Misdiagnosed and Misunderstood: When Autism Is Mistaken for Borderline Personality Disorder
In mental health services, especially during crisis, it is easy for complexity to be mistaken for clarity. A 2022 case study by Stine Iversen and Arvid Nikolai Kildahl shows just how damaging that mistake can be. The case describes a young man with autism, depression, and ADD who was misdiagnosed with Borderline Personality Disorder for years. That misunderstanding led to inappropriate treatment, repeated hospital admissions, and worsening distress, until clinicians with autism expertise looked again and saw a very different picture.
A crisis presentation led clinicians in the wrong direction
The young man in the case study, referred to as Adrian, first came into psychiatric care during a period of serious crisis. He was self-harming repeatedly, had attempted suicide, and was experiencing depression and anxiety. At the age of eighteen, he was diagnosed with Borderline Personality Disorder. On the surface, the diagnosis appeared understandable. He was emotionally distressed, unstable, and engaging in non-suicidal self-injury, all of which can be associated with BPD.
But over time, parts of the picture did not fit. Adrian was not described as highly conflictual in relationships. He did not seem driven by the classic BPD pattern of intense, chaotic closeness followed by rage or frantic efforts to prevent abandonment. Instead, he often withdrew. He felt overwhelmed by emotions in a broad, undifferentiated way rather than specifically by rejection or unstable attachment. He struggled socially, but not in the same style that clinicians often see in BPD.
This matters because in mental health services, once a diagnostic label is applied, new information can be interpreted through that label rather than prompting a fresh look. In Adrian’s case, the presence of crisis and self-harm seemed to overshadow other clues that might have pointed clinicians in a different direction.
When someone presents in crisis, the most obvious symptoms can dominate the picture and hide the real cause of distress.
What was missed was autism
A later assessment changed everything. Once Adrian was seen by a team with more specialist knowledge of autism, clinicians used gold-standard autism assessment tools and took a detailed developmental history. This more careful process revealed clear signs of autism that had previously been missed.
His communication style was rigid. His emotional world was difficult for him to name and explain. He had marked difficulty understanding social situations and other people’s intentions. These were not signs of emotional manipulation, unstable identity in the classic BPD sense, or deliberate interpersonal drama. They were signs of a neurodevelopmental difference that had not been recognised.
This is one of the most important messages in the case. Autism can be missed in adolescence and adulthood, especially when someone also has depression, anxiety, ADD, trauma, or repeated crisis presentations. Once mental health difficulties become the focus, clinicians may stop asking the developmental questions that are needed to identify autism properly.
As a result, the person may spend years being treated for the wrong condition while the real source of their difficulty remains misunderstood.
Why self-injury can lead to a misleading BPD diagnosis
One major reason Adrian was diagnosed with BPD was his repeated non-suicidal self-injury. In many clinical settings, self-harm quickly raises the possibility of BPD, especially when the person is emotionally distressed. But the case study makes an important point: self-injury does not belong only to one diagnosis, and the meaning of self-injury can differ greatly depending on the person.
In autism, self-injury may be linked less to interpersonal conflict and more to internal overload. A person may hurt themselves when emotions become intolerable, confusing, or impossible to communicate. The behaviour may serve as a way to interrupt distress, release inner tension, or create some sense of control when the emotional world feels unmanageable.
Adrian described hurting himself when alone and using self-injury to escape feelings he could not identify clearly. He was not primarily using it to influence others, gain attention, or test relationships. He was trying to cope with internal states that felt unbearable and difficult to organise.
For carers and professionals, this is a crucial distinction. If clinicians assume all self-harm points toward BPD, autistic people may be misunderstood in ways that deepen rather than reduce distress.
Self-harm may look similar across diagnoses, but the reasons behind it can be very different. Surface behaviour does not always reveal the real mechanism.
Autism and BPD can look similar on the surface
The case study shows why confusion happens. Autism and Borderline Personality Disorder can overlap in ways that mislead clinicians. Both may involve emotional dysregulation, difficulty with social relationships, confusion about identity, distress in everyday life, and periods of crisis. If assessment stays at the level of visible symptoms, the two conditions can appear deceptively alike.
But the roots are different. In BPD, emotional crises are often closely linked to fear of abandonment, unstable attachment, and rapidly shifting relationship dynamics. In autism, distress may be more closely related to social confusion, sensory overload, rigid thinking, exhaustion from masking, or a lifetime of misunderstanding and exclusion.
The rhythm of the distress is often different too. Someone with BPD may respond to emotional pain through volatile relationship patterns. Someone with autism may withdraw, shut down, or become overwhelmed by stimuli, ambiguity, or emotional complexity. These distinctions matter enormously because the right support depends on understanding what is driving the distress.
Without that understanding, clinicians may see emotional instability and assume one diagnosis when the real story lies elsewhere.
What changed once the diagnosis became accurate
One of the most hopeful parts of the case is what happened after Adrian was correctly identified as autistic. His treatment changed in important ways. Antipsychotic medication was reduced or stopped. The therapeutic focus shifted away from assumed relational pathology and toward helping him understand emotions, build structure, and manage overload.
This was not a small adjustment. It was a completely different way of seeing the person. Instead of asking why he seemed emotionally unstable in a borderline way, clinicians began asking what made him overwhelmed, what support he needed to interpret his inner world, and how the environment could become safer and more manageable.
