Smokers with a history of anxiety, mood or alcohol use disorders are significantly more likely to be in remission three years later if they quit smoking, an American study has found.¹

Data were obtained from the National Epidemiological Study of Alcohol and Related Conditions, a longitudinal survey of 43,093 nationally representative participants. Baseline interviews were conducted between 2001 and 2002, and follow-up interviews between 2004 and 2005.

Smokers were defined as those who had smoked daily during the previous 12 months. The analysis was restricted to those who attended for a follow-up interview and who had not increased their smoking by 10% or more compared with baseline.

Anxiety, mood, alcohol use and substance use disorders were diagnosed according to DSM IV criteria using a structured diagnostic interview.

Of the 4,853 smokers in the analysis, 1,915, around 40%, had a current or lifetime history of anxiety or mood disorder. Within this group, those who had quit smoking at follow-up had a significantly reduced risk of anxiety/mood disorder, adjusted odds ratio (OR) 0.6 (95% CI:0.4-0.9).

Just under half the sample, 2,299 participants, had a current or lifetime history of alcohol use disorder. Within this group, those who had quit smoking at follow-up had a significantly reduced risk of alcohol use disorder, adjusted OR 0.7 (95% CI:0.5-0.99).

Almost a quarter of the sample, 1,093, had a current or lifetime history of substance use disorder. For this group, quitting smoking was associated with a reduced risk of substance use disorder at follow-up, but this was not quite significant.

For those without a previous history of the outcome of interest, smoking cessation significantly reduced the risk of new onset in the case of substance use disorder only, adjusted OR 0.3 (95% CI:0.1-0.9).

Observational studies cannot determine the direction of causation. Smoking cessation may increase the likelihood of remission, but equally, those who recover may find it easier to quit smoking. A limitation of the study was the failure to determine which came first: smoking cessation or remission.

It has been suggested that the aggressive promotion of smoking cessation should form a routine part of the care of those with depression or bipolar disorder.²

This study suggests that this should also apply to those with anxiety or alcohol use disorders.

A number of arguments can be raised against this:

• Depressed patients are less likely to succeed

• Failure may have a detrimental psychological impact

• Success may increase the short-term risk of depression recurrence³

• FDA data has linked varenicline to suicide⁴

However, a meta-analysis suggested that, compared with smokers who were not depressed, depressed smokers were just as capable of stopping smoking;⁵ studies such as the present one suggest that the increased risk of depression in the short term is outweighed by the long-term benefits; and a UK study has found no evidence that varenicline increases the risk of suicide.⁶

Personally, I do not think that we should adopt an aggressive approach to promoting smoking cessation in patients with anxiety, mood or alcohol use disorders. Rather we should present a balanced view of the potential benefits and risks of quitting smoking, and encourage those who decide to try.