Prevention of depressive disorders: towards a further reduction of the disease burden of mental disorders

From a public health perspective, depression is one of the most important mental disorders. It is highly prevalent, has a high incidence and is associated with a substantial loss of quality of life for patients and their relatives, increased mortality rates, high levels of service use and enormous economic costs. Major depression is currently ranked fourth worldwide in disease burden, and it is expected to rank first in disease burden in high-income countries by the year 2030. Although current treatments are effective in treating depressive disorders, it is estimated that treatment alone can reduce the disease burden of depression by only about 35%, but only in optimal conditions. Prevention of the incidence of new cases of depression has been suggested as a new strategy next to treatment, which may help to further lower the disease burden. In the past 15 years, considerable progress has been made in examining the possibilities to prevent the onset of depressive disorders. In a recent metaanalysis, we were able to include 19 randomized trials examining interventions aimed at preventing the onset of depressive disorders in participants with no disorder at baseline, and currently almost 30 trials have been conducted. These studies show that preventive interventions are capable of preventing about one-quarter of the new incident cases. These studies vary considerably from each other, with some studies being aimed at adolescents, whereas others focus on adults and some on older adults. The setting in which the studies are conducted also differs considerably, ranging from studies aimed at post-partum depression to studies aimed at patients with general medical disorders and primary care patients. Some studies are aimed at universal prevention, which is aimed at the general population or parts of the general population, regardless of whether they are at elevated risk of developing a disorder (e.g. school programmes or mass media campaigns). Other studies focus on selective prevention, which is aimed at high-risk groups, who have not yet developed a mental disorder. Still other studies focus on indicated prevention (aimed at individuals who have some symptoms of a mental disorder but do not meet diagnostic criteria). The interventions used in these studies also vary considerably and include cognitive behavioural interventions, interventions based on interpersonal psychotherapy and psychoeducational interventions. Some studies explicitly focus on the first ever depressive disorder, whereas others allow lifetime depressive disorders. So, the field is still very heterogeneous in terms of target groups, setting and type of intervention. In our meta-analysis, we did not find high levels of statistical heterogeneity, which may indicate that our finding of about 25% reduction of incidence is robust across target groups, settings and interventions. It also indicates, however, that the field is still very young, and definite conclusions about the effects of these interventions cannot yet be drawn. Prevention of mental disorders in general is still at an early stage of development. Although a relatively large number of studies have examined the possibilities of preventing depressive disorders, we still have very little knowledge about effective interventions and how to apply them. Although several studies have examined the possibilities to prevent anxiety disorders, eating disorders and psychotic disorders, this is nothing compared with the thousands of studies that have examined treatment of existing disorders. Although treatment studies have examined the effects, acceptability and feasibility of many different types of treatment in many different settings, the possibilities of preventing the onset of mental disorders have only just started to be explored in a few dozen studies. Research on the possibilities of preventing mental disorders has been developed within subfields, largely independent of other subfields and with little exchange. Prevention of depressive disorders, anxiety disorders, psychotic disorders, eating disorders, conduct disorders in children and all fields has been developed from research on treatments of these disorders and epidemiological research examining each of these disorders. This has also led to differences among subfields. For example, in the Early Intervention in Psychiatry 2011; 5: 179–180 doi:10.1111/j.1751-7893.2011.00282.x First Impact Factor released in June 2010 and now listed in MEDLINE!