Can Blood Pressure Control Lower the Risk of Dementia Development? 

Lowering patients‘ blood pressure could delay or reduce dementia risk.  

Past studies have demonstrated either some potential benefits, or no significant reduction, in the risk of patients developing some form of cognitive impairment later in life when blood pressure is well controlled. A meta-analysis and systematic review, titled Association of Blood Pressure Lowering with Incident Dementia or Cognitive Impairment by Diarmaid Hughes and colleagues, have provided substantial evidence that hypertension treatment can reduce the risk of cognitive decline in patients.   

According to the study (published in JAMA on May 19, 2020), there is some statistically significant data highlighting the importance of lowering blood pressure in keeping our brains as healthy and normally functioning as possible for as long as possible. The study looked at the primary endpoints of cognitive impairment or dementia development. Secondary endpoints observed were the mean change in cognitive test scores and patient cognitive decline upon follow-up. The pooled-data was synthesized in these results using random-effects meta-analysis models to report back the treatment effects and confidence intervals. 

The analysis included 14 studies found by members of the research group through multiple medical journal sources. To be included in the calculation, the studies had to be randomized with more than 1,000 participants, having at least one year of follow-up, and providing some measurement of cognitive impairment or decline, changes in cognitive test scores, or dementia. Control groups in the included studies varied, either having different antihypertensive medications, placebo use, or higher blood pressure targets. These 14 studies provided data from 96,158 participants (average age of 69 years old, 42% female, mean systolic BP of 154mm Hg, and mean diastolic BP of 83mm Hg). 

Of the 14 studies, 12 reported dementia incidences in patients and were, therefore, able to be included in the primary endpoint analysis. These 12 trials included 92,135 patients and demonstrated statistical significance that lowering blood pressure with antihypertensive agents reduced the incidence of dementia or cognitive impairment. Compared to control groups (which showed 7.5% of patients developing some form of cognitive impairment over an average of 4 years of follow-up), the treatment arms had a 7% incidence of development of dementia or cognitive impairment over an average of 4.1 years (odds ratio [OR], 0.93 [95% CI, 0.88-0.98]; absolute risk reduction, 0.39% [95% CI, 0.09%-0.68%]; I2 = 0.0%).  

For the secondary endpoints of cognitive decline, eight of the 14 studies included reports of cognitive decline and cognitive test scores. For cognitive decline, the control group compared to the treatment arm also demonstrated statistical significance in favor of lowering blood pressure (20.2% vs 21.1% of participants over a mean trial follow-up of 4.1 years; OR, 0.93 [95% CI, 0.88-0.99]; absolute risk reduction, 0.71% [95% CI, 0.19%-1.2%]; I2= 36.1%). There was no statistically significant outcome concerning cognitive test scores when the eight studies were analyzed in the meta-analysis. 

Although the primary endpoint does not show a considerable difference between treatment and control groups, this statistically significant data still demonstrates more benefits to helping treat patients’ hypertension. As Michelle Canavan (a consultant geriatrician involved in the study) stated in the article, BP lowering with antihypertensive medication may reduce dementia risk, “[o]ur study results provide an added incentive to be adherent with blood pressure medications.” We can now counsel patients that not only is adherence crucial for heart health, but long-term brain health as well. 

Some limitations to this study exist, though, and should be considered when looking at this data. As mentioned in the publication, “the low incidence of dementia in all clinical trials, despite a large number of participants, reduced power to detect differences in treatment effect and limited exploration of subgroups or meta-regression.“ Also, the 14 trials contained different types of controls, which could significantly alter the final analysis. We would want to see more focus on these primary endpoints with more homogenous control groups and cognitive impairment measurements in future studies. 

Practice Pearls: 

• Cognitive impairment and dementia incidence are significantly reduced in patients who utilize antihypertensive medications to control their blood pressure (ARR, 0.39% [95% CI, 0.09%-0.68%]). 
• This study illustrated statistical significance that cognitive decline has an ARR of 0.71% (95% CI, 0.19%-1.2%) when blood pressure is controlled. 
• The 14 studies were not powered enough to allow for subgroup analysis and varied in control group implementations, so further research would likely help get more conclusive evidence.  

Hughes, Diarmaid, et al. “Association of Blood Pressure Lowering With Incident Dementia or Cognitive Impairment.“ Jama, vol. 323, no. 19, 2020, p. 1934., doi:10.1001/jama.2020.4249. 

Hughes, Diarmaide, and Michelle Canavan. “BP Lowering with Antihypertensive Medication May Reduce Dementia Risk.” Cardiology Today, 19 May 2020. 

Jacob Roberts, PharmD Candidate 2021 of University of Colorado Denver Skaggs School of Pharmacy and Pharmaceutical Sciences