Trends in grip strength: Age, period, and cohort effects on grip strength in older adults from Germany, Sweden, and Spain

Abstract

Grip strength is seen as an objective indicator of morbidity and disability. However, empirical knowledge about trends in grip strength remains incomplete. As trends can occur due to effects of aging, time periods and birth cohorts, we used hierarchical age-period-cohort models to estimate and disentangle putative changes in grip strength. To do this, we used population-based data of older adults, aged 50 years and older, from Germany, Sweden, and Spain from the SHARE study (N = 22500) that encompassed multiple waves of first-time respondents. We found that there were contrasting changes for different age groups: Grip strength improved over time periods for the oldest old, whereas it stagnated or even decreased in younger older adults. Importantly, we found strong birth cohort effects on grip strength: In German older adults, birth cohorts in the wake of the Second World War exhibited increasingly reduced grip strength, and in Spanish older adults, the last birth cohort born after 1960 experienced a sharp drop in grip strength. Therefore, while grip strength increased in the oldest old aged 80 years and older, grip strength stagnated or decreased in comparatively younger cohorts, who might thus be at risk to experience more morbidity and disability in the future than previous generations. Future studies should investigate factors that contribute to this trend, the robustness of the observed birth cohort effects, and the generalizability of our results to other indicators of functional health.

Keywords: Compression; Expansion; Grip strength; Morbidity; Trend.

Fig. 1

Age, period, and cohort effects on grip strength in older adults from Germany (N = 8483). In the upper row, panel A depicts the predicted value of grip strength across age; panel B depicts the changes in grip strength due to time period; and panel C depicts the changes in grip strength due to birth cohorts. Shaded areas represent 95% confidence intervals. In the lower row, panel A depicts the changes in grip strength due to time period for men and women separately, and panel B depicts the changes in grip strength due to time period for middle-aged adults, older adults and the oldest old.

Fig. 2

Age, period, and cohort effects on grip strength in older adults from Sweden (N = 6198). In the upper row, panel A depicts the predicted value of grip strength across age; panel B depicts the changes in grip strength due to time period; and panel C depicts the changes in grip strength due to birth cohorts. Shaded areas represent 95% confidence intervals. In the lower row, panel A depicts the changes in grip strength due to time period for men and women separately, and panel B depicts the changes in grip strength due to time period for middle-aged adults, older adults and the oldest old.

Fig. 3

Age, period, and cohort effects on grip strength in older adults from Spain (N = 7869). In the upper row, panel A depicts the predicted value of grip strength across age; panel B depicts the changes in grip strength due to time period; and panel C depicts the changes in grip strength due to birth cohorts. Shaded areas represent 95% confidence intervals. In the lower row, panel A depicts the changes in grip strength due to time period for men and women separately, and panel B depicts the changes in grip strength due to time period for middle-aged adults, older adults and the oldest old.