PLASMA-CATECHOLAMINE METABOLITE LEVELS IN ADHD BOYS WITH AND WITHOUT READING DISABILITIES

Examined plasma catecholamine metabolite levels in 24 boys with attent ion-deficit hyperactivity disorder (ADHD) who were divided into suhgro ups based on the presence or absence of reading disabilities. The read ing-disabled ADHD group had a significantly (p < .01) higher level of plasma 3-methoxy-4-hydroxyphenyl-glycol (MHPG), the metabolite of nore pinephrine, but the groups did not differ on the dopamine metabolite h omovanillic acid (HVA). Furthermore, MHPG levels were correlated with measures of reading and spelling ability such that high MHPG was assoc iated with poor academic achievement. These findings suggest that a fr uitful approach to understanding the neural substrates of ADHD may be to focus on homogeneous subgroups defined according to individual symp tom dimensions.