Aged monkeys exhibit behavioral deficits indicative of widespread cerebral dysfunction

Area of Science:

• Neuroscience
• Primatology
• Cognitive Aging

Background:

• Aging is associated with cognitive decline, but the extent to which this decline is selective or widespread across different cognitive domains is not fully understood.
• Previous research indicated age-related deficits in visual recognition in aged monkeys.

Purpose of the Study:

• To investigate the selectivity and breadth of age-related behavioral impairments in monkeys.
• To correlate behavioral deficits with age-related brain changes.
• To determine the timeline of cognitive decline in different cerebral systems.

Main Methods:

• Assessed 18 monkeys (3-34 years old) on a variety of cognitive tests, including spatial memory, visual habit formation, visuospatial orientation, visually guided reaching, motor skill learning, and reaction time.
• Tests were designed to assess the integrity of different cerebral systems.
• Behavioral performance was correlated with age.

Main Results:

• Age-related impairments were observed across nearly all tested cognitive categories, particularly on more challenging tasks.
• Decline in spatial abilities began in the late teens, while other abilities were affected later (late 20s).
• Correlations in performance scores were primarily within, not across, test categories, indicating varied patterns of cerebral involvement.

Conclusions:

• Age-related cognitive decline in monkeys is largely widespread, affecting multiple cognitive functions.
• Cerebral systems supporting spatial abilities appear to be compromised by aging earlier than other systems.
• Individual differences exist in the patterns of age-related cerebral dysfunction.