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Accelerated postmenopausal cognitive decline is restricted to women with normal BMI: Longitudinal evidence from the Betula project
Psychoneuroendocrinology, May 2010. Vol. 35, Issue 4, Pages 516-524. Petra P. Thilers, Stuart W.S. MacDonald, Lars-Göran Nilsson, Agneta Herlitz

The researchers sought to answer the important question of whether women experience systematic changes in cognition following the onset of menopause. They also explored the interesting question of whether a woman’s body mass index (BMI) influenced any changes related to menopause. Higher BMI is associated with higher levels of circulating estrogens, due to their increased production in fat tissue, and estrogen has been extensively researched in terms of its role in enhancing and protecting cognition and even in protecting the brain from Alzheimer’s disease (AD). The study followed 193 women between ages 40-65 years with extensive cognitive testing and measures of BMI longitudinally in the transition from pre- to late stages of post-menopause over a 10-year period. The results showed that, compared to performances premenopausally, postmenopausal women had a reduction in performance on measures of attention and visuospatial processing. Also, women with a normal BMI (18.5-25) had a more rapid decline than women with a BMI above 25 on measures of memory and visuospatial processing. These results support the notion that reduced production of estrogen after menopause may have small negative influences on cognitive abilities, mainly in women within a normal BMI range, implying that the extra estrogen created in the extra fat tissue associated with a high BMI can mitigate this negative influence on cognition. Of course, these results do not directly deal with the question of any potential long-term benefits of estrogen exposure in the 5-7 years following menopause on a woman's later risk of AD, which is also an active area of scientific research.

Thanks to my friend kitkat for posting this on the nomads forum!