Loss of Lean Body Mass in Alzheimer's Patients Linked with Brain Function Decline

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Unintentional weight loss is a frequent complication of the elderly, resulting in health complications such as poor healing and muscle wasting, or sarcopenia. A new study conducted at the University of Kansas School of Medicine has found that loss of lean body mass is associated with the rate and severity of disease progression in Alzheimer’s patients.

Lean body mass is a measure of an individual’s bones, muscles and organs without body fat.

Jeffrey M. Burns MD and colleagues used dual energy x-ray absorptiometry (DEXA) to assess the body composition of 140 patients over the age of 60, half of which had early stages of Alzheimer’s disease and half with no symptoms, serving as controls. For study of cognition and brain function decline, the researchers also used brain MRI and neuropsychological testing.

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Overall, the Alzheimer’s patients had less lean body mass than those who were healthy. They also had lower levels of physical activity than the controls. The researchers also noted a significant association between the loss of muscle mass and decreases in the volume of the brain and its white matter, called brain atrophy. Body fat did not appear to play a role in either cognitive ability or brain volume.

The authors write, “Brain atrophy is considered a neuroimaging measure reflective of Alzheimer’s disease pathology. Thus, our data are consistent with other studies suggesting that brain pathology may contribute to decline in body composition, perhaps by disrupting central nervous system regulation of energy metabolism and food intake.”

Unintended weight loss often occurs among Alzheimer’s patients and frequently begins years before signs of memory loss and other cognitive symptoms, according to the background information in the article. The weight loss is associated with the severity of dementia and with a faster progression of the disease. The loss of lean mass in particular, as opposed to overall weight or fat loss, appears to be a more sensitive measure of the changes associated with dementia.

Source reference:
Burns JM, et al "Reduced lean mass in early Alzheimer disease and its association with brain atrophy" Arch Neurol 2010; 67(4): 428-33.

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