxious and hypervigilant,5,6 but are generally receptive to feedback, assistance, and direction. However, because the connection to important others is a metric of self-worth and stability, any threat to that connection, whether real or perceived, is experienced as a significant threat to a person with BPD. Accordingly, they either react with angry retaliation, devaluation, and blame, or dissolve into self-injury and helplessness.7 These reactions confuse, scare, and irritate others so that actual abandonment is more likely. When truly alone, impulsivity and dissociation reign, and these individuals become lost, chaotic, and uncontained. This is the state in which true suicidality emerges with despair, which combines to produce truly lethal states.8 Connection to others becomes reinstated when hospitalization and other acute psychiatric intervention occur, leading to short-term stabilization of symptoms, but longer-term dependency on the healthcare system to interrupt and contain this vicious cycle.

Providing this explanation to patients as well as their families and clinical team can often serve as a clarifying framework for understanding the chaotic oscillations of symptom states for patients who have both BPD and ASD. Enhancing this model with a consideration of how ASD-related difficulties—of social cognition, repetitive restricted repertoire of behavior, need for self-stimulation for soothing, and difficulty with central coherence—shape what interventions and solutions are possible is critical. Integrating approaches to both disorders starts with prioritizing co-morbidities based on the more central agent needing stabilization prior to change in other entities. For example, with co-occurring depression and anxiety disorders, centralizing BPD as the primary clinical focus can reduce broader stress reactive vulnerabilities that drives chronicity related to treatment non-responsiveness, relapse, or both. In addition, addressing BPD first can facilitate readiness for exposure-based psychotherapies for post-traumatic stress disorder or obsessive-compulsive disorder. However, in the case of co-morbid ASD, clinicians will need to properly support and address neurodivergent characteristics to optimize the social emotional learning that BPD therapies involve.

As in Brittany’s case, collecting a thorough assessment from multiple dimensions—medical, psychological, developmental, and behavioral—with a systematic evaluation of symptoms and cognitive capacity should be routine. Involving families is essential, as they are allies who are understandably stuck or overwhelmed when in crisis, so providing support and guidance is frequently critical for optimal collaboration. Providing case management to structure and organize life outside treatment enables functioning and growth for patients in general, especially those with unique profiles such as Brittany. Educating patients, families, and their providers on the nature of a patient’s problems, tips on how to respond and support, and encouragement to foster the patient’s efforts on building a life can increase the predictability of the social network supporting the patient that enables everyone to make sense difficulties collaboratively in a good enough way to help patients survive their problems.9 Death by completed suicide is a possibility and this risk, while terrible, needs to be forthrightly shared, with a joint effort to help the patient feel more capable of living instead of imprisoning them in treatments that do not work for their special needs. More must be done to disseminate a sound basic approach to care of this important population. This case report may provide some preliminary steps to supplement the small body of work already published.

Jenna M. Traynor, PhD

Brittany’s presentation includes the characteristic ASD symptom dyad of social communication deficits and repetitive behaviors.10 The inflexibility and nonreciprocal social play observed in her development and her difficulty understanding the abstract emotional language in DBT are consistent with social communication deficits in ASD. Although several neurobiological theories have been proposed to explain social deficits in ASD (e.g.,11-13), neuroimaging findings have provided strong support for social motivation theory,14 which posits that ASD is characterized by an early intrinsic reduction in social motivation that is subserved by functional abnormalities in salience and reward-related areas of the brain (e.g., frontostriatal and limbic regions) that typically support social orienting. Functional abnormalities in these networks (e.g.,15-17) result in a cascading impact on social skill development in ASD. The resulting social impairments, often visible by the first year of life,18 can include numerous deficits in joint attention, mentalizing, reciprocal communication, and ability to understand social cues and abstract language.10 As Brittany is described as someone with “a high level of social interest,” it is important to distinguish between her desire for belongingness often seen in ASD,18 with the biologically based motivational mechanisms described in social motivation theory of ASD (i.e., unconscious reduction in social orienting). Indeed, despite Brittany’s desire to belong and exquisite sensitivity during social interactions, she may struggle socially as a result of ASD-related neurobiological alterations.

