After first scientific studies were conducted in the 1990's, the number of clinical trials has increased rapidly since 2000.
A meta-analysis of these studies (van Zoonen et al., 2014) found a total of thirty-two clinical studies in which subjects with a depressive disorder according to DSM-criteria at baseline were excluded, and only subjects with no formal depressive disorder were included.
In all these studies, it was examined whether the incidence rate of mental disorders was reduced in the recipients of preventive interventions compared to subjects who did not participate in such an intervention. The overall incidence rate ratio was 0.79 (95% CI: 0.69~0.91). The incidence rate ratio is the incidence rate of developing a depressive disorder in experimental subjects relative to the incidence rate in control subjects.
An incidence rate ratio of 0.79 indicates that the risk of developing a depressive disorder in the next year is reduced by 21% compared to individuals in the control groups. This means that prevention of depressive disorders seems to be possible. Preventive interventions could therefore become a realistic strategy to reduce the enormous burden of depressive disorders, next to "curative" approaches.
In the meantime, even more randomized trials have shown that preventive interventions are effective in reducing the incidence of depressive disorders.