1. Large variations in blood pressure, including large rises and falls in blood pressure, over a period of years is associated with an increased long-term risk of dementia.
Evidence Rating: 1 (Excellent)
Dementia is highly prevalent affecting in the elderly, and represents a major burden to the healthcare system given its association with high disabling nature. Vascular risk factors, such as hypertension, have long been recognized as one of the most important modifiable risk factors for dementia. Recent literature has found that the association between blood pressure and neurological health is more complicated than absolute cut-offs for hypertension alone, as high blood pressure variability has also been implicated as a risk factor for ischemic stroke. Variability in blood pressure has also been implicated as a risk factor for dementia, though the understanding of this association has been unclear, especially with regards to long term association and whether rises or falls in blood pressure had greater associations. This prospective cohort study gathered data starting 1989 in the Netherlands as a part of the Rotterdam study, which originally included 5,373 dementia-free participants (58.1% woman; mean[SD] age, 67.6[8.0] years). This cohort was analyzed to determine whether or not there was an association between blood pressure variation and long term dementia risk. 1,066 participants were diagnosed with dementia as of 2016, as screened by the Mini-Mental State Examination and Geriatric Mental Schedule during a median follow-up of 14.6 years. Blood pressure variation over 2 visits (median 4.2 years) was assessed, with both absolute variation in systolic blood pressure (SBP) and direction of SBP change was analyzed. A large SBP variation was associated with an increased dementia risk, with a hazard ratio of 1.08 (95% CI [CI] 0.88-1.34, P = 0.337) for risk within 5 years of SBP variation measurement to 3.13 (95% CI 2.05-4.77, P <0.001) after at least 15 years of measurement of SBP for the patients in the highest quintile of SBP variation. Increased long-term risk was associated with both large rises and falls of SBP, with the HRs of the highest quintiles being 3.31 (95% CI 2.11-5.18), and 2.20 (95% CI 1.33-3.63). A greater short-term risk was associated with large falls in SBP only (HR, 1.21 [95% CI 1.00-1.48], P = 0.017). Similar findings were observed when examining variation in diastolic BP. The study demonstrates a significantly elevated long-term risk of dementia associated with large rises and falls in blood pressure. If the observed relationship is causal, targeting stable blood pressures over time versus current hypertension target levels alone to prevent large blood pressure variability may be a potential therapeutic target for preventing dementia.
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