Correlations between serum levels of beta amyloid, cerebrospinal levels of tau and phospho tau, and delayed response tasks in young and aged cynomolgus monkeys (Macaca fascicularis)

Background: In an attempt to explore cynomolgus monkeys as an animal model for Alzheimer's disease, the present study focused on the Alzheimer's biomarkers beta amyloid 1-42 (Aβ₄₂) in serum, and total tau (t-tau) and phosphorylated tau (p-tau) levels in cerebrospinal fluid. Methods: We measured biomarker levels in Young and Aged cynomolgus monkeys and correlated these with performance on three delayed response tasks. Results: The Aβ₄₂ concentration of the Aged monkeys was significantly lower than in the Young subjects, while the t-tau and p-tau did not significantly differ between the groups. The Young subjects performed significantly better than the Aged individuals on the memory tests. Only Aβ₄₂ levels were significantly correlated with performance in the three delayed response tasks. Conclusions: Circulating Aβ₄₂ levels were lower in Aged monkeys and were correlated with inferior performance on delayed response tasks in Aged animals; therefore, both measures may be useful in establishing cynomolgus monkeys as models for studies of AD.