Metabolic Syndrome Affects Cognition in Obese Teens

Fran Lowry

September 06, 2012

September 6, 2012 — Obese, nondiabetic adolescents with metabolic syndrome score lower on tests that measure their arithmetic, spelling, attention, and mental flexibility skills than those who do not have metabolic syndrome,

The results should serve as a "wake-up call" to parents and schools to pay attention to these children, senior author Antonio Convit, MD, professor of psychiatry and medicine at New York University School of Medicine and the Nathan Kline Research Institute in New York City, told Medscape Medical News.

Dr. Antonio Convit

"These kids are performing, on average, about 10% less well than the kids without metabolic syndrome, even after controlling carefully for socioeconomic factors, age, parental education, and all those things that could be impacting on how well they do," Dr. Convit said. "Who would want their kid to be performing 10% less than their potential?"

Their findings were published online September 3 in Pediatrics.

Metabolic Syndrome and Cognition

Metabolic syndrome is a cluster of 5 obesity-associated components, which include elevated fasting glucose levels or insulin resistance, lower high-density lipoprotein levels, hypertriglyceridemia, and hypertension, and abdominal obesity.

In earlier work, Dr. Convit and his team found that middle-aged adults with metabolic syndrome had neurocognitive impairments.

In the current study, the researchers studied 49 adolescents with metabolic syndrome and 62 without metabolic syndrome. The study participants ranged in age from 14 to 20 years, the average age was 17.5 years, and none had type 2 diabetes.

Forty percent of the teens in the control (without metabolic syndrome) group were overweight or obese.

"These were garden variety kids, not a clinical population," Dr. Convit noted. "The control kids were not lean, squeaky clean, really healthy kids, but they didn't have metabolic syndrome. Their average BMI [body mass index] was 27.1, and for a 5'8" person, which is standard height for a kid of this age, the weight is 178 pounds, so the control kids were not skinny by any stretch of the imagination."

Endocrine, magnetic resonance imaging, and neuropsychological evaluations were performed.

The researchers found that the teens with metabolic syndrome showed significantly lower math (P = .001) and spelling (P = .04) scores, as well as a decreased attention span and mental flexibility.

They also found that the teens with metabolic syndrome had smaller hippocampal volumes, increased brain cerebrospinal fluid levels, and reductions of microstructural integrity in major white matter tracts in the brain. The hippocampus is an area of the brain that is involved in learning and recall of new information,

The more metabolic syndrome–related health problems the teens had, the worse their performance.

Dr. Convit maintains that pediatricians are unaware that the brain can be affected by the metabolic syndrome.

"A lot of pediatricians have no clue that the brain is impacted by obesity and metabolic dysregulation due to obesity," he said. It is unusual in many pediatric visits for blood pressure to be measured routinely, for example.

"Certainly cholesterol levels are not measured routinely, and insulin resistance, which is the main driver of the brain problem, is not measured unless there is some clinical indication that the kid is diabetic," he said.

Children should know what their blood pressure, cholesterol, triglyceride, and insulin levels are, Dr. Convit said. "We need to help them by giving them their own medical numbers and motivate them to change their lifestyle," he added.

Raise Awareness

Commenting on this study for Medscape Medical News, Stephen Pont, MD, MPH, a pediatrician at Dell Children's Medical Center, Boston, Massachusetts, and chair of the American Academy of Pediatrics (AAP) provisional section on obesity, said that the finding that metabolic syndrome is linked to poor academic performance is important for schools to realize.

Dr. Stephen Pont

"We need to raise awareness in all communities about the importance of checking for metabolic syndrome," he said. "Schools want kids to be healthy and happy and do well, but they also have to deliver on graduation rates and test score rates, and on kids sitting in the chairs, meaning that they're not sick at home, because that funds our schools."

"This is a nice study to help us work with schools to reframe the health message," Dr. Pont added. "As pediatricians, we want to help you deliver on your ultimate outcomes and have kids doing better on standardized testing and graduating, and ultimately be more successful."

Dr. Pont said that the AAP is trying to increase awareness among its members about the importance of testing children for hypertension, cholesterol, and other components of the metabolic syndrome, and that these attempts have met with some success.

"There are certainly new guidelines out there that recommend checking blood pressure and blood sugar levels in kids, and I think that that awareness is out there now. Some older studies that looked at the frequency with which the body mass index was checked in kids found that the rates were fairly low. There hasn't been a lot published yet, but it was recently shown in abstract form from one of the AAP meetings that that rate is now up into the 90s, which is great," he said.

"I think we are at the beginning of that action phase, and I'm encouraged that we'll see the impact, but there is a lot of work that still needs to be done to get everyone's attention of how obesity and the metabolic syndrome affect children's health and academic performance."

This study was funded by the National Institutes of Health. Dr. Convit and Dr. Pont have disclosed no relevant financial relationships.

Pediatrics. Published online September 3, 2012. Abstract

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