Autistic children who are born in underserved neighborhoods are more likely to exhibit heightened symptoms of attention-deficit/hyperactivity disorder (ADHD) during mid-childhood and adolescence compared to those born in more resource-rich areas, according to new research published in the journal JCPP Advances. This study is the first to explore how neighborhood factors are associated with ADHD symptoms in both autistic and non-autistic children, offering new insights into the potential interplay between environmental conditions and mental health in neurodiverse populations.
Autism, known formally as autism spectrum disorder, is a neurodevelopmental condition that affects how individuals communicate, interact socially, and process information. Autism presents a wide range of symptoms and levels of impairment, from challenges in social communication and repetitive behaviors to exceptional abilities in specific areas. The core characteristics of autism generally emerge in early childhood and persist throughout life, shaping how individuals perceive and interact with the world around them.
Attention deficit hyperactivity disorder, or ADHD, is another neurodevelopmental disorder, but it is characterized by persistent patterns of inattention, hyperactivity, and impulsivity. These symptoms can lead to difficulties in academic, occupational, and social settings. ADHD is typically diagnosed in childhood, although its symptoms can continue into adulthood, sometimes leading to significant life challenges if not properly managed.
While autism and ADHD are distinct conditions, they often coexist. A substantial proportion of autistic children also exhibit symptoms of ADHD, which can complicate diagnosis, treatment, and daily functioning. For these children, the presence of both conditions can lead to more significant challenges, including greater difficulties in school, more pronounced behavioral issues, and more complex needs in terms of support and interventions.
The need for the study arises from the growing recognition that environmental factors, including the neighborhoods where children grow up, play a crucial role in their development. While genetics undoubtedly contribute to both autism and ADHD, the environments in which children live can exacerbate or mitigate the severity of these conditions. Previous research has shown that factors like family socioeconomic status and parental stress are linked to ADHD symptoms, but less attention has been paid to the broader neighborhood environment.
To address this knowledge gap, the researchers utilized data from two large-scale, ongoing studies: the CHARGE (Childhood Autism Risks from Genetics and the Environment) Study and the ReCHARGE follow-up study. These studies provided a rich source of data on children with autism, children with developmental delays without autism, and typically developing children, all of whom were initially assessed between the ages of 2 and 5 years and then re-evaluated during mid-childhood to adolescence, between the ages of 8 and 20 years.
A key component of the study was the use of the Child Opportunity Index 2.0 (COI), a tool that measures neighborhood environments across three domains: Education, Health and Environment, and Social and Economic factors. This index captures a wide range of indicators, such as the presence of early childhood education centers, access to green spaces, median household income, and employment rates, providing a detailed picture of the neighborhood conditions at the time of each child’s birth.
ADHD symptoms were measured using the Aberrant Behavior Checklist (ABC), a well-established assessment tool specifically designed for children with neurodevelopmental disorders. The researchers focused on the Hyperactivity subscale of the ABC, which is indicative of ADHD symptoms. By comparing these symptoms across the different groups of children — those with autism, those with developmental delays but without autism, and typically developing children — the researchers aimed to uncover how neighborhood conditions at birth impacted ADHD symptoms as the children grew older.
The researchers discovered that children born in neighborhoods with lower opportunity, as measured by the COI, were more likely to exhibit higher ADHD symptoms during mid-childhood and adolescence. This relationship was particularly strong in autistic children, who showed a greater sensitivity to the influence of neighborhood environments compared to children with developmental delays without autism and typically developing children. Notably, while both autistic and typically developing children experienced ADHD symptoms, those in the lowest opportunity neighborhoods had significantly higher symptoms.
“We found that some neighborhood factors are strongly related to ADHD symptoms in autistic children,” said Catrina Calub, the first author on the paper. Calub is a postdoctoral researcher in the laboratory of Julie Schweitzer, a professor in the UC Davis Department of Psychiatry and Behavioral Sciences and the MIND Institute.
“In this study, we didn’t find this effect in typically developing kids or in kids with other developmental disabilities, only in the autistic children. It suggests that when autistic kids live in neighborhoods with fewer resources, they tend to have more pronounced ADHD symptoms,” Calub said.
Further analysis revealed that the Social and Economic domain of the COI was the strongest predictor of ADHD symptoms in autistic children. This domain includes factors such as household income, employment rates, and the proportion of single-parent households — indicators of the economic health and social support within a neighborhood. The study found that while there were no significant differences in ADHD symptoms between autistic children from high and low opportunity neighborhoods during early childhood, by mid-childhood to adolescence, those from low-opportunity neighborhoods exhibited significantly higher ADHD symptoms.
“These results are quite concerning,” Calub said. “Those with both autism and ADHD are already more likely to have additional challenges — behaviorally, cognitively, emotionally and socially. 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.”
Calub emphasized that further research is necessary to determine whether these findings can be generalized to a broader population.
“It will be important for future studies to be larger and more diverse. That should help us learn whether neighborhood conditions might also influence ADHD symptoms in other groups such as youth without autism, or in Black, Asian and Native American individuals, who were under-represented in our sample,” Calub added.
Schweitzer, a co-author of the study, noted that these findings provide insights for developing targeted preventive strategies to reduce the risk of heightened ADHD symptoms.
“ADHD is highly prevalent in the general population and is common 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 decrease long-term economic costs,” Schweitzer explained.
The study, “Examining the association of neighborhood conditions on attention-deficit/hyperactivity disorder symptoms in autistic youth using the child opportunity index 2.0,” was authored by Catrina A. Calub, Irva Hertz-Picciotto, Deborah Bennett, and Julie B. Schweitzer.