Cognitive tasks show age-related decline over a 10-year period in a natural aging monkey model, cotton-top tamarins (Saguinus oedipus).

Cotton-top tamarins (n = 14, aged 7-24 years) were tested over a 10-year period on tasks conventionally differentiating aging from dementia in humans. Three tasks were developed on iPads to collect response accuracies in tests of attention (visual search [VS]), working memory (delayed matching-to-sample), and executive processing (rule-shifting). A fourth task utilized a spontaneous object recognition paradigm to test familiarity memory in the subjects' home cages. Linear regression analyses revealed cognitive decline with increasing age in particular components of these tasks. Specifically, accuracy to direct attention in a VS to targets with overlapping features decreased with age. All older monkeys showed accuracy to remember sample items through 1- and 10-s delays in a recognition test, but their ability to remember through these delays was compromised with more extreme aging. Rule-shifting involving attending to a dimension previously irrelevant to the game was particularly problematic with increased age. Cognitive maintenance with aging occurred with simpler VS targets, rule-shifting within the same dimension or feature, and familiarity memory. Tamarins' initiation of cognitive decline mapped closely to the age found in published work of the accumulation of Aβ (beta amyloid species and plaques) in tamarins. The failures in cognition in aging tamarins corresponded with common failures in elderly humans. Moreover, eight of the 14 tamarins showed more severe cognitive deterioration that might signal a kind of dementia. Further study is needed to measure cognitive maintenance and loss across a variety of species of primates with different lifespans and backgrounds. (PsycInfo Database Record (c) 2026 APA, all rights reserved).