Abstract
(1) Cognitive decline differs among individuals and cognition function domains. We sought to identify distinct groups of immediate and delayed verbal memory in two age subsamples (50–64, 65+ years), and to analyze associated factors. (2) Latent class mixed models were used to identify verbal memory trajectories in a sample of Spanish community-dwelling individuals over 8 years’ follow up. Chi-square and Kruskal–Wallis tests were used to assess differences among trajectories. (3) Different trajectories were identified. In the case of immediate verbal memory, these were: very low/decline (6.3%), low/stable (38.2%), medium/slow decline (43.4%), and high/slow decline (12.2%) in the middle-aged group, and low/decline (20.4%), medium/slow decline (60.4%), and high/slow decline (19.2%) in the older subsample. In delayed verbal memory, more distinct patterns were found: very low/decline (12.4%), low/stable (51.4%), medium/accelerated decline (24.7%), and high/slow increase (11.4%) in the younger group, and low/slow decline (34.4%), medium/decline (52.7%), and high/slow decline (12.9%) in the older group. (4) Overall, low initial performance and decline were associated with older age, lower education, and higher diabetes/stroke prevalence. Differences found suggests heterogeneity in cognitive ageing. The high prevalence of cardiovascular diseases in those with worse cognition suggests that early interventions to prevent those conditions should be targeted in midlife to delay cognitive decline.
Highlights
By 2050, the world’s population aged 60 years and older is expected to almost double, from 12.7%in 2017 to 21.3% [1]
The use of latent class analysis techniques to classify older adults according to their trajectories of cognition over time has overall revealed the presence of at least three [9,10], if not four [11,12,13] groups
The average baseline age was 56.62 [interquartile range (IQR) = 60.00, 53.00] in the middle-aged group and 73.01 [IQR = 77.00, 68.00] in the older group; the sample comprised slightly more women than men (52.0% and 54.6%, respectively), and in the 65+ group, a higher proportion of participants had less than primary education
Summary
By 2050, the world’s population aged 60 years and older is expected to almost double, from 12.7%in 2017 to 21.3% [1]. Europe is projected to remain the most aged region, with 34% of the population aged 60+ [1] Along with this rapid increase, [2], there is huge burden placed on older individuals, Brain Sci. 2020, 10, 249; doi:10.3390/brainsci10040249 www.mdpi.com/journal/brainsci. The majority of the individuals maintain a stable trajectory or a slow decline, whereas a small part of them could be classified as rapid decliners [9,11,12] Those with low baseline cognition scores are more likely to decline faster [10,11,12]. Those groups with better initial performance on cognition are composed mainly of younger individuals with higher education levels [10,11,12]
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