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Low cardiac function may accelerate brain aging
6 August 2010
MedWire News: US researchers report that a decreased cardiac index, a measure of cardiac output in relation to body size, is associated with decreased brain volume – a sign of brain aging.
“The association cannot be attributed to cardiovascular disease (CVD) because the relationship also was seen when we removed those participants with known cardiovascular disease from our analyses,” explain Angela Jefferson, from Boston University School of Medicine in Massachusetts, and colleagues.
As reported in the journal Circulation, the team assessed the neuropsychologic function, in addition to the brain and heart magnetic resonance imaging scans of 1504 participants aged 34 to 84 years, without a history of stroke, dementia, or transient ischemic attack.
A low cardiac index, defined as <2.5 l/min/m2, was found in 30% (n=457) of the group. Even after participants with CVD were excluded (n=112), 30% (n=415) of the group still had a low cardiac index.
A positive correlation was identified between cardiac index and brain volume, with each 1 standard deviation (SD) increase in cardiac index linked to a total brain volume increase of 30% (p=0.03). When cardiac index was analyzed as a continuous measurement, it had an inverse relationship with cerebral lateral ventricle volume (another marker of brain aging), with a 1-SD increase in cardiac index associated with a 10% decrease in lateral ventricle volume (p=0.048).
After excluding participants with CVD, the positive correlation between cardiac index and total brain volume remained (p=0.02); however, the relationship between cardiac index and lateral ventricular volume became nonsignificant (p=0.08).
Dividing the participants into tertiles based on their cardiac index values revealed that those in the bottom (<2.44 l/min/m2) and middle tertiles (2.54–2.92 l/min/m2) had a 36% and 35% lower brain volume, respectively (p=0.04 for both), than those in the top tertile (>2.92 l/min/m2).
Jefferson et al explain that these 36% and 35% brain volume differences correspond to respective 1.8- and 1.9-year increases in brain age.
Of note, the correlation between cardiac index and brain volume was strongest among participants aged <60 years (p=0.01), and neuropsychological factor scores were not related to cardiac index as a continuous variable.
In a related commentary, Clinton Wright and Ralph Sacco (University of Miami, Florida, USA) said: “Whether lower cardiac index leads to reduced brain volumes and accelerates neurodegeneration on an eventual path to dementia is not yet clear.”
Jefferson et al add: “It is too early to dole out advice based on this one finding but it does suggest that heart and brain health go hand in hand.”
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