A NIH-funded imaging trial has linked intensive blood pressure treatment to reductions in lesions associated with cognitive decline, according to a JAMA paper published Tuesday.
The study adds to evidence that lowering blood pressure may slow age-related cognitive loss, providing another reason for patients and physicians to tackle hypertension.
- However, the intensive treatment was also associated with a reduction in total brain volume and earlier work by the same investigators found it had no effect on the rate of dementia.
There is a growing body of evidence linking hypertension to cognitive decline. Longitudinal studies show people who have hypertension during middle age are more likely to suffer cognitive decline later in life. The identification of vascular pathologies in dementia patients, plus evidence they may trigger Alzheimer's disease, have added weight to the longitudinal findings.
To further investigate the link, investigators involved in National Institutes of Health's Systolic Blood Pressure Intervention Trial (SPRINT) looked at magnetic resonance imaging (MRI) on patients who underwent an intensive treatment to lower their blood pressure.
Subjects on the treatment, which was designed to reduce systolic blood pressure to below 120 mm Hg, experienced significantly smaller increases in brain white matter lesion volume than their peers on less-intensive treatments. The presence of white matter lesions on MRI scans is a risk factor for cognitive decline and dementia.
While that result suggests lowering blood pressure may help stave off cognitive decline, other findings in the study and broader SPRINT program are less conclusive. Earlier this year, another SPRINT paper in JAMA found little evidence that the intensive blood pressure treatment reduces the risk of probable dementia.
The latest study offers up an alternative explanation. Participants who received the intensive blood pressure treatment suffered a greater loss of overall brain volume than their peers on the standard treatment.
Writing in a JAMA editorial accompanying the latest SPRINT paper, Shyam Prabhakaran, a neurologist at the University of Chicago, suggested the increased brain atrophy may have mitigated the positive effects on white matter lesions.
"The important clinical question is whether changes of a few cubic centimeters in [white matter hyperintensity] volume or brain volume make a difference on brain function," Prabhakaran wrote.
The lack of consensus on the level of white matter and brain volume changes needed to cause cognitive decline makes it hard to answer that question. However, Prabhakaran thinks there are signs in the SPRINT data that small changes in the volume of white matter lesions affect clinical outcomes.