Last updated: Sep 22, 2012
James Archer/Anatomy Blue

So you keep misplacing your keys and walking into the living room without remembering why. That doesn't mean you've got early Alzheimer's: "Normal memory problems—like being a little forgetful—start as early as age 27," says Majid Fotuhi, MD, chairman of the Neurology Institute for Brain Health and Fitness in Baltimore and author of The Memory Cure.

Luckily, your memory is like a muscle, Dr. Fotuhi says—you can exercise it and improve it at any age. Here are some smart moves to help you do just that.

Problem #1: Stress
The lowdown: "In our fast-paced, wired world, many of us live our lives in chronic stress," says Gary Small, MD, director of the UCLA Longevity Center and author of The Alzheimer's Prevention Program. That means we're perpetually bathing our brains in stress hormones like cortisol. The result? Studies done in mice show that chronically elevated stress hormone levels shrink the hippocampus, so you're less likely to form new memories.

You get a similar result if you're struggling with depression. "Some studies suggest that depressed individuals have fewer hippocampal neurons," says Gary Kennedy, MD, director of the division of geriatric psychiatry at Montefiore Medical Center in New York City. Other research has found that depressed people have lower levels of brain-derived neutrophic factor (BDNF), a protein that promotes the health of brain neurons, and thus boosts memory function.

The Rx: Unfortunately, there's no way to get rid of stress entirely. But you can at least try to keep your anxiety levels at a minimum. Dr. Small's number-one tactic? Meditation. One recent Harvard study found that participants who meditated for about 30 minutes a day over eight weeks increased their hippocampus size. "Meditation also fires up the frontal areas of the brain that are associated with attention," Dr. Small says. That means you'll be less likely to focus on feeling stressed or down, and more able to concentrate on the tasks at hand, so you can actually remember what's going on.

Here's a super easy way to start: Get comfortable and begin breathing slowly and deeply. Expand your rib cage as you inhale; feel your abdomen rise with each intake of breath. Stay relaxed and focus on each breath in and out. Start with three minutes and work up to 30.

If you suspect you're depressed—say, you're having persistent sad, anxious, or "empty" feelings that last more than a couple of weeks, and other symptoms such as fatigue, irritability, and loss of interest in hobbies—get a referral for a good psychologist or psychiatrist, who can provide counseling and possibly medication.

Problem #2: Estrogen in Flux
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%

George Doyle/Getty

of women going through perimenopause, when estrogen levels are sputtering out, reported decreased memory. And a study from the UK found that expectant moms—who experience wild surges of estrogen—performed worse on certain types of memory tests, and that those changes were still present three months after the women gave birth.

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.