ORLANDO — High blood levels of a brain natriuretic peptide were associated with poor cognitive function in a study of 950 community-dwelling, healthy, elderly adults.
“This is the first time this [association] has been shown,” Dr. Lori B. Daniels said at the annual scientific sessions of the American Heart Association.
Dr. Daniels, a cardiologist at the University of California, San Diego, suggested that several mechanisms that might link production of natriuretic peptide to poor cognitive function including reduced cardiac output that drops oxygen or nutrient supplies to the brain, atrial fibrillation that creates microemboli, microcirculation deficits that harm both the heart and brain, and genetic predisposition.
Cognitive function data and blood specimens were analyzed from 950 of 5,000 participants enrolled in the Rancho Bernardo study of the early 1970s.
The average age of the participants was 77 years; 61% were women. The researchers used three tests to evaluate cognitive function: The Mini-Mental State Exam (MMSE), the Trail-Making Test B, and a category fluency test that asked participants to name as many animals as they could in 1 minute.
MMSE results identified poor function in 7%, the trail-making test B identified poor function in 30%, and category fluency identified poor function in 15%.
Natriuretic peptide levels in the blood specimens were measured using a test that detects N-terminal pro-B-type natriuretic peptide (NT-proBNP). Among the 950 participants, 79% had a low level of NT-proBNP, and 21% had a high level.
In the low level group, poor cognitive scores occurred in 5%, 23%, and 12% of subjects for the three cognitive function tests, respectively. In the high level group, 17%, 54%, and 26% of the subjects scored poorly on the three tests, respectively.
When the results were adjusted for age, education, and other factors, participants with high NT-proBNP levels had significantly worse cognitive function scores on the MMSE and the Trail-Making Test B. Scores for category fluency were lower in people with high NT-proBNP in the fully-adjusted model, but the difference fell short of statistical significance.
In the fully-adjusted model, people with high levels of NT-proBNP were 82%, 75%, and 37% more likely to have poor cognitive function on the three tests, respectively, compared with people with low levels.
Dr. Daniels received research support from Roche Diagnostics, which markets an NT-proBNP assay.