Systolic blood pressure postural changes variability is associated with greater dementia risk

Objective: To determine whether orthostatic hypotension (OHYPO) and visit-to-visit blood pressure (BP) postural changes variability are associated with incident dementia.
Methods: We studied 2,131 older adults from the Health, Aging, Body Composition cohort study. Orthostatic BP was repeatedly assessed over a 5-year baseline period. OHYPO was defined as a fall ≥ 15 mmHg in systolic or ≥ 7 mmHg in diastolic BP after standing from a sitting position for ≥ 1/3 of visits. Systolic and diastolic OHYPO were also examined separately. BP postural changes variability over time was evaluated using several indicators including standard deviation and coefficient of variation (CV). Incident dementia was determined over 12 years following the baseline period by dementia medication use, ≥ 1.5 SD decline in Modified Mini-Mental State or hospitalization records.
Results: Of 2,131 participants (mean age 73 years, 53% female, 39% black), 309 (14.5%) had OHYPO, 192 (9.0%) systolic OHYPO, 132 (6.2%) diastolic OHYPO and 462 (21.7%) developed dementia. After adjustment for demographics, seated systolic BP (SBP), antihypertensive drugs, cerebrovascular disease, diabetes, depressive symptoms, smoking, alcohol, body mass index and presence of 1 or 2 APOE ε4 alleles, systolic OHYPO was associated with greater dementia risk (adjusted HR = 1.37, 95% CI 1.01-1.88) unlike diastolic OHYPO and OHYPO. SBP postural changes variability was also associated with higher dementia risk (highest tertile of variability (CV): adjusted HR = 1.35, 95% CI 1.06-1.71).
Conclusion: Systolic OHYPO and visit-to-visit SBP postural changes variability were associated with greater dementia risk. Our findings raise the question of potential preventive interventions to control orthostatic SBP and its fluctuations.

研究目标：明确体位性低血压（orthostatic hypotension, OHYPO）与随访间血压（blood pressure, BP）体位变化变异度是否与新发痴呆相关。
研究方法：本研究纳入健康、衰老与身体成分队列研究中的2131名老年受试者。在为期5年的基线期内重复评估体位血压。体位性低血压定义为坐位站立后收缩压下降≥15mmHg或舒张压下降≥7mmHg，且该情况在≥1/3的随访访视中出现。本研究同时分别评估了收缩性体位性低血压与舒张性体位性低血压。采用标准差、变异系数（coefficient of variation, CV）等多项指标评估随时间变化的血压体位变化变异度。基线期后随访12年，通过痴呆用药史、改良简易精神状态量表得分下降≥1.5个标准差或住院记录判定新发痴呆病例。
研究结果：在2131名受试者中（平均年龄73岁，女性占53%，黑人占39%），309人（14.5%）存在体位性低血压，192人（9.0%）存在收缩性体位性低血压，132人（6.2%）存在舒张性体位性低血压，462人（21.7%）新发痴呆。在校正人口学特征、坐位收缩压、抗高血压药物使用情况、脑血管疾病、糖尿病、抑郁症状、吸烟、饮酒、体质指数以及携带1或2个APOE ε4等位基因后，收缩性体位性低血压与更高的痴呆风险相关（校正后风险比HR=1.37，95%置信区间CI：1.01~1.88），而舒张性体位性低血压与总体体位性低血压则无此关联。收缩压体位变化变异度同样与更高的痴呆风险相关（变异度最高三分位组的变异系数：校正后HR=1.35，95%CI：1.06~1.71）。
研究结论：收缩性体位性低血压与随访间收缩压体位变化变异度均与更高的痴呆风险相关。本研究结果提示，可探索控制体位性收缩压及其波动的潜在预防干预手段。