Hypertension：老年高血压患者严格控制血压可增加脑血流量

研究证实老年人血压控制在150/90mmHg可减少卒中和心肌梗死风险，改善认知功能以及放缓或逆转脑血流量（CBF，cerebral blood flow ）下降。有学者认为降压药物导致的低血压对老年人造成的危害大于高血压如低灌注导致晕厥、摔倒以及有可能加速萎缩和脑白质疏松。认知功能下降与CBF减少有关。预防CBF降低可减少老年高血压患者的认知障碍和情绪障碍。然而降压治疗对CBF的影响并不清楚。研究人员通过一项随机对照研究比较老年高血压患者严格控制血压和一般血压控制的对CBF的影响。

研究对象为37例大于70岁（75±4岁）的老年患者，有收缩性高血压病史（SBP>150 mm Hg），服用1种或未服用降压药物。将受试者随机分为接受严格降压（目标血压<130/80 mm Hg））或一般降压（目标血压<140/85 mm Hg）治疗12周，每两周随访一次。分别在研究开始和治疗12周后采用3T的动脉血质子自旋标记MRI评估CBF以及行24小时动态血压检查。

两组间基线血压（动态或门诊）和基线的灰质CBF无明显差异。经过治疗后，两组血压明显降低，但严格控压组血压降低更多（26/17 比 15/5 mm Hg; P<0.01）。同时测定的灰质CBF显示严格控压组明显增加（7±11 mL/min每100 g; P=0.013），而一般降压组受试者灰质CBF未发生变化（（？3±9 mL/min 每100g; P=0.23）。

老年高血压患者严格控制血压较一般控制血压相比，前者可增加CBF。这一研究表明老年高血压患者的CBF自动调节曲线向右下移动，但随着血压降低这一过程是可逆的。

未来的研究需进一步确定是否严格控制血压白质也会产生类似的结果，老年患者严格控制血压后是否老年痴呆和认知能力下降的风险降低。

Intensive blood pressure lowering increases cerebral blood flow in older subjects with hypertension.
Abstract
Hypertension is associated with reduced cerebral blood flow (CBF). Intensive (<130/80 mm Hg) blood pressure (BP) lowering in older people might give greater reduction in cardiovascular risk, but there are concerns that this might produce hypoperfusion which may precipitate falls and possibly stroke. We determined the effect of intensive compared with usual BP lowering on CBF in hypertensive older subjects. Individuals aged >70 years with a history of systolic hypertension on 1 or no BP lowering drugs were recruited from primary care (n=37; age, 75±4 years; systolic BP, >150 mm Hg) and randomized to receive intensive (target BP, <130/80 mm Hg) or usual (target BP, <140/85 mm Hg) BP lowering for 12 weeks, with reviews every 2 weeks. CBF, determined using 3T arterial spin labeling MRI, and 24-hour ambulatory BP were performed at baseline and after 12 weeks of treatment. Baseline BP (ambulatory or in clinic) and baseline gray matter CBF were not significantly different between the groups. After treatment, BP was reduced significantly in both groups but fell more in the intensive group (26/17 versus 15/5 mm Hg; P<0.01). Over the same period, gray matter CBF increased significantly in the intensive group (7±11 mL/min per 100 g; P=0.013) but was unchanged in the usual BP target group (-3±9 mL/min per 100 g; P=0.23); P<0.01 for comparison. Intensive BP lowering in older people with hypertension increases CBF, compared with BP lowering to usual target. These findings suggest hypertension in older people shifts the autoregulatory CBF curve rightward and downward and is reversible with BP lowering.