ADHD symptoms in autistic children linked to neighborhood conditions

Autistic youth born in underserved neighborhoods are more likely to have symptoms of attention-deficit/hyperactivity disorder (ADHD) than youth born in more resourced communities, according to a new study led by researchers at the UC Davis MIND Institute.

This is the first time that researchers have examined how neighborhood factors relate to ADHD in autistic and non-autistic children. The study offers new insights into mental health issues and has the potential to inform public policy changes to improve health equity.

The work was published in the diary JCPP Progress.

“We found that some neighborhood factors are strongly related to ADHD symptoms in autistic children,” said Catrina Calub, the paper’s first author. Calub is a postdoctoral researcher in the lab of Julie Schweitzer, a professor in the Department of Psychiatry and Behavioral Sciences and the MIND Institute.

“In this study, we didn’t find this effect in typically developing children or in children with other developmental disorders, only in the autistic children. It suggests that when autistic children live in neighborhoods with fewer resources, they tend to have more pronounced ADHD symptoms,” Calub said.

Symptoms of ADHD may include increased inattention, hyperactivity, and impulsive behavior. It is associated with:

• Challenges in school performance and relationships with friends
• Lower self-esteem and increased risk of anxiety and depression
• Increased risk of substance use disorders and accidents
• Emotional dysregulation and behavioral problems

Study extends findings from long-term research

The researchers used data from two studies: the decade-long Childhood Autism Risks from Genetics and the Environment (CHARGE) study led by Irva Hertz-Picciotto of the MIND Institute and the ReCHARGE follow-up project.

CHARGE and ReCHARGE investigate how genetics, environment, and other factors influence development from early childhood (2-5 years) through adolescence (8-20 years).

The team looked at 246 autistic children, 85 with developmental delays (without autism), and 193 who were neurotypical. They then applied the Child Opportunity Index, which uses census data to track more than 30 neighborhood characteristics. These characteristics include socioeconomic characteristics, green space, single-parent households, and concentration of early childhood education centers.

The index includes three domains: education, health and environment, and social and economic resources. Higher scores are associated with better health in childhood. Of the three domains, scores for education and social and economic resources were most strongly associated with ADHD symptoms.

The analysis showed that Child Opportunity Index scores at birth were a strong predictor of ADHD symptoms in adolescence in the autistic children, but not in the other groups. Calub noted that the finding was unexpected.

“These results are quite concerning,” Calub said. “People with both autism and ADHD are already more likely to have additional challenges — behavioral, cognitive, emotional and social. Being born in a low-income neighborhood puts them at an even greater disadvantage. This just adds to the evidence that more resources are needed for underserved areas and specifically for those who have conditions like autism.”

The need for a larger, more diverse sample

Calub indicated that more research is needed to determine whether the results apply to a larger group.

“It will be important for future studies to be larger and more diverse. That should help us learn whether neighborhood conditions may also influence ADHD symptoms in other groups, such as youth without autism, or in Black, Asian, and Native American individuals, who were underrepresented in our sample,” Calub added.

These findings also provide clues for how preventive strategies can be used to reduce the risk of worsening ADHD symptoms, said Schweitzer, who was also a co-author of the study.

“ADHD is very prevalent in the general population and is very prevalent in autistic youth. If we can find ways to increase resources in these neighborhoods, we have the potential to improve academic, social, mental, and physical health outcomes, particularly for autistic youth, and also reduce long-term economic costs,” Schweitzer explained.

Calub and Schweizer believe the study’s findings should encourage policymakers to provide more resources to underserved communities. Additionally, they hope that incorporating the Child Opportunity Index and other neighborhood metrics could provide new insights for future studies to inform policy.

The study was co-authored by Irva Hertz-Picciotto and Deborah Bennett, both in the UC Davis Department of Public Health Sciences.