Effect of Aging on Cerebrospinal Fluid GABA Level

Abstract

Dysfunction of brain GABA metabolism is supposed to exist in patients with Alzheimer's disease, Huntington's disease and Parkinson's disease. Recently aged people are increasing in population, and they may be also supposed to have dysfunction of brain GABA metabolism. The purpose of this study is to clarify the effect of aging on brain GABA metabolism. For this purpose, we measured cerebrospinal fluid GABA (CSF-GABA) level which reflected dysfunction of brain GABA metabolism.
The individuals consisted of normal volunteers and patients without neurological or psychiatric disease. There were 34 individuals (19 men and 15 women) and their mean age was 49 years. The brain atrophy in these individuals was only a little on CT scan. CSF-GABA levels were measured by radioreceptor assay (RRA). As a result, the mean CSF-GABA level (mean±SEM) was 131 ±7.5 pmoles/ml in control group (age: 20-39 years). The CSF-GABA level was significantly decreased in individuals over 50 years, compared with control group. The CSF-GABA level was only 50% of control in seventies and 30% in eighties. On the other hand, no significant decrease of CSF-GABA was seen in forties. a significant negative correlation between age and CSF-GABA (p<0.01) was found both in males and in females. These data suggested that dysfunction of brain GABA metabolism progressed with age and that various neurological or psychiatric symptoms caused by that dysfunction could more easily appear in aged people.