Moreover, Brittany’s childhood was marked by restricted interests (i.e., intense fascinations on subject matter often nonsocial in nature). Importantly, restricted interests have been linked to neural disruptions in salience and reward-related brain regions19,20 overlapping with those thought to underpin social deficits in ASD. This convergence has catalyzed investigations into what, if not social in nature, may be intrinsically rewarding for people with ASD. Interestingly, visual stimuli depicting restricted interests appear to elicit heightened arousal and reward-related responses in people with ASD that are typically seen in response to social stimuli in neurotypical controls.15,20-22 Moreover, unlike controls, when given the option to expend effort to view pictures of restricted interests or social pictures, a recent study found that people with ASD will expend more effort to view their own restricted interests over social pictures, and this decision is accompanied by a heightened pupillary response, suggesting more arousal while viewing restricted interest pictures over social pictures.22 As restricted interests were observed in Brittany’s childhood—a critical developmental period marked by increased synaptic pruning and crystallization of functional brain architecture23—Brittany may be someone for whom restricted interests elicit stronger motivational responses, relative to social content. This is salient because it may help to address Brittany’s difficulty using DBT skills during moments of crisis; much of DBT is inherently social in nature. The therapy is premised on an assumption that patients are motivated and rewarded by normative social interactions. Many of the skills presume the presence of motivational prerequisites to orient to and understand the social behavior of others and oneself. For example, patients are encouraged to do what is “interpersonally effective” and to “be mindful of others,” and DBT therapists are taught to use the therapeutic relationship as a powerful reinforcer.24 However, in BPD comorbid with ASD, alternative reinforcers and goals may need to be identified, and research has shown that incorporating restricted interests into therapy for ASD may increase motivation and engagement.25-28

BPD and ASD comorbidity

Women with ASD are often diagnosed later than men due to a less visible clinical presentation29 marked by a better ability to regulate restricted interests30 and maintain comparable social attention to women without ASD.31 Importantly, Brittany’s clinical team emphasized how her high functioning presentation may have led others in her life to develop expectations of her that she was not capable of meeting, resulting in a chronically invalidating experience marked by misunderstanding by caregivers and traumatic bullying. Indeed, many prominent BPD theories emphasize these very attachment disruptions as a significant etiological factor in the development of BPD.32,33 People with ASD experience fewer close relationships, higher levels of social isolation, and significantly more mental health problems,34 with estimates of up to 72% of individuals meeting criteria for at least one comorbid mental health diagnosis,35 often in the realm of mood and anxiety disorders consistent with Brittany’s history.36 A recent pooled estimate of ASD in persons with BPD shows a prevalence rate of 4%, suggesting that BPD comorbid with ASD is not uncommon.37

Sensitivity and self-harm in BPD and ASD

Both BPD and ASD share an altered sensitivity profile. In BPD, this presents as heightened emotional sensitivity,38 whereas in ASD, sensory sensitivity is more often observed (e.g., hypo- and hyper-sensitivities to auditory, tactile, or gustatory stimuli).10 Self-harm is also a symptom of both disorders,10 and research has linked self-harm in BPD and ASD to their respective sensitivity profiles. In BPD, self-injury is often conceptualized as an emotion regulation strategy. Functional brain imaging has provided strong evidence to support the hypothesis that self-injury serves to downregulate the limbic system in BPD,7,39 which is hyperreactive during conditions of social rejection.3 On the other hand, self-injury in ASD falls under the umbrella of repetitive behavior10 and at least one study has shown that the strongest single predictor of self-harm in ASD is atypical sensory processing.40 For example, self-injury may provide desired stimulation (e.g., biting one’s hand in response to a baseline tactile hyposensitivity) or may serve as an escape from an overpowering sensory experience (e.g., headbanging in response to loud sounds). Altered sensitivity in ASD appears to be rooted in disrupted functional connections between the thalamus (the brain’s “sensory gateway”) and numerous sensory processing areas of the cortex.41,42 Further, the desire for routine that Brittany displayed in her earlier developmental years has also been identified as a strong risk factor for self-harm in ASD.43 Taken together, a functional analysis of Brittany’s self-harm to identify any sensory antecedents and consequences may further inform the function of her self-injury, which may vary according to the self-injury method used (e.g., cutting could be used as an emotion regulation strategy whereas swallowing dangerous objects could be related to sensory processing). Her report that she learned self-harm to regulate her emotions, its observed onset during a period of bullying, and its decrease in frequency and lethality subsequent to removal from the bullying environment suggest that at least some of her self-harm may function to downregulate aversive emotions as is typical in BPD.

