Does Intensive Blood Pressure Control Improve Cognition?

February 25, 2019

According to recently published results from the SPRINT MIND trial, the jury is still out.

RESEARCH UPDATE

Intensive blood pressure control may not significantly decrease the risk of developing probable dementia compared with standard treatment, according to results from the SPRINT MIND trial published recently in JAMA.1

But the results aren’t so clear-cut. The study also found that intensive blood pressure control may reduce the risk of mild cognitive impairment (MCI), a risk factor for dementia.

The authors urged caution, though, when interpreting this result. “[I]t is not clear what this effect may mean for the longer-term incidence of dementia. Although MCI considerably increases the risk of progression to dementia, such progression is not certain and reversion to normal cognition is also possible,” wrote first author Jeff Williamson, MD, MHS, of Wake Forest School of Medicine (Winston-Salem, NC), and colleagues with the SPRINT MIND trial.

Some studies have suggested that high blood pressure may be a risk factor for MCI and dementia. And there is some evidence of vascular damage in Alzheimer disease, which could be related to high blood pressure. Yet other evidence suggests that lowering blood pressure too aggressively may cause hypoperfusion to the brain and negatively affect cognition.

Randomized controlled trials have yielded inconclusive results about whether intensive blood pressure lowering improves cognitive performance. Most of these trials were short-term (less than 4 years) and may not have been able to assess cognitive impairment, which develops slowly.

To see how aggressive blood pressure lowering affects cognition over a longer period, researchers conducted a randomized clinical trial at 102 sites in the US and Puerto Rico between November 2010 and July 2018. The study included 9361 adults aged 50 years and older with hypertension (mean systolic blood pressure, 139.7 mm Hg) but without diabetes or past stroke. Average age of participants was 67.9 years; 35.6% were women, 30% black, and 10.5% Hispanic.

Researchers randomized participants to intensive blood pressure control (systolic blood pressure goal of <120 mm Hg; n=4678) or standard treatment (systolic blood pressure goal of <140 mm Hg; n=4683).

Cognitive assessments occurred at baseline and at 2 and 4 years’ follow-up. An expert panel consisting of a neurologist, neuropsychologist, geriatrician, and geropsychologist who were masked to treatment assignment classified participants as having no cognitive impairment, MCI, or probable dementia.

The trial was stopped early because of evidence of early cardiovascular benefit in the intensive treatment group.

Results and take-home points >

Results

Over a median follow-up of 5.11 years, 149 participants in the intensive treatment group developed probable dementia, compared with 176 in the standard treatment group. Results showed no significant difference in the development of probable dementia between the two groups (hazard ratio [HR], 0.83; 95% confidence interval [CI], 0.67-1.04; P=.10).

The authors noted that because the study ended early and fewer than expected participants developed dementia, the analysis may not have been able to find significant differences between groups for this outcome.

In fact, intensive blood pressure control was linked to a significantly decreased risk of MCI (HR, 0.81; 95% CI, 0.69-0.95; P=.007), as well as a composite endpoint of MCI or probable dementia (HR, 0.85; 95%CI, 0.74-0.97; P=.01).

But whether these results will translate into fewer cases of dementia over time remains unclear. Other randomized controlled trials, such as the Systolic Hypertension in Europe (Syst-Eur) trial, Hypertension in the Very Elderly Trial (HYVET), and Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial, have yielded inconsistent results. These differences in results are likely related to different blood pressure targets and methods of evaluating dementia.

“With such variability in BP targets and cognitive outcome definitions, the effect of intensive BP control on cognitive impairment and dementia in older adults remains somewhat uncertain,” the authors concluded.

Take-home points

• Results from the SPRINT MIND trial suggest intensive blood pressure control does not significantly decrease the risk of probable dementia over 5 years in individuals without diabetes, compared with standard treatment

• Results also suggest that intensive blood pressure control may decrease the risk of mild cognitive impairment

• The study ended early and may not have been able to detect a difference in the development of dementia over time

• Results do not definitively answer the question of whether intensive blood pressure control protects cognition over time

References:

1. SPRINT MIND Investigators for the SPRINT Research Group, Williamson JD, Pajewski NM, Auchus AP, et al. Effect of intensive vs standard blood pressure control on probable dementia: a randomized clinical trial. JAMA. 2019;321:553-561. doi: 10.1001/jama.2018.21442.