For many years, the effects of hormone therapy on the memory performance of postmenopausal women has been hotly debated. This week, Neurology publishes results that show no changes in memory function, regardless of when the treatment is started.

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Millions of women control their hot flashes with estrogen treatment.

Menopause generates a range of symptoms, including night sweats, mood changes, weight gain, and hot flashes.

To combat some of these effects, millions of women opt for estrogen treatment.

Estrogen treatment is still the most effective treatment for relieving menopausal hot flashes. It also helps prevent bone loss and may have benefits for heart health if started 5 years or less after menopause.

During a woman’s reproductive years, estradiol is the main type of estrogen to be produced.

Some experts believe that estradiol replacement therapy has positive effects on the memories of women who take it. However, it is thought that this effect only works of the treatment is started soon after menopause, but not later. This hypothesis is called the “timing hypothesis.”

The theory has been tested on a number of occasions, but findings have been inconclusive or contradictory.

A review of the current understanding of the timing hypothesis, published in the journal Menopause in 2012, could not find significant support for either side. The researchers’ conclusions sum up the evidence: “Current data are both supportive and not supportive of the timing hypothesis.”

Dr. Victor W. Henderson, of Stanford University School of Medicine, CA, and a Fellow of the American Academy of Neurology, designed a randomized, double-blind, placebo-controlled trial to open the debate once more.

Previous studies have used small numbers of participants and been conducted over short periods of time. This is part of the reason for the contradictory findings to date. To ensure that the results of the current study were more sturdy, Dr. Henderson cast his net a little wider.

The investigation used 567 healthy women, aged 41-84. These women were split into “early” and “late” groups. The women in the early group were all within 6 years of their menopause, whereas the members of the late group were at least 10 years postmenopausal.

Participants took either a beta-estradiol or placebo pill daily. Additionally, women who had not had a hysterectomy used either a progesterone vaginal gel or a placebo gel.

The participants were involved in the study for an average of 5 years. Each woman was put through a bank of cognitive tests at the start of the trial, at the 2-½-year mark and the 5-year mark.

These tests measured a range of cognitive skills, including verbal memory, overall thinking ability, and executive functions, which includes control of attention, reasoning, and problem-solving.

The researchers found that there was no change in cognitive ability in either the late or early groups of postmenopausal women. Both groups’ individual scores improved over the course of the study when compared with their original scores; this effect was most likely due to practice and being more used to the tasks.

There were no differences in the test scores of women with or without hot flashes or between women who had undergone a hysterectomy and those who had not.

This study fails to confirm the timing hypothesis. Our results suggest that healthy women at all stages after menopause should not take estrogen to improve memory.

At the same time, women need not be particularly concerned about negative effects of postmenopausal estrogen supplements on memory when used for less than 5 years.”

Dr. Victor W. Henderson

Dr. Henderson also pointed out some shortcomings in the research; for instance, the study only concentrated on estradiol, one of three major naturally occurring estrogens. Also, the study did not investigate the cognitive effects of estradiol on women who were already experiencing dementia or other mental impairments.

Because so many women embark on estrogen therapy, the results can be viewed in a positive light. Although cognitive abilities are not improved, at least they are not hindered.

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