Effect of Antihypertensive Treatment on Cerebral Blood Flow in Older Adults: a Systematic Review and Meta-Analysis.

Background: In older age, the benefits of antihypertensive treatment (AHT) become less evident, with greater associated risk. Of particular concern is compromising cerebral blood flow (CBF), especially in those with cognitive impairment.

Methods: We created a synthesis of the published evidence by searching multiple electronic databases from 1970 to May 2021.  Included  studies  had  participants  with  mean  age  ≥50  years,  hypertension  or  cognitive  impairment,  and  assessed  CBF  before  and  after  initiating  AHT.  Two  authors  independently  determined  eligibility  and  extracted  data.  Study  quality  was assessed using The Risk of Bias in Nonrandomized Studies of Interventions tool. We summarized study characteristics (qualitative synthesis) and performed random-effects meta-analyses (quantitative synthesis).

Results:  Thirty-two  studies  (total  n=1306)  were  included,  of  which  23  were  eligible  for  meta-analysis.  In  line  with  the  qualitative synthesis, the meta-analysis indicated no effect of AHT initiation on CBF (standardized mean difference, 0.08 [95% CI, −0.07 to 0.22]; P=0.31, I2=42%). This was consistent across subgroups of acute versus chronic AHT, drug class, study design, and CBF measurement. Subgroups by age demonstrated an increase in CBF after AHT in those aged >70 years (standardized mean difference, 4.15 [95% CI, 0.16–8.15]; P=0.04, I2=42%), but not in those aged 50 to 65 and 65 to 70 years (standardized mean difference, 0.18 [95% CI,−2.02 to 2.38]; P=0.87, I2=49%; standardized mean difference, 1.22 [95% CI, −0.45 to 2.88]; P=0.15, I2=68%). Overall, risk of bias was moderate-to-high and quality of evidence (Grading of Recommendations Assessment, Development and Evaluation) was very low, reflecting the observational nature of the data.

Conclusions:  Accepting  the  observed  limitations,  current  evidence  does  not  suggest  a  harmful  effect  of  AHT  on  CBF.  Concerns over CBF should not preclude treatment of hypertension.