Gender Differences and Individual Variability in Human Aging

Brant, L

Abstract

Studies of gender differences and individual variability in age-related phenomena are being carried out to: 1) determine the """"""""normal"""""""" range of variability in human aging, 2) identify potential sources of variability which may be responsive to intervention, and 3) determine if there are subgroups of individuals who are more susceptible or resistant to various aspects of aging. The research combines the use of sophisticated statistical methodologies and the unique time depth and multidisciplinary breadth of the existing BLSA data base to examine issues related to the concepts of """"""""normal"""""""" and """"""""successful"""""""" aging, as well as to increase the power of traditional research designs. The statistical methods used include longitudinal regression models, time dependent proportional hazards analysis, and finite mixture models. Major findings include: 1) the longitudinal rate of decline in pulmonary function is relatively constant with age in both men and women, percentile distribution curves have been calculated based on longitudinal methods that account for age-specific differences in variability (see Project Z01 AG 00634-06 LSB); 2) longitudinal patterns of change in blood pressure differ with age and gender, and individual patterns of change are highly variable; 3) hearing sensitivity declines more than twice as fast in men as in women at most ages and frequencies, individual hearing levels and longitudinal patterns are highly variable even though the BLSA study population is a highly selected group (see Project Z01 AG 00628-06 LSB); and 4) systolic blood pressure is an independent risk factor for hearing loss in the speech-range frequencies (see Project Z01 AG 00628-06 LSB). These findings represent significant contributions to the theoretical and methodological development of biomedical risk factor studies, as well as to an increased understanding of the dynamics of the aging process. Research is underway to develop more refined methods of studying variability in aging in order to develop theoretically and methodologically sound approaches to risk factor analysis which account for changes in an individual's covariates over time and the possibility that individuals differ in susceptibility or resistance to aging processes.