Exercise and dementia risk

Exercise and dementia risk

Study evidence showed that (1)

• in this study (n=78,430, mean age 61, median follow-up 6.9 years), a higher number of steps was linked to lower risk of all-cause dementia, with optimal dose (maximum risk reduction [RR]) of 9826 (HR 0.49; 95% CI,0.39-0.62) & minimal dose (RR 50% of observed maximum RR) of 3826 steps
  • participants were instructed to wear an Axivity AX3 accelerometer on their dominant wrist 24 hours a day, 7 days a week, to measure physical activity
  • total of 78,43 participants aged 40 to 79 years with at least 3 valid days (more than 16 hours wearing time) and complete data on covariates, and who were free of cardiovascular disease, cancer, or dementia at baseline were included in the analysis
  • participants were monitored through October 31, 2021, with incident dementia (fatal and nonfatal) obtained through linkage with inpatient hospitalization or primary care records, or recorded as the underlying or contributory cause of death in the death registers
  • identified walking activities using an accelerometer-based activity machine learning scheme and used a validated step-count algorithm for wrist accelerometers to estimate the number of steps
  • used cadence-based stepping metrics reflective of pace and intensity under free-living conditions:
    • incidental steps, defined as fewer than 40 steps per minute (eg, indoor walking from one room to another)
    • purposeful steps, defined as 40 or more steps per minute (eg, steps while exercising);
    • peak 30-minute cadence (ie, average steps per minute recorded for the 30 highest, not necessarily consecutive, minutes in a day)
  • analyses revealed nonlinear associations between daily steps
    • optimal dose (i.e., exposure value at which the maximum risk reduction was observed) was 9826 steps (hazard ratio [HR], 0.49; 95% CI, 0.39-0.62) and the minimal dose (ie, exposure value at which the risk reduction was 50% of the observed maximum risk reduction) was 3826 steps (HR, 0.75; 95% CI, 0.67-0.83)
    • incidental cadence optimal dose was 3677 steps (HR, 0.58; 95% CI, 0.44-0.72);
    • purposeful cadence optimal dose was 6315 steps (HR, 0.43; 95% CI, 0.32-0.58);
    • and peak 30-minute cadence optimal dose was 112 steps per minute (HR, 0.38; 95% CI, 0.24-0.60)
  • analyses highlight the importance of stepping intensity for preventing dementia. Both purposeful steps and peak 30-minute cadence (ie, an indicator of overall best natural effort in a free-living environment) were associated with lower risks of dementia
    
    
• researchers note their findings suggest that a dose of just under 10,000 steps per day may be optimally associated with a lower risk of dementia, and steps performed at higher intensity resulted in stronger associations
  
  
• study authors concluded:
  • taking more steps per day was associated with a lower risk of incident all-cause dementia
  • optimal dose was estimated at 9800 steps per day, just under the popular target of 10000 steps
  • intensity of stepping resulted in stronger associations
    
    
• an accompanying editorial discusses 2 main findings of interest from this study (2)
  • 1) the optimal step count to lessen the occurrence of dementia by at least 25% was markedly lower than the popular recommendation of 10,000 daily steps
  • 2) intensity of steps, more than the mere volume of steps, is a potent purveyor of the clinical benefits of stepping
  • adds that the mounting evidence in support of the benefits of physical activity for maintaining optimal brain health can no longer be disregarded and it is time for the management of physical inactivity to be considered an intrinsic part of routine primary care visits for older adults

An analysis (n=928) found better cardiovascular health (moderate/high “Life's Essential 8” score vs. low score) was inversely associated with risk of incidence dementia (HR 0.61, 95% CI 0.46–0.83, p=0.001), after a median follow-up of 14 years (3).

A randomized, controlled clinical trial to determine if intensive lifestyle changes may beneficially affect the progression of mild cognitive impairment (MCI) or early dementia due to Alzheimer’s disease (AD) was undertaken (4):

• showed that, in persons with mild cognitive impairment or early dementia due to Alzheimer’s disease, comprehensive lifestyle changes may improve cognition and function in several standard measures after 20 weeks
• in contrast, patients in the randomized control group showed overall worsening in all four measures of cognition and function during this time
• validity of these findings was supported by the observed changes in plasma biomarkers and microbiome; the dose-response correlation of the degree of lifestyle change with the degree of improvement in all four measures of cognition and function; and the correlation between the degree of lifestyle change and the degree of changes in the Aβ42/40 ratio and the changes in some other relevant biomarkers in a beneficial direction

Reference:

1. del Pozo Cruz B, Ahmadi M, Naismith SL, Stamatakis E. Association of Daily Step Count and Intensity With Incident Dementia in 78,430 Adults Living in the UK. JAMA Neurol. Published online September 06, 2022. doi:10.1001/jamaneurol.2022.2672
2. Planalp EM, Okonkwo OC. Is 112 the New 10000? - Step Count and Dementia Risk in the UK Biobank. JAMA Neurol. Published online September 06, 2022. doi:10.1001/jamaneurol.2022.2312
3. Li X, Jin Y, Bandinelli S, Ferrucci L, Tanaka T, Talegawkar SA. Cardiovascular health, measured using Life's Essential 8, is associated with reduced dementia risk among older men and women. J Am Geriatr Soc. 2024; 1-10.
4. Ornish, D., Madison, C., Kivipelto, M. et al. Effects of intensive lifestyle changes on the progression of mild cognitive impairment or early dementia due to Alzheimer’s disease: a randomized, controlled clinical trial. Alz Res Therapy 16, 122 (2024). https://doi.org/10.1186/s13195-024-01482-z