The study, published in Neurology, was carried out by Jeffrey Burns and colleagues, who have suggested that cardiovascular fitness either directly slows down the loss of brain tissue or that there is some other factor that is directly affecting both fitness and brain atrophy.
For the study, 64 people without dementia and 57 with early stage Alzheimer's had MRI scans and standard clinical and psychometric tests; all participants were over 60 years of age.
The researchers measured peak oxygen consumption (VO2 peak), the standard measure of cardiorespiratory fitness, during a graded treadmill test and estimated brain atrophy from the normalized whole brain volume seen on the MRI scan. They also measured white and gray matter.
Researchers found that people with early Alzheimer's disease who were physically unfit had four times more brain shrinkage related to the disease process than those who maintained cardiovascular fitness.
