d‐Aspartate in Human Brain

: The presence of the biologically uncommon D‐aspartic acid (D‐aspartate) in hu manbrain white matter has been previously reported. The earlier study has now been expanded to include D/L‐aspartate ratios from 67 normal brains. The data show that the D‐aspartate content increases rapidly from 1 year to ∼35 years of age, levels off in middle age, and then appears to decrease somewhat. The D‐aspartate content in gray matter remains at a consistently low level (half of that found in white matter) throughout the human life span. Within the limitations of current analytical methods, there was no detectable difference in D/L‐aspartateratios in white and gray matter of brains with Alzheimer's disease and several other pathologies when compared with brains of normal subjects. However, the presence of a significant D‐aspartate level in white matter during the adult life span may lead to changes in protein configuration related to dysfunctions associated with the aging brain.