Altered brain energy metabolism in demented patients with multiple subcortical ischemic lesions. Working hypotheses.

We report the results of brain metabolic studies (using magnetic resonance spectroscopy) in three groups of individuals: (1) demented patients with multiple subcortical ischemic lesions (n = 18); (2) nondemented, age-matched controls (n = 21); and (3) demented patients with neurodegenerative disease, probably of the Alzheimer type (n = 19). Patients with dementia with subcortical vascular lesions, as demonstrated by appropriate imaging studies, had an increase of phosphate energy charge in areas of the cerebral cortex (especially prominent in the frontal regions) superficial to and excluded from the subcortical lesions. We hypothesize that this increased energy charge might be caused by reduced metabolic activity of disconnected brain tissue or by astrocytic hypertrophy and hyperplasia that accompanies subtle ischemic, cortical alterations.