A group of researchers at the Central Institute of Mental Health has confirmed the connection between cigarette consumption and depression as part of the NAKO Health Study. The analysis showed that depression is more common over the life course in current and former smokers than in people who have never smoked. The focus was on dose-dependent effects of smoking behaviour and on the benefits of quitting smoking.

Smoking causes over eight million deaths per year worldwide and is considered the leading preventable cause of premature mortality. Although the link between smoking and depression is known, detailed knowledge of the mechanisms is lacking. The study therefore looked at dose-response relationships, age at start of smoking and time since weaning.

The evaluation included 173,890 participants aged 19 to 72, 50 percent of whom were women. Data on diagnosed depression, current symptoms, living conditions and smoking behaviour were collected via interviews and standardised questionnaires. There were three groups: 81,775 never-smokers, 58,004 former smokers and 34,111 current smokers. The age at the start of smoking, the daily amount of cigarettes and, in the case of alumni, the duration of abstinence were recorded.

Depression was more common among current and former smokers, especially in the age groups between 40 and 59 years. A dose-response relationship was identified: higher cigarette consumption correlated with more severe depressive symptoms, with 0.05 more symptoms occurring for each additional cigarette. A later start to smoke postponed the onset of depression by 0.24 years per year later start. Prolonged abstinence reduced the risk, with the last depressive episode occurring 0.17 years further back per year without smoking.

The consumption of other tobacco products was not taken into account. The cross-sectional design and retrospective data do not allow causal conclusions. Future longitudinal analyses as well as the inclusion of genetic and imaging data should clarify the mechanisms.

The findings emphasize the importance of preventing smoking start and promoting cessation to improve mental health. Higher consumption increases depressive symptoms, while longer abstinence alleviates them.

Original Paper:

From cigarettes to symptoms: the association between smoking and depression in the German National Cohort (NAKO) | BMC Public Health | Springer Nature Link

Editor: X-Press Journalistenbüro GbR

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