A systematic review of longitudinal studies on the association between depression and smoking in adolescents

<p>Abstract</p> <p>Background</p> <p>It is well-established that smoking and depression are associated in adolescents, but the temporal ordering of the association is subject to debate.</p> <p>Methods</p> <p>Longitudinal studies in English language which reported the onset of smoking on depression in non clinical populations (age 13-19) published between January 1990 and July 2008 were selected from PubMed, OVID, and PsychInfo databases. Study characteristics were extracted. Meta-analytic pooling procedures with random effects were used.</p> <p>Results</p> <p>Fifteen studies were retained for analysis. The pooled estimate for smoking predicting depression in 6 studies was 1.73 (95% CI: 1.32, 2.40; p < 0.001). The pooled estimate for depression predicting smoking in 12 studies was 1.41 (95% CI: 1.21, 1.63; p < 0.001). Studies that used clinical measures of depression were more likely to report a bidirectional effect, with a stronger effect of depression predicting smoking.</p> <p>Conclusion</p> <p>Evidence from longitudinal studies suggests that the association between smoking and depression is bidirectional. To better estimate these effects, future research should consider the potential utility of: (a) shorter intervals between surveys with longer follow-up time, (b) more accurate measurement of depression, and (c) adequate control of confounding.</p

The Heaviness of Smoking Index as a predictor of smoking cessation in Canada

Abstract Nicotine addiction is believed to be a major impediment for many people in quitting smoking, but measures of nicotine dependence such as the Heaviness of Smoking Index (HSI) have had mixed success in predicting cessation. Using the National Population Health Survey, the relationship between HSI at baseline in cycle 2 (1996)(1997) and successful smoking cessation at cycle 3 (1998-1999) and cycle 4 (2000-2001) was examined in 2938 Canadian adult smokers. A logistic regression model was developed for HSI as a predictor of smoking cessation, and then tested for interaction and confounding. The odds ratio of not smoking in cycle 3 was 2.08 (95% CI: 1.51, 2.86; p b 0.001) for low HSI (b2) compared to medium HSI. When the period of follow-up was extended, individuals with both high (N 4) HSI scores (OR 2.16; 95% CI: 1.11, 4.21; p = 0.02) and low scores (OR 2.22; 95% CI: 1.41, 3.49) had higher odds of not smoking at both cycle 3 and cycle 4 than those with medium HSI scores. The likelihood of reporting cessation was higher than expected in the Canadian population among highly dependent smokers, particularly among older smokers, those with middle or greater income adequacy, and those with no intention to quit smoking. There were no substantial changes to the results when those lost-to-follow-up were treated as continuing smokers. These findings indicate that nicotine dependence is only one factor in succeeding at a quit attempt. Individual and population strategies for smoking cessation may need to consider other influences such as cognitive, affective and environmental factors