Three midlife vascular risk factors were linked to nearly 13 fewer dementia-free years. Digest
- Alzheimer's
- Blood Pressure
- Cardiovascular
- Cognition
- Dementia
- Diabetes
- Inflammation
- Metabolism
- Oxidative Stress
- Stroke
- Tobacco
Poor vascular health in midlife can move dementia risk earlier while also making it less likely that people survive to the ages when it is most common. Researchers accounted for this competing mortality to examine how vascular risk factors shape dementia-free survival.
In a long-running US cohort, 12,409 middle-aged adults were grouped by how many of three risks they had: diabetes, hypertension, and current smoking. Researchers then tracked dementia and death for more than two decades and used both outcomes to estimate dementia-free survival from ages 55 to 95.
- Dementia-free years fell from 30.1 with none of the three risk factors to 26.3 with one, 21.0 with two, and 17.5 with three.
- Compared with having none of the three risk factors, having all three was associated with a 2.7-fold higher rate of dementia and a 5.6-fold higher rate of death without dementia over the follow-up period.
- Dementia occurred earlier in the highest-risk group, yet by age 95, a smaller proportion had developed dementia than in the lowest-risk group. This apparent contradiction arose because far fewer high-risk participants survived dementia-free into very old age.
Diabetes, hypertension, and smoking can injure blood vessels through chronic metabolic stress, inflammation, and oxidative damage. In the brain, this can impair small vessels, increase stroke risk, and contribute to processes involved in dementia. The same exposures also increase cardiovascular and overall mortality. Vascular burden can therefore shorten cognitively healthy life in two directions at once, by bringing dementia forward and by ending life earlier.
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Overall, greater midlife vascular burden was linked to fewer years lived before either dementia or death. At the same time, the analysis shows that failing to account for earlier death from other causes in dementia studies can influence how strongly potentially harmful and protective factors appear to be linked to the disease.