How Tamoxifen and Estrogen Impact Your Brain

Mature female patient with mobile phone in hospital waiting room
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You know it's true. Women have an excellent memory, particularly when for things that others tell them. In fact, women are much better than men when it comes to recalling all the juicy details of conversations and stories they heard from years gone by.

Why does this happen? Some of it has to do with the fact that women have better organized brains than men - and some of it also has to do with estrogen.

Dr. Pauline Maki, who is the current president of the North American Menopause Society said, "Women experience declines in verbal memory after removal of the ovaries and when estradiol and progesterone are suppressed with leuprolide acetate (a medicine that turns off hormone production from the ovaries). Giving those women estrogen reverses those changes."

So what happens to women with breast cancer when the medicine tamoxifen is used as an anti-estrogen to treat breast cancer? Tamoxifen is a selective estrogen receptor modulator or SERM, and it selectively blocks estrogen from reaching breast cancer cells and the brain. That's part of the reason why women who take it often have hot flashes and mood disturbances.

A new study in the January 2015 issue of the journal Menopause studied the effect of tamoxifen on mental function in postmenopausal women who took the drug for long periods of time.

The study followed 107 women with breast cancer who received tamoxifen for between 15 to 75 months and compared them with 43 healthy women of the same ages.

You may have heard the term "Chemo-Brain." It's a term given to people going through chemotherapy for cancer treatment. Women who received tamoxifen for an average of 31.5 months scored lower on a test of verbal ability than women who had surgery with or without radiation and healthy women who served as controls.

Women treated with tamoxifen also had lower verbal fluency; for instance, ability to name as many animals as they could that started with the letter "D”. Also, the tamoxifen-treated women were less aware that they were having a verbal problem compared with the other groups of women.

What’s the take-away from this study? First, the results seem to be reversible. It may take up to 36 months, but most women will regain their verbal ability. Second, not all SERMS have the same impact. For instance, the SERM raloxifene actually improved verbal memory.

So, don't worry. Just be empowered with the knowledge that it likely will pass.

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