Promoting brain health and reducing risk of dementia and cognitive decline
The strongest evidence for promotion of physical activity in the context of dementia relates to disease prevention.
The benefits of physical activity for prevention may be improved if combined with broader strategies to promote a healthy lifestyle and managing cardiovascular risk factors including: smoking cessation, managing high blood pressure, maintaining a healthy diet, maintaining a healthy weight and BMI, maintain alcohol consumption below 14 units per week/8 drinks, managing high cholesterol, maintain healthy blood sugars.
Maintaining recommended levels of physical activity may be associated with a 3 to 6% reduction in risk of dementia. Combined with maintaining ideal cardiovascular health across all modifiable risk factor risk reduction may be between 20 and 40%, with greatest risk reduction associated with risk of vascular dementia.
Quality of evidence
High quality – evidence strongest for adopting lifestyle changes earlier in life.
Strength of recommendation
Maintaining a healthy heart – through optimal lifestyle including being physical activity greater that 150 minutes per week – helps to maintain a healthy brain.
The Lancet Commission for Dementia Prevention, Intervention Care 2017, led by Professor Gill Livingstone, recommend:
“……..Active treatment of hypertension in middle aged (45–65 years) and older people (aged older than 65 years) without dementia to reduce dementia incidence. Interventions for other risk factors including more childhood education, exercise, maintaining social engagement, reducing smoking, and management of hearing loss, depression, diabetes, and obesity might have the potential to delay or prevent a third of dementia cases.”
Summary evidence of physical activity and dementia
Longitudinal population studies demonstrate that older adults who exercise are more likely to maintain cognition than those who are physically inactivity. However, there is no randomised control trials that show exercise prevents cognitive decline. The evidence for the preventive benefits of physical activity may also be stronger in the context of maintaining an ideal cardiovascular health profile.
Longitudinal population evidence of physical activity preventing cognitive decline
One meta-analysis by Sofi et al reported on 15 prospective cohort studies following up 33 816 individuals without dementia for 1–12 years and identified that physical activity had a significant protective effect against cognitive decline, with high levels of exercise being the most protective (hazard ratio [HR] 0·62, 95% CI 0·54–0·70).
Sofi, F. , Valecchi, D. , Bacci, D. , Abbate, R. , Gensini, G. F., Casini, A. and Macchi, C. (2011), Physical activity and risk of cognitive decline: a meta‐analysis of prospective studies. Journal of Internal Medicine, 269: 107-117. doi:10.1111/j.1365-2796.2010.02281.x
Another meta-analysis by Hamer et al; reported on follow-up of 163 797 participants without dementia, from 16 different studies, and found that the RR of dementia in the highest physical activity groups compared with the lowest was 0·72 (95% CI 0·60–0·86) and the RR of Alzheimer’s disease was 0·55 (95% CI 0·36–0·84).
Hamer, M., & Chida, Y. (2009). Physical activity and risk of neurodegenerative disease: A systematic review of prospective evidence. Psychological Medicine, 39(1), 3-11. doi:10.1017/S0033291708003681
Trial evidence of physical activity preventing cognitive decline
Brasure et al January 2018 Annals of Internal Medicine
Of 32 eligible trials
N ranges from 42 to 1635, majority small studies
- 16 with low to moderate risk of bias compared a physical activity intervention with an inactive control. Most trials had 6-month follow-up; a few had 1- or 2-year follow-up. Evidence was insufficient to draw conclusions about the effectiveness of aerobic training, resistance training, or tai chi for improving cognition.
- Low-strength evidence showed that multicomponent physical activity interventions had no effect on cognitive function.
- Low-strength evidence showed that a multidomain intervention comprising physical activity, diet, and cognitive training improved several cognitive outcomes.
- Evidence regarding effects on dementia prevention was insufficient for all physical activity interventions.
Sink et al JAMA 2015 “Effect of a 24-Month Physical Activity Intervention vs Health Education on Cognitive Outcomes in Sedentary Older Adults: The LIFE Randomized Trial.”
- Age 70 to 89
- N = 1635
- At 24 months, the mean Digit Symbol Coding task scores were 46.26 points for the physical activity group vs 46.28 for the health education group (mean difference, -0.01 points [95% CI, -0.80 to 0.77 points], P = .97). The mean Hopkins Verbal Learning Test delayed recall scores were 7.22 for the physical activity group vs 7.25 for the health education group (mean difference, -0.03 words [95% CI, -0.29 to 0.24 words], P = .84). Incident MCI or dementia occurred in 98 participants (13.2%) in the physical activity group and 91 participants (12.1%) in the health education group (odds ratio, 1.08 [95% CI, 0.80 to 1.46]).
A 2 year multidomain intervention of diet, exercise, cognitive training, and vascular risk monitoring versus control to prevent cognitive decline in at-risk elderly people (FINGER): a randomised controlled trial
- Ngandu, Tiia et al.
- The Lancet , Volume 385 , Issue 9984 , 2255 – 2263
- Age range 60 to 77
- Intervention group (n=631) or control group (n=629).
2 year multidomain intervention (diet, exercise, cognitive training, vascular risk monitoring), or a control group (general health advice).
Primary outcome was change in cognition as measured through comprehensive neuropsychological test battery (NTB) Z score
Estimated mean change in NTB total Z score at 2 years was 0·20 (SE 0·02, SD 0·51) in the intervention group and 0·16 (0·01, 0·51) in the control group. Between-group difference in the change of NTB total score per year was 0·022 (95% CI 0·002–0·042, p=0·030).
Findings from this large, long-term, randomised controlled trial suggest that a multidomain intervention could improve or maintain cognitive functioning in at-risk elderly people from the general population.