Dietary Approaches to Stop Hypertension (DASH) Eating Pattern May Reduce Age-Related Cognitive Decline
The Dietary Approaches to Stop Hypertension (DASH) diet is often recommended by physicians to people with high blood pressure or pre-hypertension. The DASH diet eating plan has been proven to lower blood pressure in studies sponsored by the National Institutes of Health. High blood pressure is considered a risk factor for Alzheimer's and dementia.
Heidi Wengreen, RD, PhD, Assistant Professor of Nutrition at Utah State University, and colleagues examined associations between how closely people adhered to the DASH diet and risk of cognitive decline and dementia among older participants in the Cache County Study on Memory, Health and Aging.
In 1995, 3,831 study participants 65 years of age or older completed a survey that included a food frequency questionnaire and cognitive assessment. Cognitive function was checked again during four assessments over 11 years using the Modified Mini-Mental State examination (3MS), which is graded on a 100 point scale. A DASH diet adherence score was created based on consumption levels of nine food-group/nutrient components -- fruit, vegetables, nut/legumes, whole grains, low-fat dairy, sodium, sweets, non-fish meat, and fish. Participants were ranked by DASH score into five groups, or quintiles.
The researchers found that higher DASH scores were associated with higher scores for cognitive functioning at the beginning of the study and over time. Those in the highest quintile scored 1.42 points higher at baseline and 1.81 points higher after 11 years on the 3MS than did those in the lowest quintile of the DASH score (p-values < 0.001).
They also found that four of the nine food-group/nutrient components used to create the DASH score were independently associated with 3MS scores -- vegetables, whole grains, low-fat dairy, nut/legumes. The scientists created a diet adherence score based on just these four components which they then tested for association with changes in cognitive abilities on the 3MS. Those in the highest quintile scored 1.72 points higher at baseline and 3.73 points higher after 11 years than did those in the lowest quintile of the four-component score (p-values < 0.001).
"Our results suggest that including whole grains, vegetables, low-fat dairy foods, and nuts in one's diet may offer benefits for cognition in late life," Wengreen said. "However, we need more research before we can confidently say how much of these foods to include in your diet to experience some benefit."
Maintaining or Increasing Activity Levels May Slow Cognitive Decline in Elderly
Studies have found that older adults who are physically active may experience slower rates of cognitive decline. Less is known about the impact of changes in physical activity levels on rate of cognitive decline.
Deborah E. Barnes, PhD, MPH, Assistant Professor of Psychiatry at the University of California, San Francisco, and a geriatrics researcher at the San Francisco VA Medical Center, and colleagues studied changes in levels of both physical activity and cognitive function over seven years in 3,075 white and black elders aged 70-79 years in the Health, Aging and Body Composition Study. Physical activity was assessed based on self-reported number of minutes walked per week at the beginning of the study and after two, four, and seven years of follow-up. Participants were classified at each time point as sedentary (0 minutes per week), low (less than 150 minutes per week) or high (150 minutes per week or more). Changes over time were classified as consistently sedentary, maintaining (low or high), decreasing, or increasing/fluctuating. Cognitive function was assessed using the 3MS.
The researchers found that 21% of study participants were consistently sedentary, 12% maintained their activity levels, 26% had declining levels, and 41% had increasing or fluctuating levels. After adjustment for age, sex, race, education, study site, diabetes, hypertension, smoking, alcohol consumption and baseline 3MS score, they found that the mean rate of decline in 3MS scores was 0.62 points/year in those who were consistently sedentary, 0.54 points/year (p=0.30) in those with declining activity levels, 0.44 points/year (p=0.01) in those with increasing/fluctuating activity levels, and 0.40 points/year (p=0.04) in those who maintained their activity levels.
"We found that older adults who were sedentary throughout the study had the lowest levels of cognitive function at the beginning and experienced the fastest rate of cognitive decline," Barnes said. "Cognitive decline also was faster in those whose physical activity levels consistently declined during the study period."
According to the researchers, sedentary elders who began new aerobic exercise programs experienced improvements in cognitive function, especially the ability to process complex information quickly. "Sedentary individuals should be encouraged to engage in physical activity at least occasionally," Barnes said. "People who are currently active should be encouraged to maintain or increase their activity levels."
Moderate Long-Term Physical Activity May Improve Late Life Cognition; Long-Term Strenuous Activity May Increase Risk of Cognitive Impairment
Long-term strenuous physical activity has been shown to decrease lifetime exposure to ovarian hormones in women and has been found to play a protective role against breast cancer. However reduction in ovarian hormone exposure has been associated with increased risk of cognitive impairment. At the same time, long-term physical activity is associated with improved cognition but the intensity required to preserve cognition is not known.
Mary C. Tierney, PhD, CPsych, Professor of Family and Community Medicine at the University of Toronto, and Senior Scientist and Director, Geriatric Research Unit, Brain Sciences Program at Sunnybrook Health Sciences Centre, and colleagues sought to examine the associations between both long-term strenuous and moderate activity levels and cognition in recently postmenopausal women.
Study participants were 90 women aged 50-63 years, one to 10 years post natural menopause, with no history of breast cancer, HRT use, psychiatric disorder, dementia or other neurological condition. Participants gave details on the amount of their strenuous and moderate physical recreational activities from high school to menopause. Eight memory and brain function tests were administered to all participants.
After adjusting for age, education, reproductive years, cigarette smoking, alcohol consumption, parity, and periods of amenorrhea, the researchers found that long-term strenuous activity was consistently associated with poorer performance on all eight of the tests; with statistically significant results on tests of semantic memory, working memory, delayed verbal recall, and sustained attention (p < 0.05). Moderate physical activity was consistently associated with better performance on all eight of the tests, with statistically significant results on cognitive flexibility, working memory, and sustained attention (p < 0.05).
"Our results suggest that long-term strenuous activity may increase the risk of cognitive impairment in recently postmenopausal women," Tierney said. "On the other hand, moderate long-term physical activity may improve later life cognition. These preliminary findings have important implications for women's health and support the need for large-scale studies including both women and men."