6 days ago
Up to 44% of Dementia Cases Preventable
Maintaining optimal vascular health throughout late life can significantly lower the risk of developing dementia before age 80 years, new research showed. Investigators estimated the proportion of new dementia cases linked to modifiable vascular risk factors.
The results suggested that 22%-44% of dementia cases by age 80 years could be attributed to poor vascular health through age 74 years.
The findings highlighted the 'potentially immense value of early detection of vascular risk factors and primordial prevention (eg, vis-à-vis promotion of physical activity and healthy body weight management) beginning in midlife,' wrote the study team, led by Jason Smith, PhD, with Johns Hopkins Bloomberg School of Public Health in Baltimore.
The study was published online on June 2 in JAMA Neurology .
Vascular Health Equals Brain Health
Hypertension, diabetes, and smoking are widely recognized modifiable vascular risk factors for dementia. While their roles have been studied individually, the cumulative impact of these risk factors across the lifespan — and how this varies by genetic background, race, and sex — has been less clear.
Smith and colleagues used data from the Atherosclerosis Risk in Communities Neurocognitive Study, with 33 years of follow-up, to assess the fraction of dementia attributable to hypertension, diabetes, and smoking measured at different life stages.
A total of 7731 participants were included in the analysis of risk factors measured at age 45-54 years (58% women, 71% White, 29% Black); 12,274 contributed data at age 55-64 years (55% women, 76% White, 24% Black); and 6787 contributed data at age 65-74 years (56% women, 80% White, 20% Black). Overall, a total of 2218 people developed dementia by their 80th birthday.
By age 80 years, the population attributable fraction of dementia attributable to at least one vascular risk factor measured at age 45-54 years was 22%; at 55-64 years, it was 26%, and at 65-74 years, it was 44%.
Only 2%-8% of dementia cases occurring after age 80 years were attributable to these vascular risk factors.
Subgroup differences emerged. For example, the attributable fractions for the vascular risk factors were higher in APOE-ε4 noncarriers aged 55 years or older (range, 33%-61%). 'This reflects the fact that in populations with lower genetic Alzheimer risk, the extent of the relative contribution of vascular disease to dementia risk is greater,' the study team explained.
Attributable fractions for the vascular risk factors were also higher in Black individuals aged 45 years or older (range, 26%-53%) and women aged 55 years or older (range, 29%-51%).
Risk factor clusters such as hypertension plus diabetes and smoking plus diabetes significantly increased dementia risk, with hazard ratios ranging from 2.00 to 3.54, depending on age and risk factor combination. The importance of hypertension and diabetes increased with age, whereas the importance of smoking decreased with age.
'Given the contribution of vascular disease to dementia and the overlap in risk factors between CVD and dementia, interventions that address these underlying risk factors have the potential to reduce the risk of both outcomes,' the co-authors of a linked editorial said.
These results also suggest that 'to be optimally effective, interventions to reduce dementia risk by addressing vascular risk factors may need to be individualized and targeted based on factors such as age, genetics, race, and sex,' Roch A. Nianogo, MD, PhD, with University of California, Los Angeles, and Deborah E. Barnes, PhD, MPH, with University of California, San Francisco, wrote.
