Smoking-related correlates of depressive symptom dimensions in treatment-seeking smokers.

INTRODUCTION: The symptomatic heterogeneity of depression poses a barrier to understanding the smoking-depression relationship. Different types of depressive symptoms have evidenced disparate relations to smoking. Yet, depression measures employed in past depression-smoking research yield symptom subdimensions, which may not be sufficiently comprehensive or distinct. The Inventory of Depression and Anxiety Symptoms (IDAS; Watson, D., O'Hara, M. W., Chmielewski, M., McDade-Montez, E. A., Koffel, E., Naragon, K., et al. (2008). Further validation of the IDAS: Evidence of convergent, discriminant, criterion, and incremental validity. Psychological Assessment, 20, 248-259. doi:10.1037/a0012570) produce 8 distinguishable depressive symptom dimensions: dysphoria (anhedonia, sadness, psychomotor disturbance, worthlessness, worry, and cognitive difficulty), lassitude (anergia and hypersomnia), suicidality (self-harm thoughts/behaviors), ill temper (anger), well-being (positive thinking), appetite loss, appetite gain, and insomnia. The present study examined common and unique relations of IDAS depression subdimensions to (a) smoking rate (cigarettes perday), (b) tobacco dependence, and (c) smoking motivation.

METHODS: Secondary analysis of cross-sectional associations in baseline data collected from 338 daily smokers enrolled in a larger cessation study.

RESULTS: In individual models examining each symptom dimension in isolation, each symptom dimension was significantly with associated smoking rate, tobacco dependence, and/or various aspects of smoking motivation (e.g., subjective addiction, habit, appetite control, affect modulation). In combined models including all 8 dimensions as simultaneous regressor variables, dysphoria was the only dimension to retain most of its significant associations to smoking characteristics.

CONCLUSIONS: Relations of depressive symptoms to tobacco dependence, smoking rate, and motivation may be explained by (a) variance specific to dysphoria symptoms and (b) shared variance across depressive symptom subdimensions. Dysphoria symptoms, which contain core DSM-IV depression criteria, may be central to depression-smoking comorbidity, whereas other symptoms may play a less prominent role.