Impairment in mitochondrial cytochrome oxidase gene expression in Alzheimer disease

Brains from 5 patients with Alzheimer's disease (AD) showed a 50%-65% decrease in mRNA levels of the mitochondrial-encoded cytochrome oxidase (COX, a marker of oxidative metabolism) subunits I and III in the middle temporal association neocortex, but not in the primary motor cortex, as compared to 5 control brains. The amount of mitochondrial-encoded 12S rRNA was not altered, nor was the amount of nuclear-encoded lactate dehydrogenase B mRNA (a marker of glycolytic metabolism). These data suggest that the decrease in COX I and III subunits mRNA in affected brain regions may contribute to reduced brain oxidative metabolism in AD.