For a long time, scientists thought that while excess fat causes problems in many parts of the body, the mind was exempt. After all, there are no fat cells in the brain, and the protective blood-brain barrier usually prevents undesirable molecules from bothering our most precious organ. New research seems to refute this too-good-too-be-true theory, however. Several recent studies indicate that obesity leaves our brains open to invasion.
It’s no secret that humans, especially those in developed nations, have a weight problem. Our weird food and sedentary lifestyle encourage obesity and all the health risks that come along with it. Still, scientists had many unanswered questions about how excessive fat affects the human brain.
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See, when there’s a build up of fat cells in the body, they begin to emit substances that irritate the heart and muscles. Soon, these substances produce severe inflammation and other conditions that can lead to poor health. But experts always assumed that the brain’s special barrier protected it from these reactions. Turns out, they may have been wrong.
“Recent disquieting studies in animals indicate that obesity weakens that barrier, leaving it leaky and permeable. In obese animals, substances released by fat cells can ooze past the barrier and into the brain,” reports Gretchen Reynolds for the New York Times.
In a series of neurological experiments conducted by researchers at Georgia Regents University in Augusta, mice were allowed to eat as much as they wanted. They soon developed a hefty layer of extra fat. When the researchers examined their animals’ blood, it “showed increasingly hefty doses of a substance called interleukin 1 that is created by fat cells and known to cause inflammation.” Unfortunately, the brain’s protective barrier showed itself weak in the face of this invasive substance.
Scientists watched as “interleukin 1 migrated to the head, [passed] the blood-brain barrier and entered areas such as the hippocampus, a part of the brain critical for learning and memory.”
As if too much interleukin 1 on the brain wasn’t bad enough, the researchers also noticed that the obese mice had extremely low levels of a biochemical associated with healthy synapse function. Healthy synapses are like air traffic controllers for the brain, but unhealthy synapses allow brain messages to get jammed up and jumbled. In subsequent tests of memory and learning capacity, the fat mice performed miserably.
Depressing, right? Our love handles could be the reason we can’t remember anyone’s name, or bombed that really important presentation at work. The good news is, there’s an easy fix for excessive fat cells that are slowing down your brain function: exercise.
After 12 weeks on a daily 45-minute exercise program (they walked on a treadmill) the obese mice not only shed the extra weight, they “did much better on cognitive tests than the sedentary mice and, when the researchers examined tissue from their hippocampi, showed little evidence of inflammation and robust levels of the chemical marker of synaptic health. The results suggested that, as the scientists write in the study,’treadmill training normalized hippocampal function,’ even in animals born to be fat and that remained heavy.”