Changes in the concentration of amino acids in serum and cerebrospinal fluid of patients with Parkinson's disease.

The concentrations of sixteen amino acids have been measured in the serum and cerebrospinal fluid (CSF) of patients with Parkinson's disease and compared with those of control subjects. The levels of most amino acids were not different between the two groups, but the level of glutamate in CSF was decreased significantly, while the level of glutamine was increased. The results may be consistent with an alteration of glutamate neurotransmission in Parkinson's disease.