Higher Genetically Influenced Lean Muscle Mass Lowers Alzheimer's Disease Risk by 12%.

The main objective of this study was to examine whether genetically proxied lean mass is associated with Alzheimer's disease risk.

The study design was a Mendelian randomisation study.

The Setting was a UK Biobank and genome-wide association study meta-analyses of Alzheimer's disease and cognitive performance.

The data on study participants include:

• UK Biobank participants included data from 450,243 individuals who had lean and fat mass measurements.
• Alzheimer's disease patients and controls: Data from an independent group of 21,982 patients with Alzheimer's disease and 41,944 controls (individuals without Alzheimer's disease).
• Replication sample: Data from 7,329 Alzheimer's disease patients and 252,879 controls.
• Cognitive performance: 269 867 individuals taking part in a genome-wide association study.

They measured the main outcome as the Effect of genetically proxied lean mass on the risk of Alzheimer's disease and the related phenotype of cognitive performance.

The study results could be summarised as follows:

• An increase in genetically proxied appendicular lean mass reduced the risk of Alzheimer's disease by 12 %.
• Higher genetically proxied appendicular lean mass had an association with increased cognitive performance, and adjusting for potential mediation through genetically proxied cognitive performance did not reduce the association between appendicular lean mass and Alzheimer's disease risk.

Based on these findings, they concluded that lean mass may be a possible modifiable protective factor for Alzheimer's disease. Further investigations are warranted for mechanisms underlying this finding and the clinical and public health implications.

Further reading:

https://bmjmedicine.bmj.com/content/2/1/e000354