Department of Epidemiology, Harvard School of Public Health, Boston, MA 02215, USA.
Epidemiology. 2011 Sep;22(5):646-59. doi: 10.1097/EDE.0b013e31822708b5.
Many epidemiologic studies have considered the association between blood pressure (BP) and Alzheimer disease, yet the relationship remains poorly understood.
In parallel with work on the AlzRisk online database (www.alzrisk.org), we conducted a systematic review to identify all epidemiologic studies meeting prespecified criteria reporting on the association between hypertension, systolic BP, or diastolic BP and incident Alzheimer disease. When possible, we computed summary measures using random-effects models and explored potential heterogeneity related to age at BP assessment.
Eighteen studies reporting on 19 populations met the eligibility criteria. We computed summary relative risks (RR(Σ)) for 3 measures of BP: hypertension (RR(Σ) = 0.97 [95% confidence interval = 0.80-1.16]); a 10-mm Hg increase in systolic BP (RR(Σ) = 0.95 [0.91-1.00]); and a 10-mm Hg increase in diastolic BP (RR(Σ) = 0.94 [0.85-1.04]). We were unable to compute summary estimates for the association between categories of systolic or diastolic BP and Alzheimer disease; however, there did not appear to be a consistent pattern across studies. After stratifying on age at BP assessment, we found a suggestion of an inverse association between late-life hypertension and Alzheimer disease and a suggestion of an adverse association between midlife diastolic hypertension and Alzheimer disease.
Based on existing epidemiologic research, we cannot determine whether there is a causal association between BP and Alzheimer disease. Selection bias and reverse causation may account for the suggested inverse association between late-life hypertension on Alzheimer disease, but, given the expected direction of these biases, they are less likely to account for the suggestion that midlife hypertension increases risk. We advocate continuing systematic review; the AlzRisk database entry on this topic (www.alzrisk.org), which was completed in parallel with this work, will be updated as new studies are published.
许多流行病学研究都考虑了血压（BP）与阿尔茨海默病之间的关系，但这种关系仍未被很好地理解。
在 AlzRisk 在线数据库（www.alzrisk.org）的工作同时，我们进行了一项系统评价，以确定所有符合既定标准的流行病学研究报告，这些研究报告了高血压、收缩压或舒张压与阿尔茨海默病发病之间的关系。在可能的情况下，我们使用随机效应模型计算了综合指标，并探讨了与血压评估时年龄相关的潜在异质性。
有 18 项研究报告了 19 个人群符合入选标准。我们计算了 3 种血压指标的综合相对风险（RR(Σ)）：高血压（RR(Σ) = 0.97 [95%置信区间 = 0.80-1.16]）；收缩压升高 10mmHg（RR(Σ) = 0.95 [0.91-1.00]）；舒张压升高 10mmHg（RR(Σ) = 0.94 [0.85-1.04]）。我们无法计算收缩压或舒张压类别与阿尔茨海默病之间的关联的综合估计值；然而，各研究之间似乎没有一致的模式。在按血压评估时的年龄分层后，我们发现晚年高血压与阿尔茨海默病之间存在反向关联的迹象，以及中年舒张压高血压与阿尔茨海默病之间存在不良关联的迹象。
基于现有的流行病学研究，我们无法确定血压与阿尔茨海默病之间是否存在因果关系。选择偏倚和反向因果关系可能解释了晚年高血压与阿尔茨海默病之间的反向关联，但考虑到这些偏倚的预期方向，它们不太可能解释中年高血压增加风险的说法。我们主张继续进行系统评价；与这项工作同时完成的 AlzRisk 数据库中关于这个主题的条目（www.alzrisk.org）将随着新研究的发表而更新。
