NEUROCOGNITIVE CHARACTERISTICS OF INDIVIDUALS WITH RESISTANCE TO THYROID-HORMONE - COMPARISONS WITH INDIVIDUALS WITH ATTENTION-DEFICIT HYPERACTIVITY DISORDER

Previous studies have demonstrated an association between resistance t o thyroid hormone (RTH) and attention-deficit hyperactivity disorder ( ADHD). To determine if the neurocognitive characteristics in individua ls with RTH are similar to those observed in ADHD, 12 children with RT H from 7 families were matched to 12 children with ADHD without RTH. S ubjects were administered standardized intellectual, developmental, an d school achievement tests. Parent and teacher ratings of children's h yperactivity and attention were similar for both groups, as were measu res of attention, impulsivity, and verbal IQ, Children with RTH displa yed lower nonverbal intelligence (performance IQ = 85) and academic ac hievement (>1-2 SD below the mean) when compared with those with ADHD only (performance IQ = 99; achievement within 2 SD). Although children with RTH have behavioral characteristics similar to those with ADHD, their significantly weaker abilities of perceptual-organization and lo wer school achievement suggest a more severe neurobehavioral impairmen t than ADHD.