29 Apr 1997

Put these two facts together: brain energy metabolism is abnormally low in Alzheimer's patients, and if your mother had Alzheimer's you are more likely to develop it than if your father had Alzheimer's. You might then logically think that something strange is happening in the mitochondria of Alzheimer's patients, since the mitochondrial genome is inherited from the mother only. A new study published today in the Proceedings of the National Academy of Sciences reported that the problem may lie with the genes for Cytochrome Oxidase (C.O.). A common variant of the mitochondrial genome in which two C.O. genes are consistently mutated appears three times more frequently in Alzheimer's patients. A diagnostic test based on the mutation assay is being developed.

Cytochrome Oxidase is part of the energy metabolism mechanism of the mitochondria. It is the terminal part of the oxidative phosphorylation respiratory chain, reducing molecular oxygen to water and phosphorylating ADP and ATP. The reduced energy metabolism in the Alzheimer's brain has been linked to reduced cytochrome oxidase activity.—June Kinoshita