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Abstract:
Since acutely reduced estrogen levels are associated with
impaired memory function, it is possible that the decline in memory
that accompanies aging is more pronounced if ovarian hormones have
been absent for a prolonged period. We have investigated this
possibility in aged female rhesus monkeys that have been
ovariectomized early in life. We compared the cognitive performance
of these long-term estrogen-deprived monkeys (N=6) with that of
age-matched controls (N=7) with intact ovaries. Subjects were
between the ages of 19 and 27 years. The assessment of cognitive
performance consisted of a battery of tasks designed to test object
and spatial memory, as well as executive function. All tasks were
administered in the Wisconsin General Testing Apparatus. The
ovariectomized females were impaired in a non-matching-to-sample
task with a 10-minute delay interval, indicating a deficit in
object recognition memory. On the other hand, the performance of
the ovariectomized monkeys was better than that of aged controls in
a spatial memory task, the Delayed Recognition Span Test. The two
groups of monkeys did not differ significantly on other tasks of
the battery. These results suggest that the long-term absence of
estrogens may result in impaired object memory and improved spatial
memory in old age.
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