The state of the cardiovascular system has a strong impact on the aging of the brain. The brain requires an sizable supply of energy, delivered via the bloodflow, and suffers when that supply is reduced. With age, the vascular system loses smaller vessels, while larger vessels become damaged. Loss of physical fitness also reduces blood supply. Additionally, damaged blood vessels allow leakage of unwanted cells and molecules into the brain to produce inflammation, while blood vessel walls can be a source of inflammatory signaling themselves. Increased blood pressure can be avoided or controlled, but where hypertension is present, it is harmful to vessels in the brain, causing a toll of small ruptures that damage brain tissue over time. All of this adds up. The study here is one of many to link vascular health with cognitive decline leading to dementia.
Midlife vascular risk factors are associated with both dementia and premature death; however, their combined association with dementia-free survival years remains unclear. We conducted a prospective cohort study (Atherosclerosis Risk in Communities study) with participants from 4 US communities. Participants were alive and dementia-free at age 55 years and had visit 2 (1990-1992) measurements of diabetes (self-report, medication use, or HbA1c ≥ 6.5%), hypertension (blood pressure ≥ 140/90 mm Hg or medication use), and current smoking. Vascular risk burden was defined as the count of these risk factors (0-3).
Among 12,409 participants (mean age 56.2 ± 5.2 years), over a median follow-up of 26.3 years, 3,008 developed dementia and 5,238 died dementia-free. Compared with 0 risk factors, 3 risk factors were associated with higher hazards of dementia (hazard ratio 2.69) and death without dementia (HR 5.61). Higher vascular burden was associated with fewer dementia-free survival years, declining from 30.1 years for 0 risk factors to 17.5 years for 3 risk factors. In conclusion, maintaining optimal midlife vascular health was associated with up to 12.6 additional dementia-free survival years, reflecting both higher dementia hazard and markedly higher competing mortality.
Link: https://doi.org/10.1212/WN9.0000000000000152
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