Like humans, primates have life-spans of multi decades. Captive rhesus monkeys can live into the decades. Monkeys older than 20 years are equivalent of human 60 to 70 years old (Bowden and Williams 1984, Adv. Vet. Sci. Comp. Med. 28:305). As they grow older, humans and primates experience many of the same age-related changes in anatomy, physiology, mental function, and behavior . Aged rhesus monkeys – those older than 23 years of age – have cognitive and memory deficits and develop senile plaques with neuritis derived from cholinergic and other neurotransmitter system  (Price et al., Brain Pathol. 1991, 1:287-296).

Alzheimer’s disease is primarily a disease of cortical derangement and cobnitive impairment. The well-developed cerebral cortex of primates makes these animals extremely valuable for research on Alzheimer’s disease.

There are 50 rhesus monkeys over 20 years old in our China facility. In aged monkey brains, we can find spontaneous senile plaque formation: one of the major histopathological features in Alzheimer’s disease. Thus aged monkey is considered as an useful animal model for Alzheimer’s disease and other aging-causative neurodegenerative disorders.

-          Physical and behavioral changes that accompany aging are recorded and scaled: reversal learning, increased stereotyping of spontaneous behavior, increased reaction time, changes in sensory processing, and reduced long-term memory, according to Bartus methods (Bartus et al. 1983, Psychopharmacol. Bull., 19:168) including food reward scale and visual recognition memory task, etc.

-          Immunohistochemistry reaction in the brain sections showed A deposits (senile plaques) significantly increased with age.

-          Biochemistry analysis for measuring level of acetylcholine (Ach), a neurotransmitter decreased in Alzheimer’s disease and other monoamines such as catecholamine, GABA, serotonin, as well as neuroactive peptides.