The causes of Alzheimer’s are not exactly known, but it is known that there are risk factors for developing this disease and obesity is one of them, since numerous studies have associated it with its appearance, something that scientists attribute to inflammation , insulin resistance and higher levels of amyloid beta protein – which is harmful to the brain – in adipose tissue, which are complications that often accompany being overweight.
A new study has now found a factor that would help prevent this dementia. According to their results, which have been published in BMJ Medicine, having high levels of lean muscle could protect against Alzheimer’s disease, although the authors of the work point out that further research is necessary to identify the biological pathways behind this effect. protective. Lower levels of lean muscle have also been linked to a higher risk of the disease, but it is not clear if this would help the diagnosis.
The researchers used Mendelian randomization to conduct the study. This is a technique that uses genetic variants as proxies for a particular risk factor, which in this case was lean muscle, to obtain genetic evidence to support a particular outcome, which in this study was Alzheimer’s disease risk.
More physical exercise to combat Alzheimer’s disease
To validate the findings, they drew on data from 450,243 UK Biobank participants; an independent sample of 21,982 people with Alzheimer’s and 41,944 people without the disease; an additional sample of 7,329 people with Alzheimer’s and 252,879 people without the disease; and 269,867 people participating in a study of genes and intelligence. Bioimpedance, an electrical current that flows at different speeds through the body depending on its composition, was used to estimate lean muscle and fat tissue in the arms and legs, and the results obtained were adjusted for age, sex, and ancestry. genetics.
If future studies confirm the findings: “campaigns to promote exercise and physical activity could reduce the burden of Alzheimer’s in the population”
Some 584 genetic variants were associated with lean muscle mass; none were located in the region of the APOE gene that is related to vulnerability to Alzheimer’s. These combined genetic variants explained 10% of the difference in lean muscle mass in the study participants’ arms and legs. On average, higher lean muscle mass (represented genetically) was associated with a modest, but statistically robust, reduction in Alzheimer’s disease risk. This finding was repeated in the additional sample of 7,329 people with the disease and 252,879 healthy people, using different measures of lean muscle mass: trunk and whole body.
They also found an association between lean mass and better performance on cognitive tasks, although this association did not explain the protective effect of lean mass on Alzheimer’s disease risk. Body fat, adjusted for lean mass, was also not associated with Alzheimer’s disease risk, but was associated with poorer cognitive performance on tasks.
“These analyzes provide new evidence supporting a cause-and-effect relationship between lean mass and Alzheimer’s disease risk,” the researchers say, adding that the findings also “refute a large effect of fat mass on Alzheimer’s risk.” Alzheimer’s disease and highlight the importance of distinguishing between lean mass and fat mass when investigating the effect of measures of adiposity on health outcomes.”
However, they also caution: “Our findings should be replicated with independent lines of complementary evidence before reporting to public health or clinical practice. In addition, more work is needed to determine cut-off values for age and the degree of Alzheimer’s disease pathology, after which changes in lean mass could no longer reduce risk.” It is also unclear whether increasing lean mass could reverse this dementia in patients with preclinical disease or mild cognitive impairment, they note.
Despite this, in the opinion of these scientists, if future studies confirm their findings: “public health efforts to change the distribution of lean mass in the population, potentially through campaigns to promote exercise and physical activity, could reduce the burden of Alzheimer’s disease in the population.
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