Trajectories of Cognitive and Motor Function Between Ages 45 and 90 Years: A Population-Based Study

Abstract

Background To establish trajectories of cognitive and motor function, and to determine the sequence of change across individual tests in community-dwelling individuals aged 45-90 years. Methods Between 1997-2016, we repeatedly assessed cognitive function with five tests in 9,514 participants aged 45-90 years from the population-based Rotterdam Study. Between 1999-2016, we measured motor function with three tests in 8,297 participants. All participants were free from dementia, stroke, and parkinsonism. We assessed overall and education-specific cognitive and motor trajectories using linear mixed models with age as time scale. Next, we determined the sequence of change across individual tests. Results The number of assessments per participant ranged between 1-6 (mean interval, years[SD]: 5.1[1.4]) for cognitive function, and 1-4 (5.4[1.4]) for motor function. Cognitive and motor trajectories declined linearly between ages 45-65 years, followed by steeper declines after ages 65-70 years. Lower educated participants had lower cognitive function at age 45 years (baseline), and declined faster on most cognitive, but not on motor tests than higher educated participants. Up to a 25-year age difference between the fastest and slowest declining test scores was observed. Conclusions On a population-level, cognitive and motor function decline similarly. Compared to higher educated individuals, lower educated individuals had lower cognitive function at baseline, and a faster rate of decline thereafter. These educational-effects were not seen for motor function. These findings benefit the understanding of the natural course of cognitive and motor function during aging, and highlight the role of education in the preservation of cognitive but not motor function

Effects of cognitive ageing trajectories on multiple adverse outcomes among Chinese community-dwelling elderly population

“…Besides, our study has revealed several key determinants of heterogeneous cognitive trajectories. Among them, advanced age, low education level and cognitive reserve, as the most commonly identified risk factors of dementia, have been shown to be important predictors of faster cognitive decline [8,22,43,51]. In addition to baseline cognitive function, a notable difference in physical function was also observed across trajectory groups: older adults with IADL deficits tended to have a higher risk of being on the rapid decline trajectory.…”

“…Furthermore, although cognitive deterioration has been reported to be associated with several functional deficits such as frailty [17], falls [18], rapid eye movement behavior disorders (RBD) [19], depression [20], motor cognitive risk syndrome (MCR) [21] and etc., it remains undetermined whether cognitive ageing trajectory is associated with these functional deficits as well. Likewise, previous efforts which probed into factors shaping cognitive ageing trajectories were limited by small sample size, specific risk factors, or conflicting results primarily from western populations [8,9,11,[22][23][24]. A vast number of factors remain untested among Chinese older adults on this issue.…”

Exploring bi-directional temporal associations between timed-up-and-go and cognitive domains in the Irish longitudinal study on ageing (TILDA)

“…Cognitive decline is associated with ageing and in some cases, it can lead to loss of independence and dementia [3,4]. However, as with most aspects of ageing, individual mobility and cognitive trajectories are extremely heterogeneous [2,5,6], dependent on the aspect of mobility or cognition being measured [6], and a product of multiple behavioural factors and biological mechanisms that occur and accumulate over a lifetime [1,7,8].…”

Educational attainment and trajectories of cognitive decline during four decades—The Glostrup 1914 cohort

“…Previous findings in this area have been inconsistent and most studies do not report significant differences in the rate of cognitive decline due to educational attainment [ 11 , 17 ]. Although two previous studies found steeper cognitive decline in Verbal Memory, Processing Speed, and Verbal Fluency among those with higher education [ 20 , 21 ], results were inconsistent in a recent population study finding higher education to be associated with less steep decline on three attention and memory tests, but steeper decline for three other tests within the same domains [ 35 ]. These results are corroborated by the inconsistent findings reported in a review [ 11 ] and in a recent meta-analysis [ 17 ] finding substantial heterogeneity and no significant association with education for decline in six cognitive domains, including global cognition.…”