NEW YORK (Reuters Health) - For adults who suffer from major depression, psychological interventions and drug therapy are both effective and "each has its own merits," Dutch researchers report.

However, drug therapy may be more effective than psychological interventions in the treatment of dysthymia -- a type of depressive disorder characterized by moods that are consistently low, but not as extreme as other types of depression, Dr. Pim Cuijpers of Vrije Universiteit Amsterdam and associates report.

"A large number of studies suggest that both psychological and pharmacologic therapies are effective in the treatment of mild-to-moderate depressive disorders. Whether both types of intervention are equally effective has not been established definitively," the investigators note in the Journal of Clinical Psychiatry.

To investigate, they pooled data from 30 comparative studies of psychological and pharmacologic therapies involving a total of 3,178 patients diagnosed with a depressive disorder. A total of 1,612 of the study subjects were treated with psychotherapy and 1,566 were treated with antidepressant drug therapy.

The difference between psychological and pharmacologic therapy was not significant in patients with major depressive disorder, they report.

As mentioned, results showed that antidepressant drug therapy was significantly more effective than psychotherapy in studies of patients with dysthymia-type depression.

While treatment with widely used antidepressants called selective serotonin reuptake inhibitors was significantly more effective than psychological treatment, treatment with other antidepressants did not differ significantly from psychotherapies.

Further analyses did not show an association between the severity of depressive symptoms and the differential impact of psychological and pharmacologic treatments for major depression.

The investigators also found that the drop-out rate was significantly smaller in psychological treatments compared with drug treatments.

Most of the treatment differences were small "and probably have little meaning from a clinical point of view," the investigators note.

"More research is needed to examine our findings further," Cuijpers and colleagues emphasize. "It is especially important to examine the mechanisms through which both treatments work and to examine which patients may benefit more from 1 of the 2 types of treatment. It is also important to examine for which cases combined treatment is better."

SOURCE: Journal of Clinical Psychiatry, November 2008.

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