Estrogen's effects on aging brain explored

The role estrogen plays in women's brains remains murky but researchers are beginning to clarify it.

The first Women's Brain Health Academic Symposium in Toronto on Wednesday brought together experts from North America leading a discussion about trying to better understand the female brain.

"Seventy per cent of Alzheimer's patients are women," said Lynn Posluns, founder and chair of the Women of Baycrest, which aims to raise $5 million for a research chair devoted to women's brain health. 

Yet most laboratory studies today are done on male rats because female rats are considered too complex, Posluns said.

"I'm saying there's a real disconnect here. It is time for scientists to better understand the female brain."

At the symposium, Gillian Einstein, a professor of psychology and public health at the University of Toronto, talked about her early findings exploring the role of estrogen on brain functions such as mood and memory.

"I want women to be circumspect about the effect of their hormones on their mood and cognition," said Einstein. "It may or may not be PMS that makes you grumpy. It's possible that your husband really did do something crappy, and you have a reasonable response to it. [On the other hand] I also think it's important to think they may be having an effect."

Estrogen and memory

One of the ways Einstein's lab is investigating the role of estrogen in the brain is to study women who have ovarian cancer or at are at risk. They are recruiting women with these BRCA 1 and BRCA 2 mutations that increase their risk of developing the disease.

Her team is comparing women who've had prophylactic oophorectomy — preventive removal of the ovaries and Fallopian tubes — to those who also carry the mutations but haven't had the surgery, and women without the mutations.

The surgery affects estrogen levels and leads to menopause symptoms 10 year earlier than average. 

The researchers want to uncover exactly how estrogen affects the brain's hippocampus, which plays important roles in consolidating information from short-term memory and long-term memory, and spatial navigation. The hippocampus is one of the first regions of the brain to suffer damage in Alzheimer's disease.

Women who've had oophorectomies are an important population to look at for memory effects, said Deborah Schwartz, a PhD student in psychology at U of T.

"We want to inform these women, if you have the surgery, don't be surprised if you see this happen," Schwartz said. "But there's ways to compensate for this."

Women often find ways to compensate naturally. The researchers are exploring ways to help the brain adapt by using unaffected regions.

When women are diagnosed with ovarian cancer, they're given general information about  what it means and what their options are, Schwartz said. But she's heard from many who want to know about the brain implications of the surgery, too.

One factor for researchers to consider is how different forms of estrogen act in the body. One form, 17beta-estradiol, is made in the ovaries and has reproduction functions. The other, 17alpha-estradiol, is made in the brain.

"We've always assumed that women's brains would be like men's brains, and data that are coming are showing this is not necessarily the case," Einstein said. "This will have important ramifications for the aging brain and also for disease, the progression of disease and the treatment of disease."