On the link between attention deficit/hyperactivity disorder and obesity: do comorbid oppositional defiant and conduct disorder matter?

The link between attention deficit/hyperactivity disorder (ADHD) and elevated body weight/obesity can be regarded as well established. Because oppositional defiant disorder (ODD)/conduct disorder (CD) has also been found to be associated with these characteristics and ADHD and ODD/CD often occur comorbidly, we investigated whether ODD/CD and ADHD are independently linked with body weight and obesity. The clinical records of 360 children, 257 (6-12 years) with diagnoses of ADHD, ODD/CD, or comorbid ADHD and ODD/CD and 103 children with adjustment disorder (as a control group) constituted the database. All children were seen for the first time in two outpatient psychiatric clinics. Associations of the psychiatric diagnoses (ADHD present vs. not present; ODD/CD present vs. not present) with the standard deviation scores (according to German reference data) of the child's body mass index (BMI-SDS) and presence of obesity were analyzed by ANCOVA and hierarchical logistic regression analysis, respectively. Children with ODD/CD showed higher BMI-SDS (F = 7.67, p < 0.006) and rate of obesity (Wald = 4.12, p < 0.05, OR = 2.43) while controlling for ADHD comorbidity. While adjusting for ODD/CD comorbidity, the links between ADHD and BMI-SDS or obesity did not reach statistical significance. Given a cross validation of these findings, future (preferably prospective longitudinal) research should analyze the mediating mechanism between the psychiatric conditions and obesity. This knowledge could be helpful for preventive interventions.