Determinants of response to a nutritional intervention in depression: sociodemographic factors and lifestyle changes

Purpose Dietary interventions are needed alongside the treatment of depression, with a focus on factors contributing to their effectiveness. This study aims to assess the influence of sociodemographic factors, intervention adherence and lifestyle changes on response to a nutrition intervention and a social support group intervention for depressive disorder. Design/methodology/approach The authors examined the impact of sociodemographic and lifestyle factors as well as adherence on response to an 8-week controlled trial with two arms (a nutrition intervention group, a social support group) to which 93 patients with moderate to severe depressive disorder were randomized. Analyses were taken at baseline, eight weeks, six months and 12 months. We performed chi-square tests, independent-samples t-tests and Mann–Whitney U tests to analyze the differences between responders (i.e. = reduction of at least one 1 point decrease in the Center for Epidemiologic Studies Depression Scale, CES-D) and non-responders (i.e. = no change or an increase of at least 1 point in CES-D), separately for each group. Findings At 8 weeks and 6 months, non-responders consistently differed from responders in two ways: lower baseline depressive symptoms (p = 0.002, p = 0.02) in the social support group, and increased fast-food intake (p = 0.025, p = 0.025) in the nutrition group. Neither sociodemographic factors nor adherence influenced the responses. Research limitations/implications The overall weak effects on depression and the small sample size may have attenuated the results. Practical implications Based on the findings, offering social support groups may be beneficial for individuals with high levels of depression. Originality/value The findings are novel and valuable when designing interventions for depression.