Abstract
Attention-Deficit/Hyperactivity Disorder (ADHD) is the most widespread neurodevelopmental disorder, and it still persists into adulthood in 2–6% of the population. Psychiatric comorbidities are very common in adult ADHD (A-ADHD) patients; in particular, Substance Use Disorder (SUD) is found in 40% of these patients. Co-occurrence of ADHD and SUD is described as detrimental to clinical outcome by many authors, while only a few studies describe good clinical results in A-ADHD-SUD patients when they were treated for ADHD, both for the efficacy and the compliance of patients. In this study we tested to determine whether SUD can influence the treatment outcome of A-ADHD patients by correlating lifetime, past and current substance use in A-ADHD patients with their outcome (retention rate) during a 5-year follow-up of patients treated with stimulant and non-stimulant medications, using Kaplan–Meier survival analysis with overall and pairwise comparison. The association between demographic, symptomatological and clinical aspects with retention in treatment, adjusting for potential confounding factors, was summarized using Cox regression. After 5 years of observation, the cumulative treatment retention was 49.0%, 64.3% and 41.8% for A-ADHD patients without lifetime SUD (NSUD/A-ADHD), A-ADHD with past SUD (PSUD/A-ADHD) and A-ADHD with current SUD (CSUD/A-ADHD), respectively. Overall comparisons were not significant (Wilcoxon Rank-Sum (statistical) Test = 1.48; df = 2; p = 0.477). The lack of differences was confirmed by a Cox regression demonstrating that the ADHD diagnosis according to DIVA, gender, education, civil status, presence of psychiatric comorbidity, and psychiatric and ADHD familiarity; severity of symptomatological scales as evaluated by WHODAS, BPRS, BARRAT, DERS, HSRS, and ASRS did not influence treatment drop-out (χ2 22.30; df = 20 p = 0.324). Our A-ADHD-SUD patients have the same treatment retention rate as A-ADHD patients without SUD, so it seems that substance use comorbidity does not influence this clinical parameter.
Highlights
Attention-Deficit/Hyperactivity Disorder (ADHD) is the most common neurodevelopmental disease, and about 2–6% of the adult population fulfill the criteria for the disorder [1]
Co-occurring disorders are frequent in adult-ADHD (A-ADHD) patients; in particular, about 40% of A-ADHD patients have Substance Use Disorder (SUD) [3,4,5]
We demonstrated that A-ADHD cocaine users strongly reduced their addiction behaviors once treated with methylphenidate (MPH), and the reduction was proportional to the improvement in A-ADHD symptomatology [16]
Summary
Attention-Deficit/Hyperactivity Disorder (ADHD) is the most common neurodevelopmental disease, and about 2–6% of the adult population fulfill the criteria for the disorder [1]. ADHD shows some features, such as impulsivity, sensation-seeking behavior, and difficulty in modulating reward and gratification [7], all of which give rise to a propensity towards substance use and a major risk for illicit or licit involvement with drug-taking [8]. From a neurobiological perspective, delayed gratification is mediated by tonic dopaminergic signaling in striatal and prefrontal regions, while immediate processes are predominantly driven by phasic dopamine firing [9]. These neural circuits are deficient in ADHD due to the impairment of dopaminergic physiology [11] and drugs of abuse, such as cocaine, amphetamine, and methamphetamine increase the dopaminergic transmission, especially in the nucleus accumbens [12]. The use of alcohol, cannabinoids, and heroin by ADHD adolescents was reported to relieve the specific psychopathological features derived from the disorder [17,18]
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