Plasma Catecholamine Metabolite Levels in ADHD Boys With and Without Reading Disabilities

Abstract

Examined plasma catecholamine metabolite levels in 24 boys with attention-deficit hyperactivity disorder (ADHD) who were divided into subgroups based on the presence or absence of reading disabilities. The reading-disabled ADHD group had a significantly (p < .01) higher level of plasma 3-methoxy-4-hydroxyphenylglycol (MHPG), the metabolite of norepinephrine, but the groups diet not differ on the dopamine metabolite homovanillic acid (HVA). Furthermore, MHPG levels were correlated with measures of reading and spelling ability such that high MHPG was associated with poor academic achievement. These findings suggest that a fruitful approach to understanding the neural substrates of ADHD may be to focus on homogeneous subgroups defined according to individual symptom dimensions.