While many smokers believe their habit relieves feelings of stress and depression, the latest findings show that stopping could be better for their mental health.
Writing online in the British Medical Journal (BMJ), researchers said the effect of quitting smoking was the same, if not bigger, than taking tablets to combat depressive symptoms.
Health campaigners in Scotland said there was now a clear link between giving up smoking and improvements in mental as well as physical health.
For the latest study, the team of researchers from the universities of Birmingham, Oxford and King’s College London, analysed 26 studies looking at the effects of smoking on mental health.
Quitters experienced a significant drop in anxiety, depression and stress compared to those who kept smoking.
The effect was the same among the general population of smokers as those with a diagnosed mental health problem.
“Both psychological quality of life and positive affect significantly increased between baseline and follow-up in quitters, compared with continuing smokers,” the researchers said.
They concluded: “Smoking cessation is associated with reduced depression, anxiety and stress, and improved positive mood and quality of life compared with continuing to smoke.”
Participants in the studies were aged 44 on average, smoked about 20 cigarettes a day, and were followed up for an average of six months.
The researchers said healthcare professionals who had been reluctant to offer stop-smoking advice to people with mental health disorders, for fear of quitting making the conditions worse, should be encouraged by the findings.
They said: “Although most smokers report wanting to quit, many continue as they report that smoking provides them with mental health benefits.
“Research shows that regular smokers report smoking cigarettes to alleviate emotional problems and feelings of depression and anxiety, to stabilise mood, and for relaxation as well as relieving stress.”
Gemma Taylor, the University of Birmingham researcher who led the study, said: “It is hugely encouraging to be able to demonstrate smoking cessation leads to an improvement in mental health. Smoking rates in the general population have declined substantially over the last 40 years. However, rates of smoking in those with mental health problems have barely changed.
“Part of this disparity is due to the myth that stopping smoking will worsen mental health.
“This research debunks this myth and I hope these findings motivate people with and without mental health problems.”
Sheila Duffy, chief executive of Action on Smoking and Health (Ash) Scotland, said: “Giving up can lead to an improvement in the symptoms of anxiety and depression, won’t worsen mental wellbeing and will improve overall health.”