In recent years, all western industrialized countries, and to a growing extent even many developed and developing Asian nations, have witnessed a remarkable growth in numbers of older people [1]. Future projections anticipate continued increases, particularly in numbers of individuals who are 85 years and older [1]. Although US statistics have indicated recent declines in disability trends [2], overall numbers of older individuals living with disability and functional dependence are likely to increase given projected increases in life expectancy [3]. For example, average life expectancy for women born today in the United States is nearly 80; for men, it is nearly 75 [1]. With these considerations in mind, many investigators have begun to pay increasing attention to identifying factors which may predict the transition from health and independence to disability and dependence in older individuals, eventually providing useful targets for interventions [3, 4]