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Obesity Gene And Alzheimer's Disease

A new Swedish study finds that a variant of the gene known as FTO, which is thought to be related to tendencies toward obesity and diabetes, appears to raise the risk for both Alzheimer's disease and dementia.

Leptin Levels

Earlier studies had found that FTO has an effect on the body mass index (BMI), leptin levels (leptin is a hormone that is associated with regulating metabolism and appetite), as well as the risk for diabetes. All of these issues are risk factors relating to the vascular system and all have been implicated in the risk for Alzheimer's disease.

The new study was conducted at Stockholm's Karolinska Institute and included over 1,000 Swedish participants aged 75 and above who were observed over a period of nine years. Each participant underwent genetic studies at the time the study period began.

The researchers found that the participants who were found to have the gene variant of the FTO gene known as AA had a 58% higher risk for getting Alzheimer's with a 48% higher risk for developing dementia in comparison to those who lacked this gene variant. Even more significant, the researchers discovered that those participants who had both the FTO-AA variant and the gene mutation known as APOE4, had up to a 100% higher risk for Alzheimer's or dementia. APOE4 carries the highest risk for these conditions of all the Alzheimer's-linked genes in the family of APOE.

Different Mechanism?

Study author Dr. Caroline Graff commented that her research team was intrigued by the fact that the increase in risk for dementia and Alzheimer's associated with FTO appears to be independent of the other traits that have come to be associated with the gene, for instance diabetes and obesity in the case where these were measured at baseline. This fact leads the Karolinska team to posit that the mechanism by which FTO leads to Alzheimer's and dementia may be quite different from those that increase the risks for obesity or diabetes. 

The study was presented at the July 12 Alzheimer's Association International Conference which focused on the subject of Alzheimer's disease.  Maria Carrillo, who is the senior director for medical and scientific relations for the Alzheimer's Association says that while these findings are still early, they offer much fascination for those studying the compelling connections between brain and heart health. But Carrillo states that these new results must be confirmed by further studies.