The odds ratios for any frequency of moderate exercise were 0.61 (95% CI 0.43 to 0.88; P = 0.008) for midlife (age of 50 to 65 years) and 0.68 (95% CI 0.49 to 0.93; P = 0.02) for late selleck products life. A recent meta-analysis reported by Hamer and Chida  included 16 studies with exercise measures, including 163,797 controls at baseline and 3,219 incident cases of dementia or PD. The authors found that the relative risks in the highest physical activity category compared with the lowest were 0.72 (95% CI 0.60 to 0.86; P < 0.001) for dementia, 0.55 (95% CI 0.36 to 0.84; P = 0.006) for AD, and 0.82 (95% CI 0.57 to 1.18; P = 0.28) for PD. While this provides support that exercise may be protective against dementia, there is less support of its being protective against dementia in PD.
Aarsland and colleagues  completed a meta-analysis evaluating whether exercise might protect against VaD and found five studies that met criteria for meta-analysis, including 10,108 nondemented control subjects and 374 individuals with VaD. The meta -analysis demonstrated a significant association between physical exercise and a reduced risk of developing VaD (odds ratio 0.62, 95% CI 0.42 to 0.92). 3. Randomized control trials A recent Cochrane systematic review of 11 studies of aerobic exercise programs for healthy older persons  indicated that 8 of the studies reported cognitive improvement associated with fitness improvement. According to the review, the largest and most consistent cognitive effects in meta-analyses were observed on measures of cognitive speed and attention.
Changes across other cognitive domains (for example, memory, language, and visuospatial) were also present but varied across individual studies. In a single-blind study  from Australia, moderate exercise (50 minutes three times per week for 6 months) was shown to enhance cognition in cognitively normal older persons as well as in individuals Anacetrapib who complained of memory difficulty. This was a randomized controlled trial of a 24-week physical activity intervention with a total of 170 participants, and 138 participants completed the 18-month assessment. The main outcome measure was the Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) at 18 months. The investigators found that, in an intent-to-treat analysis, participants in the intervention group improved 0.26 points (95% CI -0.
89 to 0.54) and those in the usual care group deteriorated 1.04 points (95% CI 0.32 to 1.82) on the ADAS-Cog at the end of the intervention. This showed a modest improvement at 18 months after 6 months of exercise intervention. In a randomized control trial by Erikson and colleagues , 120 cognitively normal sedentary adults from 55 to 80 years old were randomly selleck bio assigned to aerobic exercise (building up to walking 40 minutes four times per week) or toning and stretching.