Craving for heroin: difference between methadone maintenance therapy patients with and without ADHD.

Introduction: Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder persisting in adulthood in 40-60% of cases. Clinical and neuroimaging studies suggest that patients affected by both drug addiction and ADHD show higher rates of craving for drug than patients without ADHD. We designed a pilot open-label study to investigate the effects of ADHD on craving for heroin in methadone maintenance therapy patients.

Method: Patients were recruited from outpatient facilities in an addiction treatment unit in the municipality of Alba, Italy. They were assessed using the Structured Clinical Interview for DSM-5 (SCID-5), the SCID-5 for Personality Disorders (SCID-5-PD), the Diagnostic Interview for Adult ADHD, second edition (DIVA 2.0), and the Clinical Opiate Withdrawal Scale (COWS). Categorical variables were examined using the chi-square test, and continuous variables, the t-test and Mann-Whitney's U test for normally and non-normally distributed data, respectively. Data distribution was evaluated using Shapiro-Wilk's test. Significance was set at p=0.05. Bonferroni correction was applied (0.0063) to avoid type I error.

Results: A total of 104 patients were included in the study: 14 affected by ADHD (13.5%) and 90 were not affected (86.5%). Patients with ADHD showed higher intensity of craving for heroin than patients without ADHD in the absence of withdrawal symptoms.

Conclusion: Drug addiction and ADHD share various neurobiological mechanisms that mutually influence the evolution of both disorders. In particular, dopamine dysfunction within various brain circuits may influence impulsivity levels, motivation, inhibitory control, executive functions, and behavior and, consequently, the intensity of craving.