Co-occurring conditions

It’s reported that at least 1 in 3 people with autism also have attention deficit hyperactivity disorder (ADHD). Some research even indicates that anywhere between 30-80% of autistic people will meet the ADHD diagnostic criteria.  

Autism and ADHD share a lot of common characteristics, including sensory sensitivities, language delays, social and communication challenges and issues around emotional regulation.

People on the autism spectrum are often more likely to experience mental ill-health or develop a mental health condition than non-autistic people. For example, rates of anxiety and depression are 70% higher among autistic people than the general population. Here are some of the more common co-occurring mental health conditions experienced by people with autism:

• ‍Anxiety: One in five autistic people is reported to also have an anxiety disorder, with 40-60% of autistic children experiencing anxiety frequently in their day-to-day lives. Social Anxiety Disorder and Obsessive Compulsive Disorder are the most common anxiety disorders that can co-occur with autism. For people with autism, anxiety can manifest as repeatedly asking questions, having difficulty sleeping or engaging in self-harm or self-injurious behaviours. The social and communication challenges some people with autism face can also trigger anxiety in social situations.
• Depression: Depression is four times more common among autistic individuals than people who are not on the autism spectrum. Late adolescents, adults and those with substantial support needs and a higher verbal IQ are the most likely to develop a depressive disorder within the autistic population, particularly if they experience bullying. It’s important to note that depression in autistic people often doesn’t present as simply feeling or appearing sad. For example, many children with autism who also have depression experience irritable moods in addition to feeling low.
• Bipolar disorder: Around 1 in 20 autistic people experience a serious mental health condition, such as bipolar disorder or schizophrenia. As is the case for neurotypical people, people with bipolar disorder and autism usually begin to experience symptoms in their late teenage years or early twenties. Some people can begin to experience bipolar disorder symptoms in childhood, but this is rare, particularly for autistic people.  
• Eating disorders: Growing research suggests that there may be a link between autism and eating disorders, with one in four people with an eating disorder also meeting the diagnostic criteria for autism. Anorexia nervosa is one of the most common eating disorders experienced by autistic people, with 20% of people with the condition also demonstrating autistic traits. Other eating disorders that disproportionately impact people with autism include Avoidant Restrictive Food Intake Disorder (ARFID) and PICA.

Epilepsy and other seizure disorders are more common among autistic people than the general population. Around 12% of the autistic population will also have epilepsy, in comparison to 1% of the general Australian population. People with autism and a co-occurring intellectual disability are also more likely to develop epilepsy.

Roughly 7% of children with cerebral palsy also have autism spectrum disorder. These 2 conditions are not related to one another but can co-occur and affect childhood development. CP primarily affects movement while autism mostly affects communication, behavior, and social interactions. However, causes and symptoms can overlap.