High Body Mass Index (BMI) might affect cognitive function

Researchers from the University of Arizona have found that having a higher body mass index, or Body Mass Index, can negatively impact cognitive functioning in older adults.

“The higher your Body Mass Index (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.”

Bourassa and his co-author, UA psychology professor David Sbarra, analyzed 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.

Using two separate samples from the study — one of about 9,000 people and one of about 12,500 — researchers looked at aging adults over a six-year period. They had information on study participants’ BMI, inflammation and cognition, and they found the same outcome in both samples.

“The higher participants’ body mass at the first time point in the study,” Bourassa said, “the greater the change in their CRP levels over the next four years. 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.”

Sbarra added a word of caution in trying to understand the findings. “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.”

Publication: Body mass and cognitive decline are indirectly associated via inflammation among aging adults.
DOI: http://dx.doi.org/10.1016/j.bbi.2016.09.023
Journal: Brain, Behavior and Immunity

Adapted from press release by University of Arizona