Being overweight is not good for your body, and new research suggests it’s not good for your brain either. Researchers from the University of Arizona say having a high body mass index, or BMI, can cause inflammation that can impair cognitive functioning in older adults. "The higher your BMI, the more your inflammation goes up," said Kyle Bourassa, lead author of the study, which is published in the journal Brain, Behavior and Immunity. "Prior research has found that inflammation, particularly in the brain, can negatively impact brain function and cognition." The conclusions were reached using data from the English Longitudinal Study of Aging, which “includes over 12 years' worth of information on the health, well-being and social and economic circumstances of the English population age 50 and older.” They looked specifically at two groups over a six-year period. "The higher participants' body mass at the first time point in the study, the greater the change in their CRP levels over the next four years,” Bourassa said. “CRP stands for C-reactive protein, which is a marker in the blood of systemic inflammation in your body. Change in CRP over four years then predicted change in cognition six years after the start of the study. The body mass of these people predicted their cognitive decline through their levels of systemic inflammation." The researchers say their study adds to existing literature about inflammation and cognitive decline by showing BMI has a role to play. "The findings provide a clear and integrative account of how BMI is associated with cognitive decline through systemic inflammation, but we need to remember that these are only correlational findings," he said. "Of course, correlation does not equal causation. The findings suggest a mechanistic pathway, but we cannot confirm causality until we reduce body mass experimentally, then examine the downstream effects on inflammation and cognition." While cognitive decline is normal as one gets older, linking BMI to inflammation could help stave off the worst effects. "If you have high inflammation, in the future we may suggest using anti-inflammatories not just to bring down your inflammation but to hopefully also help with your cognition," Bourassa said. "Having a lower body mass is just good for you, period. It’s good for your health and good for your brain."