The lowdown: In addition to its many other bodily functions, estrogen may help keep women's brains sharp, Dr. Small says. The hormone increases the concentration of an enzyme needed to synthesize the memory-boosting brain chemical acetylcholine and enhances communication between neurons in your hippocampus.
So it's no surprise that we often experience brain fog during a time of life when estrogen levels wax and wane: A study published in the journal Neurology found that 60%
The Rx: If you're going through menopause, talk to your doctor about going on hormone replacement therapy (HRT) for a year or two, Dr. Small suggests. The Neurology study found that women who start HRT in perimenopause (before menopause, when periods stop completely) have better memory and cognitive function than those who go on it post-menopause. Even if you opt against HRT, there's good news: Your cognitive function should rebound after menopause, once your body has had a chance to adjust to its newly stabilized hormone levels.
Problem #3: Weight and sleep troubles
The lowdown: Memory problems are often attributable to (changeable!) lifestyle factors. Take weight: A 2010 study found that for every one-point increase in a woman's BMI (body mass index), her memory score dropped by one point.
If you're thin and a couch potato, you're still at risk. "There's a link between physical fitness, which improves blood flow, and brain volume," Dr. Fotuhi says. "Exercise can actually increase the size of the hippocampus."
Lack of sleep impairs your memory, too. "When you're sleep deprived, your stress-hormone levels increase, which is toxic to your neurons," Dr. Fotuhi explains.
The Rx: If you're overweight, losing weight should help: A 2011 Kent State University study, for example, found that people who underwent bariatric surgery improved their memory loss 12 weeks post-procedure. And especially if you're feeling less than sharp, make a good night's sleep a priority.