Study: DEXA+MRI show loss of mean mass may point to dementia
Loss of lean mass--the weight of an individual’s bones, muscles and organs without body fat--is accelerated in patients with Alzheimer’s disease (AD) and is associated with brain atrophy and cognitive performance, according to a study published in the April issue of the Archives of Neurology.
Jeffrey M. Burns, MD, of the department of neurology at the University of Kansas School of Medicine in Kansas City and colleagues, said that the loss of lean mass may be a direct or indirect consequence of AD pathophysiology or through shared mechanisms common to both AD and sarcopenia, the loss of muscle mass typically associated with aging.
“Unintended weight loss often occurs among individuals with Alzheimer’s disease and frequently begins prior to memory loss or other cognitive symptoms,” said the researchers. “This weight loss is associated with the severity of dementia and with faster progression of AD.”
In order to examine body composition in individuals with early AD and without dementia and its relation to cognition and brain volume, the researchers selected 70 individuals without dementia and 70 individuals with early-stage AD for inclusion in their cross-sectional case-control study from the Alzheimer and Memory Program at the University of Kansas School of Medicine.
According to the authors, the participants were each evaluated by way of brain MRI, neuropsychological testing and dual-energy x-ray absorptiometry (DEXA) to determine whole-body fat and lean masses. They calculated the body mass index as weight in kilograms divided by height in meters squared.
Lean mass was found to be reduced in the individuals with early AD compared with those in the control group without dementia, after controlling for sex. After controlling for age and sex, whole-brain volume, white matter volume and global cognitive performance were associated with lean mass, the authors wrote. However, the total body fat and percentage of body fat values were not different across groups or related to cognition and brain volume, said the researchers.
Lean mass may be a more sensitive measure of the changes in body composition associated with dementia, compared to body mass index or other measures of overall weight or fat levels, said Burns and colleagues.
“We observed a direct correlation between whole-brain volume (an estimate of brain atrophy) and lean mass, suggesting that brain atrophy and loss of muscle mass may co-occur,” wrote the authors.
“Brain atrophy is considered a neuroimaging measure reflective of AD 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,” the authors concluded.
Jeffrey M. Burns, MD, of the department of neurology at the University of Kansas School of Medicine in Kansas City and colleagues, said that the loss of lean mass may be a direct or indirect consequence of AD pathophysiology or through shared mechanisms common to both AD and sarcopenia, the loss of muscle mass typically associated with aging.
“Unintended weight loss often occurs among individuals with Alzheimer’s disease and frequently begins prior to memory loss or other cognitive symptoms,” said the researchers. “This weight loss is associated with the severity of dementia and with faster progression of AD.”
In order to examine body composition in individuals with early AD and without dementia and its relation to cognition and brain volume, the researchers selected 70 individuals without dementia and 70 individuals with early-stage AD for inclusion in their cross-sectional case-control study from the Alzheimer and Memory Program at the University of Kansas School of Medicine.
According to the authors, the participants were each evaluated by way of brain MRI, neuropsychological testing and dual-energy x-ray absorptiometry (DEXA) to determine whole-body fat and lean masses. They calculated the body mass index as weight in kilograms divided by height in meters squared.
Lean mass was found to be reduced in the individuals with early AD compared with those in the control group without dementia, after controlling for sex. After controlling for age and sex, whole-brain volume, white matter volume and global cognitive performance were associated with lean mass, the authors wrote. However, the total body fat and percentage of body fat values were not different across groups or related to cognition and brain volume, said the researchers.
Lean mass may be a more sensitive measure of the changes in body composition associated with dementia, compared to body mass index or other measures of overall weight or fat levels, said Burns and colleagues.
“We observed a direct correlation between whole-brain volume (an estimate of brain atrophy) and lean mass, suggesting that brain atrophy and loss of muscle mass may co-occur,” wrote the authors.
“Brain atrophy is considered a neuroimaging measure reflective of AD 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,” the authors concluded.