Clinical correlates of tobacco smoking in OCD: A UK, case-controlled, exploratory analysis.

Background Obsessive-compulsive disorder (OCD) is a biologically heterogeneous neuropsychiatric disorder. It is associated with impulsive as well as compulsive neurocognitive mechanisms. Cigarette smoking is common among most psychiatric patients; however, OCD patients are thought to show reduced rates. OCD smokers may thus represent a relatively uncommon OCD subtype, characterised by increased impulsivity. In this study, we aim to establish the prevalence of smoking in a large, well-defined OCD cohort. We investigate whether smokers with OCD differ from non-smokers with OCD on clinical measures of behavioural impulsivity and domains of personality and temperament, including reward-dependence and novelty-seeking. Method 183 of 200 outpatients with DSM-IV OCD were interviewed to determine smoking status. A sub-sample of 10 smokers was compared with 10 non-smokers, pair wise matched for age and gender. Patients were assessed for DSM co-morbidity, symptom profile, OCD severity, behavioural impulsivity and personality dimensions. Results Only 10 individuals (5.46%; five males) were smokers. Compared to OCD non-smokers, OCD smokers scored significantly higher on the Barratt Impulsiveness Scale (p < 0.001). They also scored significantly higher on TCI measures of novelty seeking (p < 0.001) and reward dependence (p < 0.001) and significantly lower on measures of harm avoidance (p < 0.001). Conclusions Tobacco smoking is rare in OCD. Significantly higher levels of behavioural impulsivity and temperamental factors associated with reward driven impulsivity are seen in OCD smokers compared to non-smokers. Tobacco smoking may indicate a possible source of neurocognitive heterogeneity in OCD.