Clinical recommendations

The results of Brittany’s neuropsychological assessment suggest that she requires additional time to process information and may benefit from assistance generating solutions to problems. Her slower processing speed may translate functionally to an inability to keep up with DBT homework at a pace equivalent to her same-aged peers. As processing speed is a pre-requisite for the comprehension of novel and complex information, therapy should focus on one topic at a time using simplified handouts with minimal text and should provide extra time for skills practice. Moreover, Brittany is described as having impaired ability to reason abstractly and therefore might have difficulty forming concepts from abstract verbal information (e.g., understanding DBT skills such as “making lemonade out of lemons”). DBT skills renamed with concrete language and accompanying visual depictions may be helpful. As Brittany’s other verbal abilities are described as intact (e.g., verbal knowledge store and fluency), modified DBT may be an appropriate intervention. Other adaptations may include using simplified DBT behavior chain analysis to help Brittany identify sensory antecedents and consequences of self-injury. Solution analysis may include DBT skills that are individually tailored to Brittany’s sensory profile. For example, sensory activities to calm the nervous system (e.g., weighted blanket) may be more effective than those typically suggested in DBT, which for some people with ASD may be insufficient to activate the parasympathetic nervous system or may trigger hypersensitivities (e.g., an ice dive). Finally, incorporating restricted or strong interests of Brittany’s into therapy may increase the saliency or reward of therapy (e.g., using restricted interests to reinforce effective interpersonal behavior). Accordingly, a recent pilot study with some of these modifications suggests that an adapted DBT intervention for ASD without intellectual disability demonstrates preliminary efficacy.27

Robert B. Dudas, MD

The importance of the overlap

Differentiating clinically between ASD and BPD can be challenging.44 As awareness of both conditions increases, specialists encounter this problem increasingly often; as more and more people have sought medical attention and clinicians in primary and secondary care started to refer more often to specialists in both diagnostic domains, who at present are unable to provide specific guidance.

There are some important gender differences in both conditions in terms of prevalence, presentation, and diagnostic and management challenges,29 which is relevant to how health care systems organize diagnostic assessment and care provision. For example, relatively few men are diagnosed and treated with BPD and those who are diagnosed are likely to receive somewhat less psychiatric medication and fewer psychological therapies compared to women.45 Males are more frequently diagnosed with autism than females. ASD presents differently among high-functioning females, often with fewer social and communication difficulties, and this may lead to many of them remaining undiagnosed, getting diagnosed later, or getting an incorrect diagnosis.29,46 Age is another factor here. Health visitors and the school system often pick up signs that are suggestive of ASD or signs that might indicate the possibility of a future diagnosis of BPD, but once the person has left the school system, diagnosis is often delayed. If the person has not been diagnosed until old age, both the individual affected and clinicians would be less likely to think of either condition (let alone their combination) as an explanation for the person’s difficulties.

