Preserved motor asymmetry in late adulthood: is measuring chronological age enough?

When comparing motor performance of the dominant and nondominant hands, older adults tend to be less asymmetric compared to young adults. This has suggested decreased motor lateralization and functional compensation within the aging brain. The current study further addressed this question by testing whether motor asymmetry was reduced in a sample of 44 healthy right-handed adults ages 65-89. We hypothesized that the older the age, the less the motor asymmetry, and that 'old old' participants (age 80+) would have less motor asymmetry than 'young old' participants (age 65-79). Using two naturalistic tasks that selectively biased the dominant or nondominant hands, we compared asymmetries in performance (measured as a ratio) across chronological age. Results showed preserved motor asymmetry across ages in both tasks, with no difference in asymmetry ratios in the 'old old' compared to the 'young old.' In the context of previous work, our findings suggest that the aging brain may also be characterized by additional measures besides chronological age.