Study finds link between obesity and vascular dementia Fox News senior medical analyst Dr. Marc Siegel joins 'America's Newsroom' to discuss an increase in colon cancer in people under 50 despite an overall lowering cancer deaths and a new study linking obesity to vascular dementia. NEW You can now listen to Fox News articles! A new blood test could determine a woman’s dementia risk as early as 25 years before symptoms emerge. That’s according to new research from the University of California