By Laura Williamson, American Heart Association — MedicalXPress, 13 January 2022
Research shows obesity impacts brain health from childhood well into adulthood, affecting everything from executive function skills to substantially raising dementia risk. By middle age, the consequences of excess weight are substantial — several studies have shown middle-aged adults who have a body mass index (BMI) at or above 30 are more likely to get dementia than their healthy-weight peers.
According to the Centers for Disease Control and Prevention, more than 42 percent of adults qualified as obese in 2018, with the pandemic accelerating the rate at which BMI was increasing, roughly doubling compared with the period preceding it. Researchers are still teasing out how and why the extra pounds harm the brain. One possibility is that the excess fat increases inflammation, which over time can lead to “changes in connectivity and structure and function of the brain,” said researchers. Another theory is that the hormones secreted by fat cells, such as leptin, play a role; people with too many fat cells produce such high levels of leptin that the body becomes insensitive to it, creating a cycle in which the person keeps eating because they never feel full.
People who have obesity are also more likely to have Type 2 diabetes, hypertension and high cholesterol — conditions that collectively can have a detrimental effect on the aging brain, whether contributing to Alzheimer’s disease or vascular dementia. There is also a possibility that cognitive challenges come first, as children with lower cognitive function may be predisposed to poor eating behaviors. A large federally funded long-term study of a weight loss intervention found no associated cognitive benefit, though it is possible no brain health benefit was seen because all study participants had Type 2 diabetes, which itself can accelerate aging. The message remains clear: “Preventing obesity from occurring is so very important” for brain health and the rest of the body.