An autism misdiagnosis is possible because there are many other disorders that have similar symptoms. As rates of autism have risen, more people have become concerned that the condition is being misdiagnosed.

Diagnosing Autism

The Centers for Disease Control and Prevention (CDC) explains that there is no laboratory test for autism. Before they can determine the presence of autism, doctors and specialists must observe the behaviors and listen to the concerns of parents and caregivers of young children who are suspected to be neurodevelopmentally challenged. 

What can make diagnosing autism difficult and misdiagnosis possible is that autism spectrum disorder has a wide range of symptoms. Some autistic people have high IQs and live independently. Others have severe developmental disabilities and will likely need some form of supervised care for their entire lives. Still others fall somewhere in between.

The 18-Month Checkup

Getting an autism diagnosis starts with a pediatrician giving an assessment to young children, starting as early as their routine 18-month checkup. The pediatrician will watch the child and engage with them to see if they respond to smiles, facial expressions, and external stimuli. 

The pediatrician will also ask the parents if they have noticed if the child is slow to talk, play with others, and react to sounds, and if there is any family history of autism. 

Specifically, the pediatrician will ask if the child started smiling by 6 months, mimicking facial expressions by 9 months, and verbalizing (cooing and other baby sounds) by 12 months. 

Additionally, the pediatrician will ask about any kinds of repetitive or unusual behavior, such as the child:

  • Not making eye contact.
  • Being unresponsive when someone tries to get their attention.
  • Showing extreme sensitivity to lights, sounds, or tactile sensations.
  • Having problems with sleep or digestion.

Autism Specialists

Any one of these criteria could be a sign of autism, but the pediatrician will not make that determination; instead, they will refer a child to specialists. These can include the following: 

  • Child psychologists 
  • Speech-language pathologists 
  • Occupational therapists 
  • Developmental pediatricians 
  • A neurologist 

These specialists are trained to evaluate the child’s cognitive abilities and their motor skills, and to assess how the child performs basic tasks like dressing themselves, eating, and going to the bathroom. 

In order for there to be a positive diagnosis of autism spectrum disorder (ASD), the child must meet the criteria set out in the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association. The DSM-5 (5th edition) says that a child suspected of having autism must fit into at least two of the following categories:

  • Communication and social interaction challenges (difficulty connecting with other people, making eye contact, understanding social dynamics, or even having a conversation)

  • Restricted and repetitive behaviors (such as rocking back and forth, reacting badly to any changes in routine, repeating phrases when they are stressed, and obsessive levels of interest in a single subject)

Is Autism Being Misdiagnosed?

Over time, as more people have become more aware of autism and its different presentations, the rate of diagnosis of the condition has risen

As recently as the 1980s, many people with autism symptoms were institutionalized. Now the research has shown that parents who are aware of how autism presents are more likely to consult specialists for a diagnosis compared to parents who have little to no knowledge on the topic. 

This knowledge is mainly derived from knowing someone with ASD, having an autistic family member, or having access to health care and educational resources that explain what autism is and what the signs are.

There are other reasons people might be more aware of autism than they were in the past. In 2006, the American Academy of Pediatrics recommended that the 18-month screening for autism be extended for all children during routine pediatric visits and not just for infants who displayed signs of potential developmental delays.

This might have led to diagnoses specialists might otherwise have missed. It could also have increased the possibility of misdiagnosis in children who did not have autism. 

The Diagnosis Debate

In the attempt to increase the scope of what neurodiversity entails, some scientists and researchers have wondered if the criteria for autism diagnoses have been diluted so much that any form of neurodiversity, no matter how mild, becomes a possibility for an autism diagnosis. 

Some advocates have praised this, suggesting that more people being diagnosed with ASD means that more people will be able to access treatment and find community. But critics have suggested this reframing of neurodiversity will make autism overdiagnosed. 

An article in JAMA Psychiatry warns that the time might come when there will be “almost no difference” between people who are diagnosed with autism and those who are not. The findings of a meta-analysis of 11 studies suggest that differences between individuals with autism and those without autism have decreased over time, which may be associated with changes in diagnostic practices

Another researcher suggested it might even be possible that the gap between the neurodiverse and neurotypical population could one day be closed due to the greater awareness of autism and its many presentations. This has led to more support, more accessible health care, less stigma, and more autistic people feeling empowered to claim their diagnoses and their neurodiversity. 

Conversely, this could mean that diagnosing autism becomes muddier because the medical understanding of the condition is constantly evolving

Similar Conditions & Diagnosis Errors

Another factor that might add to the rate of autism misdiagnosis is that there are other conditions that have similar symptoms, which might cause some initial confusion for caregivers and specialists alike. Examples of such conditions include the following:

  • Intellectual disability describes below-average intelligence or cognitive functioning. People are often very delayed and slow to learn skills they need for everyday living. This is, again, similar to how some people with autism can experience cognitive development delays.

    But intellectual disability is not the same kind of neurodevelopmental disorder as autism. Since some people with autism might have intellectual disability, there is overlap even though the two conditions are separate. This may lead some specialists to diagnose autism in a person with intellectual disability.

  • Schizophrenia has a history of mistakenly being identified as autism. There is a significant deal of overlap between these two conditions because people who have one share a number of cognitive and interpersonal challenges with people who have the other.

    Some research has found that people with disorders on the schizophrenia spectrum have high levels of autism symptoms when compared to those in a control group. 

Obsessive-Compulsive Disorder & Selective Mutism

Specialists sometimes mistake obsessive-compulsive disorder (OCD) for autism because people display similar signs, such as unusual and repetitive behavior. They might react negatively if their routines are disrupted. However, people with OCD generally do not experience any delays in their communication and social skills. 

Selective mutism is a condition where a child cannot communicate and engage with others in specific social settings, but they can communicate and speak typically in places where they feel safe and comfortable. Selective mutism is categorized as an anxiety disorder rather than a developmental disorder, such as autism.

The Neuropsychiatric Disease and Treatment journal reports that there is a “high risk of overlap” between the two conditions, however. This might lead to some children receiving erroneous autism diagnoses because of the more immediate presentation of symptoms similar to those shown in selective mutism.

Avoidant Personality Disorder

Avoidant personality disorder (APD) describes a condition where a person displays a consistent pattern of being incredibly shy and very sensitive to criticism from others. They have a deep feeling of inadequacy and a pathological sensitivity to rejection. This causes them to avoid exposing themselves to that kind of risk in professional, social, and personal situations.

APD is very distinct from autism. People with APD tend to want social connections but are deeply afraid of seeking them out for fear the experience will be scary or humiliating. 

People with ASD, however, are much less inclined to want social engagements. But the two different conditions have this similar presentation, which is why people who might have avoidant personality disorder might get a diagnosis of autism.

Reactive Attachment Disorder

Reactive attachment disorder is a rare condition where an infant or young child does not establish any healthy attachments with their parents or caregivers. This can happen in households where the child’s primal needs for comfort and affection are not met. But it can also happen in situations where the caregivers try to offer caring, stable engagements with the child. 

Reactive attachment disorder is more typically found in children who grew up in disruptive environments or had to move around a lot. In rare cases, in situations where parents and caregivers are loving and attentive, the children do not respond to overtures of comfort and can even appear fearful of their parents or caregivers for no discernible reason. 

This is a rare condition with obvious similarities to autism, so much so that a specialist immediately thinks ASD is the correct diagnosis. However, if the child does not display the other classic symptoms of ASD (such as stimming or having an obsessive interest in only one pursuit), this might be another case of an autism misdiagnosis.