Obesity Might Lower Teens' Thinking Skills, Study Suggests

MONDAY, Sept. 3 (HealthDay News) -- As the childhood obesity epidemic continues in the United States, more kids are developing an array of heart risk factors linked to obesity known as the "metabolic syndrome."

Now, a study suggests that these obesity-linked changes may be affecting kids' minds as well as their bodies.

The new study finds that adolescents with these conditions -- which include abdominal obesity, unhealthy cholesterol/trigylceride levels and high blood pressure -- are more likely to perform more poorly on tests of mental ability compared to their healthy peers.

MRI scans also showed certain worrisome differences in brain structure among children with the metabolic syndrome, the researchers said.

According to study lead author Dr. Antonio Convit, until recently it's been thought that "the bad things that can happen among kids with metabolic syndrome are 20 years in the future. But, this work demonstrates that these health issues are having a deleterious impact on a kid's brain now. Today."

Convit is a professor of psychiatry and medicine at the NYU Langone School of Medicine. He and his team published the findings online Sept. 3 and in the October print issue of Pediatrics.

The finding stems from U.S. National Institutes of Health-funded research that involved roughly 110 teens. A little under half of them had been diagnosed with at least three or more of the five specific health conditions that characterize metabolic syndrome: abdominal obesity, low good (HDL) cholesterol, high triglycerides, high blood pressure, and/or pre-diabetic levels of insulin resistance.

Previous research has shown such an association among adults, but this latest report suggests the effect on intellect from metabolic syndrome may occur more rapidly and at a much younger age than thought.

"It's also important to note that this was really a real-world study with a very conservative approach," added Convit, who is also a member of the New York State Office of Mental Health's Nathan Kline Research Institute. "We didn't compare kids with metabolic syndrome against kids who were squeaky clean, but against healthier kids who still might have had one or two of the things that make up metabolic syndrome rather than the three or more minimum [needed] for a metabolic syndrome diagnosis," he explained.

"And with that, what we found was that those with metabolic syndrome performed about 10 percent less well, on average, on a series of cognitive [intellectual] tests that look at things like spelling and math. They were still performing within the normal range, but significantly less well on skills that are very relevant for predicting school performance," Convit said. "And who would want their kids to perform 10 percent less than their potential, even if they're performing within the normal range?"

Convit also pointed out that 54 percent of American teens are now either overweight or obese. And an estimated 30 percent to 40 percent of those weight-challenged adolescents struggle with metabolic syndrome.

"So the numbers," he stressed, "are huge."

In the study, the scientists focused on 49 teens diagnosed with metabolic syndrome and 62 who were not, making sure that both groups were similar in terms of age, school grade, gender, ethnicity and socio-economic background.

All the children underwent a battery of 17 tests that probed, among other things, abilities in the realm of attention, mental flexibility, reading, writing and arithmetic.

Those with metabolic syndrome performed more poorly on all of the tests than those without the condition. Seven of those tests reached what the team deemed to be "statistical significance."

Adding to what the authors described as "alarming results" on the tests, MRI scans revealed that the group with metabolic syndrome had experienced a relative 10 percent reduction in the volume of the hippocampus region of their brains. What's more, brain atrophy was also found to be more prevalent among these teens in the parts of the brain that make connections between different neurological regions.

"So, what this means is that even though the hippocampus reductions were not so severe as to be in the abnormal range, the brains of [these] kids are not working on all pistons," Convit said. "Which means there is probably a good reason that those who are obese often tend to drop out of school more often than those who are not. They probably are more frustrated because they can't learn as readily. That 10 percent drop probably does make a difference."

So what should be done? "We should be doing more than simply looking at blood pressure when children visit the doctor," Convit said. "We should be looking at a wide range of health measures, and looking out for how these kids' brains are working. And parents should be made aware that lifestyle changes at home, where it really needs to begin, may be critical to keeping their kids healthy and ensuring that they can perform to their potential."

Lona Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas, agreed that "this study just further supports the need to find ways to prevent childhood obesity in the first place."

She noted that "a lot of this does start at home. Pediatricians need to work to encourage parents to help their children adopt good diets and nutritional patterns and activity patterns, so they can stay lean and physically fit. Because the problems kids experience from being overweight or obese aren't just about looks or self-esteem. And they're not just about heart disease issues that can develop 20 or 30 years from now. We're talking about cognitive ability impairment that can affect school performance pretty immediately. It's a here-and-now problem that needs to be tackled head on."

While the study found an association between poor test scores and metabolic syndrome in kids, it didn't prove a cause-and-effect relationship.

More information

For more on metabolic syndrome, visit the U.S. National Library of Medicine.

SOURCES: Antonio Convit, M.D., professor, psychiatry and medicine, NYU School of Medicine, and member, Nathan Kline Research Institute, New York State Office of Mental Health, New York City; Lona Sandon, R.D., registered dietician and assistant professor, clinical nutrition, University of Texas Southwestern Medical Center at Dallas; Sept. 3, 2012, Pediatrics, online

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