The effect was striking. Within weeks, Adrian became more communicative and more engaged. Self-harm reduced significantly. Most importantly, he finally felt understood. That sense of being accurately seen appeared to bring greater safety and calm.
This illustrates something very important for carers. Diagnosis is not just a label. It shapes the whole direction of treatment, the assumptions professionals make, and the kinds of support a person receives. When the diagnosis is wrong, everything that follows may be built on the wrong foundation.
When Adrian was understood through the lens of autism rather than BPD, treatment became more appropriate, distress reduced, and safety improved.
Why autism is often missed in complex mental health presentations
This case also raises a broader question: why is autism still missed so often, especially in people with complex mental health needs? One reason is that autism is sometimes imagined too narrowly. Some clinicians still look mainly for very visible childhood signs or for stereotypical presentations, and may not recognise autism in young adults whose difficulties have been masked by depression, anxiety, ADHD or ADD, trauma, or years of trying to fit in.
Another reason is that mental health crises naturally pull attention toward immediate risk. When someone is self-harming, suicidal, distressed, or repeatedly admitted to hospital, services often focus on managing danger first. That is understandable. But if deeper developmental assessment never follows, the person may remain trapped in a cycle of crisis care without anyone asking whether autism is part of the picture.
In Adrian’s case, only a more detailed and autism-informed assessment revealed what had been missed. This suggests that services need not only more awareness, but also better access to the right tools and expertise.
What carers can learn from this case
For carers, the case offers both warning and reassurance. The warning is that a diagnosis given during crisis may not always be complete or accurate, especially when the person’s history and developmental profile have not been explored carefully. The reassurance is that when a person is properly understood, treatment can improve dramatically.
Carers are often the people who notice patterns that services miss. They may know that the person has always struggled with rigidity, sensory distress, social misunderstandings, or difficulty naming feelings. They may also see that crises happen less around fear of abandonment and more around overload, confusion, and exhaustion. These observations are not minor details. They may be central to understanding the whole picture.
That is why carers should feel justified in asking for fuller assessment when something does not seem to fit. If the diagnosis explains some behaviours but leaves major parts of the person unexplained, it may be worth asking whether autism, ADHD, trauma, or other developmental factors have been properly considered.
Accurate diagnosis is not about collecting labels. It is about making sure the person gets support that fits their actual needs.
Carers often hold the developmental story that crisis services do not see. That story can be vital in preventing misdiagnosis.
The cost of getting it wrong
Misdiagnosis is not a neutral mistake. As this case shows, it can lead to years of inappropriate treatment, repeated hospitalisation, unnecessary medication, and worsening despair. It can also damage the person’s sense of self. If someone is repeatedly told they have a personality disorder when the real issue is misunderstood autism, they may begin to see themselves as emotionally manipulative, fundamentally disordered, or beyond help.
That kind of misunderstanding can deepen shame and make engagement with services harder. It can also strain family relationships, because carers may be given explanations that do not match what they actually observe. Everyone ends up trying to make sense of behaviour through the wrong lens.
In Adrian’s case, correct diagnosis did not erase all difficulty, but it changed the meaning of the difficulty. He was no longer seen as someone whose distress mainly reflected borderline pathology. He was understood as someone with autism struggling with depression, attention difficulties, emotional confusion, and overload. That difference changed everything.
What mental health services need to do better
The case report points to an urgent need in mental health services. Clinicians working with people in crisis need more training in autism, especially how autism can present in adolescence and adulthood when combined with self-harm, depression, anxiety, trauma, or attention difficulties. Services also need pathways that allow developmental assessment to happen even when the immediate presentation is complex.
A rushed diagnosis based on surface similarity does not serve the person at the centre of care. Services need to listen more closely, gather fuller histories, involve the individual in understanding their own experience, and remain open to revising earlier assumptions. Good assessment is not a one-off act. It is an ongoing process of getting closer to the truth.
This is especially important because the cost of getting it wrong can be so high. Accurate diagnosis is not just a technical matter. It is part of dignity, safety, and hope.
Accurate diagnosis is not only a clinical task. It is a human responsibility that shapes treatment, dignity, and the possibility of recovery.
Conclusion
The case of Adrian is a powerful reminder that complexity in mental health should invite deeper curiosity, not quicker conclusions. Autism can be hidden beneath crisis, depression, self-harm, ADD, or trauma, and when clinicians rely only on surface features, it can be mistaken for Borderline Personality Disorder.
This matters because autism and BPD may look similar in some ways while requiring very different understanding and treatment. Adrian’s story shows how damaging misdiagnosis can be, but also how transformative accurate diagnosis can become. Once clinicians looked beneath the surface, his care changed, his distress reduced, and he finally began to feel understood.
For carers, this case underlines the importance of full assessment, developmental history, and services that are willing to question their first assumptions. The goal is not simply to name symptoms. It is to see the whole person clearly enough to offer care that truly fits.
Behind a crisis presentation there may be a very different story. When services look beneath the surface, understanding can replace years of avoidable suffering.
Source note
This article is based on the 2022 case report by Stine Iversen and Arvid Nikolai Kildahl, Mechanisms in Misdiagnosis of Autism as Borderline Personality Disorder, published in Frontiers in Psychology.
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