Comorbid ADHD and mental health disorders: are these children more likely to develop reading disorders?

While attention-deficit/hyperactivity disorder (ADHD) has been associated with both internalizing and externalizing childhood behaviour disorders, the specific relationship of these comorbid disorders to ADHD and reading problems is less well defined. The present study analysed data from the Australian Twin ADHD Project, which utilized DSM-IV-based ratings of ADHD, separation anxiety disorder, generalized anxiety disorder, depression, conduct disorder, and oppositional defiant disorder for twins and siblings aged 6 to 18 years. While differences between children with and without ADHD were demonstrated for those with separation anxiety disorder, generalized anxiety disorder, depression, conduct disorder, oppositional defiant disorder and a reading disorder, for all age groups, regression analysis of ADHD diagnostic subtypes by age and reading disorder showed that only generalized anxiety disorder remained significant after controlling for ADHD subtypes. Analysis of the mean reading disorder scores in children with and without ADHD showed that children with conduct disorder had significantly more reading problems, as did children with multiple comorbid disorders. In summary, both age and ADHD diagnosis were associated with variations in these comorbid disorders, and multiple comorbid disorders were associated with greater reading impairment.