In a new study, researchers found that excessive belly fat gives our brain’s immune cells heavy exposure to a signal that turns them against us, setting in inflammation that damages cognition.
They identified a specific signal that is generated in belly fat, released into the blood that gets through the blood-brain barrier and into the brain where it impairs cognition.
The research was conducted by a team at the Medical College of Georgia at Augusta University.
It’s known that belly fat is particularly bad for our bodies and brains.
This study shows for the first time one way belly fat is bad for brains is by enabling easy, excessive access for the pro-inflammatory signal.
The brain typically does not see much of this signal interleukin-1 beta, but the researchers have found that belly fat generates high, chronic levels of the signal that in turn over-activate the usually protective microglia, the resident immune cells in our brain.
Microglia typically function as watchdogs, constantly surveilling and roaming the brain, eliminating dead cells and other debris as well as a myriad of other tasks like forming and pruning connections between neurons.
A bit like a smoldering pot, this chronic inflammation from visceral fat prompts the formation of inflammasome complexes that further amplify the immune response and inflammation.
The team found the signal levels increased in the hippocampus, a center of learning and memory in the brain, and impaired cognition.
They also found that just transplanting the visceral fat caused essentially the same impact as obesity resulting from a high-fat diet.
There is also emerging evidence that bariatric surgery, which sometimes includes removing visceral fat, can improve attention, mood and executive function.
There are many hypotheses about why belly fat is so inflamed, including its proximity to the gut microbiota, a centerpiece of our immune response, which is programmed to attack invaders.
Increased rates of cognitive decline have been linked to obesity in humans, including shrinkage of key brain areas like the hippocampus, although there also have been contradicting reports about the overall health impact of obesity.
Waist to hip ratio is a better indicator of belly fat than the standard body mass index, or BMI, that divides weight by height.
The study is published in The Journal of Clinical Investigation.
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