Re: Change in mental health after smoking cessation: systematic review and meta-analysis
To the editor:
Smoking cessation should be promoted both for general people and psychiatric patients from a public health perspective and in this sense the study by Taylor et al. (1) is crucially relevant. There are however a couple of points that are worthy of consideration in order for their findings to be generalised to psychiatric patients, a special population.
First, while the data were from 26 studies of which 14 reflected general population only six at most were inclusive of chronic psychiatric conditions. As is clearly seen in Table 8 for instance, estimates were much less reliable in psychiatric conditions compared with general population, well because of lower availability of the studies for such patients (and hence fewer number of subjects studied).
Second, psychiatric patients not infrequently smoke in a manner that appears even compulsive, which plausibly results in heavy smoking. This may notoriously contribute to premature mortality (2). The average number of cigarette smoking was 20 a day in this study, which is not surprisingly large. Less compulsive, or in essence, less amount of smoking may still be meaningful in terms of not only physically but also mentally among psychiatric patients who smoke quite a lot. Further a possible association between less smoking and resultant better mood (or vise versa) would be a topic worthy of investigation, even when complete abstinence is not feasible.
Finally it is important to note that smoking peripherally affects pharmacokinetics of psychotropic medications in part by interfering with cytochrome CYP 450 system for instance (3). It centrally affects central neurotransmitters such as dopamine as well (4). In this context the net effect of smoking under psychotropic medications in the central nervous system is challenging to accurately and dynamically appreciate in a variety of psychiatric disorders for which psychotropic medications are clinically indicated.
1. Taylor G, McNeill A, Girling A, Farley A, Lindson-Hawley N, Aveyard P. Change in mental health after smoking cessation: systematic review and meta-analysis. BMJ. 2014 Feb 13;348:g1151. doi: 10.1136/bmj.g1151.
2. Banham L, Gilbody S. Smoking cessation in severe mental illness: what works? Addiction. 2010 Jul;105(7):1176-89. doi: 10.1111/j.1360-0443.2010.02946.x.
3. Sugahara H, Maebara C, Ohtani H, Handa M, Ando K, Mine K, Kubo C, Ieiri I, Sawada Y. Effect of smoking and CYP2D6 polymorphisms on the extent of fluvoxamine-alprazolam interaction in patients with psychosomatic disease. Eur J Clin Pharmacol. 2009 Jul;65(7):699-704. doi: 10.1007/s00228-009-0629-4.
4. Le Foll B, Guranda M, Wilson AA, Houle S, Rusjan PM, Wing VC, Zawertailo L, Busto U, Selby P, Brody AL, George TP, Boileau I. Elevation of dopamine induced by cigarette smoking: novel insights from a [(11)C]-(+)-PHNO PET study in humans. Neuropsychopharmacology. 2014 Jan;39(2):415-24. doi: 10.1038/npp.2013.209.
Competing interests: No competing interests