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Cardiorespiratory fitness linked to brain atrophy in early Alzheimer's disease
By Ben Wasserman
Jul 15, 2008 - 10:57:37 AM

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TUESDAY JULY 15, 2008 (foodconsumer.org) -- Cardiorespiratory fitness has something to do with brain atrophy in Alzheimer’s disease, according to a new study published in the July 15, 2008, issue of Neurology, the medical journal of the American Academy of Neurology.

Cardiorespiratory fitness was measured by peak oxygen consumption expressed as milliliters per kilogram per minute (ml kg (-1) min (-1)), which indicates one’s capability to get oxygen into his body. A high number indicates more oxygen for the body boosting physical and mental activities. It’s been known that lack of oxygen kills never cells and causes brain damage affecting brain functions possibly in Alzheimer’s patients.

The study led by Jeffrey M. Burns, MD, of the University of Kansas School of Medicine in Kansas City and member of the American Academy of Neurology  and colleagues showed that increased cardiorespiratory fitness is associated with reduced brain atrophy in Alzheimer's disease (AD).

"People with early Alzheimer's disease who were less physically fit had four times more brain shrinkage when compared to normal older adults than those who were more physically fit, suggesting less brain shrinkage related to the Alzheimer's disease process in those with higher fitness levels," said Dr. Bruns.

The study was meant to examine the correlation between cardiorespiratory fitness and brain atrophy and cognition in patients with early-stage Alzheimer’s disease.

In the study, 64 subjects without dementia and 57 subjects with early-stage Alzheimer's disease received MRI scans and standard and psychometric evaluations.

Cardiorespiratory fitness was measured by peak oxygen consumption during a graded treadmill test.   Brain atrophy was estimated based on the normalized whole brain volume determined by MRI.

The researchers found cardiorespiratory fitness was moderately reduced in those with Alzheimer’s disease compared to those without dementia, 34.7 ml/kg/min versus 38.1 ml/kg/min. This means the Alzheimer’s patients got less oxygen than those without dementia.

The peak oxygen consumption (also known as peak oxygen uptake) was associated with whole brain volume and white matter volume in early AD patients after adjustment for age.

Other factors such as sex, dementia severity, physical activity, and physical frailty did not affect the association.

Additionally, peak oxygen uptake was linked with performance on delayed memory in early Alzheimer's patients. The association did not hold after controlling for age though.

In those who had no dementia, no association between fitness and brain atrophy was observed. However, those who had better fitness were more likely to have better global cognitive performance and performance on Trailmaking A and B, Stroop, and delayed logical memory. But again, the association disappeared after considering the effect of age.

The researchers concluded "Cardiorespiratory fitness may moderate AD-related brain atrophy or a common underlying AD-related process may impact both brain atrophy and cardiorespiratory fitness."

"People with early Alzheimer's disease may be able to preserve their brain function for a longer period of time by exercising regularly and potentially reducing the amount of brain volume lost," Burns said.