A new study suggests that aggressive blood pressure control may have modest benefits for cognitive function (The SPRINT MIND investigators, JAMA, Jan. 28, 2019). That is the conclusion from a follow-up on a clinical trial that originally showed getting systolic blood pressure to 120 could prevent some heart attacks and strokes.
How Well Did Aggressive Blood Pressure Control Work?
In 2010 researchers recruited 9,300 people over 50 to participate in the SPRINT trial. This stands for Systolic Blood Pressure Intervention Trial. The participants all had high blood pressure. However, none had diabetes or cognitive dysfunction when the study began.
The investigators randomly assigned these volunteers to get their blood pressure down to 120 (intensive blood pressure control) or under 140 (standard control). The group on standard treatment served as the control group for the trial.
Those who were assigned to intensive blood pressure control were prescribed as many drugs as were necessary to achieve the goal. Some subjects took as many as three or four different medications (SPRINT Research Group, New England Journal of Medicine, Nov. 26, 2015).
This secondary study was dubbed SPRINT MIND. The volunteers participated in cognitive tests both at baseline and after three to five years of treatment.
The Results of SPRINT MIND:
People in the intensive blood pressure control arm were slightly less likely to develop dementia during the five years of the study. Unfortunately, the difference was too small to be statistically significant. There were 149 cases in the aggressive blood pressure control arm. In comparison, 176 in the standard treatment group developed dementia. That works out to 7.2 per 1,000 person-years for the intervention. Conversely, the rate was 8.6 cases/1,000 person-years in the control group.
Mild cognitive impairment is a less severe problem, but it’s more common. This complication occurred in 14.6 cases per 1000 person years in the intensive treatment arm. People in the standard treatment arm had a rate of mild cognitive impairment of 18.3 per 1000 person years. Unlike the results on dementia, this difference was statistically significant. The relative risk reduction was 19 percent, but absolute risk dropped by a modest 0.4 percent.
The authors concluded that:
“Among adults with hypertension, intensive blood pressure control did not significantly reduce the risk of probable dementia.”
They speculated that the study may have been underpowered to detect the influence of aggressive blood pressure control on dementia. Nonetheless, that still suggests that any effect that might have been missed is probably not very large.