In older adults with cognitive impairment and cardiovascular risk factors, aerobic exercise improved executive function, a set of complex mental processes that are important for attention, organization, planning, decision-making, and regulating emotions . Researchers also found that the greatest improvement in executive function was seen in participants who combined aerobic exercise with the Dietary Approaches to Stop Hypertension (DASH) diet.
These findings come from the Exercise and Nutritional Interventions for Neurocognitive Health Enhancement (ENLIGHTEN) study, a randomized controlled trial that included 160 sedentary men and women over the age of 55 who had cognitive impairments without dementia, and risk factors for cardiovascular disease. Participants were randomly assigned to one of four groups: aerobic exercise alone, DASH diet alone, aerobic exercise combined with DASH diet, or a control group that just received health education. The intervention lasted six months.
At baseline, participants had executive function comparable to that of people in their early 90s, approximately 28 years older than their chronological age. Participants who engaged in aerobic exercise showed significant improvement in executive function, while those in the DASH diet alone did not. Interestingly, however, the greatest improvement in executive function was seen in participants who engaged in both aerobic exercise and the DASH diet. After six months, the exercise plus DASH diet group showed improvement in executive function that was equivalent to taking off 8.8 years. In contrast, the health education control group had performance that was worse than their baseline. Although positive effects were seen in executive function, none of the study interventions resulted in significant improvement in memory or language fluency.
Participants in the aerobic exercise group exercised three times a week for six months. The first 10 minutes consisted of warm-up exercises and these were followed by 30 minutes of continuous walking or stationary cycling.
The DASH diet group received instructions on modifying their diet. A series of half-hour sessions were conducted by a nutritionist weekly for the first three months, then biweekly for the subsequent three months. The DASH diet plan emphasizes high intakes of fruits, vegetables, whole grains, and low-fat dairy products, as well as increased potassium and reduced sodium intake. Participants in the DASH diet group were asked not to exercise.
Participants in the exercise plus DASH diet received both interventions as described above. Those in the health education (control) group received half-hour calls from a health educator who discussed cardiovascular health-related topics, weekly for the first three months, then biweekly for the subsequent three months.
Although the precise mechanisms underlying the benefits of exercise on executive function are not clear, increased aerobic fitness, reduced cardiovascular disease risk, and reduced sodium intake were all associated with improved executive function. There is growing evidence that multi-component lifestyle changes (e.g., exercise, nutrition, cognitive training, and management of risk factors) may protect people from cognitive decline. Problems with blood vessels, including high blood pressure, diabetes, and high cholesterol have all been associated with cognitive decline and dementia, while exercise and a healthy diet counter these conditions. In addition, both exercise and a healthy diet increase a protein called BDNF that supports the growth and survival of brain cells . Findings from this randomized clinical trial are consistent with the seven steps we recommend for brain health.
Yuko Hara, PhD, is Director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation. Dr. Hara was previously an Assistant Professor in Neuroscience at the Icahn School of Medicine at Mount Sinai, where she remains an adjunct faculty member. Her research focused on brain aging, specifically how estrogens and reproductive aging influence the aging brain's synapses and mitochondria. She earned a doctorate in neurology and neuroscience at Weill Graduate School of Medical Sciences of Cornell University and a bachelor's degree in biology from Cornell University, with additional study at Keio University in Japan. Dr. Hara has authored numerous peer-reviewed publications, including articles in PNAS and Journal of Neuroscience.
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