To the Editor.
—The intriguing possibility that glutamate-mediated neuronal toxicity is implicated in dementia related to acquired immunodeficiency syndrome (AIDS) has gained increasing interest in recent years. The new findings of Dr Ferrarese and coworkers1 on elevated glutamate levels in AIDS patients' cerebrospinal fluid (CSF) accentuate this issue and raise hopes that glutamate antagonists may be developed as potential neuroprotective drugs for delaying and restricting AIDS-associated dementia. Clinical applications for these findings require identification of the source for the elevated CSF glutamate levels. The authors suggest that their data are consistent with impaired glial glutamate uptake induced in situ by human immunodeficiency virus (HIV) gp 120. However, HIV infection is commonly associated with neurologic disease that occurs in the apparent absence of extensive infection of brain cells by HIV, suggesting that indirect mechanisms may account for AIDS-related dementia.An alternative explanation is that elevated CSF glutamate levels are a