Background: Quality of life in late adulthood is a function of physical, emotional, and intellectual health, and maintenance of functional ability is central to sustaining independent living. Generational differences in health behaviors and health care may result in differences in how functional ability changes with age. Cohort differences in rates of decline would provide support for environmental or behavioral influences on aging of physical functioning.

Method: Twenty assessments of functional ability were collected as part of the longitudinal Swedish Adoption/Twin Study of Aging from twins aged 50–88 at the first wave. Participants completed up to 7 assessments covering a 21-year period. Factor analysis was used to create 3 factors: flexibility, fine motor skills, and balance. Individuals born 1900-1924 (N=441) were compared with individuals born 1925-1948 (N=418).

Results: Latent growth curve modeling incorporating two linear slopes was used to compare rates of decline between the two cohorts. For the early born cohort, slopes assessed change from 60-80 (slope 1) and 80-95 (slope 2); for the later born cohort, slopes assessed changes from 50-60 and 60-80. The balance and flexibility factors showed equivalent increase in difficulty in functioning in the overlapping age range (age 60-80); however, difficulties in fine motor skills increased faster in the later born cohort in that age range.

Conclusions: Cohort differences in experiences have modest impact on increases in difficulty in physical functioning; generally, aging of physical functioning is occurring at the same pace for two distinct cohorts, providing support for internal mechanisms of decline.