The SPRINT MIND investigators conducted a randomised clinical trial, at 102 sites in the United States and Puerto Rico, that included 9,361 men and women aged at least 50 years (mean 67.9 years) with hypertension, but without diabetes or history of stroke. Participants were randomised to either ‘intensive treatment’ with a systolic blood pressure target of <120mmHg, or to ‘standard treatment’ with a target of <140mmHg. The primary cognitive outcome was occurrence of adjudicated probable dementia; secondary cognitive outcomes included adjudicated mild cognitive impairment and a composite outcome of mild cognitive impairment or probable dementia.
Randomisation began on 8th November 2010 but was stopped early on 20th August 2015, for benefit on its primary outcome (a composite of cardiovascular events) and all-cause mortality. The final date for follow-up of cognitive outcomes was 22nd July 2018; 8,563 (91.5%) of randomised participants completed at least one follow-up cognitive assessment, and the median intervention period was 3.34 years.
The researchers reported that during a total median follow-up of 5.11 years, there was no statistically significant difference between groups in the rate of adjudicated probable dementia, which occurred in 149 participants in the ‘intensive treatment’ group compared with 176 in the ‘standard treatment’ group (hazard ratio, HR 0.83). However, intensive control significantly reduced both the risk of mild cognitive impairment (HR 0.81) and the combined rate of mild cognitive impairment or probable dementia (HR 0.85).
The study authors pointed out that the study was limited by its early termination; its exclusion of people with type 2 diabetes, previous stroke, advanced kidney disease, or symptomatic heart failure; and by its choice of thresholds for mild cognitive impairment.
They concluded: “Among ambulatory adults with hypertension, treating to an SPB [systolic blood pressure] goal of less than 120 mm Hg compared with a goal of less than 140 mm Hg did not result in a significant reduction in the risk of probable dementia. Because of early study termination and fewer than expected cases of dementia, the study may have been underpowered for this end point.”
*The SPRINT MIND Investigators for the SPRINT Research Group. Effect of intensive vs standard blood pressure control on probable dementia: a randomized clinical trial. JAMA. Published online January 28, 2019. doi:10.1001/jama.2018.21442.