In vivo brain concentrations of N-acetyl compounds, creatine, and choline in Alzheimer disease.

Abstract
ALZHEIMER DISEASE (AD) results in substantial loss of brain tissue.1-15 This decline is attributable to deterioration of cell processes, shrinkage of neurons, and perhaps neuronal death.10,16-20 Healthy elderly individuals show an age-related gray matter volume decline in the neocortex21-24 (see Guttman et al25) but their volume loss may not be accompanied by neuronal death.26-29 At issue is the functionality of the tissue remaining in the brains of healthy elderly patients and patients with AD.