Smoking and mental health - NCSCT

Smoking and mental health
disorders); schizophrenia, schizotypal and delusional disorders (including
schizoaffective disorders and psychotic disorder); mood and affective disorders
(including manic episode, bipolar affective disorder, depressive disorder); and
neurotic and stress-related disorders (including anxiety disorder,
obsessive–compulsive disorder, post-traumatic stress disorder). We excluded
organic mental disorders (including dementia, mental and behavioural
disorders due to psychoactive substance use, learning disability and disorders of
psychological development). Separate literature searches were carried out to
identify studies that assessed the effect of smoking on dementia and those
assessing mortality and morbidity among people with mental health disorders.
We also scanned and checked the reference lists from original research papers
and reviewed articles to identify further eligible studies. No language
restrictions were imposed during the search and translations were sought
where necessary.
The systematic reviews were conducted in accordance with the Meta-analysis
Of Observational Studies in Epidemiology (MOOSE) guidelines. 2 We extracted
adjusted estimates of association from the publications, where available; otherwise
we calculated unadjusted (crude) figures from the results presented. Where more
than one method of diagnostic ascertainment of mental disorder was reported, we
used estimates based on clinical diagnoses in preference to those reported by
parents or teachers. Estimates of pooled relative risks (RRs) were generated, where
possible, for each outcome by random effect meta-analyses using a generic inverse
variance method within Review Manager software (Review Manager (RevMan),
Version 5.1). Heterogeneity was quantified using I 2 .
The searches identified 10,522 publications, of which 814 were selected based
on the relevance of their titles. We excluded 528 of these after scrutiny of their
abstracts, and screened 286 full text papers, of which 201 were excluded, largely
because the association between smoking and mental disorder was not assessed
prospectively. Thus, 85 studies were identified as suitable for inclusion in the
following reviews, and these covered the following diagnostic groups: any mental
disorder, emotional and behavioural problems, bipolar disorder, schizophrenia,
anxiety, eating disorders, and depression.
4.3 Smoking and onset of any mental disorder
Three studies identified in our searches measured the onset of any mental
disorder (relating to the most common mood disorders, anxiety disorders and
substance use disorders) over a 12-month period among smokers and nonsmokers
who had no mental disorder at the start of the follow-up period. 3–5 In
one of these studies, of 2,726 adults from the Netherlands, smoking was
associated with a significant increase in the incidence of mental disorder in the
following year (incidence rate ratio [IRR] = 1.62, 95% confidence interval [CI]
1.15–2.30), 3 but in the second, carried out in the UK and including 651 adults
64 © Royal College of Physicians 2013