Importantly, self-harming is associated with both conditions and evidence is accruing that having both conditions may increase the risk of suicide.47-50 Although we only have a partial understanding of exactly what drives this increased risk of suicide, we know that it is difficult for people with BPD to navigate social relationships due to their frequent mood fluctuations, attachment difficulties, and impulsivity. For patients with both BPD and ASP the situation is even more challenging if, in addition to varying levels of empathy impairment associated with the mood fluctuations, the person’s cognitive empathy is also impaired and they have increased sensory sensitivity due to having ASD. Camouflaging autistic traits, such as when one is trying to fit into a group in education, as in the case of Brittany, has been found to be associated with an increased risk of experiencing thwarted belongingness and lifetime suicidality.51

Clinical management

Differential diagnosis. As many features are shared between the two conditions, accurate differentiation requires significant high-level clinical skill and experience. Preference for predictability in daily life, obsessive behaviors, difficulties with eating, difficulty getting on with one’s peers or maintaining a relationship, difficulties at school or work, challenges with empathy or mentalization, communication challenges, unusual mood patterns, anxiety or panic states, cognitive challenges, and self-harm behaviors are often spotted in the individual but the subtle differences in how these manifest in the two conditions are rarely obvious to nonspecialists. A history of childhood neglect and/or abuse is very common in BPD,52 but it is also significantly higher in ASD than in neurotypical people.53

It is even more difficult to diagnose comorbid ASD and BPD. Very little research has been done on the symptomatology. Our study54 found that people diagnosed with both conditions reported higher levels of autistic traits than people with autistic spectrum conditions alone. This is perhaps unsurprising as individuals with BPD also reported higher levels of autistic traits than people from the general population without either diagnosis. In terms of self-reported empathy, the comorbid group was not different from the group with autistic spectrum conditions, and both groups reported poorer empathy than the BPD and the control groups, who did not differ from each other.

In addition to the underdeveloped diagnostic infrastructure and the epidemiology, symptomatic overlap, and possible comorbidity of the two conditions, other factors that can obfuscate the diagnosis relate to attitudes toward diagnosis.

Two or three decades ago, many patients with BPD who did not agree with their diagnosis said they had bipolar illness rather than a personality disorder. More recently, autism seems to be mentioned more often. People with these diagnoses often struggle to fit in and maybe diagnoses like bipolar illness and ASD carry less stigma55 and offer better social acceptance. Also, it is increasingly common that people gather a lot of information before attending the clinic. All these can affect help-seeking behavior and the subjective description of one’s symptoms in clinic.

Correct diagnosis is important because it can help people start moving toward recovery, while misdiagnosis can have negative consequences.56 Statistical analyses are rare in this area, but international expert consensus suggests that the person’s ability to understand neurotypical social dynamics, the description of their emotions, the presence of attachment difficulties, the intactness of cognitive empathy when they are not emotionally aroused, their justification for interrupting relationships, and different contexts of self-harming can help in differentiating BPD from ASD.53 In summarizing behavior differences between children with ASD and those with significant attachment problems, the Coventry Grid57,58 is particularly helpful to determine whether the overlapping features are due to ASD or attachment problems. The person’s relationship with their own body may also offer a clue. Self-disgust, especially related to one’s own body, has been linked to BPD.59,60

Treatment. Although medications are prescribed very widely in BPD (and sometimes even in ASD), the current evidence base for this, especially to treat the core symptoms or to reduce overall symptoms severity, is still very sparse.61,62 Psychological treatments, such as DBT or mentalization-based therapy (MBT), reduce symptom severity in BPD and this is supported by moderate-quality meta-analytic evidence from a Cochrane review.63

Promisingly, a small study of mentalization-based treatment adapted for adults with ASD (MBT-ASD) produced evidence of improvement in mentalization.64

Relevant to Brittany’s case, there is some evidence that adapted DBT may work for people with ASD.27

Challenges for health services. The specific needs of these individuals are currently not catered for well in most healthcare systems. Services with experience in diagnosing both conditions are few and far between and those that are also able to offer treatment for ASD to patients over 18 years of age are even rarer.

If the positive findings about MBT and DBT in ASD become replicated, there is hope that services that are routinely available may be set up for adults with ASD. However, this will take time, and because specialist services for comorbid ASD and BPD are unlikely to be funded anytime soon in the current economic climate, training up workers in personality services would probably be more likely to the situation, at least in the short run.

