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Abstract:
Abstract: Several lines of evidence (e.g., quantitative MRI,
functional neuroimaging, neurocognitive) suggest that prefrontal
abnormalities charcaterize attention deficit hyperactivity disorder
(ADHD) in children. In this report we describe the results of the
first study of frontal lobe tissue in ADHD utilizing proton
magnetic spectroscopy (1H-MRS). ADHD children (N =17) met DSM IV
diagnostic criteria and were carefully screened for learning
disabilities. They were compared to controls (N =18) matched for
age, sex, and SES. The Connors Continuous Performance Test (CPT)
provided a quantitative measure of attention deficit. Right and
left dorsolateral frontal cortex volumes were assessed with
MEASURE. 1H-MRS detects signals from neurometabolites, including
N-acetylaspartate (NAA), creatine and phosphocreatine (Cre),
choline-containing compounds (Cho), and lactate. A STEAM pulse
sequence, including water suppression, was used to sample a 2x2x3
cm voxel in right frontal white matter (TE=30ms, TR=2000ms, 128
averages). Water resonances were removed using HLSVD filtering.
Time-domain fitting of gaussian lineshapes to NAA, creatine, and
choline was carried out using VARPRO. No group differences were
evident in any neurometabolite. Right (but not left) dorsolateral
volume was reduced in the ADHD group. In the ADHD participants
greater right dorsolateral volume predicted greater attention
problems. Further, in the ADHD group alone, neurometabolite
concentrations strongly correlated with right dorsolateral volume
and performance on the CPT.
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