Amantadinesulfate is a well known substance which has proven useful in the treatment and prophylaxis of viral infections, in treating symptoms of Parkinson's disease, cocaine dependence, and apathy in multiple sclerosis. It has also been reported as having mild antidepressive effects not sufficient to warrant its use as an antidepressant. Striking antidepressive effects in some patients have been attributed to its antiviral activity against human Borna disease virus (BDV) infection which is frequently seen in patients with depressive episodes. In this 8 to 12 week open study of oral amantadine in 30 depressed patients with various states of BDV infection we found a significant antidepressive response in 19 of 30. Peripheral BDV antigen indicating acute infection was cleared in both responders and non-responders, but only in responders peripheral infection was significantly reduced.

The high rate of BDVAG, especially in fatigued patients with recurrent major depression or bipolar disorder, may be a nonspecific aspect of immunosuppression. The question remains whether this neurotropic virus may contribute to the pathogenesis of some types of affective disorder.