Effect of gamma-vinyl GABA in tardive dyskinesia.

gamma-Vinyl GABA (gamma-aminobutyric acid), a drug that increases brain GABA via GABA transaminase inhibition, was evaluated in a blind, placebo-controlled trial in 10 patients with stable tardive dyskinesia. Drug effects during active treatment (2 to 6 g/day) and during pre- and posttreatment placebo periods were determined by scoring randomly sequenced videotapes of tardive dyskinesia and parkinsonian symptoms recorded weekly during standardized examinations. Tardive dyskinesia was significantly reduced, and correlated to increased parkinsonism. Eye blinking rates decreased, but psychiatric symptoms were unchanged during treatment.