Stigma is certainly a major problem in both conditions, probably more so in BPD.65 In BPD, self-stigma seems to be associated with the severity of the disorder, number of hospitalizations, and employment, and targeting it with psychological interventions appears very relevant.66

Values-based practice is key to good practice. Good medical practice stands on two feet: facts and values.67 In the developed world, over the last two decades evidence-based medicine (EBM) has become the dominant paradigm to help us choose between various diagnostic and treatment options. While EBM can guide us about the efficacy and safety of diagnostic and treatment interventions, it is silent about the personal importance attached to these by patient and doctor.68 Values are things or actions that are important to us and in healthcare these could present as concerns, preferences, and expectations about any intervention or care. To help doctors and patients to navigate the inherent value diversity in healthcare, another important, complementary framework of clinical theory and skills, called values-based practice (VBP), has been developed. The objective of VBP is to facilitate a good process whereby the values involved in clinical decision-making can be recognized and balanced productively. To achieve this, VBP draws on psychology, sociology, anthropology, law, and philosophy. People with ASD may find it more difficult to access and express their health-related values and the values of people with BPD may fluctuate significantly. VBP can help us overcome these challenges and aim at person-centered care more efficiently.

A Delphi study on the differential diagnosis of autism in women55 provided some pointers to a good process, highlighting that autism is generally regarded more positively than most psychiatric diagnoses. Diagnostic assessments should ideally be thorough (preferably over more than one session) and consider several diagnostic possibilities using relevant tools, and ask for specific personal examples of lived experience (rather than the result of the individual’s research on the subject). The study further suggested drafting the final report in collaboration with the patient. Importantly, in cases where autism is not diagnosed, it recommended validating the patient’s difficulties and offering other options for support and alternative diagnoses. It pointed out that autistic women often demonstrate high emotional empathy toward others, but poor understanding or awareness of their own emotions. Similarly, many people with BPD want to provide care to people or other creatures, and some find a route to recovery working as a peer support worker, looking after animals, or caring for plants as a gardener. The Delphi study also demonstrates that autistic women are often able to apply their special interests and use them as social currency.


Brittany’s case illustrates a common and complex clinical challenge, where the double doses of emotional dysregulation, disrupted social interchange, and repetitive self-destructive behavioral compulsions overwhelm either ASD or BPD approaches considered separately. In addition, women with ASD, who have better abilities to mask restricted interests and build social engagement than males with the disorder, often camouflage the full extent of their autism-specific vulnerabilities. Our dialogue here represents an important emerging area of research and treatment development. More work and clinical discussion is needed to better understand what works and what does not work for these patients and their families so that they can build relationships and a sense of identity that not only makes life worth living but also hopeful.

Declaration of interest

Dr. Choi-Kain receives royalties from American Psychiatric Publishing as an author and editor of GPM books. For the remaining authors none were declared. The authors alone are responsible for the content and writing of this article.

We thank Brittany and her family for sharing their story, which we four find increasingly common and difficult for specialist services to coherently manage. We also appreciate the work of both Isabella Nadel and Julia Jurist for their assistance preparing the documents for this manuscript.


