New Study Suggests Blood Pressure Variability is What Matters for Cognitive Decline

A new study has found a new insight on the relationship between blood pressure and cognitive decline. Since hypertension is a well-established – and controllable – risk factor for cognitive decline, scientists assumed that reducing it is the best strategy. But this seems to be missing a crucial piece of the puzzle.

The Problem: Mixed Results on Lowering Blood Pressure

The new paper points out that different studies disagree about the cognitive benefits of interventions to reduce blood pressure.  

The SPRINT-MIND study recruited people with hypertension but not diabetes. It found a reduced risk of mild cognitive impairment for people on a more intensive blood pressure reduction regimen, but no difference in probable dementia.

Conversely, the ACCORD-MIND trial focused on people with type 2 diabetes and included a similar comparison of a more intensive vs. less intensive blood pressure reduction regimen. In this case, though, there was no difference in cognitive function.

What the New Study Did

The new research [1] pooled data from both of these trials, and analyzed the data again at participant-level. The paper notes that blood pressure variability (BPV) is linked to both cardiovascular events and cognitive decline, and tends to be higher in people with diabetes.

To test whether this is the important factor, researchers looked at BPV between each visit in the original studies. The original researchers used varying cognitive tests, but the authors identified two essentially equivalent measures of psychomotor processing speed among them. They used these to compare results across both studies.

What They Found: Higher Variability, Greater Decline

People with more variability in their blood pressure saw greater cognitive decline over the study period. In particular, those in the highest third of BPV had a faster rate of decline than those in lower thirds. The relationship seemed to be linear: each 10% increment of BPV led to consistently higher levels of decline.

What the Study is Missing

The study only focused on one measure of cognitive decline, rather than a global score. All participants also had a high cardiovascular risk, so the results might not carry over to other populations.

 What Doctors Can Do

One thing the study suggests is optimizing drug selection and timing to reduce BPV where possible. Doctors can also try novel interventions specifically designed to bring down BPV.