Irs possible that its not the research that's the issue, but
its interpretation. The press often sensasionalize results from
research beyond their original conclusions.
Its well known that estrogen diminishes certain cognitive functions
even in humans, namely those relating to spatial awareness,
but the effect is not uniform. Many women have higher spatial
awareness than many men. But, on ** average **, men have a
better spatial awareness than women, mostly due to the
effect of estrogen and testosterone on the brain (they're not sure
what mechanism in the brain causes this).
Estrogen also increases
verbal skills, which they posit is an effect of increase connection
between hemispheres.
This positive effect of estrogen, would be much harder to test on rats
than the loss of spatial awareness which can be tested in a simple maze.