Adults who adhere to a healthy lifestyle by following a healthy diet, keeping a healthy weight, and maintaining a non-smoking status significantly reduce their risk of developing depressive symptoms, according to a study published in the Journal of Affective Disorders. The association between an unhealthy lifestyle and incidence of depression should additionally signal clinicians to target lifestyle modificationns in the prevention of depressive symptoms.
This prospective cohort study sought to measure the combined effects of 5 modifiable lifestyle indicators (diet, weight, physical activity, smoking, and alcohol consumption) on the incidence of depressive symptoms and to evaluate the population attributable risk associated with these lifestyle indicators.
The study cohort included 25,837 individuals recruited by the French NutriNet-Santé study who were free of depressive symptoms at the start of the study. Physical activity, height and weight, and dietary data were collected at baseline and every 6 months thereafter; socio-demographic information was also provided at enrollment, including gender, age, marital status, occupation, and smoking status. The Healthy Lifestyle Index was used to calculate each of the participant’s lifestyles by assigning a point for adherence to each indicator: healthy diet, healthy weight, moderate to high physical activity, never smoking, and low alcohol consumption. The French version of the Center for Epidemiologic Studies Depression Scale was used to evaluate incidence of depressive symptoms during follow-up.
Of the 25,837 participants, the researchers identified 2112 incident cases of depressive symptoms reported over the 5-year follow-up period. The results of the study show that for each point increase in the Healthy Lifestyle Index, the associated risk for depressive symptoms was reduced by 10%. And for participants who adhered to 3 or more healthy lifestyle indicators, their reduction in risk was significantly more than those with fewer healthy lifestyle indicators.
The population attributable risk was calculated to quantify the relationship between the proportion of depressive symptoms cases and nonadherence to specific healthy lifestyle indicators. Findings showed that 8% of the 2112 cases could be attributed to nonadherence of a healthy diet; 5% nonadherence to a healthy weight; 5% nonadherence to a non-smoking status. Not adhering to a combination of these 3 indicators was associated with 14% of depressive symptoms cases. Physical activity and alcohol consumption were deemed statistically insignificant.
Limitations of the study included unreported factors related to depression and lifestyle, such as family history of depressive disorder, stressful life events, and sleep disorders, which could contribute to potential confounding. The observational nature of the study also made it difficult to exclude reverse causality, in which depression may have led to an unhealthy lifestyle.
The study authors suggest adherence to a healthy diet, weight, and non-smoking status can decrease the risk of developing depressive symptoms in adults. The association between certain unhealthy lifestyle indicators and incidence of depression should signal clinicians to target lifestyle modifications in the prevention of depressive symptoms.
Adjibade M, Lemogne C, Julia C, et al. Prospective association between combined healthy lifestyles and risk of depressive symptoms in the French NutriNet-Santé cohort. J Affect Disord. 2018; 238:554-562.