Jm. Halperin et al., NORADRENERGIC MECHANISMS IN ADHD CHILDREN WITH AND WITHOUT READING DISABILITIES - A REPLICATION AND EXTENSION, Journal of the American Academy of Child and Adolescent Psychiatry, 36(12), 1997, pp. 1688-1697
Objective: To examine noradrenergic (NA) function in children with att
ention-deficit hyperactivity disorder (ADHD) by replicating and expand
ing upon a previous finding that ADHD children with and without readin
g disabilities (Raj differ in plasma levels of the NA metabolite 3-met
hoxy-4-hydroxyphenylglycol (MHPG). Method: Plasma levels of MHPG were
compared in ADHD children who were subdivided on the basis of the pres
ence or absence oi RD. Subsequently, this replication sample was combi
ned with a previously studied sample to further explore the relationsh
ip between plasma MHPG levels and measures of cognitive function in ch
ildren with ADHD. Results: Plasma levels of MHPG were significantly lo
wer in ADHD children without RD, compared with those with RD, replicat
ing a previously published finding, Analyses in the combined sample in
dicated that, among children with ADHD, plasma MHPG levels were invers
ely associated with measures of academic achievement and verbal proces
sing, but not parent or teacher ratings of behavior or continuous perf
ormance test measures of attention and impulsivity. Conclusions: These
data indicate that children with ADHD are not homogeneous with regard
to NA function and that neurochemical variation is closely associated
with differences in clinical characteristics of the children.