Objective: Subthreshold depression has a considerable impact on the quality of life and carries a high risk of developing major depressive disorder. Psychological treatments for subthreshold depression may be able to reduce depressive symptomatology and prevent the onset of major depression.
Method: We conducted a meta-analysis of randomized controlled studies examining the effects of psychological treatments for subthreshold depression. We examined the effects on depressive symptoms and the preventive effects on the incidence of major depression.
Results: Seven high-quality studies with a total of 700 subjects were included. The mean effect size at post-test was 0.42 (95% CI: 0.23-0.60), with very low heterogeneity. The relative risk of developing a major depressive disorder in subjects who received the intervention was 0.70 (95% CI: 0.47-1.03; P = 0.07).
Conclusion: Psychological treatments have significant effects on subthreshold depression. Furthermore, these interventions may prevent the onset of major depression.