Adult symptoms of ASD and ADHD in relation to alcohol use: Potential roles of transdiagnostic features.

Attention Deficit Hyperactivity Disorder (ADHD) is the most common comorbidity in Autism Spectrum Disorder (ASD). ADHD is a risk factor for alcohol misuse whereas ASD is often regarded as protective; however, research on ASD and alcohol use has yielded conflicting findings, sometimes implicating the role of comorbid ADHD. The possibility that certain transdiagnostic features (i.e., characteristics associated with multiple disorders) may underlie relationships of both disorders to alcohol use in adults was examined in the present study. A nonclinical young adult sample of 248 alcohol users (117 men, 131 women) completed validated self-report measures of ASD and ADHD symptoms as well as the transdiagnostic features alexithymia, impulsivity, and negative moods. ASD and ADHD symptoms were normally distributed, suggesting that the respective disorders represent extreme, dysfunctional ends of population distributions of symptoms. Path analysis indicated that the significant positive association between ASD and ADHD symptom measures was fully mediated by alexithymia, impulsivity, and negative moods. Hierarchical regression and path analysis indicated that the positive relationship between ADHD symptoms and alcohol use severity was fully mediated by transdiagnostic features, particularly alexithymia and impulsivity, whereas the relationship between ASD and alcohol use severity was positively mediated by these features (especially alexithymia), with a highly significant and negative direct effect. Present findings may help reconcile previous conflicting evidence on the relationship of ASD to alcohol use, and the role of comorbid ADHD, by emphasizing the roles of alexithymia and impulsivity in both ASD and ADHD as transdiagnostic traits promoting excessive drinking.