Schizophrenia, depression: is tobacco the cause?
June 9, 2020
Par: chef-projet@dnf.asso.fr
Dernière mise à jour: June 9, 2020
Temps de lecture: 3 minutes
The harmful effects of smoking on our bodies are numerous: cancers, cardiovascular or respiratory diseases, type 2 diabetes, etc. But tobacco consumption also doubles the risk of schizophrenia or depression. These alarming figures come from a study conducted by British geneticists and published in Psychological Medicine[1].
Results that challenge
The study was based on DNA analysis of nearly 500,000 British people. It found that:
- people affected by schizophrenia or depression smoked more regularly than other participants,
- tobacco-dependent subjects suffered from schizophrenia or depression twice as often as non-smokers in the study.
Results that challenge
The study was based on DNA analysis of nearly 500,000 British people. It found that:
- people affected by schizophrenia or depression smoked more regularly than other participants,
- tobacco-dependent subjects suffered from schizophrenia or depression twice as often as non-smokers in the study.
Disrupted neurotransmitters
These findings could be due to the dysfunctions of serotonin and dopamine that nicotine can cause. Commonly called the "happiness hormone", serotonin plays a vital role in our mental health. Thus, a low level of serotonin in a subject can induce a depressive state.
Dopamine, known as the "desire hormone," impacts mood, motivation, and the pursuit of pleasure. A significant drop in dopamine can lead to depression, decreased alertness and attention, a lack of interest in previously enjoyed activities, etc.
A cause and effect relationship, but in what sense?
If smoking can lead to mental illness, can suffering from schizophrenia or depression predispose you to smoking? According to the British study, both are possible. The same team had already highlighted a link between smoking and bipolar disorder, via a study published in the British Journal of PsychiatryThey warn that "not only (...) can smoking harm mental health, but a large part of excess mortality linked to mental illness is due to smoking."
Regular smokers suffering from mental illness should therefore quickly receive specific care.
Also read:
[i] “Tobacco and psychiatric illnesses, a toxic relationship” https://www.generationsanstabac.org/actualites/tabac-et-maladies-psychiatriques-une-relation-toxique/
[1] “Evidence for causal effects of lifetime smoking on risk for depression and schizophrenia: a Mendelian randomization study”, www.cambridge.org https://www.cambridge.org/core/journals/psychological-medicine/article/evidence-for-causal-effects-of-lifetime-smoking-on-risk-for-depression-and-schizophrenia-a-mendelian-randomisation-study/AA82945360EC59FEC4331A7A567309C9/core-reader#
"Smoking May Cause Schizophrenia and Depression," Sputnik, November 6, 2019 https://fr.sputniknews.com/sci_tech/201911061042378789-le-tabagisme-serait-responsable-de-la-schizophrenie-et-de-la-depression/
"Smoking may promote schizophrenia and depression," www.santemagazine.fr, November 8, 2019, https://www.santemagazine.fr/actualites/actualites-sante/le-tabagisme-favoriserait-la-schizophrenie-et-la-depression-428262
