Schizophrenia, depression: is tobacco the culprit?

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 and 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 emerged 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 emerged 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 may be rooted in the serotonin and dopamine dysfunctions that nicotine can cause. Commonly referred to as the "happy hormone," serotonin plays a vital role in our mental health. Low serotonin levels can lead to depression.

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, and more.

A cause and effect relationship, but in what sense?

If smoking can lead to mental illness, can suffering from schizophrenia or depression predispose one 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.