The signs and symptoms of the AIDS Dementia Complex can be alleviated by zidovudine (ZDV). However, ZDV therapy has been associated with significant toxicities, particularly bone marrow suppression. The efficacy of ZDV appears to decrease during the second and third years of therapy. It is not known whether this reflects cumulative toxicity. In addition, the efficacy of other antiretroviral agents remains uncertain. Hence, adjunctive therapy for cognitive and motor symptoms of AIDS is important.