Nearly everyone who lives long enough experiences some cognitive decline, which is considered normal. However, dementia, including Alzheimer’s disease, is not a normal part of aging, even though its incidence rises rapidly after age 65.
In between normal cognition and early dementia is the gray area known as mild cognitive impairment (MCI), which involves cognitive problems more severe than the normal ones seen with aging, but less severe than dementia. Depending on how MCI is defined, it’s estimated that 10 to 20 percent of Americans over 65 have the condition-far more than those who have dementia-with men affected more often than women, and at earlier ages.
MCI shouldn’t be thought of as pre-dementia or early Alzheimer’s disease, since it doesn’t doom people to these more serious memory problems. Still, anywhere from 5 to 20 percent of those with MCI progress to dementia each year, depending on its severity as well as genetic, pathological (such as microbleeds in the brain), and other variables. That’s about a fourfold higher risk of dementia than for cognitively healthy people.
However, many people with MCI remain stable for years or follow a fluctuating course, while some actually improve and revert to normal cognition, thanks to treatment of underlying problems (such as depression, hypothyroidism, vitamin B12 deficiency, cognition-impairing medications, or excessive alcohol consumption) or due to unknown reasons. Recent research offers cautious hope about preventing and treating MCI. Here’s a sampling.
Stimulate your brain
Many observational studies suggest that engaging in mentally stimulating activities, starting in early life to midlife, helps preserve cognition later on. One such study focusing specifically on how such activities affect the risk of MCI was published online in JAMA Neurology in 2016. The study looked at 1,929 “cognitively normal” people (ages 70 and older) who initially underwent assessment and provided information about mental activities they had done during the previous year. Over an average of four years of follow-up, 24 percent of them developed MCI.
Subsequent assessment revealed that participants who said they regularly played games, did crafts, used a computer, or took part in social activities were 25 percent less likely to develop MCI than those who seldom did these things. In people with the APOE4 gene, which increases the risk of late-onset Alzheimer’s disease, only computer use and social activities were associated with reduced MCI risk.
While the researchers controlled for age and education (less schooling is linked with higher dementia risk), they suggested that engaging in mentally stimulating activities may be associated with other protective lifestyle factors, such as physical exercise, which might in sum lead to a reduced risk of cognitive decline.
Similar findings came from a study, published in Neurology in 2015, that focused on people over age 85. Of the 256 participants, who were cognitively normal at baseline, nearly half developed MCI over an average of four years of follow-up.
The researchers found that predictors of MCI included the APOE4 gene, depression, midlife onset of hypertension, and overall chronic (especially vascular) disease burden. However, the risk of MCI was reduced in people who reported that they had undertaken artistic, craft, and social activities both in midlife and late life as well as computer use in late life. Participating in beneficial lifestyle activities in midlife only, or initiating them in late life, did not consistently confer benefit, the study found.
It is important to note that both of these studies have a limitation that is true for all observational studies; they can’t prove cause and effect. For example, it’s possible that some “cognitively normal” people who engaged in more activities did so because they did not yet have symptoms of Alzheimer’s. Even though they tested normal at baseline, the brain changes associated with Alzheimer’s disease accumulate for years before symptoms are detectable. The only way to overcome this bias is to randomize people to activity or no activity, as was done in the studies that follow.
Most well-designed studies and systematic reviews on “brain training” programs have found few, if any, lasting real-life benefits for cognitively healthy older people or those with dementia. However, a 2016 analysis suggested that computer-based training may be useful in people with MCI. This analysis, published in The American Journal of Psychiatry, looked at 17 clinical trials on people with MCI as well as 12 on those with dementia.
For people with MCI, the studies found that computer-based training was moderately effective for global cognition, memory, and attention (but not processing speed or executive function, the latter being the ability to solve problems, set and meet goals, and exert self-control). In contrast, such training appeared not to be helpful for people with dementia. The researchers noted, however, that the data wasn’t sufficient “to determine whether training gains can be maintained over the long term without further training” and whether such training “can indeed delay or prevent progression of MCI to dementia.” That will require larger and longer studies.
Strength training shows strength
Numerous studies have linked various types of exercise to a reduction in age-related cognitive decline. One Australian trial, published in the Journal of the American Geriatrics Society, focused on strength training for people with MCI, ages 55 to 86. Researchers divided the 100 participants into four groups: progressive resistance training plus computerized cognitive training; progressive resistance training plus placebo cognitive training; computerized cognitive training plus placebo exercise (mostly stretching); or placebo exercise plus placebo cognitive training. Training was done two or three times a week; the strength training was fairly strenuous.
After six months, only those who did strength training had improvements in global cognitive function (though not memory). Also, the greater the strength gains, the greater the overall cognitive benefits were.
Can medication or dietary supplements help?
Research on this front has been discouraging. For instance, a 2013 review in the journal CMAJ looked at eight clinical trials and found that “cognitive enhancer” drugs such as donepezil (Aricept) and memantine (Namenda) had no long-term benefits in people with MCI. Also, there’s no convincing evidence that any dietary supplements can improve cognitive function, unless there is a clear deficiency, as with vitamin B12 (if you have a normal level of B12, taking supplemental B12 will not help).
Mounting evidence indicates that modifying the following factors, preferably starting in midlife, can help maintain healthy cognition and, it’s hoped, slow or even reverse the progression of MCI once the condition develops:
- Avoid or control chronic disorders such as hypertension, diabetes, and heart disease. In general, reducing cardiovascular risk factors benefits the brain. However, excessive lowering of blood pressure via medication may increase cognitive decline in older people with MCI or dementia.
- Treat depression, along with anxiety and sleep disorders.
- Undertake stimulating mental, physical, and social activities.
- Eat healthfully, maintain a healthy weight, and drink alcohol only in moderation. One eating plan that may help preserve cognition is the so-called MIND diet, which is a hybrid of the Mediterranean and anti-hypertension DASH diets.
- Review any medications you take with your doctor to make sure they are not affecting your cognition. That includes over-the-counter drugs such as antihistamines and sleep aids.
- Don’t smoke.
The bottom line
Talk to your healthcare provider about any memory or other cognitive issues you may be having. You should have a full physical and neurological exam. However, in the absence of symptoms or signs of cognitive decline or dementia, cognitive screening is not recommended. According to the U.S. Preventive Services Task Force, there’s insufficient evidence to assess the balance of benefits and harms for routine cognitive screening in older people.