November 3, 2017 — A team led by Georgetown College Department of Psychology Chair Chandan Vaidya has conducted the first study on the effects of weight-loss surgery on the brains of adolescents with obesity.
Vaidya and graduate student Alaina Pearce teamed up with psychologist Eleanor Mackey, bariatric surgeon Evan Nadler and a team from Children’s National Health System to examine functional changes in adolescent brains after vertical sleeve gastrectomies, bariatric surgeries that reduce the size of the stomach to control weight gain.
Their paper, “Effect of Adolescent Bariatric Surgery on the Brain and Cognition: A Pilot Study,” was named an Editor’s Choice in the November issue of the scientific journal Obesity.
OBESITY AND THE BRAIN
Children with obesity exhibit deficits in cognitive functioning and have lower academic achievement. There is extensive evidence that bariatric surgeries and their corresponding weight loss have positive impacts on various health outcomes — insulin regulation and inflammation, for example, tend to improve when individuals with obesity undergo the operation.
Vaidya and the Children’s National team wanted to see if any of these benefits extend to the brain and cognitive functioning.
“Brain functioning is central to this discussion, because when you’re thinking about what might maintain or promote obesity, you’re looking at rewarding behaviors that people cannot control,” Vaidya said. “So we’re looking at places in the brain that are important for self-regulation and processing of rewards.”
The 36 subjects, all adolescents recruited from the Children’s National Bariatric Surgery program, were split into three groups: A normal-weight control group that did not undergo surgery, an group with obesity that underwent the surgery, and another that has committed to the surgery but had not undergone it yet.
The researchers used functional magnetic resonance imaging (fMRI) to measure brain activity, while subjects completed a variety of tasks designed to gauge executive function and anticipation of reward. All subjects were scanned twice, with an interval of 4 months between scans.
The team hoped to identify whether there are meaningful differences in brain functioning among the groups, as well as before and after the surgical intervention.
A MORE EFFICIENT BRAIN
Vaidya’s team’s paper details the results of a 1-year pilot study — a small-scale experiment designed to show that a full study would be worth exploring — funded by the National Institute of Diabetes and Digestive and Kidney Diseases.
The results hint at the potential to reverse the negative effects of obesity on cognitive functioning and grabbed the attention of the editors at Obesity.
“Speed of information processing and accuracy were both better among the group that got the surgery,” Vaidya said. “These adolescents also lost nine Body Mass Index points, which is a significant amount of weight loss.”
Furthermore, the fMRI scans revealed less activity in the prefrontal cortex and striatal regions among these subjects — in other words, their brains didn’t have to work as hard as before to complete the same tasks.
“You could think of it as becoming more efficient,” Vaidya said. “The amount of activity decreased after the surgery, to the extent that it looked similar to the healthy control group.”
The waitlisted adolescents, meanwhile, gained weight in the 4 month interval and showed increased brain activity, signaling that their brain had to work harder.
The team’s research is noteworthy both because the literature on adolescent post-surgical outcomes is very limited and because similar studies in adults only tested cognitive responses to food-related imagery.
“We’re looking at baseline cognitive functions,” Vaidya said. “If we show that these change, it’s even more impactful, because it goes beyond just responses to food.”
The study did have some limitations — subjects with a Body Mass Index of more than 50, for example, could not fit in the MRI scanner — and the research team can’t draw conclusions about generalizing the results, due to the small sample tested. Vaidya hopes to replicate their findings with a larger group, funded by a five-year grant.
“There are also other factors we’d like to explore — better sleep, for example, might be related to both the weight loss and the improvements in neurocognitive functioning,” Vaidya said. “It is also important to know whether these effects translate into better food and activity choices and improved academic functioning in the adolescents.”
— Patrick Curran