Central nervous system gamma-aminobutyric acid activity in man. Relationship to age and sex as reflected in CSF.

Central nervous system gamma-aminobutyric acid (GABA) activity was demonstrated to be an age- and sex-dependent phenomenon through the study of GABA concentration in lumbar CSF obtained from 87 drug-free normal individuals. Evaluation of the data from homogeneous subgroups of this population disclosed that both the propensity of lumbar CSF GABA levels to decrease with age and the magnitude of the rostrocaudal GABA concentration gradient are more pronounced in females, suggesting possible neuroendocrine involvement. Thus, age and sex are important variables that normally influence central GABAergic activity. Patient populations included in clinical investigations must be age- and sex-matched to avoid invalid conclusions biased by these physiologic variations in CSF GABA concentrations.