“Namenda saved my life,” says Miami’s F.D.R. “Fluffy” Sullivan. Now 48, Sullivan began having HIV-related cognitive kinks 10 years ago: “I’d throw my keys away with the trash and forget what I was talking about.” Then peripheral-neuropathy (PN) pain landed him in a wheelchair, so he steered straight for a Namenda trial in 1997. Within a month, he’d ditched his chair and cane. “Namenda made me young again,” he raves. (His seven-drug HAART combo helps, too.)

Namenda protects brains injured by Alzheimer’s, strokes or HIV. These illnesses cause neurons to release too much glutamate (an amino acid that helps you learn and remember), flooding and damaging brain cells. Namenda binds to some of the brain’s receptors, blocking the glutamate glut; those receptors may also play a role in how neuropathy pain is felt.

In lab and animal studies, Namenda performed as promised, but Fluffy’s 140-person ACTG 301 trial proved statistically insignificant. Yet 301 lasted just 16 weeks; in Alzheimer’s trials, the drug didn’t shine until 24 weeks. And “among HIVers with detectable virus in their cerebrospinal fluid, the rate of neurological progression was significantly lower in the memantine group,” says lead investigator Bradford Navia, MD. Though Namenda had “no obvious effect” on neuropathy, it didn’t interfere with HIV meds and side effects were minor—mostly insomnia and agitation. It can cause hallucinations, so “be careful [with] patients predisposed to neuropsychiatric problems,” Navia says.

Experts agree that effective HAART is the first line against HIV dementia. But adding Namenda may help older HIVers, those with resistant virus and others at risk for cognitive decline. “Given its good safety profile, I’d probably prescribe it,” Navia says. “There’s nothing to lose.”