OBJECTIVE: Because the caudate nuclei receive inputs from cortical
regions implicated in executive functioning and attentional tasks, caudate
and total brain volumes were examined in boys with attention deficit
hyperactivity disorder (ADHD) and normal comparison subjects. To gain
developmental perspective, a wide age range was sampled for both groups.
METHOD: The brains of 50 male ADHD patients (aged 6-19) and 48 matched
comparison subjects were scanned by magnetic resonance imaging (MRI).
Volumetric measures of the head and body of the caudate nucleus were
obtained from T1-weighted coronal images. Interrater reliabilities
(intraclass correlations) were 0.89 or greater. RESULTS: The normal pattern
of slight but significantly greater right caudate volume across all ages
was not seen in ADHD. Mean right caudate volume was slightly but
significantly smaller in the ADHD patients than in the comparison subjects,
while there was no significant difference for the left. Together these
facts accounted for the highly significant lack of normal asymmetry in
caudate volume in the ADHD boys. Total brain volume was 5% smaller in the
ADHD boys, and this was not accounted for by age, height, weight, or IQ.
Smaller brain volume in ADHD did not account for the caudate volume or
symmetry differences. For the normal boys, caudate volume decreased
substantially (13%) and significantly with age, while in ADHD there was no
age-related change. CONCLUSIONS: Along with previous MRI findings of low
volumes in corpus callosum regions, these results support developmental
abnormalities of frontal-striatal circuits in ADHD.