Scientists from the University of California have found that people with a high percentage of muscle mass are less likely to develop Alzheimer’s disease. Research published in the journal BMJ Medicine.
Previous studies have shown that low muscle mass levels are associated with an increased risk of Alzheimer’s disease, but it is unclear whether muscle wasting is the cause or consequence of the disease.
In the new study, scientists analyzed data from 450,000 medical records from the British Biobank. Bioimpedance analysis was used to evaluate muscle and adipose tissue in the arms and legs. Electrical current travels through fat and muscle at different speeds, so knowing the time it takes to travel through the body can tell you body composition.
The analysis results of the participants’ bodies were adjusted for age, sex, and 584 genetic variants (mutations) responsible for muscle mass. Combined, these genetic variants accounted for 10% of the difference in lean muscle mass in the arms and legs of the study participants. This approach (known as Mendelian randomization) allowed scientists to exclude the influence of other potential dementia risk factors, such as diet and physical activity, since the presence of genetic variants in an individual is not lifestyle dependent.
On average, higher genetically determined muscle mass was associated with a small but statistically significant reduction in Alzheimer’s disease risk. High lean mass has also been associated with better performance on cognitive tasks. The findings mean there may be a causal relationship between high muscle mass and a reduced risk of Alzheimer’s disease.
Also, the study disproved the effect of fat mass on Alzheimer’s disease risk. However, the authors cautioned that their findings could not be used in medical practice until further research is done.
Previous studies have shown that obesity is associated with an increased risk of Alzheimer’s disease. This is believed to be due to higher levels of beta-amyloid protein, which plays a role in the development of obesity-related inflammation, decreased insulin sensitivity, and the development of Alzheimer’s disease, in adipose tissue.
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