Summary: Smokers who show stronger tobacco dependence are more likely to report depressive symptoms.
Source: University of Helsinki
An international study coordinated by the University of Helsinki offers new evidence about how depressive symptoms and smoking dependence are connected.
The findings highlight the need to understand the specific motivations that sustain smoking dependence in order to design better support for smokers with depression and potentially ease their symptoms by helping them quit.
Previous research has consistently shown that people with depression tend to smoke more than the general population, but the mechanisms behind this relationship have remained unclear.
Research specifically examining the link between smoking dependence and depression has been limited. This study, led by researchers at the University of Helsinki, examined self-reported reasons for smoking to identify which dependence-related motives are most strongly associated with depressive symptoms.
The questionnaire used in the study was developed in collaboration with teams at the Universities of Wisconsin and Missouri in the United States.
The analysis is based on data from more than 1,400 Finnish twins who were smokers and who provided detailed information about their smoking habits and depressive symptoms via questionnaires.
The results were published on February 24 in the peer-reviewed journal Addiction.
Overall, the study found that higher levels of nicotine dependence were associated with greater odds of reporting depressive symptoms. Among the different smoking motives evaluated, those reflecting strong craving and automatic, habitual smoking behavior, as well as smoking motivated by attempts to regulate mood, showed the strongest associations with depression.
“Our results suggest that people with depressive symptoms are not primarily smoking for taste or simple sensory reward,” says Senior Researcher Maarit Piirtola, first author of the study from the Institute for Molecular Medicine Finland at the University of Helsinki. “Instead, depression appears to relate more closely to core dependence motives and the use of smoking to manage mood.”
A distinctive strength of this research is its twin-cohort design, which allowed the investigators to account for familial influences, including shared genetic factors. By comparing twin pairs—especially identical (monozygotic) pairs—researchers could examine whether the association between smoking dependence and depression persisted after controlling for family-level confounding.
Senior Researcher Tellervo Korhonen, who led the study, emphasizes the clinical relevance: understanding the individual reasons that maintain smoking dependence is crucial for providing tailored, multidisciplinary cessation support to smokers experiencing depression.
The authors caution that the study used a cross-sectional design, which limits conclusions about causality.
“Because this analysis is cross-sectional, we cannot determine the direction of the association—whether more severe smoking dependence leads to depressive symptoms or whether depression contributes to stronger dependence among daily smokers,” says Professor and Research Director Jaakko Kaprio from the University of Helsinki.
About this depression research news
Source: University of Helsinki
Contact: Press Office – University of Helsinki
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Original Research: Open access. “The associations of smoking dependence motives with depression among daily smokers” by Maarit Piirtola et al., published in Addiction.
Abstract
The associations of smoking dependence motives with depression among daily smokers
Aims
The study aimed to assess how strongly overall smoking dependence and specific smoking dependence motives relate to depressive symptoms among daily smokers, and whether these relationships remain after accounting for measured confounders and shared familial factors.
Design
Cross-sectional analyses were performed at the individual level and within twin pairs to separate individual influences from familial ones.
Setting
Data came from the fourth wave of the population-based Finnish Twin Cohort, collected in 2011.
Participants
The analytic sample included 918 daily smokers born 1945–1957 (48% men), with a mean age of 59.5 years; the sample contained 38 twin pairs discordant for depression.
Measurements
Depressive symptoms were measured with the Center for Epidemiologic Studies Depression scale (CES-D), using a cut-off score of ≥20 to indicate depression. Smoking dependence was assessed with the Fagerström Test for Cigarette Dependence (FTCD). Motives for dependence were evaluated using three subscales from the Brief Wisconsin Inventory of Smoking Dependence Motives (WISDM): primary dependence motives (PDM), affective enhancement (AE), and Taste. Individual-level logistic regressions used standardized predictor scores and adjusted for multiple confounders, with correction for twin-pair sampling; conditional logistic regression examined associations within twin pairs to control for shared familial factors.
Findings
Depression prevalence in the sample was 18% (n = 163: 61 men [14%], 102 women [22%]). Higher smoking dependence measured by FTCD (OR 1.45; 95% CI 1.20–1.75) and dependence motives captured by PDM (OR 1.56; 95% CI 1.30–1.87) and AE (OR 1.54; 95% CI 1.28–1.85) were associated with increased odds of depression. These associations largely persisted after adjusting for individual confounders, although adjustment for neuroticism attenuated the effects. Notably, FTCD, PDM and AE remained associated with depression within monozygotic twin pairs discordant for depression, indicating that these relationships are not fully explained by shared familial influences.
Conclusions
Depressive symptoms appear to be linked to overall smoking dependence and to dependence motives characterized by heavy, automatic smoking and smoking used to regulate affective states. While neuroticism may confound or mediate these associations, the observed relationships are not solely attributable to shared familial or genetic influences. These findings underscore the importance of identifying the specific dependence motives of smokers with depressive symptoms to inform personalized smoking cessation strategies.