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Extreme Obesity in Tots Tied to Low IQ

Difference of 25-30 Points Seen in IQs of Those Very Obese by Age 4
WebMD Health News
Reviewed by Louise Chang, MD

Aug. 31, 2006 -- Children who are very obese by age 4 may be more likely to have lower IQ scores, a new study shows.

The findings are preliminary, but, "It just raises a red flag," Daniel J. Driscoll, MD, PhD, tells WebMD.

Driscoll is a professor of pediatrics and the John T. and Winifred M. Hayward professor of genetics research at the University of Florida.

He notes "a sense of urgency to really address the obesityobesity problem -- the younger the better.

"It's right to worry about heart diseaseheart disease in 20-30 years, or hypertensionhypertension in 20 years, and diabetesdiabetes in 10 years," Driscoll says. "But there could be consequences now," he says.

Morbidly Obese by Age 4

The study by Driscoll and colleagues appears in The Journal of Pediatrics' August edition.

Driscoll's team studied 18 people who had been morbidly obese by age 4. That means they were more than 150% of the ideal weight for their height.

"We're not talking about a little baby fat," Driscoll says. "We're talking about a very select group."

At the time of the study, participants were 4-22 years old (average age: nearly 11). First, they were screened to make sure their early obesity wasn't due to known genetic disorders.

Next, they got their IQ and cognitive skills tested.

For comparison, 24 of their brothers and sisters who hadn't been obese at an early age were also studied. So were 19 children with Prader-Willi syndrome from other families.

Prader-Willi syndrome is "the most commonly-recognized genetic cause of childhood obesity" and is linked to mental retardation, the researchers write.

IQ Gap

The children with Prader-Willi syndrome and those who had been morbidly obese for unknown reasons by age 4 had the lowest test scores.

Average IQ scores were as follows:

  • Prader-Willi syndrome: 63
  • Early morbid obesityobesity with unknown cause: 77
  • No early morbid obesity: 106

The lower scores are "not in the mentally retarded range but it's cognitively impaired, getting borderline" Driscoll says.

The gap between the morbidly obese children and those of more normal weight was about 25-30 points, Driscoll says, adding that IQ scores varied.

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