The authors studied the excretion of 3-methoxy-4-hydroxyphenyl glycol
(MHPG), normetanephrine (NM), metanephrine, and homovanillic acid in 7
hyperactive and 12 control children. MHPG was lower but NM was
significantly higher in hyperactive children than in controls.
Administration of d-amphetamine for 2 weeks depressed the levels of MHPG,
NM, and metanephrine. The authors suggest a decreased central
norepinephrine activity, which may be secondary to the interruption of
norepinephrine fibers in the medial forebrain bundle.