Amino acid neurotransmitter deficits in adult Down's syndrome brain tissue.

Neurotransmitter amino acids have been measured in several brain regions taken postmortem from 5 adults cases of Down's syndrome and 6 age-matched control subjects. A significant deficit of glutamate was found in the hippocampus in Down's syndrome, and gamma-aminobutyric acid was reduced in the hippocampus and temporal cortex in those patients with neocortical neurofibrillary tangles. These results are consistent with losses of cortical neurones containing these neurotransmitters, and resemble the deficits exhibited by the more severely affected cases of Alzheimer's disease.