People with a diagnosis of autism spectrum disorder often have a variety of co-occurring health and mental health conditions, such as gastrointestinal problems and ADHD. More than 95 percent of children with autism have at least one co-occurring disorder or condition, according to a recent study from researchers at the Centers for Disease Control and Prevention. (1) More than half of the children studied (53 percent of 4-year-olds and 69 percent of 8-year-olds had four or more additional conditions.
These conditions are not part of the diagnosis of autism spectrum disorder, but occur frequently in people with autism. Identifying and treating these conditions is important but may be especially difficult in people who are nonverbal or have difficulty expressing themselves. For example, stomach discomfort or other physical problems, for example, may show up as an increase in challenging behaviors.
A person may have well above average intellectual ability and have a diagnosis of autism, however; autism is frequently associated with intellectual disability. A large national study from CDC’s Autism and Developmental Disabilities Monitoring Network in 2012 found that 32 percent of children with autism were identified with intellectual disability, 25 percent were identified in the borderline range and 44 percent were identified as average or above average intellectual ability. (2)
Gastrointestinal and eating problems
Children with autism are much more likely than other children to experience chronic gastrointestinal problems, such as constipation, diarrhea or gastroesophageal reflux. Eating related issues, including very limited food choices or avoiding particular foods, eating non-food items (pica) or overeating, are also common in children with autism.
An estimated 50–80 percent of children with autism have sleep problems, particularly trouble falling asleep or staying asleep. Sleep issues can worsen other symptoms and impact quality of life for individuals and their families. Autism researcher Olivia Veatch, Ph.D., and colleagues at Vanderbilt University note that, “disturbed sleep exacerbates core and related ASD symptoms and has a substantial negative impact on the entire family. Treatment of sleep disturbance holds promise for ameliorating many of the challenging behavioral symptoms that children with ASD and their families face.” (3)
Epilepsy (seizure disorder) is also common among people with autism, affecting as many as one in three people with autism. Epilepsy is a neurological disorder involving abnormal brain activity. Seizure symptoms can vary, but may include periods of confusion, brief periods of staring blankly, twitching in the arms or legs or loss of awareness. Epilepsy is typically treated with medication.
Behavioral health conditions
Many people with autism have psychiatric symptoms that are not part of the diagnosis of autism. About 70 percent of people with autism have one co-occurring mental health disorder and 40 percent may have two or more. (4) Anxiety, attention deficient hyperactivity disorder (ADHD) and obsessive-compulsive disorder are among the more common. ADHD affects at least one in three people with autism and because some of the symptoms and behaviors are similar between the two conditions, diagnosis can be difficult. Similarly, symptoms of OCD may be like the repetitive behavior and restricted interest symptoms of autism.
Co-occurring physical and mental health conditions may worsen autism symptoms and, in some instances, they can delay a diagnosis of autism. For example, research has found that a diagnosis of ADHD can delay a diagnosis of autism. Coping with these related or co-occurring conditions adds challenges on top of the core symptoms of autism for many individuals and their families. But identifying and treating these related conditions can help.
Many related resources for parents are available from Autism Speaks, such as help with eating issues, strategies to help with sleep, a guide to managing constipation, and a Special report on Autism and Health.
Soke GN, et al. Prevalence of Co-occurring Medical and Behavioral Conditions/Symptoms Among 4- and 8-Year-Old Children with Autism Spectrum Disorder in Selected Areas of the United States in 2010. J Autism Dev Disord. 2018 Aug;48(8):2663-2676.
CDC. Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 years – Autism and Development Disability Monitoring Network, 11 Sites, United States, 2012. Surveillance Summaries. April 1, 2016, 65(3);1-23.
Veatch, OJ, Maxwell-Horn, AC, Malow, BA. Sleep in Autism Spectrum Disorders. Curr Sleep Med Rep. 2015, 1(2): 131–140.
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Arlington, VA, American Psychiatric Association, 2013.
White SW, et al. Anxiety in Children and Adolescents with Autism Spectrum Disorders. Clinical Psychology Review, 2009, (29);216-229
Chaidez, V, Hansen RL, Hertz-Picciotto I. Gastrointestinal problems in children with autism, developmental delays or typical development. J Autism Dev Disord. 2014 May; 44(5): 1117–1127.