Smoking tobacco could increase your chances of developing depression and schizophrenia, according to researchers at the University of Bristol.
A new report has analysed data from 462,690 people of European ancestry and found evidence that smoking tobacco increases a person's risk of developing the conditions.
It also revealed people with depression or schizophrenia are more likely to start smoking.
The study is being published in the journal of Psychological Medicine today (Wednesday 6 November).
It's coinciding with the release of another report, from Action on Smoking and Health (ASH), which is requesting more to be done to help smokers with mental health conditions to quit the habit.
According to ASH, smoking is the single largest contributor to the average 10-20 year reduction in life expectancy among people with mental health conditions.
The public health charity also reveals smoking rates are more than 50% higher among people with serious mental health conditions than in the general population.
Dr Robyn Wootton, senior research associate in Bristol University's School of Experimental Psychology, said people with mental illnesses are commonly "overlooked" in public efforts to reduce smoking rates.
She continued: "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."
The team at the University of Bristol used data from 462,690 people of European ancestry to carry out the research.
They used an approach called 'Mendelian randomisation', which uses genetic variants associated with exposure - in this case smoking - to support conclusions about cause-and-effect relationships.
Ann McNeill, Professor of Tobacco Addiction and co-chair of the Mental Health and Smoking Partnership said: ""Helping people with mental health conditions to quit smoking is the best way to help them live longer.
"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 Bristol researchers also published their findings in the British Journal of Psychiatry, revealing evidence that smoking tobacco increases the risk of developing bipolar disorder.