Poor blood pressure control from mid- through late-life increases dementia risk

1. In this prospective cohort study, patients with midlife hypertension and either late-life hypertension or hypotension had higher risks of dementia than mid-life normotensive participants.

2. Midlife hypertension and late-life hypotension were also associated with greater risk of mild cognitive impairment.

Evidence Rating Level: 2 (Good)

Study Rundown: Though midlife hypertension has been associated with dementia in later life, it is unclear how the progression of blood pressure changes through late-life increases dementia risk. In addition, late-life hypotension has been associated with poorer cognition, but it is unclear how if this increased risk is caused by dementia pathogenesis or is instead its cause. In this prospective cohort, both late-life hypertension and hypotension combined with midlife hypertension increased the risk of dementia. In addition, midlife hypertension with late-life hypotension were also associated with greater risk of mild cognitive impairment, but not late life hypertension. It was found that younger but not older adults in this study showed increased risk if they had midlife hypertension followed by late life hypotension. White but not black participants showed a similar pattern.

Though this study suggests continually aberrant blood pressure from mid- to late-life is associated with dementia, there are many caveats and limitations of this study. First, the definition of hypertension was based on measurements of elevated blood pressure and use of anti-hypertensives with normal blood pressure, and when analyses were restricted to measured hypertension, no differences were found. In addition, there were non-significant increases in risk in those with midlife normotension and late-life aberrant blood pressure, which may still indicate increased dementia risk for poor blood pressure control in late life that was not detectable due to low statistical power. In addition, patients with worse blood pressure and cognition were more likely to drop out of the study, and so the competing risk for mortality was not accounted for in the analyses.

Click to read the study in JAMA

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In-Depth [prospective cohort]: The Atherosclerosis Risk in Communities (ARIC) study recruited 4761 patients (whole cohort ~16,000; 59% women, 21% black) to be followed with blood pressure measurements at baseline, 3, 6, 9, 24, and 28 years, establishing mid-life (visits 1-4) and late-life (visits 5) blood pressures. Hypertension was defined as blood pressure >140/90 or normotensive on antihypertensives for the primary analysis and only measured >140/90 for sensitivity analysis. Hypotension was defined as systolic blood pressure <90/60. At visit 6, the participants underwent a neuropsychiatric battery of tests and dementia was defined when 3 criteria were met: Functional Activities Questionnaire greater than 5 or Clinical Dementia Rating sum of boxes greater than 3; at least 2 cognitive domain scores greater than 1.5 standard deviations below the normative mean; and an overall decline from visit 5 on the study’s cognitive battery of greater than 0.055 standard deviations per year. An expert panel confirmed each diagnosis based on the National Institute of Aging and Alzheimer’s Association criteria or the DSM-V. Mild cognitive impairment was defined as aberrations in one of the top three criteria. Dementia incidence per 100 person-years was 1.31 (CI₉₅ 1.00 to 1.72) for the midlife and late-life normotension group, 1.99 (CI₉₅ 1.69 to 2.32) for the midlife normotension and late life hypertension group, 2.83 (CI₉₅ 2.40 to 3.35) for the midlife and late-life hypertension group, 2.07 (CI₉₅ 1.68 to 2.54) for the midlife normotension and late-life hypotension group, and 4.26 (CI₉₅ 3.40-5.32) for the midlife hypertension and late-life hypotension group. Only mild-life hypertension and late-life hypotension was associated with mild cognitive impairment (OR 1.65; CI₉₅ 1.01 to 2.69). Younger patients with mid-life hypertension and late-life hypertension had a higher dementia risk than older patients, who did not have statistically elevated risk (p = 0.02). A similar pattern was seen for white patients over black patients (p = 0.02).

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