A variant of the obesity-related gene FTO may increase the risk of Alzheimer's disease and dementia, finds a new Swedish study.
Previous research has shown that the FTO gene affects body mass index (BMI), levels of leptin (a hormone involved in appetite and metabolism), and the risk for diabetes - all vascular risk factors that have also been linked with the risk of Alzheimer's disease.
This new study, conducted by the Karolinska Institute in Stockholm, included more than 1 000 Swedish people, aged 75 and older, who were followed for nine years. They all underwent genetic testing at the start of the study.
Participants who carried an AA gene variant in the FTO gene had a 58% increased risk of developing Alzheimer's and a 48% increased risk for dementia, compared to those without the variant.
The researchers also said the risk could be 100% higher for a person with the FTO-AA variant and a gene mutation called APOE4, which is the highest-risk variant of the known Alzheimer's-related gene called APOE.
"One of the intriguing aspects of the results is that the increased risk was independent of the traits previously associated with FTO, such as obesity and diabetes measured at baseline," wrote Dr Caroline Graff and colleagues at the Karolinska Institute. "Our results suggest that the mechanism by which FTO is associated with an increased risk for Alzheimer's and dementia may be different from how it increases the risk for obesity."
"This is a fascinating early finding, which fits with the known connections between heart health and brain health," Maria Carrillo, senior director of medical and scientific relations at the Alzheimer's Association, said in an association news release. "However, we do need to see these results confirmed by other researchers." - (HealthDay News, July 2010)