Attention-deficit/hyperactivity disorder (ADHD) occurs more frequently
than expected in prevalent cohorts with epilepsy. The association has been
attributed to the epilepsy or its treatment, although it is impossible to
determine in previous studies which condition occurs first.
To conduct a population-based case-control study of all newly diagnosed
unprovoked seizures among Icelandic children younger than 16 years to address
the question of time order.
Children with seizures were matched to the next 2 same-sex births from
the population registry. The Diagnostic Interview Schedule for Children was
used to make a DSM-IV diagnosis of ADHD in a standardized
fashion among cases and controls aged 3 to 16 years.
A history of ADHD was 2.5-fold more common among children with newly
diagnosed seizures than among control subjects (95% confidence interval [CI],
1.1-5.5). The association was restricted to ADHD predominantly inattentive
type (odds ratio [OR], 3.7; 95% CI, 1.1-12.8), not ADHD predominantly hyperactive-impulsive
type (OR, 1.8; 95% CI, 0.6-5.7) or ADHD combined type (OR, 2.5; 95% CI, 0.3-18.3).
Seizure type, etiology, sex, or seizure frequency at diagnosis (1 or >1) did
not affect findings.
Attention-deficit/hyperactivity disorder occurs more often than expected
before unprovoked seizures, suggesting a common antecedent for both conditions.