Smoking tobacco may increase the risk of developing depression and schizophrenia, according to a new study.
Researchers from the University of Bristol analysed data from 462,690 people of European ancestry.
They found evidence that tobacco smoking increased the risk of depression and schizophrenia, while results also showed people with those conditions are more likely to start smoking.
The study is published in the journal Psychological Medicine on Wednesday, the same day as a report from Action on Smoking and Health (ASH).
That report calls for more to be done to help smokers with mental health conditions to stop.
Smoking killed 78,000 people in England last year and is the largest single contributor to the average 10-20 year reduction in life expectancy among people with mental health conditions, ASH states.
Dr Robyn Wootton, senior research associate in Bristol University's School of Experimental Psychology, said: "Individuals with mental illness are often overlooked in our efforts to reduce smoking prevalence, leading to health inequalities.
"Our work shows that we should be making every effort to prevent smoking initiation and encourage smoking cessation because of the consequences to mental health as well as physical health."
Action on Smoking and Health (ASH) said smoking rates among people with serious mental health conditions are more than 50 per cent higher than in the general population.
Ann McNeill, Professor of Tobacco Addiction and co-chair of the Mental Health and Smoking Partnership said: "While we have seen smoking rates fall dramatically for the population as a whole over the last four decades, we haven't seen the same decline for people with mental health conditions."
Earlier this year, the researchers published a study in the British Journal of Psychiatry showing evidence that tobacco smoking increases the risk of bipolar disorder.
Australian Associated Press