The goal of this study was to examine the clinical significance of co-occurring
tics and attention-deficit hyperactivity disorder (ADHD) as indicators of a more
complex symptomatology in children with and without pervasive developmental
disorder. Parents and teachers completed a Diagnostic and Statistical Manual of
Mental Disorders-IV-referenced rating scale for 3- to 5- (n = 182/135) and 6- to
12- (n = 301/191) year-old children with pervasive developmental disorder and
clinic controls, respectively. The percentage of children with tic behaviors
varied with age: preschoolers (25%, 44%) versus elementary schoolchildren (60%,
66%) (parent and teacher ratings, respectively). For many psychiatric symptoms,
screening prevalence rates were highest for the ADHD + tics group and lowest for
the group with symptoms of neither, but the pattern of group differences varied
by age group and informant. In general, there were few differences between the
ADHD only and tics only groups. The pattern of ADHD/tic group differences was
similar for both children with and without pervasive developmental disorder. We
concluded that these findings support the notion that the co-occurrence of ADHD
and tics is an indicator of a more complex psychiatric symptomatology in
children with pervasive developmental disorder. (J Child Neurol
2005;20:481-488).