Overweight people may have impaired brain function, report neuroscientists in a new study published in the February edition of the Journal of Neuroscience. Fat impairs cognitive function, the researchers says, and exercise can help.
The researchers bred rodents to become overweight, and then encouraged them to overeat. The extra weight that the lab animals carried released a substance known as an “inflammatory cytokine” into the blood stream that promotes inflammation in the body. What’s more, this inflammation-producing substance was able to reach the brain, and slowed the brain regions important for learning and memory. Inflammatory molecules are naturally produced in the body in response to an injury, and are designed to promote healing. When no injury is present, though, the molecules hang out long-term and can actually cause harm to healthy tissue.
In order to confirm that the substance released from fat cells impaired learning and memory, scientists first gave the mice a series of cognitive tests to evaluate their skills. The mice, which normally perform rather well on such tests, did poorly. Because this finding didn’t necessarily prove a link between extra fat and a decline in mental status, the scientists removed the fat from the mice next, like a mouse–size liposuction. If removing the fat resulted in better test performance, then the researchers could confirm that the fat, and whatever it releases, probably caused the fuzzy learning and memory.
The researchers were able to confirm that the weight was responsible for slowing the mice down mentally.
After recovering from surgery, the now-thin mice demonstrated decreased levels of the inflammation molecule, and performed well on the cognitive tests they had failed when chubby. As a final confirmation of the link between fat and brain power, the researchers implanted the removed fat into thin mice to see if it impacted their brains at all. The mice that received the fat implants suddenly performed poorly on the tests on which they had been previously done wel. Thus the researchers were able to confirm that the extra poundage (or ounce-age, in the case of mice!) was responsible for slowing the mice down mentally.
Since it’s not feasible (or safe) for most humans to have all of their extra fat removed surgically, the researchers ran the same experiments, but instead of giving the fat mice liposuction, they put them on an exercise regimen. The fit mice showed the same improvements of the liposuction mice, leading researchers to conclude that exercise is just as effective at removing fat and the substance it produces. An important finding, since most people can (and should!) exercise before turning to surgical means.
What does this mean for you? If you’re on a workout program, it’s further motivation to keep doing it! By already exercising, you’ve already won half the battle against fat and its negative effects on brain function.
If you don’t currently work out, here’s a good reason to start! Any fat-blasting cardio exercise could help you slim down and “smarten up.” The American Heart Association recommends 150 minutes of moderate, or 75 minutes of intense, exercise per week. Start small if you have to – just 15 or 20 minutes a day, and work up from there! Your brain – and your waistline – will thank you for it.
For more details, check out the study at the National Institutes for Health library.