Autism spectrum disorder (ASD) and schizophrenia are considered separate disorders. Both can vary a lot in their symptoms, but both affect how the brain develops.

The two conditions may share similar symptoms, but there are key differences that are important to know in order to get a correct diagnosis.

The National Institute of Mental Health (NIMH) considers ASD to be a spectrum disorder since symptoms vary a lot from person to person. The main symptoms include both:

  • restricted and repetitive behaviors
  • difficulties communicating or being in social situations

According to a 2019 review, some researchers also consider schizophrenia to be a spectrum disorder because of the variations in symptoms. The NIMH says that schizophrenia is usually diagnosed based on:

  • symptoms of psychosis, like hallucinations and delusions
  • negative (or missing) symptoms
  • cognitive impairments

People with schizophrenia may also have symptoms that are seen in ASD.

On the other hand, 2018 research suggests that autistic people are up to 3.55 times more likely to also have a schizophrenia diagnosis. But this doesn’t mean that an autistic person will automatically develop schizophrenia, or vice versa.

Genetics

ASD and schizophrenia may have a genetic link. Some disorders are caused by changes to our chromosomes, the molecules that carry our genetic code. A 2017 study shows that a deletion on chromosome 22 may lead to the development of certain disorders, including ASD and schizophrenia.

But according to another 2017 study, they’re unlikely to develop together. Scientists think that ASD and schizophrenia may be two different outcomes from the same genetic syndrome.

A 2021 study also suggests that children of parents with schizophrenia are much more likely to have autistic traits. These findings support older studies, which showed that children of parents with schizophrenia were up to three times more likely to receive an ASD diagnosis.

Studies so far have had small sample sizes. More research is needed to fully understand how genetics influence ASD and schizophrenia.

Brain imaging

Both ASD and schizophrenia are neurodevelopmental disorders. That means they affect how the brain develops. Through brain imaging, scientists can see similarities between the brains of autistic people and those with schizophrenia.

According to 2018 research, similarities include:

  • reduced gray matter, the outer part of the brain where processing takes place
  • altered white matter, deeper brain tissue where the brain’s connections are made
  • reduced activity in parts of the brain related to social interactions and language

Symptoms of both ASD and schizophrenia are grouped into the following categories:

  • positive
  • negative
  • cognitive

We’ll explain what these mean, how they might be seen in both conditions, and which symptoms are unique.

Positive symptoms

Positive symptoms are those that are present in people with the condition, but not present in neurotypical people.

Positive symptoms of ASD and schizophrenia tend to be unique to each condition. They’re the simplest way to tell the two conditions apart.

Symptoms vary significantly between individuals. But according to a 2020 study, some of the most common positive symptoms include:

SymptomASDSchizophrenia
hallucinations
delusions
exaggerated speech
incoherent speech
talking to oneself
echolalia
repetitive body movements
lack of body movements
repetitive behaviors
sensory sensitivities

Negative symptoms

Negative symptoms are the absence of “normal” functions. They’re things that are present in most people, but absent in people with the condition.

Negative symptoms of ASD and schizophrenia tend to be similar. Research shows that such similarities mainly affect communication and emotional interactions with others. These may include:

  • perceived inability to identify or express emotions
  • “flat” voice tones
  • lack of facial expressions
  • reduced eye contact
  • perceived apathy
  • reduced physical gestures
  • social withdrawal or lack of social interest
  • reduced speech

Cognitive symptoms

Cognitive symptoms are when understanding, memory, and concentration are impaired. This can affect someone’s ability to learn or complete tasks.

Like with negative symptoms, ASD and schizophrenia have some similar cognitive symptoms. But cognitive differences in people with schizophrenia tend to be more severe.

According to a 2019 review, some cognitive abilities that may be different include:

  • processing speed
  • attention
  • verbal learning
  • visual learning
  • language comprehension
  • working memory
  • spatial perception
  • reasoning and problem solving

In a 2020 study, people with schizophrenia had more severe impairments across the board than autistic people. This was especially true for working memory, language, perception, and reasoning.

It’s important to know the difference between ASD and schizophrenia. This can help you get a correct diagnosis and connect you with helpful therapies and interventions.

Several other conditions may also co-occur with either ASD or schizophrenia. Many of these conditions share similar symptoms. This can further increase the chances of misdiagnosis.

