Antidepressant treatment of psychotic major depression: potential role of the sigma receptor.

Psychotic major depression is a severe condition that frequently proves difficult-to-treat. The most effective traditional treatments (electroconvulsive therapy and combinations of antipsychotics with tricyclic antidepressants) are associated with significant side effects, and the use of tricyclic antidepressants alone is largely ineffective. Recent evidence has indicated that the selective serotonin reuptake inhibitors, either alone or in combination with antipsychotics, may provide a desirable alternative to traditional treatments. Among selective serotonin reuptake inhibitors, fluvoxamine has been the best studied and, somewhat surprisingly, has proven effective in several studies as a monotherapy without the need to combine with an antipsychotic. It is proposed that the apparent efficacy of fluvoxamine in psychotic major depression may be related to its unique property of high affinity for the sigma 1 receptor, which is thought to play a role in psychosis and in the action of some antipsychotic drugs.