Weight Gain Can Harm Your Brain

Excess weight is known to raise the risk for diabetes, hypertension, heart disease, and other health problems. Now, research shows it impacts brain health, too.

Carrying around excess pounds isn’t just a problem because you can’t fit into your favorite jeans. It raises the risk for serious health problems. And researchers have a new warning: Weight gain can harm your brain.

It is well established being overweight is associated with a higher risk of hypertension, heart disease, stroke, metabolic syndrome, type 2 diabetes, and even certain types of cancer. It puts stress on joints and can cause or worsen gastroesophageal reflux disease (GERD), too.

Now there’s evidence being significantly overweight can also impact your brain by decreasing blood flow — and that potentially may raise the risk for dementia and other cognitive problems.

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How being significantly overweight affects brain function

A team of scientists from the University of California Irvine (UC Irvine), Johns Hopkins University, the brain-centered mental health Amen Clinics, and Thomas Jefferson University and Hospital in Philadelphia analyzed over 35,000 functional brain scans from more than 17,000 people to see the relationship between how much the people weighed and their brain health.

High-tech single-photon emission computerized tomography (SPECT) documented blood flow and brain activity in the research subjects who represented a wide range of weight categories — from underweight and normal weight to overweight, obese, and morbidly obese.

The SPECT scans were performed while the study participants were simply resting and when they were performing a task requiring concentration. The results of the study, published in the Journal of Alzheimer’s Disease, showed that as a person's weight increased, activity in virtually all regions of the brain was reduced and blood flow decreased.

The possible way weight gain can harm your brain

Because this dramatic pattern of progressively reduced blood flow had an impact on parts of the brain known to be vulnerable to Alzheimer's disease (the temporal and parietal lobes, hippocampus, posterior cingulate gyrus, and precuneus), the results of the study raises an important question:

Does being overweight increase the risk for dementia?

In fact, low cerebral blood flow seen in brain imaging is a significant predictor that a person will likely develop Alzheimer's disease, according to the researchers. In addition, decreased blood flow to the brain has been linked in previous research to depression, ADHD, bipolar disorder, schizophrenia, traumatic brain injuries, and other conditions, they noted.

"This study shows that being overweight or obese seriously impacts brain activity and increases the risk for Alzheimer's disease as well as many other psychiatric and cognitive conditions," said the study’s lead author, psychiatrist and neurologist Daniel G. Amen, MD.

Bottom line: Getting and keeping weight under control is a smart move

The research indicating excess pounds could raise the risk for Alzheimer’s and other memory problems is concerning, especially when you consider the majority of adults in the US — 72 percent — are overweight, and almost 43 percent are obese, according to the Centers for Disease Control and Prevention.

However, instead of seeing the findings suggesting weight gain can harm your brain as frightening news, consider it a wake-up call indicating that lifestyle changes to reduce or prevent excess weight might potentially help keep Alzheimer’s and other cognitive disorders at bay.

"One of the most important lessons we have learned through 30 years of performing functional brain imaging studies is that brains can be improved when you put them in a healing environment by adopting brain-healthy habits, such as a healthy calorie-smart diet and regular exercise,” Amen said.

Neuroscientist and Alzheimer’s researcher George Perry, PhD, Editor-in-Chief of the Journal of Alzheimer's Disease and chairman of the University of Texas at San Antonio neurobiology department, calls the discovery lifestyle choices appear to play a role in the development of Alzheimer’s disease a “breakthrough.”

“Dr. Amen and collaborators provide compelling evidence that obesity alters blood supply to the brain to shrink the brain and promote Alzheimer's disease. This is a major advance because it directly demonstrates how the brain responds to our body,” Perry noted.

The research team concluded additional studies targeting obesity as a potential intervention to improve brain function and possibly prevent Alzheimer’s disease are needed.

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