For example, 2020 research found that ASD can co-occur with:

Schizophrenia may co-occur with:

Diagnosing ASD

ASD may be diagnosed during a young child’s wellness exam with their pediatrician. The pediatrician will ask the child’s caregiver a series of questions about the child’s development, such as their speech and communication skills. They will also ask about any restricted and repetitive behaviors.

ASD is a complex condition. Your child’s pediatrician may refer them to one or more of the following professionals for additional evaluation:

  • pediatric neurologist
  • child psychologist or psychiatrist
  • neuropsychologist
  • speech-language pathologist
  • occupational therapist

Diagnosing schizophrenia

A mental health professional may make a schizophrenia diagnosis after someone has experienced symptoms of psychosis. They may focus less on developmental stages and social-communication skills.

The first episode of psychosis will usually occur in late adolescence or early adulthood. But the NIMH says most people with schizophrenia will experience some symptoms, such as mood and thinking changes, as early as mid-adolescence.

Childhood-onset schizophrenia

In very rare instances, doctors may diagnose schizophrenia in someone under the age of 13. This is called childhood-onset schizophrenia (COS). Less than 1 in 40,000 children get this diagnosis, according to a 2019 review. Because COS is so rare, it is not well understood and difficult to diagnose.

Early negative symptoms of COS can look like autism. In fact, until 1980, autism was called “childhood schizophrenia.”

It can also be difficult to accurately identify positive symptoms in COS. Some childish behaviors can be confused for psychosis. It’s also harder for children to describe their symptoms to a doctor.

Before positive symptoms occur, children usually show warning signs. According to 2014 research, these may include:

  • shyness
  • loneliness
  • depression
  • aggression
  • thoughts of suicide
  • theft
  • bizarre behavior

Therapies and support for ASD

“Treatment” for ASD is a subjective term. Instead, you may consider “treatment” as a way to help you feel better and function in social situations, work, and school.

Interventions for ASD may start at a young age and include a combination of the following:

  • behavioral therapy
  • social groups
  • occupational therapy
  • speech therapy
  • educational support, such as an individualized education plan (IEP) at school
  • medications to help treat anxiety, aggression, and other concerns if needed

Treating schizophrenia

Treatment for schizophrenia mainly involves medications and therapies, including:

  • antipsychotic drugs to help treat symptoms of psychosis
  • cognitive behavioral therapy, which may also help address negative symptoms
  • psychosocial therapies to help improve coping skills for participating in school, work, and social situations
  • coordinated specialty care, which combines the above medications and therapies for a comprehensive treatment approach
  • assertive community treatment to support people with repeated hospitalizations or homelessness

ASD and schizophrenia share genetic components. According to 2020 research, genetics may increase the chances of developing either condition, and sometimes both. However, there’s not a single gene known to predict whether or not they will develop.

Factors that increase the chance of having ASD may include:

  • being born at a low birth weight
  • being born to older parents
  • having an autistic sibling
  • the presence of certain genetic conditions, such as fragile X, Down, or Rett syndrome

The NIMH says that known risk factors for schizophrenia include:

  • brain changes that may occur before birth or during puberty
  • exposure to viruses before birth
  • nutritional problems before birth
  • growing up in a high stress environment
  • living in poverty

It’s important to understand that having any one of these factors doesn’t automatically mean a person will develop ASD or schizophrenia.

Both ASD and schizophrenia tend to develop at a young age. Therapies and other interventions may be most effective when started at a younger age.

The symptoms of each condition can differ a lot from person to person. The outlook can also differ with each person.

ASD is considered lifelong, but early interventions can increase the likelihood of independence in adulthood.

The outlook for schizophrenia is also varied. Some people go into remission from their symptoms. Others may continue to experience symptoms or go through periods of remission and recurrence. Worldwide, the World Health Organization (WHO) estimates that one in three people will fully recover.

ASD and schizophrenia share some similar symptoms, especially when it comes to social interaction and communication. However, despite any similarities, ASD and schizophrenia are two separate conditions that each have unique symptoms.

It’s important to avoid self-diagnosing any developmental or mental health condition. If seeking therapies or other interventions, a professional diagnosis is essential to help you get started.