1. Shah R, Zanarini MC. Comorbidity of borderline personality disorder: current status and future directions. Psychiatr Clin North Am 2018;41:583–93.
2. Sicorello M, Schmahl C. Emotion dysregulation in borderline personality disorder: a fronto-limbic imbalance? Curr Opin Psychol 2021;37:114–20.
3. Rappaport BI, Barch DM. Brain responses to social feedback in internalizing disorders: a comprehensive review. Neurosci Biobehav Rev 2020;118:784–808.
4. Gunderson JG, Links P. Handbook of Good Psychiatric Management for Borderline Personality Disorder. Washington, DC: American Psychiatric Publishing 2014.
5. Sharp C, Vanwoerden S. Hypermentalizing in borderline personality disorder: a model and data. J Infant Child Adolesc Psychother 2015;14:33–45.
6. Somma A, Ferrara M, Terrinoni A, et al. Hypermentalizing as a marker of borderline personality disorder in Italian adolescents: a cross-cultural replication of Sharp and colleagues’ (2011) findings. Bord Personal Disord Emot Dysregul 2019;6:1–4.
7. Olié E, Doell KC, Corradi-Dell'Acqua C, et al. Physical pain recruits the nucleus accumbens during social distress in borderline personality disorder. Soc Cogn Affect Neurosci 2018;13:1071–80.
8. Brodsky BS, Groves SA, Oquendo MA, et al. Interpersonal precipitants and suicide attempts in borderline personality disorder. Suicide & Life-Threat Behav 2006;36:313–22.
9. Guillén V, Díaz-García A, Mira A, et al. Interventions for family members and carers of patients with borderline personality disorder: a systematic review. Fam Process 2021;60:134–44.
10. American Psychiatric Association. Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Association Publishing, 2013.
11. Baron-Cohen S, Ring HA, Bullmore ET, et al. The amygdala theory of autism. Neurosci Biobehav Rev 2000;24:355–64.
12. Dapretto M, Iacoboni M. The mirror neuron system and the consequences of its dysfunction. Nat Rev Neurosci 2006;7:942–51.
13. Gallese V, Rochat M, Cossu G, et al. Motor cognition and its role in the phylogeny and ontogeny of action understanding. Dev Psychol 2009;45:103–13.
14. Chevallier C, Kohls G, Troiani V, et al. The social motivation theory of autism. Trends Cogn Sci 2012;16:231–9.
15. Benning SD, Kovac M, Campbell A, et al. Late positive potential ERP responses to social and nonsocial stimuli in youth with autism spectrum disorder. J Autism Dev Disord 2016;46:3068–77.
16. Dichter GS, Felder JN, Green SR, et al. Reward circuitry function in autism spectrum disorders. Soc Cogn Afftect Neurosci 2012;7:160–72.
17. Zwaigenbaum L, Bryson S, Rogers T, et al. Behavioral manifestations of autism in the first year of life. Int J Dev Neurosci 2005;23:143–52.
18. Deckers A, Muris P, Roelofs J. Being on your own or feeling lonely? loneliness and other social variables in youths with autism spectrum disorder. Child Psychiatry Hum Dev 2017;48:828–39.
19. Cascio JC, Foss-Feig JH, Heacock J, et al. Affective neural response to restricted interests in autism spectrum disorders. J Child Psychol Psychiatry 2014;55:162–71.
20. Kohls G, Antezana L, Mosner MG, et al. Altered reward system reactivity for personalized circum- scribed interests in autism. Molecular Autism 2018;9:9.
21. Sabatino A, Rittenberg A, Sasson NJ, et al. Functional neuroimaging of social and nonsocial cognitive control in autism. J Autism Dev Disord 2013;43:2903–13.
22. Traynor JM, Gough A, Duku E, et al. Eye tracking effort expenditure and autonomic arousal to social and circumscribed interest stimuli in autism spectrum disorder. J Autism Dev Disord 2019;49:1988–2002.
23. Selemon L. A role for synaptic plasticity in the adolescent development of executive function. Transl Psychiatry 2013;3:e238.
24. Linehan MM. Cognitive-behavioral treatment of borderline personality disorder. New York: The Guilford Press, 1993.
25. Baker MJ. Incorporating the thematic ritualistic behaviors of children with autism into games: increasing social play interactions with siblings. J Posit Behav Interv 2000;2:66–84.
