What kind of therapy is best for depression?
This a question that can only be answered by saying "it depends." Diagnosis, severity, duration, and the life context all figure in to the answer.
Psychotherapy, especially cognitive behavior therapy or interpersonal therapy, can be helpful for individuals with mild to moderate depression in many circumstances. Family or couples issues may also need to be addressed, as might medical problems, financial stresses, and other external causes of demoralization and discouragement that can lead to depression.
More severe major depression, as well as milder forms, will also often benefit from medication, but there is currently no way to predict which particular type of medicine is best for an individual.
Chronic, mild depression, known as dysthymic disorder, also benefits from the above treatments. Depression in people who also have had manic or hypomanic episodes is part of bipolar disorder, and any treatment with antidepressants usually should be balanced by mood stabilizing or anti-manic medication. Phototherapy (bright lights) is helpful in seasonal affective disorders and perhaps in some people with non-seasonal depression.
In depression accompanied by psychotic features - delusions and hallucinations - it is essential to use medication, generally the combination of an antidepressant with an antipsychotic drug. Electronconvulsive therapy is perhaps the most effective treatment for severe depression, both psychotic and non-psychotic, though it is often avoided until other treatments have failed. Often, however, it should be considered as a prime option earlier in the course.