Exercise Prevents Dementia

Exercise, both physical and mental, has been repeatedly found beneficial in preventing the onset on dementia.  Perhaps, exercise increases blood flow to the brain as well as promoting general health.

Exercise Reduces Risk of Dementia in Women: In a 2-year follow-up of 18,766 nurses ages 70-81, those who had been the least active showed more mental decline even though the exercise data came from 10 years earlier, presumable before any impairment due to incipient dementia was occurring. Even walking 1.5 hours per week added 1.5 years of cognitive ability over those with little exercise. Robert P Friedland et al. Case Western, JAMA 9/22/04.

Exercise Linked to Less Dementia: In a 5.4 year follow-up study of 3,375 men and women over age 64 and free of dementia at baseline (the Cardiovascular Health Cognition Study), 480 developed dementia. Those in the highest quartile of physical energy expenditure had a 15% lower risk of dementia (RR 0.85) and participants engaging in at least 4 activities had a 49% lower risk of dementia (RR 0.51) compared with those engaging in 0-1 activity. These associations were more marked in apolipoprotein E genotype (APOE) epsilon4 allele noncarriers and were absent in carriers. A similar pattern was observed for Alzheimer's disease and vascular dementia. Physical Activity, APOE Genotype, and Dementia Risk: Findings from the Cardiovascular Health Cognition Study. Podewils LJ, Guallar E, et al. Johns Hopkins. Am J Epidemiol. 2005 Apr 1;161(7):639-51.

Exercise, Alcohol Reduced Appearance of Dementia; DM, HBP, CHD, CVD, Cancer, Arthritis, Depression, Smoking All Increase Dementia: In a 3 ½ year follow-up of 2,581 Seattle elderly over 65, researchers found exercise and moderate alcohol intake were associated with lower likelihood to develop dementia. Diabetes mellitus, hypertension, coronary heart disease (CHD), cerebrovascular disease (CVD), osteoporosis, arthritis, and cancer, low cognitive function, depression, and smoking were associated with worse functional outcomes. Predictors of functional change: a longitudinal study of nondemented people aged 65 and older. Wang L, Van Belle G, Kukull WB, Larson EB., U Wash, J Am Geriatr Soc 2002 Sep;50(9):1525-34.

Exercise Cuts Alzheimer's: Regular exercise controls the expression of genes in an area of the brain important for memory and maintaining healthy cells in the brain; this maintenance breaks down in cases of Alzheimer's. The connection between the genes that control growth hormones and other important molecules and the genes' ability to be stimulated by exercise. In three weeks of running on their cage wheels, rats had changed the expression, or activity, of genes in an area of the brain called the hippocampus, a structure usually associated with higher cognitive functions like memory, thinking and learning. 6/02 Trends in Neurosciences. UC Irvine Carl Cotman. BDNF, short for brain-derived neurotrophic factor, which helps amplify nerve signals important in maintaining a healthy nervous system; IGF-1, part of the immune system that helps in the growth of new nerve cells and aids in protection of cells from injury; running increases the growth factor levels in rat brains and improves the rats' learning ability in mazes.

Mental Activity Linked, May Be Helpful: 801 older Catholic nuns and priests without dementia from across U.S. at baseline rated were rated for their frequency of participation in common cognitive activities (e.g., reading a newspaper), from which a previously validated composite measure of cognitive activity frequency was derived. Baseline scores of cognitive activity ranged from 1.57 to 4.71 (mean, 3.57; SD, 0.55), with higher scores indicating more frequent activity. During an average of 4.5 years of follow-up, 111 persons developed AD. In a proportional hazards model that controlled for age, sex, and education, a 1-point increase in cognitive activity score was associated with a 33% reduction in risk of AD (hazard ratio, 0.67). Results were comparable when terms for the apolipoprotein E epsilon4 allele and other medical conditions were added. In random-effects models that controlled for age, sex, education, and baseline level of cognitive function, a 1-point increase in cognitive activity was associated with reduced decline in global cognition (by 47%), working memory (by 60%), and perceptual speed (by 30%). JAMA 2002 Feb 13;287(6):742-8

Mental Activity, Not Physical Activity Associated With Decreased Risk: In a 4 year follow-up study of 842 normal adults over age 65 and free of AD, mental activity, e.g. newspaper reading, ranged from 1.28-4.75. In a logistic regression model adjusted for age, education, sex, race, and possession of the APOE epsilon4 allele, a one-point increase in cognitive activity score was associated with a 64% reduction in risk of incident AD (OR 0.36; 95% CI 0.20 to 0.65). By contrast, weekly hours of physical activity (mean 3.5; SD 5.1) was not related to disease risk (OR 1.04; 95% CI 0.98 to 1.10). 139 developed AD in 4 yr. Education was associated with risk of AD and a similar trend was present for occupation, but these effects were substantially reduced when cognitive activity was added to the model. Cognitive activity and incident AD in a population-based sample of older persons. Wilson RS, Bennett DA, Bienias JL, Aggarwal NT, Mendes De Leon CF, Morris MC, Schneider JA, Evans DA. Neurology 2002 Dec 24;59(12):1910-4; Rush

Walking May Lower Dementia Risk: In a 5-year follow-up study of 2,257 physically capable Japanese-American men ages 71-93 years in the Honolulu-Asia Aging Study, 158 cases of dementia were identified (15.6/1000 person-years). After adjusting for age, men who walked the least (less than 0.25 mile/day) experienced a 77% excess risk of dementia compared with those who walked more than 2 mile/d (17.8 vs. 10.3/1000 person-years. Those walking less than 1 mile/day also did quite poorly.  These associations persisted after accounting for other factors, including the possibility that limited amounts of walking could be the result of a decline in physical function due to preclinical dementia. Walking and dementia in physically capable elderly men. Abbott RD, White LR, Ross GW, Masaki KH, Curb JD, Petrovitch H. University of Virginia JAMA. 2004 Sep 22;292(12):1447-53