In an October 2016 study published in Neurology, researchers found that even with the same amount of decline in the brain as men, women scored better on tests of verbal memory, or memory that has to do with words and language. Because verbal memory tests are the ones used in diagnosing dementia and Alzheimer’s disease, this advantage may mask early symptoms, says lead study author Erin Sundermann, PhD, assistant project scientist at the University of California San Diego School of Medicine. “At the score that indicates the start of verbal memory impairment on a clinical test, women are more advanced in the disease,” she says. This means that because of their better verbal memory, women are able to compensate for that decline in brain activity for longer, Sundermann explains, so they may be diagnosed later along in the progression of Alzheimer’s disease than men. However, experts aren’t quite sure what causes this advantage in women to begin with. Perhaps, Sundermann says, it has something to do with the way we learn. In cognitive tests where people are asked to memorize a list of words, women are more likely to recall the words by clustering them in groups based on their meanings, whereas men tend to recall the words in order, she says, but there’s little understanding of how this difference of styles leads to long-lasting memory benefits. The two hemispheres of women’s brains also seem to communicate better than the two sides of men’s brains, she says, which may also improve verbal memory.
A team of researchers from Finland and the UK reported in January 2016 that women lost more total brain volume than men over a study period of almost 9 years. The researchers tracked a small group of adults from age 34 to 43 and found women lost a greater percentage of their overall brain size than men from start to finish of the study. Research in older adults, ages 65 to 82, found a similar pattern of greater shrinkage in women’s brains.
Yes, total brain size decreases more in women, but the sexes differ in where that shrinkage occurs. MRI studies have shown a bigger reduction in brain volume in the frontal and temporal lobes, which govern personality, emotion, and cognition, in men, compared to shrinking in volume of the hippocampus and parietal lobes, which are involved in memory, language, and spatial and visual perception, in women. (This simple habit makes your brain grow and cuts your dementia risk by 50%.)
There’s still a lot experts don’t totally understand about how those physical changes in the brain tie into sex differences in memory changes or even full-blown disease. Women have higher rates of Alzheimer’s, while men have higher rates of Parkinson’s, for example, and perhaps it’s the changes in different brain structures that set the sexes up for those variable risks.
There’s (obviously) a dramatic drop in estrogen at menopause that corresponds for many women with some memory loss. “Many women will tell you that menopause feels like you’re in a brain fog,” says Dorene M. Rentz, PsyD, associate professor of neurology at Harvard Medical School. “When women go through menopause, it’s like they lose their memory advantage over men and ‘catch up’ to where men have always been.” But what’s still not entirely clear is exactly what benefit estrogen plays—especially because hormone therapy doesn’t seem to improve any of that initial loss.