A longitudinal study of neurobiological mechanisms in boys with attention-deficit hyperactivity disorder: Preliminary findings

Background: The stability and developmental variation of severl neurobiolog ical measures in boys with attention-deficit hyperactivity disorder (ADHD) were examined, Methods: The prolactin (PRL) response to fenfluramine (FEN) challenge was u sed to assess central serotonergic (5-HT) functioning in 10 8-11-year-old b oys with ADHD, In addition, platelet 5-HT, as well as plasma levels of the catecholamine metabolites 3-methoxy-4-hydroxyphenylglycol (MHPG) and homova nillic acid were ascertained, These neurobiological variables were reassess ed in the same children 2-3 years later using the identical procedures. Results: The PRL response to FEN challenge was the only measure found to be stable across the evaluations (r = .58), although the magnitude of the res ponse decreased significantly with age. Plasma MHPG level significantly inc reased with age. Conclusions: Central 5-HT function, as measured by the PRL response To FEN, may represent a stable trait. The importance of considering developmental factors when interpreting neurobiological data is discussed. Biol Psychiatr y 1994;45:371-373 (C) 1999 Society of Biological Psychiatry.