VIENNA – Early-onset idiopathic epilepsy occurring before age 7 years nearly doubles the likelihood that a child with autism spectrum disorder will later develop comorbid attention-deficit/hyperactivity disorder, Johnny Downs, MD, reported at the annual congress of the European College of Neuropsychopharmacology.
Comorbid ADHD is common in the setting of autism spectrum disorder (ASD). In a search for risk factors for the comorbid condition, he and his coinvestigators reviewed the physical health records prior to age 7 years of 3,032 patients with ASD referred at ages 3-17 years to child and adolescent mental health services clinics serving South London.
Bruce Jancin/Frontline Medical News
Dr. Johnny Downs
“That’s information that often doesn’t make it into the clinical psychiatric record,” noted Dr. Downs, a child psychiatrist at King’s College London.
Half of the 3,032 subjects were diagnosed with ASD at age 6-12 years and another 39% at age 13-17. During 5 years of prospective follow-up after being diagnosed with ASD in this longitudinal observational study, 25.5% of patients were diagnosed with comorbid ADHD. Looking back through the early physical health records, 114 (3.76%) of study participants had experienced early-onset epilepsy before age 7 years.
This large sample size allowed for robust multivariate adjustment for potential confounders. In a multivariate analysis, ASD patients with a history of early-onset epilepsy were at a significant 1.75-fold increased risk for subsequent comorbid ADHD. The analysis was adjusted for family history of epilepsy, sociodemographic factors, intellectual disability, previous head injury, perinatal complications, central nervous system tumors, early meningitis, and other confounders.
“The take-home message would be if you’ve got social and communication difficulties in a young child appearing at the age of 5, 6, or 7 [years], and there’s a history of seizures, we are seeing from observational data that the child is at increased risk of ADHD over the age of 7,” Dr. Downs said in an interview.
Compared with white subjects with ASD, the risk of developing comorbid ADHD was reduced by 37% in black and by 52% in Asian patients with ASD.
He plans further studies aimed at determining whether conventional ADHD management strategies have the same risk/benefit ratios in children with ASD and comorbid ADHD as in those with ADHD alone.
Dr. Downs reported having no financial conflicts of interest regarding his study, which was conducted free of commercial support.