When Naomi Rance first started studying menopause and the brain, she pretty much had the field to herself. And what she was discovering surprised her. In studies of post-mortem brains, she had found neurons in a region called the hypothalamus that roughly doubled in size in women after menopause. “This was changing so much in postmenopausal women,” says Rance, a neuropathologist at the University of Arizona in Tucson. “It had to be important.
They increasingly recognize that menopause and the transition to it, a phase labelled perimenopause, could set the stage for brain health in later life, and there are even hints that it could correlate with the risk of neurodegenerative diseases, such as Alzheimer’s disease. Oestrogen does a lot for the brain: it stimulates glucose uptake and energy production. Once the transition to menopause is complete, neurons grow accustomed to its absence. But in the perimenopausal period, levels of the hormone can crash one week only to soar the next. The result can be a period of neuronal discord in which brain cells are periodically deprived of oestrogen, but not for long enough to forge the pathways needed to adapt to life without it, says Brinton.
Meanwhile, a dearth of treatment options has left some women seeking unproven treatments, such as herbal supplements. “Women are frustrated that they’re trying to function, and no one knows how to help them,” says Susan Davis, an endocrinologist at Monash University in Melbourne, Australia.Momentum is building to address such questions.
Alongside this growing attention, research methods are also getting an upgrade. A few species of whale are the only animals known to undergo a natural menopause like humans. Most species remain capable of reproducing until they die. “Menopause is a human thing,” says Teresa Milner, a neuroscientist at Weill Cornell Medicine in New York City. “That’s why it’s difficult to study.”