Ever been at a party and can't remember the name of the person you're talking to? Or find yourself tearing apart your house trying to find your keys? Your first thought may be, "What the heck is wrong with me?" and you might even jump to, "Could I be developing early Alzheimer's?"
In fact, they may seem slightly worse now as an after-effect of the months of isolation during the COVID-19 pandemic, Dr. Small says. (This should resolve as we return to regular activities and life settles back to normal, though.)
But it's also true that subtle changes in memory can occur as early as your 20s. Here's a look at how memory declines with age, plus what you can do about it.
1. The Volume of Your Brain Shrinks
It's a dirty little secret that your memory naturally declines about 2 percent with each decade of life, which means your memory's worse at 30 than at 20 (sorry!).
But there's a bona fide scientific explanation: "It's due to the shrinking of your hippocampus, the part of your brain that stores memories,' explains neurologist Majid Fotuhi, MD, PhD, medical director of NeuroGrow Brain Fitness Center in McLean, Virginia.
2. Other Health Conditions Affect Memory
High blood pressure, especially in middle age, is associated with a higher risk of dementia later in life, according the American Heart Association. Untreated hypertension narrows and blocks arteries everywhere, including in your brain, Dr. Fotuhi explains.
Elevated cholesterol is also toxic to your brain: It triggers the formation of amyloid-beta protein, a key player in the development of Alzheimer's disease, according to May 2018 study in Nature Chemistry.
Other conditions, such as untreated sleep apnea or depression, can also hurt your brain, Dr. Fotuhi notes.
And if you're having trouble hearing, get it checked: September 2019 research in The Hearing Journal shows a link between hearing loss and dementia. (It's not yet clear if one causes the other, but it can't hurt to see a doctor for hearing problems.)
3. Your Hormones Change
You may notice you're especially forgetful when you're pregnant, or in your 40s or 50s as you go through menopause. This is due to the temporary dip in estrogen, Dr. Small says. Once your hormones regulate, though, your memory should return to normal.
Surprise! Some Parts of Your Brain Actually Function Better With Age
While short-term memory starts to drop around age 35, crystalized intelligence, or the accumulation of facts and knowledge, peaks in the late 60s or early 70s, according to an April 2015 Harvard study in Psychological Science.
"That's very different from what we would have expected to see, say, 30 years ago, and a lot of this is due to the fact that older people today, aka Baby Boomers, are more likely to be college-educated, have professional white-collar jobs that involve a lot of reading and thinking, and are just more intellectually stimulated in general," Dr. Small says.
And while younger folks may be able to recall things more quickly or grasp new concepts faster, older people have an advantage because they're sometimes able to take shortcuts.
"The older you are, the more likely you are to draw on past experiences or wide social networks to solve a problem," Dr. Small says.
5 Ways to Support Your Memory as You Age
While some parts of age-related memory decline are outside of your control, there are a host of things you can do to help support a healthy memory into your golden years.
1. Break a Sweat
"A third of your brain is made up of blood vessels, so it should come as no surprise that there's a link between physical fitness and brain volume," Dr. Fotuhi says.
He points to February 2011 research in PNAS, in which older adults did brisk walking for 40 minutes three times a week for a year. The result? Their hippocampi grew by about 2 percent (the hippocampus normally shrinks about 0.5 percent per year).
"They basically walked away four years of brain aging," Dr. Fotui says.
Here's another one: A June 2017 study in The Journals of Gerontology: Series A found an association between low physical activity and the risk of dementia. Researchers conducted MRI scans on about 2,000 people older than 60 and found that the more active they were, the larger their hippocampus — with the most protective effects seen in those older than 75.
In other words: "It's never too late to start [exercising]," Dr. Fotuhi says.
2. Limit Sitting
It's also important to avoid sitting too much during the day, even if you tend to be physically active.
