No Difference in Memory, Processing Speed With Tight BP Control

Aggressively lowering blood pressure in hypertensive older adults did not produce a clinically relevant difference in memory or processing speed compared with standard blood pressure treatment, a SPRINT substudy showed.

The annual decline in mean standardized memory domain scores was −0.005 in participants who had intensive treatment that targeted systolic blood pressure of 120 mm Hg, and −0.001 in those with standard treatment targeting 140 mm Hg (between-group difference −0.004, 95% CI −0.012 to 0.004, P=0.33), reported Stephen Rapp, PhD, of Wake Forest University in Winston-Salem, North Carolina, and co-authors.

Mean standardized processing speed domain scores declined more in the intensive group (between-group difference −0.010, 95% CI −0.017 to −0.002, P=0.02), with a yearly change of −0.025 for intensive versus −0.015 for standard treatment, a difference of “doubtful clinical significance,” Rapp and colleagues wrote in Lancet Neurology.

The substudy was a preplanned analysis of SPRINT trial participants to look at the effects of blood pressure control on domain-specific cognitive function, with composite scores for memory and processing speed as the primary outcomes.

SPRINT aimed to determine whether aggressively lowering blood pressure could protect the heart, kidney, and brain over 5 years. The success of the heart disease portion — which raised questions about trial design and how results should be applied — led to the trial’s early termination at 3.3 years.

A substudy of the trial, SPRINT MIND, showed that intensive blood pressure control did not significantly reduce dementia risk (HR 0.83, 95% CI 0.67-1.04), but did lead to a 19% lower rate in mild cognitive impairment (HR 0.81, 95% CI 0.69-0.95).

“The results from this study complement those from SPRINT MIND,” Rapp told MedPage Today.

“The two analyses asked different questions. SPRINT MIND asked whether intensive BP control protected against cognitive impairment compared to standard control. Results indicated that it did; there was a significantly lower occurrence of mild cognitive impairment and a non-significant trend in the same direction for dementia,” Rapp said.

“The present study asked whether intensive blood pressure control had an overall effect on particular cognitive functions — memory, processing speed, executive function, language, or global cognitive function — compared to standard control. The results showed it did not have a clinically meaningful effect,” he continued.

“In short, intensive blood pressure control had a beneficial effect on cognitive impairment, yet did not produce an effect that concentrated in a particular cognitive function. Given the extent of vascularization in the brain, it is not surprising that a particular region and associated cognitive function were not selectively affected.”

Rapp and his team followed participants randomly selected from SPRINT, including 1,448 people in the intensive treatment group and 1,473 in the standard treatment group who enrolled from November 2010 to December 2012. Mean age of participants was about 68, and 37% were women. Median follow-up was 4.1 years.

Participants had cognitive tests administered at baseline and during follow-up. Memory composite scores were based on Logical Memory I and II tests, Modified Rey-Osterrieth Complex Figure (immediate recall), and Hopkins Verbal Learning Test-Revised (delayed recall). Processing speed scores included the Trail Making Test and Digit Symbol Coding.

In other domains — language, executive function, and global cognitive function — there was no evidence that intensive blood pressure control had a beneficial or detrimental effect.

The results suggest a “healthy skepticism is needed about the use of intensive treatment to lower systolic blood pressure in older adults to prevent cognitive decline and dementia,” observed Philip Gorelick, MD, and Farzaneh Sorond, MD, both of Northwestern University in Chicago, in an accompanying commentary.

“A better mechanistic understanding of the link between elevated blood pressure and cognitive impairment will also be crucial for the success of future intervention studies,” they wrote. “The ongoing SPRINT MIND extension study and multidomain intervention studies that test combinations of interventions might provide a clearer perspective on the role of intensive lowering of systolic blood pressure.”

The substudy may have been limited by the decision to end the SPRINT trial early, which may have caused the analysis to be underpowered. In addition, cognitive assessors were not masked to treatment assignment.