It is known that smoking is much more common among people with mental illnesses, especially depression and schizophrenia. However, most of the studies that have analyzed this association have not been able to decipher whether it is a cause and effect relationship and, if so, in which direction: Does mental illness increase the likelihood of smoking, or is smoking a risk factor for mental illness?
Researchers from the University's Tobacco and Alcohol Research Group (TARG) with the support of the Bristol MRC Integral Epidemiology Unit (UIS) and the Bristol Biomedical Research Center (BRC) of NIHR, used UK Biobank data of 462,690 individuals of European descent, comprising the current 8% smokers and 22% former smokers.
The team applied an analytical approach called Mendelian randomization, which uses genetic variants associated with an exposure (eg smoking) to support stronger conclusions. on the cause and effect relationships.
And they found evidence that smoking tobacco increases the risk of depression and schizophrenia, but also that depression and schizophrenia increase the likelihood of smoking (Although the evidence was weaker in this direction for schizophrenia). His study is published in the magazine Psychological Medicine.
"We should encourage quitting because of the consequences for mental and physical health"
Research adds to a growing work that suggests that smoking can have adverse effects on mental health. The same group published a similar study in the British Journal of Psychiatry Earlier this year in collaboration with the University of Amsterdam, it shows evidence that smoking tobacco increases the risk of bipolar disorder.
The UK government mental health working group made the recommendation in its 2016 review that psychiatric hospitals should be smoke free by 2018. This new evidence adds more weight to Support the implementation of smoke-free policies.
There is not only evidence that smoking can be detrimental to mental health, but much of the excess mortality associated with mental illness is due to smoking.
Dr. Robyn Wootton, Senior Research Associate at the School of Experimental Psychology and lead author of the study, notes that "the people with mental illnesses are often ignored in our efforts to reduce the prevalence of smoking, which leads to health inequalities. "
"Our work shows that we should be making every effort to prevent the onset of smoking and encourage quit smoking due to mental health consequences and physical health, "he adds.