26. Baker MJ, Koegel RL, Koegel LK. Increasing the social behavior of young children with autism using their obsessive behaviors. J Assoc Persons Sev Handicaps 1998;23:300–8.
27. Bemmouna D, Coutelle R, Weibel S, et al. Feasibility, acceptability and preliminary efficacy of dialectical behavior therapy for autistic adults without intellectual disability: a mixed methods study. J Autism Dev Disord 2021;9:1–18.
28. Boyd BA, Conroy MA, Richmond Mancil G, et al. Effects of circumscribed interests on the social behaviors of children with autism spectrum disorders. J Autism Dev Disord 2007;37:1550–61.
29. Kirkovski M, Enticott PH, Fitzgerald PB. A review of the role of female gender in autism spectrum disorders. J Autism Dev Disord 2013;43:2584–2603.
30. Hiller RM, Young RL, Weber N. Sex differences in autism spectrum disorder based on DSM-5 criteria: evidence from clinician and teacher reporting. J Abnorm Child Psychol 2014;42:1381–93.
31. Harrop C, Jones D, Zheng S, et al. Sex differences in social attention in autism spectrum disorder. Autism Research 2018;11:1264–75.
32. Crowell SE, Beauchaine TP, Linehan MM. A biosocial developmental model of borderline personality: elaborating and extending Linehan's theory. Psychol Bull 2009;135(3):495–510.
33. Gunderson JG, Lyons-Ruth K. BPD’s interpersonal hypersensitivity phenotype: a gene- environment-developmental model. J Pers Disord 2008;22:22–41.
34. van Heijst BFC, Geurts HM. Quality of life in autism across the lifespan: a meta-analysis. Autism 2015;19:158–67.
35. Leyfer OT, Folstein SE, Bacalman S, et al. Comorbid psychiatric disorders in children with autism: interview development and rates of disorders. J Autism Dev Disord 2006;36849–61.
36. Geurts HM, Jansen MD. A retrospective chart study: the pathway to a diagnosis for adults referred for ASD assessment. Autism 2012;16:299–305.
37. May T, Pilkington PD, Younan R, et al. Overlap of autism spectrum disorder and borderline personality disorder: a systematic review and meta-analysis. Autism Research 2021;14:2688–2710.
38. van Zutphen L, Siep N, Jacob GA, et al. Emotional sensitivity, emotion regulation and impulsivity in borderline personality disorder: a critical review of fMRI studies. Neurosci Biobehav Rev 2015;51:64–76.
39. Niedtfeld I, Schmitt R, Winter D, et al. Pain-mediated affect regulation is reduced after dialectical behavior therapy in borderline personality disorder: a longitudinal fMRI study. Soc Cogn Affective Neurosci 2017;12:739–47.
40. Duerden EG, Szatmari P, Roberts SW. Toward a better understanding of self-injurious behaviors in children and adolescents with autism spectrum disorders. J Autism Dev Disord 2012;42:2515–8.
41. Traynor JM, Doyle-Thomas KAR, Hanford LC, et al. Indices of repetitive behaviour are correlated with patterns of intrinsic functional connectivity in youth with autism spectrum disorder. Brain Res 2018;1685:79–90.
42. Cerliani L, Mennes M, Thomas RM, et al. Increased functional connectivity between subcortical and cortical resting-state neteworks in autism spectrum disorder. JAMA Psychiatry 2015;72:767–77.
43. Duerden EG, Oatley HK, Mak-Fan KM, et al. Risk factors associated with self-injurious behaviors in children and adolescents with autism spectrum disorders. J Autism Dev Disord 2012;42:2460–70.
44. De Cagna F, Squillari E, Roccheti M, et al. Personality disorders and ASD. In: Keller R, ed. Psychopathology in adolescents and adults with autism spectrum disorders. Cham: Springer International Publishing, 2019.
45. Dehlbom P, Wetterborg D, Lundqvist D, et al. Gender differences in the treatment of patients with borderline personality disorder. Personal Disord 2022;13:277–87.
46. Lai MC, Lombardo MV, Pasco G, et al. A behavioral comparison of male and female adults with high functioning autism spectrum conditions. PloS One 2011;6:e20835.
47. Ryden G, Ryden E, Hetta J. Borderline personality disorder and autism spectrum disorder in females – a cross-sectional study. Clin Neuropsychiatry 2008;5:522–30.
