A STRATEGY FOR IDENTIFYING BIOMARKERS OF AGING - FURTHER EVALUATION OF HEMATOLOGY AND BLOOD-CHEMISTRY DATA FROM A CALORIE RESTRICTION STUDYIN RHESUS-MONKEYS

We examined a dataset derived from a battery of hematology and blood c hemistry tests to identify candidate biomarkers of aging in a sample o f 33 male rhesus monkeys (Macaca mulatta) ranging in age from 4-27 yea rs. About half this sample comprised an experimental: group subjected to 30% calorie restriction for six to seven years compared to the cont rol group fed the same nutritionally fortified diet to approximate ad lib levels. Variables that met the following criteria were selected: ( 1) longitudinal change within the cohorts of control monkeys, (2) cros s-sectional correlation with age across the adult lifespan in the cont rol group; (3) stability of individual differences within all groups; and (4) no obvious redundancy with other selected variables, Five vari ables emerged from this step-wise selection, including the percentage lymphocytes, and serum levels of alkaline phosphatase, albumin, creati nine, and calcium. These variables were then submitted to a principal component analysis, which yielded a single component accounting for ab out 58% of the total variance. Based on this marked degree of covarian ce, these candidate biomarkers of aging could he combined into a biolo gical age score (BAS) for the control and experimental groups. When ch ronological age was regressed onto BAS, the slopes of the control and experimental groups could be compared. Although a trend toward a slowe r aging rate in calorie-restricted monkeys was apparent, this analysis did not detect a statistically significant difference in the rate of aging between these groups estimated by this index. Despite this resul t, a logical strategy was confirmed for expanding the search for candi date biomarkers of aging to apply to this and to other studies assessi ng interventions that purport to affect the rate of aging in long-live d species. Published by Elsevier Science Inc.