ADHD, Obesity Link May Depend on Where You Live

Medscape

30-05-2025

The well-documented link between attention-deficit/hyperactivity disorder (ADHD) and obesity in both children and adults has typically been attributed to individual traits and behaviors, with limited attention paid to environmental and social factors.
However, a new study challenged this perspective, proposing that ADHD may contribute to obesity by reducing physical activity — a connection shaped by the urban environment in which a person lives.
'Our research reveals a surprising urban advantage: As cities grow, both obesity and ADHD rates decrease proportionally,' first author Tian Gan, a PhD student at the Center for Urban Science and Progress, NYU Tandon School of Engineering in Brooklyn, New York, said in a news release.
Larger cities may offer 'protective factors against these interconnected health challenges,' Gan added, citing access to better mental health care, education, and opportunities for recreation and physical activity.
The study was published online in PLOS Complex Systems .
Urban Impact
While impulsivity — a core ADHD trait — has long been suspected to contribute to weight gain through poor food choices and reduced physical activity, this new study highlighted how an individual's urban environment can either amplify or dampen those risks.
Researchers analyzed public health data from 915 cities in the United States using 'urban scaling' methods, which describe how features of cities change with population size.
They observed that both obesity and ADHD prevalence decrease 'sublinearly' with population — meaning that as cities grow, the per capita prevalence of these conditions declines. At the same time, access to mental health care and higher education rises 'superlinearly,' growing faster than the population.
In other words, larger cities seem to offer not just more services, but disproportionately more support for conditions linked to impulsivity, the authors theorized.
But city size alone doesn't tell the whole story.
Using advanced causal discovery methods, the researchers mapped a network of interrelated variables. ADHD prevalence was linked to higher physical inactivity, which in turn increased obesity. Access to mental health care helped reduce inactivity and indirectly lowered obesity risk. Higher prevalence of college education correlated with better mental health access and more physical activity.
This causal map revealed a dynamic system in which impulsivity, health behaviors, and urban infrastructure interact — suggesting that city environments can either reinforce or weaken these effects.
The link between ADHD and obesity was stronger in cities with fewer opportunities for physical activity or greater food insecurity and weaker in cities with better access to mental health care and higher education levels, they explained.
To validate their findings, the researchers examined individual-level data from the National Survey of Children's Health, which included 19,333 US children. This analysis confirmed the city-level data: Children with more severe ADHD were more likely to be obese, especially when physical activity and household education were low.
Taken together, the findings reinforce evidence that ADHD contributes to obesity and point to the urban environment as a potentially modifiable target for intervention, the authors said.
'These findings underscore the importance of city-level interventions in mitigating the impact of impulsivity disorders on the obesity epidemic,' Maurizio Porfiri, PhD, who heads the Center for Urban Science and Progress at NYU Tandon School of Engineering, added in the news release.