48. Chabrol H, Raynal P. The co-occurrence of autistic traits and borderline personality disorder traits is associated to increased suicidal ideation in nonclinical young adults. Compr Psychiatry 2018;82:141–3.
49. Dell'osso L, Cremone IM, Carpita B, et al. Correlates of autistic traits among patients with borderline personality disorder. Compr Psychiatry 2018;83:7–11.
50. Dell'osso L, Cremone IM, Amatori G, et al. Investigating the relationship between autistic traits, ruminative thinking, and suicidality in a clinical sample of subjects with bipolar disorder and borderline personality disorder. Brain Sci 2021;11:621.
51. Cassidy SA, Gould K, Townsend E, et al. Is camouflaging autistic traits associated with suicidal thoughts and behaviors? Expanding the interpersonal psychological theory of suicide in an undergraduate student sample. J Autism Dev Disord 2020;50:3638–48.
52. Porter C, Palmier-Glaus J, Branitsky A, et al. Childhood adversity and borderline personality disorder: a meta-analysis. Acta Psychiatr Scand 2020;141:6–20.
53. McDonnell CG, Boan AD, Bradley CC, et al. Child maltreatment in autism spectrum disorder and intellectual disability: results from a population-based sample. J Child Psychol Psychiatry 2019;60:576–84.
54. Dudas RB, Lovejoy C, Cassidy S, et al. The overlap between autistic spectrum conditions and borderline personality disorder. PLoS One 2017;12:e0184447.
55. Cumin J, Pelaez S, Mottron L. Positive and differential diagnosis of autism in verbal women of typical intelligence: a Delphi study. Autism 2021;5:1153.
56. McQuaid G, Strang J, Jack A. Borderline personality and late, missed, and misdiagnosis in female autism: a review of the literature. PsyArXiv; 2022.
57. Moran H. Clinical observations of the differences between children on the autism spectrum and those with attachment problems: the Coventry Grid. Good Autism Practice (GAP) 2010;11:46–59.
58. Cox C, Bulluss E, Chapman F, et al. The Coventry Grid for adults: a tool to guide clinicians in differentiating complex trauma and autism. Good Autism Practice (GAP) 2019;20:76–87.
59. Abdul-Hamid S, Denman C, Dudas RB. Self-relevant disgust and self-harm urges in patients with borderline personality disorder and depression: a pilot study with a newly designed psychological challenge. PLoS One 2014;9:e99696.
60. Dudas RB, Mole TB, Morris LS, et al. Amygdala and dlPFC abnormalities, with aberrant connectivity and habituation in response to emotional stimuli in females with BPD. J Affect Disord 2017;208:460–66.
61. Stoffers J, Völlm BA, Rücker G, et al. Pharmacological interventions for borderline personality disorder. Cochrane Database of Syst Rev 2010.
62. Gartlehner G, Crotty K, Kennedy S, et al. Pharmacological treatments for borderline personality disorder: a systematic review and meta-analysis. CNS Drugs, 2021;35:1053–67.
63. Storebø OJ, Stoffers-Winterling JM, Völlm BA, et al. Psychological therapies for people with borderline personality disorder. Cochrane Database Syst Rev 2020.
64. Krämer K, Vetter A, Schultz-Venrath U, et al. Mentalization-based treatment in groups for adults with autism spectrum disorder. Front Psychol 2021:3365.
65. Aviram RB, Brodsky BS, Stanley B. Borderline personality disorder, stigma, and treatment implications. Harv Rev Psychiatry 2006;14:249–56.
66. Grambal A, Prasko J, Kamaradova D, et al. Self-stigma in borderline personality disorder - cross-sectional comparison with schizophrenia spectrum disorder, major depressive disorder, and anxiety disorders. Neuropsych Dis Treat 2016;12:2439–48.
67. Fulford KWM. Facts / values: ten principles of values-based medicine. In: Radden J, ed. The philosophy of psychiatry: a companion. Oxford University Press, 2006.
68. Dudas RB. Values-based practice: how can history taking help psychiatrists explore the values involved in clinical decision-making? BJPsych Advances 2022;28:153–62.
Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the President and Fellows of Harvard College.