The health conditions that tend to accompany autism in adolescence grow even more prevalent by early adulthood, according to a new longitudinal study.
The findings underscore the importance of continually screening for these conditions in autistic children as they age, especially as they transition from pediatric to adult care.
“There are many health conditions, both psychiatric as well as physical health, that are common in autism. And they don’t go away as teens become adults,” says Beth Ann Malow, professor of neurology at Vanderbilt University in Nashville, Tennessee, and lead investigator of the study.
The transition to adulthood can be difficult for everyone, but “when you overlay that with aspects of autism and/or autism-related services, it can become pretty complicated,” says Kristin Long, associate professor of psychological and brain sciences at Boston University in Massachusetts, who wasn’t involved in the study.
For example, entering young adulthood means aging out of pediatric care and developmental services, and many autistic young adults struggle to find an adult provider. “A lot of adult practitioners, regardless of their specific area of practice, really aren’t trained on autism and don’t know what to do to support their autistic patients or clients in adult settings,” Long says.
On top of that, adults with autism have a higher-than-average prevalence of most medical conditions, including seizures, obesity and diabetes as well as immune, gastrointestinal and sleep disorders. These also include psychiatric conditions such as depression, anxiety and bipolar disorder. This makes access to health care even more critical, Malow says.
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n the new study, which was published in Autism Research in June, Malow and her colleagues analyzed the electronic health records of 1,418 autistic people and 6,029 non-autistic people aged 14 to 22 who received health care through Kaiser Permanente Northern California from 2014 to 2019. Participants who were 14 at the start of the study were followed until age 19, whereas those who were 17 at the start were followed until age 22. The data from both cohorts were combined and used to model the prevalence of each condition over time.Malow and her team focused on health conditions that affect quality of life and for which they had sufficient sample sizes: obesity, anxiety, ADHD and depression, as well as cardiovascular, neurological and sleep disorders.
All tracked conditions were more common in autistic youth than in non-autistic youth, and the prevalence of all conditions increased with age in both groups. At age 14, obesity and ADHD were more prevalent in autistic boys than girls, but by age 22, all conditions were more prevalent in autistic women than men.
“I think this paper is great because we have always looked at the prevalence of health conditions in autism at one given time point, but no one’s ever followed it over time,” says Ann Neumeyer, associate professor of neurology at Harvard Medical School, who wasn’t involved in the study. “And that's the beauty of this paper.”
The prevalence of psychiatric conditions in the non-autistic cohort may be underestimated because those people may not visit the doctor as regularly as those with autism do, says Eric Rubenstein, assistant professor of epidemiology at Boston University, who was not involved in the study. “An autistic person going in to get certain therapies might be more likely to pick up those diagnoses because they’re seeing the provider, whereas other people may not.”
Obesity and dyslipidemia, or high levels of lipids in the blood, were more abundant in autistic youth at all ages but also rose at a faster rate than in non-autistic youth.
“The rates of obesity are really, really high among the autistic population,” says James McCauley, assistant professor of psychology at Saint Mary’s College of California in Moraga, who was not involved in the study. “And it’s concerning to see here and in other work, the trajectories of obesity increasing across adolescence into adulthood.”
These findings indicate clinicians who treat autistic youth and adults should pay close attention to sleep, activity levels and diet, McCauley says. Neumeyer says she plans to incorporate lipid testing into her neurology practice. “When I’m treating a 14-year-old, I can say I know that the rate of obesity is high, so we have to start making lifestyle changes now so that your child isn’t one of the ones who have high lipids,” she says.
Because the study relied on medical records, it did not include uninsured people or those who did not visit the doctor, which is a limitation of the findings, Rubenstein says. The study also did not stratify the results by intellectual ability, race or income level, which could have revealed additional disparities.
Future studies should focus on how these co-occurring conditions interact with one another, McCauley says, such as the proportion of autistic people with both obesity and a sleep disorder, or with ADHD and anxiety.
