Preliminary research results presented on July 25 at this year’s Alzheimer’s Association International Conference (AIC) in Chicago suggests that aggressive blood pressure control may lower the risk of mild cognitive impairment (MCI), often described as the precursor to Alzheimer’s dementia, as well as the combined risk of MCI and all-cause dementia. This is great news for a field that has been plagued by a number of high profile drug failures that have left some in the Alzheimer’s community discouraged and others questioning whether they really understand the etiology of the disease.
The SPRINT MIND study
The SPRINT MIND study was funded by the National Institutes of Health (NIH) and is a part of a well-designed series of studies known as the Systolic Blood Pressure Intervention Trial (SPRINT) Study. It includes data from 9,361 adults aged 50 or older with systolic blood pressures (SBP) of 130 mm Hg or higher and at least one other cardiovascular risk factor. People with diabetes, prior stroke, or polycystic kidney disease were excluded. Participants were older, with a mean age of 67.9; 35.6% were women. The study was randomized and controlled, generally considered a high-quality study design.
Individuals participating in the study were randomly assigned to an intensive-treatment group with a target SBP of 120 mm Hg or less or comparison group with a target SBP of 140 or less. At one year, the mean SBP in the intensive-treatment group was 121.4 mmHg compared to 136.2 in the group with a target of 140 or less.
The trial participants were followed over an average of three years with a variety of tests including cognitive skills testing of memory and ability to process new information. 8,626 of the original study participants completed at least one of these cognitive studies.
The researchers found that people in the group with the lower target SBP of 120 mm Hg or less lowered their risk of developing MCI by a statistically significant 19% compared to people who only lowered their SBP to a target of 140. For the combined outcome of MCI plus probably all-cause dementia, the lower blood pressure group was 15% lower than the higher blood pressure group. The researchers reported a “non-significant reduction” in the primary outcome of dementia alone.
Why is this study important?
It is important because:
- It is the first time a rigorous randomized trial has documented that something can lower the risk of MCI and the combined risk of MCI and dementia (although not dementia alone).
- Also, the intervention – aggressively lowering blood pressure – is in the control of people at risk (with help from their doctors) unlike other risk factors, such as aging or genetics that people cannot control.
- It holds out the hope that perhaps Alzheimer’s can be prevented by a relatively simple intervention using relatively inexpensive drugs that already exist.
What the preliminary data from the study does not do, however, is show that lowering blood pressure can provide benefit to people who already have Alzheimer’s or other forms of dementia. We also do not know if these findings can be generalized to other high-risk populations or to people without cardiovascular risk factors.
The vision for the future
When discussing the findings, Maria C, Carrillo, Ph.D., the Alzheimer’s Association Chief Science Officer notes that “the reduction in new cases of MCI seen in the SPRINT MIND study adds credibility to the vision of future Alzheimer’s therapy that combines drugs and modifiable risk factor interventions – as we do now in cardiovascular disease.
A related study
Another interesting study presented at the same meeting, called the SPRINT MIND MRI trial, looked at a subset of 454 SPRINT trial participants who had follow-up brain MRIs about 4 years after the study began. The researchers found cerebral white matter lesions increased less in the intensive-treatment group (target 120 mmHg) than in the group treated to a higher SBP (0.28 cm3 vs 0.92 cm). There was no significant difference in brain volume decrease between the two groups.
It is anticipated that both of these studies will be submitted for peer-review publication later this year.