AIDS and the brain

Acquired immune deficiency syndrome (AIDS) continues to increase in incidence worldwide. The AIDS-associated virus selectively infects and destroys T-helper/ inducer (T4) lymphocytes, causing profound deficits in cell-mediated immune responses. Consequently, the nervous system is often affected by opportunistic infections and lymphomas. In addition, the AIDS virus itself appears neurotropic, and may be the direct cause of dementia, myelopathy, and neuropathy; these complications may precede other systemic manifestations of AIDS. This has profound implications on strategies of treatment; comparisons with immune responses of equines and ruminants to related lentiviruses bode ill for vaccine development. On the other hand, the association of a human retrovirus with progressive neurological syndromes in AIDS gives impetus to a search for retroviruses in other chronic inflammatory, degenerative or demyelinating diseases of the nervous system.