Insights on Maintaining Cognitive Health
By Sophia Glezos Voit
Two NIH scientists recently discussed research on how cognitive health or "brain fitness" can last a lifetime.
Speaking at an NIMH-sponsored Seminar Café at the Neuroscience Center in Rockville, researchers Dr. Bruce Cuthbert, an NIMH emotion psychophysiologist, and Dr. Molly Wagster, a behavioral neuroscientist at NIA, underscored the message that memory loss, dementia and aging don't have to go hand in hand.
"There are things we can do to gain or maintain proper cognitive function as we age," Wagster said, "and it's not eating potato chips, watching TV or taking some magic pill."
Wagster, the NIA program director for research on the neuropsychology of aging, prefaced her discussion by describing normal cognitive changes as time marches on. These include slower rates of learning and remembering new information; less efficient working memory (or information needed for a short time, such as parking location after shopping); declines in language ability (e.g., correct spelling); sluggish retrieval of nouns; and increased difficulty performing several tasks at once (such as talking on the phone and working on the computer).
The bad news, she said, is that the changes begin in our 20s; the good news is they're subtle as each decade passes and don't interfere with normal functioning, irritating though they may be. Also, where we decelerate in some areas, research shows we advance in others, particularly in world knowledge or wisdom, she said.
An example of the difference between these normal age-related cognitive changes, Wagster explained, and the symptoms of Alzheimer's disease is that normal aging enables us ultimately to retrieve the right word or name, whereas impairments from dementing neurodegenerative disease almost fully prevent a person from ever pulling up the information, she said. People with AD "usually forget they ever wanted to remember it in the first place."
Some rare forms of dementia have a genetic basis, Wagster said, and there are genetic risk factors that may increase a person's likelihood of developing dementia. But new research shows there also may be ways to influence how we age cognitively. Studies she discussed included the cognitive benefits of aerobic exercise, e.g., walking at a moderate pace 2-3 times weekly; and, based on animal research, a diet rich in antioxidants (in particular, blueberries, spinach and strawberries) and enriched living environments.
Although the effects of enriched environments (e.g., challenging toys, others to interact with, etc.) have thus far only been explicitly demonstrated in rodents and to a lesser extent in non-human primates, scientists assume that similar effects occur in humans as well, said Cuthbert, chief of the NIMH Adult Psychopathology & Prevention Research Branch. "A similar complex environment for humans," he said, "may be in the form of plentiful sources of mental stimulation and rich social relationships." Somehow, these experiences enhance the brain's capacity to form new cells, a process called neurogenesis, as well as new connections between cells.
While scientists thought this was impossible just a few years ago, Cuthbert said, research now shows "the brain is constantly re-making itself." Researchers are "energetically testing the hypothesis that neurogenesis helps to maintain the brain's ability to learn new information and preserve cognitive functioning as we age."
But stress affects neurogenesis adversely, Cuthbert added. It even destroys brain cells we already have, and compromises the immune system's ability to fight invading pathogens or heal wounds, which can indirectly affect cognitive function.
However, there are stress buffers that people can adopt, Cuthbert said. These include developing healthy social networks and simply getting a good night's sleep on a daily basis.
"In our culture, it's popular to get by on 4 or 5 hours of sleep a night and drink lots of coffee and be a power person," Cuthbert said. "But the need for 8 hours of sleep is increasingly becoming more evident. In fact, it appears we may need 8 ¼ to 8 ½ hours."
Skimping on just one night's sleep, he said, can result in impaired memory and concentration the next day. Coffee may temporarily sharpen those skills, but a short nap is the better antidote. Better still is adherence to good sleep habits.
Research also shows that nurturing healthy emotions throughout the aging process can help people thrive cognitively. Studies show this includes maintaining positive self-esteem, autonomy (self-sufficiency), good relationships and a sense of purpose in life. "People who feel self-efficacy experience less cognitive decline," Cuthbert said.
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