Timing of estrogen therapy is crucial

October, 2011

A rat study provides further evidence that the conflicting findings on the benefit of estrogen therapy stem from the importance of timing.

The very large and long-running Women's Health Initiative study surprised everyone when it produced its finding that hormone therapy generally increased rather than decreased stroke risk as well as other health problems. But one explanation for that finding might be that many of the women only received hormone replacement therapy years after menopause. There are indications that timing is crucial.

This new rat study involved female rats equivalent to human 60-65 year olds, about a decade past menopause.  An enzyme called CHIP (carboxyl terminus of Hsc70 interacting protein) was found to increase binding with estrogen receptors, resulting in about half the receptors getting hauled to the cell's proteosome to be chopped up and degraded. When some of the aged rats were later treated with estrogen, mortality increased. When middle-aged rats were treated with estrogen, on the other hand, results were positive.

In other words, putting in extra estrogen after the number of estrogen receptors in the brain has been dramatically decreased is a bad idea.

While this study focused on mortality, other research has produced similar conflicting results as to whether estrogen therapy helps fight age-related cognitive impairment in women (see my report). It’s interesting to note that this effect only occurred in the hippocampus — estrogen receptors in the uterus were unaffected.

Reference: 

Related News

The first detailed characterization of the molecular structures of amyloid-beta fibrils that develop in the brains of those with Alzheimer's disease suggests that different molecular structures of amyloid-beta fibrils may distinguish the brains of Alzheimer's patients with different clinical his

A study involving mice lacking a master clock gene called Bmal1 has found that as the mice aged, their brains showed patterns of damage similar to those seen in Alzheimer's disease and other neurodegenerative disorders. Many of the injuries seemed to be caused by free radicals.

A new study involving 96 older adults initially free of dementia at the time of enrollment, of whom 12 subsequently developed mild Alzheimer’s, has clarified three fundamental issues about Alzheimer's: where it starts, why it starts there, and how it spreads.

Analysis of 5715 cases from the National Alzheimer's Coordinating Center (NACC) database has found that nearly 80% of more than 4600 Alzheimer's disease patients showed some degree of vascular pathology, compared with 67% of the controls, and 66% in the Parkinson's group.

The jugular venous reflux (JVR) occurs when the pressure gradient reverses the direction of blood flow in the veins, causing blood to leak backwards into the brain.

The

Following on from the evidence that Alzheimer’s brains show higher levels of metals such as iron, copper, and zinc, a mouse study has found that amyloid plaques in Alzheimer’s-like brains with significant neurodegeneration have about 25% more copper than those with little neurodegeneration.

An Italian study has found that a significant percentage of Alzheimer’s patients suffer from Obstructive Sleep Apnea Syndrome. This respiratory disorder, which causes people to temporarily stop breathing during their sleep, affects cerebral blood flow, promoting cognitive decline.

Data from 70 older adults (average age 76) in the Baltimore Longitudinal Study of Aging has found that those who reported poorer sleep (shorter sleep duration and lower sleep quality) showed a greater buildup of amyloid-beta plaques.

A new discovery helps explain why the “Alzheimer’s gene” ApoE4 is such a risk factor.

Pages

Subscribe to Latest newsSubscribe to Latest newsSubscribe to Latest health newsSubscribe to Latest news
Error | About memory

Error

The website encountered an unexpected error. Please try again later.