Is Autism a Mental Illness?

Autism spectrum disorder is a developmental disorder, not a mental illness in the traditional sense. Though listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5)—a handbook used by healthcare professionals to diagnose mental health conditions—autism is classified as a neurodevelopmental disorder.

This question often comes up because people with autism are at a greater risk for developing mental health problems, and characteristics of autism overlap with certain mental illnesses. As a result, autism is often not only incorrectly believed to be a mental illness, but misdiagnosed as one.

While there can be, and often are, people who have autism and a mental health concern, developmental disorders and mental illnesses are defined, treated, and managed very differently.

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Developmental Disability vs. Mental Illness

According to the National Institute of Mental Health (NIMH), a developmental disability is "a severe, long-term disability that can affect cognitive ability, physical functioning, or both. These disabilities appear before age 22 and are likely to be lifelong. The term 'developmental disability' encompasses intellectual disability but also includes physical disabilities."

Any mental illness, according to the NIMH, is "a mental, behavioral, or emotional disorder. A mental illness can vary in impact, ranging from no impairment to mild, moderate, and even severe impairment."

Serious mental illness, according to the NIMH, is "defined as a mental, behavioral, or emotional disorder resulting in serious functional impairment, which substantially interferes with or limits one or more major life activities."

Developmental Condition
  • Present at birth or before age 18

  • Symptoms are persistent, day in and day out

  • May cause physical, cognitive, and/or behavioral challenges

  • Core symptoms cannot be cured or effectively treated with medication

  • Will effect someone for life

  • Are typically diagnosed by a psychologist or developmental pediatrician

Serious Mental Illness
  • May arise at any point in one's life

  • Symptoms may be temporary or cyclical

  • Cause disturbances in thinking and perception

  • May cause hallucinations and delusions

    May be effectively treated with medication

  • Diagnosed by a psychiatrist or other mental health professional

Other Conditions

To further understand the difference between these, it may help to know issues other than autism that are characterized as developmental disorders, as well as some defined as mental illnesses.

Other developmental disorders include:

  • Cerebral palsy
  • ADHD
  • Hearing loss
  • Learning disabilities
  • Down syndrome
  • Blindness from birth

Other mental illnesses include:

Common Misdiagnoses

Autism is not always a child's first diagnosis, particularly if they are verbal and of average intelligence. Not infrequently, children who wind up with an autism diagnosis receive a range of other diagnoses first including, in some cases, mental disorders such as attention deficit hyperactivity disorder (ADHD).

There is a simple reason for these misdiagnoses: A child who is bright and verbal may not be evaluated for autism. As a result, the child's symptoms are viewed not as a set of related challenges, but as individual issues that could potentially be signs of another mental illness.

There are a number of behaviors in autism and other mental illnesses that may share characteristics and lead to an erroneous diagnosis.

Anxiety-Related Behaviors

Children with autism may perseverate on particular routines, objects, or phrases. This behavior is usually a tool for self-calming in autism.

However, the behavior can also seem nearly identical to the anxiety-related behaviors that are a hallmark of obsessive-compulsive disorder.

Deficits in Social Communication

Children with autism may hyper-focus on their areas of particular interest, essentially ignoring the interests and concerns of others. In autism, this behavior is the result of deficits in social communication. In essence, children with autism may be unaware that others have thoughts and feelings different from their own.

This could be another potential area of misdiagnoses, however, since the behavior itself can very much resemble some of the self-obsession that may be present in narcissistic personality disorder.

Losing Control of Emotions

Children with autism often lose control of their emotions and experience meltdowns (emotional and sometimes violent temper tantrums). In autism, meltdowns are almost always the result of either sensory assaults, anxiety, frustration, or a combination of all three.

In a child who has not been diagnosed with autism, however, the symptoms may look like oppositional defiant disorder which is considered a behavioral disorder.

Children with higher-functioning autism may also receive a range of inappropriate diagnoses before receiving their autism diagnosis. Some of the most common include ADHD, hyperlexia, learning disabilities, and speech delays.

It's important to note that some children with very high-functioning autism may not be diagnosed until they are well into their teens or even adulthood. When that happens, it can be tricky. Developmental disabilities usually appear in childhood, and it may be necessary to dig into an individual's past to unearth signs that disabilities existed prior to adulthood.

If childhood information isn't readily available, it may be impossible to provide an autism spectrum diagnosis even if it is the most appropriate diagnosis based on symptoms and behavior.

Common Conditions Among People With Autism

Though autism may be mistaken for (and misdiagnosed as) a mental illness, it is important to note that it is common for people with autism to also have one. In fact, mental illness is more common among people with autism than it is among the general population.

The most common co-occurring mental illnesses for people with autism include depression and anxiety.

It's not completely clear why this may be the case. One theory suggests that there is a genetic link between autism and mental illness. Another theory points to the challenges of living in the modern world faced by people with autism. The fact is that for many people with autism, it is anxiety-provoking and depressing to attempt to overcome social, sensory, and/or intellectual challenges that are simply part of who they are.

In addition to mental illness, many children and adults with autism receive additional developmental diagnoses. While it can be argued in many cases that the symptoms are associated with autism, it is sometimes helpful to know that a child is both autistic and, for example, diagnosable with ADHD, learning disabilities, hyperlexia, Savant Syndrome, or another disorder.

A secondary diagnosis, while it may or may not be completely appropriate, can sometimes provide direction for therapy, academic support, and services. Hopefully, in doing so, this could correct any potential misdiagnoses moving forward.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Alliance on Mental Illness. Autism.

  2. National Institute of Mental Health. Mental Illness.

Additional Reading

By Lisa Jo Rudy
Lisa Jo Rudy, MDiv, is a writer, advocate, author, and consultant specializing in the field of autism.