With so much of the conversation on obesity focusing on prevention of future disease, it’s easy to forget that obesity causes immediate changes in the body. It forces everything to work harder, from the heart to the bones, which must carry the extra weight. The brain isn’t exempt either; as it metabolizes all the excess sugar, it falls behind in other cognitive functions. In trying to regain this function, some obese patients may want to go through with bariatric surgery, according to a new study.

“When we studied obese women prior to bariatric surgery, we found some areas of their brains metabolized sugars at a higher rate than normal weight women,” said study author Dr. Cintia Cercato, of the University of São Paolo in Brazil, in a press release. “In particular, obesity led to altered activity in a part of the brain linked to the development of Alzheimer’s disease — the posterior cingulate gyrus. Since bariatric surgery reversed this activity, we suspect the procedure may contribute to a reduced risk of Alzheimer’s disease and other forms of dementia.”

Other studies have found links between obesity and dementia. A study from last week found that people who became obese sometime before their 50s were far more likely to develop dementia once they reached their 60s and 70s. However, those who became obese in their 60s or 70s were able to maintain brain function, most likely because obesity had little or no time to cause harm. Another 35-year study published last year found that people who maintained a healthy lifestyle, with a focus on exercise and healthy diet, were about 60 percent less likely to develop dementia later in life. But although the researchers’ focus in the current study was on prevention of future disease, the effects of bariatric surgery were still immediate.

For their study, the researchers looked at the effect of a bariatric surgery known as Roux-en-Y gastric bypass (RYGB) surgery, which involves closing up the stomach so it becomes a small pouch, on a group of 17 obese women. They used positron emission tomography (PET) scans to assess their brain function before surgery, and compared their results to 16 women of a healthy weight. Six months after surgery, both the test and control participants underwent scans again, and researchers found comparable brain function among both groups, indicating that the surgery helped more than just the women’s weight.

“Our findings suggest the brain is another organ that benefits from weight loss induced by surgery,” Cercato said. “The increased brain activity the obese women exhibited before undergoing surgery did not result in improved cognitive performance, which suggests obesity may force the brain to work harder to achieve the same level of cognition.”

Alzheimer’s disease is an extremely debilitating conditions that affects an estimated five million Americans, killing about 500,000 of them each year — it’s the sixth leading cause of death in the U.S., according to the Alzheimer’s Association. As brain function declines, patients start to forget how to conduct even the most basic daily activities. Searching for something becomes a daunting task, as the patient forgets what it was they were searching for, causing a mess in the meantime. When someone tells them they caused the mess, they may become angry, believing they aren’t to blame. These helpless feelings can then lead to depression and other psychological conditions.

Source: Cercato C, Coutinho N, Marques E, et al. Changes in Neuropsychological Tests and Brain Metabolism after Bariatric Surgery. Journal of Clinical Endocrinology & Metabolism. 2014.