New research has shown that those who smoke face the highest odds for depression, followed by ex-smokers and non-smokers respectively. However, researchers added that more studies are needed before a definite causal path can be established. A study of cross-sectional data obtained from the US National Household Survey on Drug Abuse(collected from different respondents each year from 1994 to 1996) was conducted. A total of 13,827 young people aged from 12 to 17 years participated. The researchers measured variations in depression among current and former smokers as compared with depression in non-smokers, using ordinal logistic regression. They focussed on the association between time since last smoke and depression severity in former smokers to ascertain whether the level of tobacco/depression relationship might have a time-dependent component. It was observed that smokers were more prone to depression as compared to non smokers. Also, females had higher odds of depression, compared with males. The odds varied in subgroups of former smokers and were lower with more elapsed time since the last smoke.
The researchers concluded that the study added new evidence on depression associated with tobacco smoking.