When it comes to research on memory loss, most studies have shown that it is very common in normal aging to have reduced memory, even in the absence of Alzheimer’s disease or other late-life diseases.
But much of this research has been done on people who are in their 80s or older. What happens to memory in those who aren’t quite that old? After all, by the time we’ve reached our 60s or 70s, most of us have memory lapses, whether it’s misplaced eyeglasses or a forgotten name.
Important recent discovery: By investigating somewhat younger adults, scientists are now uncovering a new breed of “super agers,” who do as well on memory tests as those who are 40 or 50 years younger. This research is contributing to a growing body of evidence that could provide significant clues about new ways to prevent and treat memory loss.
To learn more, Bottom Line Health spoke with Bradford Dickerson, MD, a neurologist at Massachusetts General Hospital and a leading expert on brain changes and memory disorders…
How much does memory decline in the typical older adult? In clinical settings, memory can be tested in a variety of ways. One approach involves giving people a short list of words to memorize. When people in their 20s are presented with a list of 16 words—and given time to really study the list—they’ll probably remember 13 or 14 of the words. Most people in their early or mid-70s might remember just eight or nine of the words. This would be considered “normal” memory loss.
To test yourself: Study a list of 16 words for a few minutes and then see how many you can remember 20 minutes later.
But some people do better on these tests? Actually, some do a lot better. Based on research conducted at Northwestern University, it is known that a small percentage of people who are age 80 or older—maybe about 10%—do as well or better on memory tests as people who are in their 50s and 60s.
Our study included adults closer to traditional retirement age. However, we found the same thing: Some people simply don’t experience the same degree of memory loss as their peers. This has huge implications.
If we can figure out why some people maintain robust memories, we might find ways to prevent or even reverse age-related memory loss—and possibly some forms of dementia, which can cause other cognitive problems such as impaired reasoning and behavior and personality changes.
Do we know how the brains of super agers differ from those of other people? Even though the brain is roughly the same size in all adults (about the size of a cantaloupe and weighing approximately three pounds), we found in our studies of super agers that the size of specific brain areas correlated with memory: They were larger in those with exceptional memories and smaller in those with normal memories. This means that we now have a “biomarker” that may be used to study age-related memory changes.
Is it possible to strengthen these brain regions and prevent memory loss? This is the million-dollar question. Some people, due to genetics, may simply be born with “young” brains. We know that exercise (see below) and following a Mediterranean-style diet with fruits and vegetables, fish, legumes and whole grains can stimulate brain growth. Good sleep and reducing stress can also make a difference. Do the brain changes that are associated with these or other activities lead to better memory? At the moment, we’re not sure.
How does exercise help? Aerobic exercise has been shown to reduce circulating cortisol, a stress hormone that can cause brain shrinkage. It also stimulates the release of growth factors (such as brain-derived neurotrophic factor) that prevent brain cells from shrinking and may even help new ones grow.
A recent study showed that sedentary older adults who take up moderate-intensity exercise—for example, a regular walking program for 30 minutes at least four days a week—for six months to a year show growth in the hippocampus (a part of the brain associated with memory) and also do better on memory tests. This reinforces the idea that exercise is protective.
Important: Don’t talk on your cell phone while walking or biking, since you may be more likely to fall. Head trauma raises risk for Alzheimer’s disease.
What about diet? Studies suggest that heart-healthy diets (such as the Mediterranean diet) can reduce the risk for Alzheimer’s disease and other forms of dementia. We’re just not sure whether the diet specifically improves brain functions.
However, in a new study from Mayo Clinic, researchers found (based on MRI scans) that the brains of adults who consumed the most foods typical of a Mediterranean diet for a year—legumes, fish, whole grains and vegetables—had greater thickness in some parts of the cortex, which plays a role in memory, language and other cognitive functions. People who ate large amounts of carbohydrates, sugar and/or red meat had less cortical thickness.
And stress reduction? In studies of older adults, those who participated in an eight-week meditation training program had improved connectivity between the frontal lobes and the hippocampus and other brain structures, which improves memory. It’s possible that other relaxing practices, such as yoga, have similar effects. We’re hoping to study this more.
How important is sleep? Very! People who don’t sleep well will obviously find it difficult to focus their attention and obtain and retain memories. Also, the brain consolidates memories during sleep (particularly during the deep, slow-wave stages of sleep)—the memories are shifted to brain regions where they become more stable.
It’s important to remember, though, that we all require different amounts of sleep. Most adults seem to do best when they get seven to nine hours of sleep a day.
Any other advice? Socialize. Studies show that adults who regularly connect with friends are less likely to develop dementia. Working past typical retirement age and/or volunteering after retirement also keeps older brains engaged.
