Special needs

Co-occurring Conditions with Autism

ADHD, anxiety and OCD are common among autistic people.

Co-occurring Conditions with Autism


My son Andrew exhibited puzzling behaviours as a child. He was impulsive, easily distracted and couldn’t sit still. He constantly worried about everything and repeatedly asked for reassurance. The initial diagnosis was ADHD and anxiety, but my husband and I felt that there was more to it.

Andrew couldn’t maintain eye contact and had tics, emotional meltdowns and repetitive behaviours. He would flap his hands and rub the top of his head in a circular motion.

At nine, he suddenly erupted into non-stop compulsive rituals, sweeping the floor with his hands for hours, endlessly walking back and forth through doors, and repeatedly brushing his head against poles.

It was at that point that he was fully diagnosed with autism as his umbrella diagnosis, along with Tourette Syndrome, Obsessive Compulsive Disorder, ADHD and learning disabilities.

The majority of autistic children have co-occurring conditions. In fact, according to the 2019 Canadian Health Survey on Children and Youth, “Children and youth with ASD were three times more likely to have another long-term health condition compared to those without ASD.”

Co-occurring versus comorbid

Many autism advocates and allies have moved away from using the term “comorbid” to describe conditions that accompany autism. Instead, they prefer to use “co-occurring conditions” so as not to frame autism in a negative, “morbid” light.

child standing in front of other kids and a school bus and looking sad iStock

What are some common physical health co-occurring conditions?

Medical issues are common in autistic children and can be particularly difficult to diagnose in those who cannot express how they feel. Luckily, there are many ways to help so that children do not have to experience these issues over the long-term.

Sleep disturbances

Many autistic children have chronic sleep problems, whether falling asleep or staying asleep. These can exacerbate behavioural and learning problems. Your child’s clinician can share tips on how to set up their bedroom and consistent routines to create an optimal sleep environment.

Gastrointestinal issues


Dr. Melanie Penner, Senior Clinical Scientist and developmental paediatrician at Holland Bloorview Kids Rehabilitation Hospital and Senior Clinician Scientist at the Bloorview Research Institute, calls GI issues “frequent fliers” with autism, ranging from constipation and diarrhea to abdominal pain and gastroesophageal reflux.

Clinicians carefully assess factors such as what and when the child eats, how their food is prepared and how much water they drink before proposing potential solutions.

child sad looking at a light up water feature iStcok

Feeding and eating issues

Many autistic children have restricted food habits, sensory issues with certain food textures, tastes and smells, the need for sameness, and the inability to sense when they are full. Andrew has eaten the same peanut butter and banana sandwich every day for years, dislikes the texture of non-smooth foods like cottage cheese and eats so quickly that he consistently overeats.


Studies consistently report a higher prevalence of epilepsy in autistic children than in the general population. There can be a genetic link, and seizures can start at birth through adolescence. Children with intellectual disabilities also have a greater incidence of seizures.

In addition to classic, obvious seizures, Dr. Penner says there can be more subtle seizures in which a child doesn’t respond to other people or to touch, making them tricky to diagnose. Doctors often order an electroencephalogram (EEG) to measure activity in the brain, and medications may be prescribed.

What about mental health and neurodevelopmental co-occurring conditions with autism?


Many common co-occurring conditions have behaviours that overlap and look alike, making them difficult to diagnose. As with autism, they are treated through various therapeutic approaches, as well as medications as needed.


Dr. Penner calls autism and ADHD “chummy bedfellows.” A number of the symptoms are hard to separate. She focuses on developing an integrated understanding of a child’s strengths, challenges, and what soothes them and makes them tick. Common therapeutic approaches include behavioural therapies and education for families and children.


Anxiety disorders affect more autistic children than those in the general population. These can include generalized anxiety, separation anxiety, and specific phobias. Dr. Penner notes it can be difficult to determine if the anxiety is occurring on its own or resulting from difficulties related to autism.

For example, sensory sensitivities related to autism may cause distress when the school bell loudly rings. Common therapeutic approaches include cognitive behavioural therapy, relaxation techniques and strategies like mindfulness when a child has difficulty expressing themselves.

child sitting on the floor with his head in his knees looking defeated iStock


In OCD, disturbing thoughts force an individual to engage in repetitive rituals to try and relieve these thoughts. Andrew’s brain told him that his sister would be kidnapped unless he touched his bedroom walls repeatedly — for hours.


The child knows their obsessions and compulsions make no sense, but their brain overrides reason and they cannot stop. And these behaviours can be difficult to differentiate from autism at times. Dr. Penner explains that we need to distinguish between repetitive egosyntonic behaviours that make sense to a child, like calming behaviours, and repetitive egodystonic behaviours, like OCD, which cause distress.

This means it is sometimes important not to teach a child to stop certain rituals that soothe them. Common therapeutic approaches include exposure and response prevention.


Studies report that mood disorders are generally more prevalent in autistic children than in the general population. Depression tends to increase with age and is correlated with intellectual ability. Communication challenges in autism can mask depression, so Dr. Penner and her colleagues look for changes in behaviour, such as a lack of enthusiasm for favourite activities, increased withdrawal or changes in appetite or sleep.

Additional common co-occurring neurodevelopmental disorders include intellectual disabilities, learning disabilities and speech disorders.

It’s important to identify your child’s co-occurring conditions, although they can complicate diagnoses and services. As outlined above, each disorder can benefit from different therapeutic approaches and supports. As parents, we need to take a holistic view of our child in order to optimize their success.


When Andrew rubs his shoulders repeatedly, I sometimes cannot tell if he is stimming (autism), engaging in a ritual (OCD) or ticcing (Tourette Syndrome). There’s lots of trial and error involved, but with determination, perseverance and consistency, our children can significantly benefit. Andrew certainly has.


Jan Stewart is a highly regarded mental health and neurodiversity advocate. Her brutally honest memoir Hold on Tight: A Parent’s Journey Raising Children with Mental Illness describes her emotional roller coaster story parenting two children with multiple mental health and neurodevelopmental disorders.

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Jan Stewart is a highly regarded mental health and neurodiversity advocate. Her brutally honest memoir Hold on Tight: A Parent’s Journey Raising Children with Mental Illness describes her emotional roller coaster story parenting two children with multiple mental health and neurodevelopmental disorders. Her mission is to inspire and empower parents to persevere through the most difficult of times and have hope, as well as to better educate their families, friends, health care professionals, educators and employers. Jan chairs the Board of Directors at Kerry’s Place Autism Services, Canada’s largest autism services provider, and was previously Vice Chair at the Centre for Addiction and Mental Health. She spent most of her career as a senior Partner with the global executive search firm Egon Zehnder. Jan is a Diamond Life Master in bridge and enjoys fitness, genealogy and dance.