Possible link between hormones and Alzheimer's Dementia
3 July 2020
It has been recognised for many years that more women than men are affected by Alzheimer's Dementia (AD). Female hormones have been thought to play a role and new information adds more evidence to the debate.
A recently published study investigated the differences in brain biomarkers of AD in men and women. (A biomarker is a measurable characteristic of normal, or abnormal, function). The biomarkers measured were ß-amyloid levels, glucose metabolism and gray and white matter volume of the brain; all well-established AD biomarkers. It is believed that brain biomarkers are more sensitive than tests of cognitive function for assessing risk of AD in individuals without any symptoms of AD.
85 healthy women and 36 healthy men aged 40 to 65 were assessed. Women showed higher ß-amyloid levels, lower glucose metabolism, and lower gray and white matter volume and hence increased risk of AD. Further, being menopausal was found to be most consistently and strongly associated with the observed brain biomarker differences, suggesting an important effect of lower levels of estrogen.
The loss of gray matter showed that areas of the brain affected matched with those areas where estrogen receptors are widely found. Higher glucose metabolism (a favourable biomarker) was seen in women who had taken hormone replacement therapy (HRT) than those who had not. Thyroid disease and having had a hysterectomy also influenced the biomarkers.
Although this is a relatively small study, it provides important information which strengthens the belief that menopausal estrogen lack may increase the risk of, as evidenced by measurable risk factors. In addition, these findings suggest that the window of opportunity for interventions which may prevent Alzheimer's Dementia in women is early in the menopausal transition. The role of HRT to reduce risk has not been confirmed but deserves further larger and longer research.
Reference: Sex-driven modifiers of Alzheimer risk. A multimodality brain imaging study. Rahman A, Schelbaum E, Hoffman K et al. First published June 14, 2020 Neurology
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