Impulsivity is the principal correlate of problematic internet use in young adults with attention-deficit/hyperactivity disorder: a cross-sectional clinical study

Introduction Attention-deficit/hyperactivity disorder (ADHD) and problematic internet use share clinical features such as impulsivity, emotional dysregulation and impaired inhibitory control, but most evidence comes from children, adolescents and non-clinical samples. It remains unclear which dimension carries this association in adults with a formally established diagnosis. Methods Retrospective, cross-sectional study of young adults (aged 18 to 38 years) consecutively assessed at a second-level outpatient service for adult ADHD in Milan, Italy. Diagnosis was established with a semi-structured diagnostic interview (DIVA-5), which also yielded symptom counts for childhood and adult inattention and hyperactivity/impulsivity. Participants completed the Internet Addiction Test, the Barratt Impulsiveness Scale, the Difficulties in Emotion Regulation Scale, measures of depressive and anxiety symptoms, a quality-of-life questionnaire and two ADHD symptom questionnaires. Impulsivity and emotional dysregulation were prespecified variables of interest. Analyses comprised correlations with correction for multiple comparisons, group comparisons, multivariable linear regression and bootstrapped mediation. Results Two hundred and fourteen patients had a valid Internet Addiction Test score (mean 52.96, standard deviation 15.16); 22.9% were average users, 62.1% problematic users and 15.0% highly problematic users. Problematic internet use correlated with impulsivity (rho = 0.345) and emotional dysregulation (rho = 0.229), both surviving corrections, while no significant association was detected with the four interview-derived symptom counts (rho from 0.004 to 0.119), the two symptom questionnaires, quality of life or trait anxiety. In the multivariable model impulsivity was the strongest correlate (b = 0.317, p < 0.001; standardized beta 0.33), whereas emotional dysregulation was weaker and varied across specifications (b = 0.091, p = 0.052). Severity, presentation, symptom counts and demographic and clinical covariates were not significantly associated with the outcome. Mediation analysis identified an indirect association between severity and internet use through impulsivity (indirect effect 1.56, 95% confidence interval 0.41 to 2.96). Discussion In young adults with ADHD, impulsivity is the dimension most consistently related to problematic internet use, whereas no association was detected with core symptom severity; the confidence intervals remain compatible with weak associations. Assessment of online behavior should not be restricted to the most severely affected patients. The design does not support causal inference.