Childhood obesity in the United States has doubled since 1980. Obese children are at risk for a number of physical health problems during childhood and in adulthood. Now, a new study carried out by researchers at Duke University Medical School suggests that these children may be at risk for psychiatric disorders as well. This study is the first to demonstrate an association between chronic obesity and psychological problems in children and adolescents. This is important because it alerts doctors to the need to pay attention to obesity as a risk factor for psychiatric disorders in their child and adolescent patients. This study also found that childhood obesity comes in different forms and that not every child who is at risk of obesity will be at risk for psychiatric disorders.
One of the strengths of the Duke study is that it was drawn from repeated measures of height and weight in the general population over an eight-year period, rather than from a clinical sample of children with obesity or psychological problems. Researchers collected data on family characteristics and mental health. The goals of the study were to determine age-related projections of obesity in the general population of children and adolescents, to determine whether the obesity was associated with family vulnerabilities and to test the relationship between obesity and psychiatric disorders. Included in the study were 991 non-Hispanic white children, aged 9 to 16, recruited from the Great Smoky Mountains Study of the need for mental health services for rural youth. Children were assessed yearly for height and weight, for psychiatric disorder and vulnerabilities for psychiatric disorder. Obesity was defined at weight in the top 95th percentile for age and sex. Psychopathological indicators were assessed using the Child and Adolescent Psychiatric Assessment. Children were screened for conduct disorder, oppositional defiant disorder, depression, anxiety disorders, bulimia, substance abuse and attention-deficit/hyperactivity disorder. The study also tested for variables that linked obesity and psychiatric disorder. The variables examined included gender; family income; parental education; single-parent family; parental history of mental illness, drug abuse or criminal history; parenting style (harsh or overprotective); lax supervision; and traumatic life events.
Children were placed in one of four weight categories: never obese, childhood obesity, adolescent obesity, or chronic obesity. Seventy-three percent of the study group fell into the never-obese category,15 percent were chronically obese, 5 percent were obese in childhood and 7 percent were obese during adolescence. The researchers found no overall differences among the four groups in gender, family structure, parenting style, family history of mental illness,drug abuse, crime or traumatic events. But they found that obesity was three to four times more prevalent in this study of rural youth relative to national rates from the U.S. Centers for Disease Control and Prevention. There was both an increased prevalence of early obesity and an increased risk of obesity with age. At 16 years of age, more than 20 percent of the sample were obese.
Obesity was more common among boys than girls, although the difference was not statistically significant. Youngsters with chronic or childhood obesity were more than twice as likely to come from families where one or both parents had not completed high school. This held true even after controlling for having a single, unemployed or teenage parent. Researchers reported that they were surprised at the low number of family and environmental risk factors associated with obesity in this population. Parental income was the only other risk factor associated with chronic obesity in this study.
Chronic obsesity linked with psychiatric disorder
Chronic obesity was the only weight category associated with a statistically significant increase in the risk of psychiatric disorder. Chronically obese girls and boys were 2.5 times more likely than other youngsters to be diagnosed as having oppositional defiant disorder. Chronically obese boys (but not girls) were 3.7 times more likely to meet the criteria for depression. No significant associations were found between the weight categories and bulimia ,ADHD, substance use, conduct disorder or anxiety.According to researchers, no family variables were found to explain the link between weight and psychopathology.
This study was unable to conclude definitively whether obesity increases the risk of psychopatholog yor vice versa. The results suggest tha tchronic obesity is linked to psychopathology in children and adolescents, but determining which comes first is critically important. There is some biologic evidence linking depression and obesity, but researcher sneed to find out why they are linked.
“Obesity and Psychiatric Disorder: Developmental Trajectories”, Pediatrics, 2003, Number 111, pp. 851-859.
Published in ERN June 2003 Volume 16 Number 5