BACKGROUND: Due to their similarities in behavior and disease pathology to humans, non-human primate models are desirable to complement small animals as models for the study of age-related dementia.

MATERIALS AND METHODS: Based on their performance on delayed response task (DRT) tests of memory, aged cynomolgus monkeys were divided into two groups to compare high-performing (n=6) and low-performing (n=6) subjects. Both groups were tested for biomarkers related to Alzheimer's disease and their brains were scanned using structural magnetic resonance imaging.

RESULTS: The subjects with poor DRT performance had evidence of atrophy in the hippocampus and cortical areas, significantly lower cerebrospinal fluid levels of amyloid beta amino acid 1-42 (p<0.001) and higher cerebrospinal fluid total tau levels (p<0.05) compared to the group performing well on the DRT tests.

CONCLUSION: Old, memory-impaired Cynomolgus monkeys may be useful as a spontaneous non-human primate model for investigations of age-related neurodegenerative diseases.