Women who smoke are at greater risk of developing major depressive disorder, according to new research published in the October issue of the British Journal of Psychiatry.
The researchers studied a group of women in Australia, who had been followed for a decade as part of the Geelong Osteoporosis Study.
Among 165 women with major depressive disorder and 806 controls, smoking was clearly associated with increased odds for major depressive disorder. Indeed, the odds more than doubled for heavy smokers (those who smoked more than 20 cigarettes a day) compared with non-smokers.
The researchers also examined longitudinal data to determine the risk of women developing a new major depressive disorder over time. A total of 671 women with no history of major depressive disorders were studied.
Of the 87 women who were smokers, 13 went on to develop major depressive disorder. However, among 584 non-smokers, just 38 developed major depressive disorder during a decade of follow-up.
The researchers concluded that smoking increased the risk of major depressive disorder by 93%.
Previous research has shown that smoking is a risk factor for depression. There is also increasing evidence that smoking may aggravate mental illness or contribute to its onset. However, most previous studies have involved short time frames, and this study is the first to investigate smoking using longitudinal data that extends over a ten-year period.
The researchers observed that depression is a leading cause of global disease burden, and called for greater efforts to encourage smokers to quit.
Source: Royal College of Psychiatrists; Pasco JA, Williams LJ, Jacka FN, Ng F, Henry MJ, Nicholson GC, Kotowicz MA and Berk M (2008) Tobacco smoking as a risk factor for major depressive disorder: population based study, British Journal of Psychiatry, 193: 322-326
