Divergence by ADHD subtype in smoking cessation response to OROS-methylphenidate

Introduction: Attention deficit hyperactivity disorder (ADHD) is a neuropsychiatric condition subclassified in DSM-IV according to its core symptoms domains as (a) predominantly inattentive (ADHD-IN), (b) predominantly hyperactive/impulsive (ADHD-H), and (c) combined inattentive and hyperactive/impulsive (ADHD-C). Whether these subtypes represent distinct clinical entities or points on a severity continuum is controversial. Divergence in treatment response is a potential indicator of qualitative heterogeneity. This study examined smoking cessation response by ADHD subtype to osmotic-release oral system methylphenidate (OROS-MPH). Methods: Male and female adult smokers (ADHD-C = 167 and ADHD-IN = 87) were randomized to receive OROS-MPH or placebo as augmentation treatment to nicotine patch and counseling. Logistic regression was conducted to test the effect of OROS-MPH versus placebo on prolonged smoking abstinence by ADHD subtype. Results: The subtypes were similar in baseline demographic, smoking, and psychiatric history but differed in smoking cessation response to OROS-MPH or placebo as a function of nicotine dependence level. The 3-way interaction was significant; x ²(1) = 8.22, p < .01. Among highly dependent smokers, the prolonged abstinence rates were greater with OROS-MPH than with placebo in the ADHD-C group (60% vs. 31.3%, respectively, p < .05) but higher with placebo than with OROS-MPH in the ADHD-IN group (60% vs. 11.8%, respectively, p < .01). Abstinence rates did not differ by subtype or treatment among smokers who were less nicotine dependent. Conclusion: Contrasting treatment response and divergence in the impact of nicotine dependence level support the hypothesis comof ADHD subtypes as distinct clinical entities and may indicate the need and directions for personalized targeted treatments of smokers with ADHD.