"This study paints a comprehensive picture of childhood obesity, and we were surprised to see just how many conditions were associated with childhood obesity," said lead author Dr. Neal Halfon, a professor of pediatrics, public health and public policy at UCLA, where he directs the Center for Healthier Children, Families and Communities. "The findings should serve as a wake-up call to physicians, parents and teachers, who should be better informed of the risk for other health conditions associated with childhood obesity so that they can target interventions that can result in better health outcomes."
With the dramatic rise in childhood obesity over the past two decades, there has been a parallel rise in the prevalence of other childhood-onset health conditions, such as attention deficit–hyperactivity disorder, asthma and learning disabilities. But previous studies on the topic have been limited due to a narrow focus on a specific region of the county, a small sample size or a single condition.
The new UCLA research, a large population-based study of children in the United States, provides the first comprehensive national profile of associations between weight status and a broad set of associated health conditions, or co-morbidities, that kids suffer from during childhood.
Overall, the researchers found, obese children were more likely than those who were classified as not overweight to have reported poorer health; more disability; a greater
tendency toward emotional and behavioral problems; higher rates of grade repetition, missed school days and other school problems; ADHD; conduct disorder; depression; learning disabilities; developmental delays; bone, joint and muscle problems; asthma; allergies; headaches; and ear infections.
For the childhood obesity study, the researchers used the 2007 National Survey of Children's Health, analyzing data on nearly 43,300 children between the ages 10 and 17. They assessed associations between weight status and 21 indicators of general health, psychosocial functioning and specific health disorders, adjusting for sociodemographic factors.
Of the children in the study, 15 percent were considered overweight (a body mass index between the 85th and 95th percentiles), and 16 percent were obese (a BMI in the 95th percentile or higher).
The UCLA researchers speculate that the ongoing shift in chronic childhood conditions is likely related to decades of underappreciated changes in the social and physical environments in which children live, learn and play. They propose that obesity-prevention efforts should target these social and environmental influences and that kids should be screened and managed for the co-morbid conditions.
The researchers add that while the strength of the current study lies in its large population base, future studies need to examine better longitudinal data to tease out causal relationships that cannot be inferred from a cross-sectional study.
"Obesity might be causing the co-morbidity, or perhaps the co-morbidity is causing obesity — or both might be caused by some other unmeasured third factor," Halfon said. "For example, exposure to toxic stress might change the neuroregulatory processes that affect impulse control seen in ADHD, as well as leptin sensitivity, which can contribute to weight gain. An understanding of the association of obesity with other co-morbidities may provide important information about causal pathways to obesity and more effective ways to prevent it."
Halfon's co-authors on the study included Kandyce Larson and Dr. Wendy Slusser, both of UCLA.
The childhood obesity study was supported by funding from the Maternal and Child Health Bureau of the Health Resource Services Administration.