Mediating role of alcohol dependence in the associations between adult ADHD symptoms and a wide range of physical comorbidities

Adults with attention-deficit/hyperactivity disorder (ADHD) experience a high burden of physical comorbidities; however, the underlying mechanisms are not fully understood. This study investigated the association between ADHD symptoms and a wide range of physical comorbidities and quantified the statistical mediating role of alcohol dependence in a large sample of the general Japanese population. We analyzed cross-sectional data obtained from 29,268 participants (aged ≥ 16 years) as part of The 2024 Japan Society and New Tobacco Internet Survey (JASTIS). ADHD symptoms were assessed using the Adult ADHD Self-Report Scale (ASRS-J-6), and alcohol dependence was assessed using the Alcohol Use Disorders Identification Test (AUDIT). Physical comorbidities (18 in total) were assessed by self-report. A mediation analysis was conducted to estimate the proportion of the association between ADHD and physical comorbidities that was statistically mediated by alcohol dependence while accounting for sociodemographic factors. Following adjustment for covariates, ADHD symptoms were significantly associated with higher odds of 17 of the 18 examined physical comorbidities (all except allergic rhinitis). In the separate multivariable binomial logistic regression analyses, relatively stronger associations were observed for chronic hepatitis/cirrhosis (adjusted odds ratio [aOR] = 4.50). Alcohol dependence statistically mediated several of these associations. The proportion mediated was notably high for cancer (91.5%) and stroke (74.6%). ADHD symptoms were associated with widespread physical comorbidities, and alcohol dependence statistically mediated part of these associations. These findings suggest that alcohol dependence may represent a potentially modifiable behavioral factor related to physical health risks in individuals with ADHD symptoms. Considering alcohol use may be helpful when addressing the broader health needs of adults with ADHD symptoms.