Observational studies have consistently found that older people who get regular exercise are less likely to decline mentally and/or develop dementia. Aerobic exercise such as running or cycling seems especially beneficial, but any activity can help, including strength training, walking and tai chi, which have all been the focus of recent studies. Exercise probably benefits the brain just as it helps the cardiovascular system—by improving blood pressure, blood flow, weight, cholesterol levels and blood sugar. In addition, brain scans show that aerobic exercise can actually improve brain activity and produce new brain cells and connections between them.
Use it or lose it: the old adage also applies to mental ability. Read, take a class, work a puzzle, pursue an absorbing hobby—whatever makes you think. Exercising the brain can enrich your life, banish boredom, help treat depression, confer a sense of accomplishment and be a way to make new friends—all good for mental health. A few studies on commercial “brain fitness” programs have yielded promising results, but usually the benefits are short-term and involve a limited set of mental skills.
Being socially active helps older people maintain cognitive abilities and may reduce the risk of dementia, according to much research. Notably, a 2011 study from Rush University Medical Center in Chicago concluded that social activity and the complex interpersonal exchanges it entails help older people stay sharp. The most socially active people had only 25 percent the rate of cognitive decline, compared to the least social. Social activity was beneficial independent of physical activity and other factors related to brain function, such as age and overall health.
Untreated hypertension can increase the risk of cognitive decline and dementia. In a study from the Women’s Health Initiative, women over 65 who had hypertension were at increased risk for developing brain lesions associated with dementia over eight years. Even moderately elevated blood pressure can harm small blood vessels in the brain, resulting in white matter damage that increases dementia risk as well as stroke. Lowering blood pressure—by diet, exercise and weight loss or by medication—is good for the heart and the brain.
There’s strong evidence that type 2 diabetes (and possibly prediabetes) increases the risk of age-related cognitive decline and dementia. For instance, a 2012 study in the Archives of Neurology followed people over age 70 for nine years. Those with type 2 diabetes at the start or who later developed it showed faster cognitive decline than others, especially if blood sugar was poorly controlled. This may be because diabetes damages blood vessels, including those in the brain, and increases inflammation. Also, high levels of insulin appear to go along with declining memory.
Obesity, especially in the abdomen, has been linked to an increased risk of dementia. For instance, a Swedish study in Neurology followed 1,500 middle-aged women for 30 years. Those who initially had an above-average waist-to-hip ratio were twice as likely to develop dementia after age 70, compared to thinner women. Since obesity often goes along with other factors that can increase dementia risk—such as diabetes, hypertension and lack of physical activity—it is hard to know which is the main culprit.
Despite some anecdotal reports that statin drugs increase memory loss in some people, studies over the years have not found a link. In fact, some research suggests that statins may actually reduce the risk of cognitive decline and dementia. High blood cholesterol may contribute to the brain plaques typical of Alzheimer’s. Thus, people taking cholesterol-lowering statin drugs may get an added benefit—for the brain.
Studies have found that people taking NSAIDs (nonsteroidal anti-inflammatory drugs, such as aspirin, ibuprofen and naproxen) have a reduced risk of cognitive decline or dementia. But the jury is still out, since clinical trials have had conflicting results. The drugs may help, in part, by reducing the chronic inflammation that plays a role in Alzheimer’s. Don't start taking NSAIDs to protect your brain, since the benefit is uncertain and the drugs have potential side effects. But if you're taking one for other purposes, you may be getting this added benefit.
Many studies have found that a heart-healthy diet based on vegetables, fruits and whole grains, can be good for cognition and may well help protect against dementia. (This includes the so-called Mediterranean diet.) It’s not known which nutrients or plant compounds are most beneficial. Research has also found a link between fish consumption as well as moderate alcohol intake with a reduced risk of cognitive decline and dementia.
There’s no solid evidence that vitamins or other supplements (including ginkgo, ginseng and omega-3s) or special “memory formulas” can prevent mental decline. Exception: a vitamin B12 deficiency can cause confusion and memory loss that can be misdiagnosed as Alzheimer’s. Large doses of B12 supplements, taken under a doctor’s supervision, may alleviate this.