ADHD diagnoses are significantly elevated among autistic adults on Medicaid

An analysis of U.S. Medicaid data found that 26.7% of autistic adults without intellectual disability had an ADHD diagnosis. This was the case for 40.2% of autistic adults with intellectual disability. The paper was published in JAMA Network Open.

Autism, or autism spectrum disorder, is a neurodevelopmental condition characterized by specificities in social communication, sensory processing, and patterns of behavior or interests. It is called a spectrum because its manifestations vary widely, from individuals who need substantial daily support to those who live independently.

Autism itself is not a disease and does not inherently imply poor health. However, autistic people have higher rates of certain co-occurring physical and mental health conditions compared with the general population. These commonly include anxiety, depression, ADHD, epilepsy, sleep disorders, and gastrointestinal problems.

Barriers to healthcare access, such as communication difficulties and lack of healthcare provider training for working with autistic individuals, can worsen overall health outcomes. Chronic stress from social exclusion, stigma, or masking autistic traits can negatively impact long-term physical and mental health. At the same time, when healthcare is accessible and appropriately adapted, autistic individuals can achieve health outcomes comparable to non-autistic peers.

Study author Benjamin E. Yerys and his colleagues note that attention-deficit/hyperactivity disorder (ADHD) is one of the most commonly co-occurring mental health conditions for autistic youths. At the same time, ADHD is associated with poorer health outcomes for both autistic and non-autistic children. These authors wanted to assess how often ADHD and autism occur together.

They analyzed Medicaid claims data from 2008 to 2019. Medicaid is a joint U.S. federal and state government health insurance program that provides free or low-cost medical coverage to people with low income, disabilities, or those meeting certain other eligibility criteria.

From these data, study authors constructed four groups: autistic individuals without intellectual disability, adults with intellectual disability without autism, autistic adults with intellectual disability, and (a random sample of) adult Medicaid enrollees without autism or intellectual disability. Only data of adults (i.e., 18 years of age and above) were analyzed.

The analysis included data belonging to a total of 3,506,661 individuals. Fifty-three percent were female, 20% were Black, 17% were Hispanic, and 60% were White.

The group without autism or intellectual disability had the lowest share of ADHD diagnoses at 2.7%. This percentage was 19% in the group with intellectual disabilities but without autism. In the group of autistic adults without intellectual disability, 26.7% had ADHD, and this was the case for 40.2% of autistic adults with intellectual disability.

Among people with an ADHD diagnosis, 36% of those without autism or intellectual disability were prescribed ADHD medication, while this was the case for 17.4% of individuals with intellectual disability (but no autism) and 26.8% of individuals who had both autism and intellectual disability. Forty-seven percent (46.7%) of participants with autism but no intellectual disability who were diagnosed with ADHD were prescribed ADHD medication.

“In this cohort study of Medicaid-enrolled adults, autistic adults experienced high rates of co-occurring ADHD and were more likely to receive ADHD medication prescriptions than adults in the general population. Negative health outcome rates are higher among autistic people with co-occurring ADHD, although ADHD medication prescriptions are associated with lower rates of negative health outcomes,” study authors concluded.

The study contributes to scientific knowledge about the co-occurrence of autism and ADHD. However, it should be noted that these data come solely from individuals enrolled in Medicaid. Results in the broader, non-Medicaid enrolled population may differ.

The paper, “Attention-Deficit/Hyperactivity Disorder in Medicaid-Enrolled Autistic Adults,” was authored by Benjamin E. Yerys, Sha Tao, Lindsay Shea, and Gregory L. Wallace.