Ronald Lazar, PhD
Ronald Lazar, PhD, E.F. McKnight Endowed Chair of Learning and Memory in Aging and director of the Division of Neuropsychology at the University of Alabama at Birmingham School of Medicine.
A 2021 poll found that people over age 65 fear dementia more than any other disease. The good news is that a new study, published in the journal Alzheimer’s & Dementia, suggests that older adults can reduce their risk and maybe their fear of dementia with a very simple strategy: taking more steps every day.
Researchers from the School of Public Health and Human Longevity at University of California San Diego compared older women who averaged less than 1,867 steps per day (just under one mile) to women who averaged about 4,000 steps (just under two miles). The women who took more steps were 64 percent less likely to develop mild cognitive impairment (MCI) and 52 percent less likely to develop dementia over a period of four years.
The study was done only on women, who tend to have a higher risk for dementia than men, mainly because they live longer. It is assumed that results would be similar for men.
MCI and dementia both cause cognitive impairment, which is the loss of mental abilities like memory, thinking clearly, understanding, communicating, and learning.
It is normal to have some age-related memory loss, which refers to cognitive loss after age 65. Most of us will have “senior moments” like taking longer to find the right word or remember a name.
About 10 to 20 percent of people over age 65 will develop MCI. MCI is a step further on the path to dementia, and most people with MCI will continue to follow the path, with about 10 to 15 percent developing dementia each year, usually diagnosed as Alzheimer’s disease (AD). AD is, by far, the most common cause of dementia.
MCI will show up as a low score on a cognitive test. Common cognitive tests like the Mini-Mental State Exam or the Montreal Cognitive Assessment can take only 10 to 15 minutes. A low score is a significant warning of cognitive impairment. During these tests, a health-care provider may ask a person to repeat a short list of words, name objects from pictures, copy shapes from a drawing, or answer simple questions related to well-known facts.
The period before symptoms of cognitive loss are noticeable is called the preclinical phase. During this phase, the brain changes that cause MCI and AD have already started.
Protein clumps are starting to build up in the brain. The protein is called amyloid, and it can form into the tangles and plaques that destroy nerve cells called neurons, leading to eventual dementia. It can take 10 to 20 years for a preclinical brain to become a dementia brain.
MCI is diagnosed when cognitive loss is more than would be expected for a person’s age, and the symptoms have become noticeable to the person or to friends and family. These symptoms will show up on a cognitive test, but they are not significant enough to affect the activities of daily living. AD is the most severe form of cognitive impairment, and the symptoms of impairment become obvious even without testing. AD is severe enough to progressively interfere with the everyday needs of living.
Lack of exercise is one of many known risk factors for MCI and dementia. Other risk factors include older age, smoking, high cholesterol, diabetes, depression, obesity, sleep deprivation, social isolation, and a lack of stimulating mental and social activities.
Exercise, or lack thereof, is one of the most important risk factors because it is a pleotropic risk factor, which means it checks several of the boxes for risk reduction, including benefits for high blood pressure, high blood sugar, obesity, and sleep deprivation.
Recent research suggests that exercise has another very specific effect on amyloid plaques and tangles. Exercise increases a brain protein called brain-derived neurotrophic factor (BDNF). BDNF stimulates neurons to form more connections with other neurons. These are like new roads that allow brain signals to travel through the brain. When amyloid plaques and tangles destroy neurons in one part of the brain, connectivity offers side roads to detour around the damage, preserving cognitive health. In fact, brain imaging studies show that people who have more connectivity may have the same amount of amyloid plaques and tangles as people with AD, but none of the signs and symptoms.
There are many ways to get more steps into your day:
Every little bit counts, so look for opportunities to walk a little more.
Researchers from the School of Public Health and Human Longevity stress that the earlier you start adding steps, the better chance you have of delaying or avoiding MCI and dementia. That is important because once you have MCI or dementia, there has been no treatment to slow, stop, or reverse the buildup of the amyloid plaques and proteins.
That may finally be changing. On July 6, the FDA gave final approval to lecanemab-irbm (Leqembi), the first drug that can slow the course of AD in the earliest stages of the disease. This is a new type of drug called an anti-amyloid antibody. It attaches to and removes the amyloid proteins needed to form AD plaques and tangles. These new drugs (there are more anti-amyloid antibody drugs in the clinical trial pipeline) offer hope for people with MCI and early AD and make it more important for everyone to know the early warning signs when treatment is most effective.
