Blood pressure and dementia risk: what's the link?

  • Gregson J & al.
  • Eur J Neurol
  • 24 Jun 2019

  • curated by Sarfaroj Khan
  • UK Clinical Digest
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Takeaway

  • Elevated blood pressure (BP) was associated with reduced risk for dementia in the short-term, possibly because of reverse causation.
  • Long-term (>10 years) associations of elevated BP were less marked for dementia and differ by dementia subtypes.

Why this matters

  • Confusion exists over the associations between BP and dementia or its sub-types.

Study design

  • 2,593,629 patients (age, ≥40 years) with ≥1 BP measurement and without dementia were included using data from the UK Clinical Practice Research Datalink (CPRD).
  • Funding: Alzheimer’s Society (UK grant 280).

Key results

  • During a median follow-up of 8.2 years, 65,618 patients (incidence rate [IR], 2.91 per 1000 person-years) had incident dementia, of which 49,161 (IR, 2.18 per 1000 person-years) had Alzheimer’s disease (AD), 13,816 (IR, 0.61 per 1000 person-years) had vascular dementia and 2541 (IR, 0.11 per 1000 person-years) had other sub-types.
  • During the 5 years of follow-up:
    • Systolic BP (SBP) was moderately inversely associated with the risk for dementia (rate ratio [RR] per 10mmHg higher long-term average SBP, 0.84; 95% CI, 0.83-0.85).
    • It was negatively associated with AD (RR, 0.83; 95% CI, 0.82-0.84) than vascular dementia (RR, 0.90; 95% CI, 0.87-0.93).
  • During the 5-10 years of follow-up:
    • A negative association between higher SBP and dementia was less marked (RR, 0.94; 95% CI, 0.92-0.95).
    • SBP was negatively associated with AD (RR, 0.93; 95% CI, 0.92-0.95), but the association with vascular dementia was non-significant (RR, 0.97; 95% CI, 0.94-1.01).
  • During >10 years of follow-up, a very weak inverse association was observed between SBP and dementia (RR, 0.98; 95% CI, 0.97-0.99), which varied by age at index measurement (Pinteraction<.0001>

Limitations

  • Risk of bias.

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