An April 2018 study (published by Dr. Small) in PLOS One looked at adults between the ages of 45 and 75 and found that those who sat for anywhere from three to seven hours each day had a substantial thinning of their medial temporal lobe (MTL), which is where the brain forms new memories. It also usually precedes dementia, Dr. Small notes.
3. Practice Mindfulness
Stress itself is toxic to brain cells: "It kills them off and shrinks both the prefrontal cortex and the hippocampus, both areas of the brain responsible for memory and learning," Dr. Fotuhi says.
An April 2018 review of studies in BMJ Open that followed almost 30,000 people for at least 10 years found that people who reported "clinically significant anxiety" were more likely to develop dementia later in life.
But practicing mindfulness techniques such as meditation or yoga may help. One May 2016 UCLA study in the Journal of Alzheimer's Disease had people older than 55 enroll in a 12-week program consisting of an hour of meditative yoga once a week as well as 20 minutes of at-home meditation. They had significant improvements in both verbal memory (measured by the ability to remember word lists) and visual-spatial memory (measured by the ability to find and remember locations).
These mindfulness techniques "appear to enhance production of brain-derived neurotrophic growth factor, a protein that stimulates connections between your brain neurons," Dr. Fotuhi says.
Even if downward-facing dog or saying ommm isn't your thing, you can reap benefits by just including 5 to 10 minutes of deep breathing exercises into your daily routine, Dr. Fotuhi says.
4. Dine Mediterranean-Style
The Mediterranean diet — which is loaded with fruits, veggies, healthy fats like olive oil and fish, as well as legumes and whole grains — offers heart-healthy benefits. But the Mediterranean way of eating also appears to benefit your brain, for many of the same reasons.
"It makes sense that any diet that also helps to lower your blood pressure and cholesterol would help your brain too," Dr. Small says. "The healthy fats in the diet also reduce brain inflammation, while the antioxidants in many of the foods help protect brain cells from wear and tear."
In fact, following the Mediterranean diet is linked to a 35 percent decrease in risk of cognitive impairment in older adults, according to an August 2017 University of California San Francisco study in the Journal of the American Geriatric Society. (Most people in the study were in their 60s or 70s.)
It's also a good idea to try to eat foods in as whole of a form as possible, and avoid processed foods, Dr. Small adds. A study of almost 500,000 people in the U.K. found that those who ate 25 grams of processed meat a day — the equivalent of just a slice of bacon — had a 44 percent increased risk of developing dementia. The results were published July 2021 in the The American Journal of Clinical Nutrition.
5. Get Enough Sleep
While you're sound asleep, your brain's busy strengthening connections between its cells, transferring info from your hippocampus (responsible for short-term memory) to your neocortex (responsible for long-term).
"This process essentially shifts memories and skills to a more efficient brain region so they become more stable and you can easily recall them, a process called memory consolidation," Dr. Small says.
When people were told an unfamiliar, made-up word and then asked to remember it 12 hours later, after either a period of sleep or wakefulness, those who had gotten rest were more likely to recall it, according to a January 2016 study in Cortex.
Sleep also allows your brain to clear out waste like beta-amyloid that raises Alzheimer's risk, Dr. Small adds.
If you have trouble sleeping, you may be tempted to ask your physician for a prescription for either anti-anxiety or sleep meds. But try to avoid it if you can, Dr. Small says. People who regularly take a benzodiazepine — drugs such as diazepam (Valium), lorazepam (Ativan) or alprazolam (Xanax) — are about 50 percent more likely to develop Alzheimer's, according to a January 2019 review in the Journal of Clinical Neurology.
Another November 2017 study in the Journal of the American Geriatrics Society found a link between long-term use of the sleeping pill zolpidem (Ambien) and Alzheimer's. While that study looked at older adults, the effects can probably be felt at any age, Dr. Small notes.
Instead, practice good sleep habits, including going to bed and waking up around the same time each day and avoiding screens (like your phone or the TV) for a couple hours before bed.