Stopping smoking is associated with an improvement in mental health, researchers at the universities of Oxford and Birmingham have found.
The researchers say the size of the effect is equal to that seen in antidepressant treatment of mood and anxiety disorders.
They say their findings should give hope to many smokers who want to stop but continue smoking as they believe it can help with stress or anxiety.
And healthcare professionals can be encouraged to offer smoking cessation advice to people with mental health problems, where some might have previously been worried that quitting could make their conditions worse.
'Patients often say to me, "Doctor, I'm too stressed to stop smoking now",' says Professor Paul Aveyard from the Nuffield Department of Primary Care Health Sciences at the University of Oxford. 'I hope doctors will now reassure those patients that there's a good chance that stopping smoking will make you less stressed.
'In fact, for people with chronic mental health problems, stopping smoking might be an effective treatment.'
The researchers from the universities of Birmingham, Oxford and King's College London analysed the results of 26 studies looking at mental health before stopping smoking and at least six weeks after stopping – in healthy adults and in patients with long-term physical and psychiatric conditions.
The team found consistent evidence that stopping smoking is associated with improvements in mental health compared with continuing to smoke, including measures of depression, anxiety, stress, psychological quality of life, and positivity. The effect was similar in all groups, including those with mental health disorders.
'It is hugely encouraging to be able to demonstrate that smoking cessation leads to an improvement in mental health,' says first author Gemma Taylor from the University of Birmingham. 'Smoking rates in the general population have declined substantially over the last 40 years. However, the rates of smoking in people with mental health problems have barely changed. Part of this disparity is due to the myth that stopping smoking will worsen mental health. I believe this research debunks this myth and I hope that these findings motivate people with and without mental health problems to stop smoking.'