VIENNA—Early-onset idiopathic epilepsy occurring before age 7 nearly doubles the likelihood that a child with autism spectrum disorder (ASD) will later develop comorbid ADHD, reported Johnny Downs, MD, a child psychiatrist at King’s College in London, at the 29th Annual Congress of the European College of Neuropsychopharmacology.
Comorbid ADHD is common in the setting of ASD. In a search for risk factors for the comorbid condition, Dr. Downs and his colleagues reviewed the physical health records prior to age 7 of 3,032 patients with ASD referred at ages 3 to 17 to child and adolescent mental health services clinics serving South London. “That’s information that often doesn’t make it into the clinical psychiatric record,” said Dr. Downs.
Johnny Downs, MD
Half of the 3,032 subjects were diagnosed with ASD at ages 6 to 12 and another 39% at ages 13 to 17. During five years of prospective follow-up after being diagnosed with ASD, 25.5% of patients were diagnosed with comorbid ADHD. When reviewing early physical health records, researchers observed that 114 (3.76%) of study participants had experienced early-onset epilepsy before age 7.
A large sample size allowed for robust multivariate adjustment for potential confounders. In a multivariate analysis, patients with ASD and 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, CNS tumors, early meningitis, and other confounders.
Compared with white subjects with ASD, the risk of developing comorbid ADHD was reduced by 37% in black patients and by 52% in Asian patients with ASD.
“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, 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,” said Dr. Downs.
—Bruce Jancin