Evidence suggests that the majority of AIDS patients suffer from progressive dementia, a central nervous system dysfunction resulting from human immunodeficiency virus (HIV) infiltration of brain structures. The most common initial behavioral symptoms are apathy, social withdrawal, and emotional blunting. Several factors may impede the professional's ability to detect incipient dementia, including inability to detect dementia processes through intake interviews and medical tests. The three categories of dementia are neuropathologic abnormalities involving cortical structures, subcortical structures, and both cortical and subcortical regions. It appears that AIDS-related dementia is a subcortical dementia. Characteristics of subcortical dementia include lack of attention, intelligence, and memory; visuospatial deficits; difficulty in abstract reasoning; motor abnormalities; and mood or affective disturbance. Once clinicians have gained an understanding of the common mental changes resulting from AIDS-related dementia, they will be able to take several approaches to appropriate treatment, including mobilizing resources to assist the patient in functioning adequately, providing ongoing supportive psychotherapy, and providing support groups and education sessions for family and friends. Uninformed professionals who are not aware of AIDS-related dementia may do a disservice to patients by using inappropriate interventions and allowing the degenerative process to develop unrecognized or unattended. 11 notes and references.