Smoking and mental health - NCSCT

Epidemiology of the association between smoking and mental disorders 4
included studies also assessed the relationship between smoking and onset of
eating disorders, 51 and found no clear association between smoking and the
incidence of purging (OR = 0.9, 95% CI 0.3–2.5) or binge eating (OR = 1.4,
95% CI 0.6–3.0) in females. 51
4.9 Smoking and depression
We identified 47 longitudinal studies of smoking and depression in our
searches. 3,21,24,26,27,47,54–94 One cohort was reported in two studies, 63,84 the Add
Health cohort in three studies, 55,80,93 and the Teenage Attitudes and Practices
Survey (TAPS) also in three studies 54,78,83 (see Table A6).
4.9.1 Smoking and onset of depression
There were 32 studies of the effect of smoking on the onset of depression, most
of which included males and females combined and some of which provided
gender-specific estimates for males 54–58,60 or females; 54–56,59,60,76,90,91 the latter
group included three studies of postpartum depression. 76,90,91
A meta-analysis of 26 studies found regular or daily smoking significantly
increased the risk of onset of depression by 52% (RR = 1.52, 95% CI 1.36–1.71;
I 2 = 68% – Fig 4.4), 24,47,54–75,86,87 with a slightly larger magnitude of effect in
females (RR = 1.79, 95% CI 1.24–2.58) than in males (RR = 1.39, 95% CI
1.15–1.68). Similar findings were seen in two studies that could not be included
in the meta-analysis (IRR = 1.28, 95% CI 0.76–2.16; 3 light smoking: HR = 1.29,
95% CI 0.74–2.25; moderate smoking: HR = 2.01, 95% CI 1.17–3.43; heavy
smoking: HR = 4.34, 95% CI 1.85–10.18 94 ); however, no effect was seen in a
further study assessing the association between daily smoking and the onset of a
depressive disorder (RR = 1.0, p = 0.9 26 ). A subgroup analysis of the 26 studies
found similar magnitudes of effect for the association between smoking and the
onset of depression in adolescents (RR = 1.49, 95% CI 1.25–1.77, I 2 = 69%, 11
studies) and in adults (RR = 1.56, 95% CI 1.32–1.83, I 2 = 67%, 15 studies) (test
for subgroup difference p = 0. 71) (Fig 4.5).
A meta-analysis of six studies found that ex-smokers were no more likely to
develop depression than never smokers (RR = 1.02, 95% CI 0.82–1.27, I 2 =
60%), 56–58,60,71,75 and one study found no significant association between being a
former smoker and the risk of onset of depression compared with being a
current smoker (RR = 0.88, 95% CI 0.56–1.40). 86
Three studies 76,90,91 (see Table A6) assessed the association between smoking
and postpartum depression and revealed a twofold increase in the risk of
development of postpartum depression in women who were smokers during
pregnancy (RR = 2.08, 95% CI 1.50–2.91, I 2 = 0% – Fig 4.6).
© Royal College of Physicians 2013 71