Memory performance of young and old subjects related to their erythrocyte characteristics

Several papers reported in recent years on a change in the age population distribution of the circulating erythrocytes in old mice, rats, rabbits, and humans. The results indicate the presence of a chronologically younger cell population in old animals and humans. The cells are typically lower in density and larger. In some reports, the cells have higher levels of enzymatic activity. We wanted to know whether changes in the characteristics of the circulating erythrocytes in old people are related to the changes in cognitive performance often observed in the elderly. Twenty young (20-40) and 21 old (70-90) volunteers submitted to memory and blood tests. Density and size distribution, aspartate aminotransferase/glutamic oxalacetic transaminase (AST/GOT) activity, and the level of glycosylated hemoglobin (HbA1) of erythrocytes were determined. The Wechsler Memory Scale--Revised (Wechsler, 1987) was used to determine general memory and delayed recall scores for each subject. We have confirmed that old subjects have larger and less dense cells. Erythrocyte volume was the only blood parameter examined that revealed statistically significant correlations with memory performance. The old subjects with no age-related memory impairment had significantly smaller cells than the other old subjects.