Depression is a common mental health disorder that negatively affects daily functioning and quality of life. Unfortunately, depression is often a recurrent disorder. Current treatment guidelines are based on clinical features of the disease, but new evidence points to sociodemographic and psychosocial characteristics that influence the severity and prognosis of depression. Specifically, a study published in the Canadian Medical Association Journal highlights smoking and a feeling of lack of control over one’s life as significant predictors of a negative long-term prognosis of depression.

The population-based survey evaluated nearly 600 people aged 16 or older who participated in a national health survey. The national survey included more than 17,000 participants, and the subjects in this evaluation were those who had reported a major depressive episode in the first year of the survey. The participants were followed for six years. More than half (64.5%) of the participants were women, and, at baseline, the average age of the group was approximately 39 years. Most of the participants were white (91.7%) and earned a middle to high income (81.5%). Nearly two-thirds had achieved greater than a high school education.

Over the follow-up period, slightly more than half (55.3%) of the survey population experienced repeated episodes of depression. The authors evaluated numerous physical, emotional, psychological, social, and demographic characteristics of the participants to examine their association with depressive episodes. Daily smoking and low mastery (feeling that life circumstances are beyond one’s control) were significant predictors of recurrent depression. A history of depression, which is already a well-established risk factor for future episodes of depression, was also significantly related to recurrent depressive episodes in this study. The association between risk factors and depressive episodes varied with the severity of depression.

Due to the nature of the study and the small sample size, the direction of effect and causal mechanisms are unclear. However, interventions that promote smoking cessation and increase mastery may provide positive mental health outcomes. Smoking cessation has obvious health benefits, and high levels of mastery are linked to regular physical activity, a healthy diet, decreased metabolic risk factors, and a decreased risk of death from cardiovascular factors. In fact, high levels of mastery at baseline were protective against recurrent episodes of depression in this population.

Smoking and mastery are simple and straightforward to assess in routine clinical practice. According to the authors of the current study, these novel prognostic factors may offer new avenues for treatment of depression and prevention of recurrent depressive episodes.

References

Colman I, Naicker K, Zeng Y, Ataullahjan A, Senthilselvan A, & Patten SB (2011). Predictors of long-term prognosis of depression. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne, 183 (17), 1969-76 PMID: 22025655

Howland RH, Wilson MG, Kornstein SG, Clayton AH, Trivedi MH, Wohlreich MM, & Fava M (2008). Factors predicting reduced antidepressant response: experience with the SNRI duloxetine in patients with major depression. Annals of clinical psychiatry : official journal of the American Academy of Clinical Psychiatrists, 20 (4), 209-18 PMID: 19034753

Katon W, Unützer J, & Russo J (2010). Major depression: the importance of clinical characteristics and treatment response to prognosis. Depression and anxiety, 27 (1), 19-26 PMID: 19798766

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