Multimorbidity Trajectories From Early to Middle Adulthood and Physical Activity

Multimorbidity is associated with lower physical function in older adults. Less is known about multimorbidity and physical activity earlier in the life course. This study examined multimorbidity trajectories across adulthood with physical activity and explores if multimorbidity accelerates age-related activity decline.

Data are from Coronary Artery Risk Development in Young Adults (CARDIA), an ongoing prospective cohort of participants recruited when they were aged 18-30 years. Six multimorbidity trajectories from baseline (1985-1986) through year 30 follow-up exam (2015-2016; ages 48-60 years) were based on age of disease onset and rate of accumulating additional conditions: mid-20s-fast, mid-20s-slow, late-20s-slow, mid-30s-fast, mid-40s-fast, and early-50s-slow. Activity was device-measured at year 30 and year 35 (2021-2023; ages 53-65). Multivariable linear models were used to estimate differences in activity by multimorbidity trajectory at year 30 and change (%) from year 30 to year 35. Data were collected through June 2023 and analyzed in May 2024.

The sample included 1,425 CARDIA adults at year 30 (mean age 55.1 years) with 749 (mean age 61.3 years) wearing the device again at year 35. Compared with early-50s-slow, mid-20s-slow (β=-14.1; 95% CI= -24.6, -3.6) and mid-30s-fast (β=-14.2; 95% CI= -26.2, -2.2) had lower light-intensity physical activity and mid-20s-fast (β=-5.1; 95% CI= -9.6, -0.6) and late-20s-fast (β=-9.5; 95% CI= -14.1, -4.9) had lower moderate-to-vigorous physical activity. There were significant differences in 5-year behavior change across multimorbidity trajectories.

Early onset and faster accumulation of chronic conditions was associated with lower activity in midlife. Lower intensity activity for people with multimorbidity may be a feasible target for healthy aging.