E-Mail COLUMBUS, Ohio - Though obesity in midlife is linked to an increased risk for Alzheimer's disease, new research suggests that a high body mass index later in life doesn't necessarily translate to greater chances of developing the brain disease. In the study, researchers compared data from two groups of people who had been diagnosed with mild cognitive impairment - half whose disease progressed to Alzheimer's in 24 months and half whose condition did not worsen. The researchers zeroed in on two risk factors: body mass index (BMI) and a cluster of genetic variants associated with higher risk for Alzheimer's disease.