A new study revealed that people with high Body-Mass Index (BMI) are most likely to experience inflammation in the brain, resulting to decrease brain function and cognition.
The study, published in the journal Brain, Behavior and Immunity, supports previous claim that body mass play a crucial role in the link between inflammation and cognitive decline. However, the researchers noted that association found between BMI, inflammation and cognitive decline is correlation and does not prove causation.
"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," explained David Sbarra, a psychology professor at University of Arizona and co-author of the study, in a press release. "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."
For the study, the researchers analyzed data from the English Longitudinal Study of Aging. Sbarra, together with the study's lead author, UA psychology doctoral student Kyle Bourassa, used two separate samples from the aging study. Both samples, which contains about 9,000 and 12,500 participants, were observed over a six-year period. The researchers recorded each participant's BMI, inflammation and cognition.
The researchers discovered that BMI could predict changes in systemic inflammation levels of the participants over four years, the higher the BMI of the participants, the greater the change in their systemic inflammation levels. In turn, these changes in the systemic inflammation levels of the participants over four years could predict changes in brain function and cognition.
Bourassa noted that cognitive decline is part of the aging process, even in healthy adults. However, their findings could provide valuable insights for possible interventions and new research directions in that area. Additional experimental studies involving improvement of cognition and brain function through the reduction of systemic inflammation levels could better establish the causal effect of inflammation and cognitive decline.