Rhythmic timing in aging adults: On the role of cognitive functioning and structural brain integrity.

Here we asked whether impaired timing in older adults results from an aging clock or a more general brain and cognitive decline. Healthy aging adults (N = 70, aged 62-83 years) tapped to the beat of a periodic and a syncopated rhythm. Analyses focused on performance differences between rhythms (periodic-syncopated), which reduced the impact of timing unrelated processes. Apart from tapping, participants completed a cognitive assessment and neuroimaging of gray matter volume (GMV) and fractional anisotropy (FA) globally as well as regionally (cortical: auditory, premotor, paracentral; subcortical: putamen, caudate, cerebellum). The rhythm difference showed no significant age effects for tapping asynchrony and an age-related decrease for tapping consistency. Additionally, age reduced cognitive functioning, global GMV/FA, and, beyond this, auditory GMV. Irrespective of age, the rhythm difference in tapping asynchrony was linked, not to GMV, but to caudal, premotor, and paracentral FA after controlling for global FA. Tapping consistency was associated with global rather than regional brain integrity. Additionally, age differences in tapping consistency were mediated by a decline in global brain integrity as well as cognitive functioning. Together these results agree with previous proposals differentiating between timing accuracy and reliability and suggest that aging largely preserves the former but not the latter. Whereas timing accuracy may depend on an internal clock supported by robust striatocortical circuitry, timing reliability may depend on global brain and cognitive functioning, which show a pronounced age-related decline. (PsycInfo Database Record (c) 2020 APA, all rights reserved).