The authors measured gamma-aminobutyric acid (GABA) levels in the lumbar
CSF of patients with depression, with psychosis, or undergoing evaluation
for a neurologic disorder. GABA levels in the CSF from depressed patients
were significantly decreased compared with neurologic control patients. CSF
GABA levels in psychotic patients were not different from those in
neurologic patients, although the data suggested a decrease in CSF GABA
levels in patients with schizoaffective disorder.