Serum level of semicarbazide-sensitive amine oxidase in children with ADHD

BACKGROUND: The objective of this study was to analyze the extracellularly acting semicarbazide-sensitive amine oxidase (SSAO) serum levels in children with ADHD for the first time. SSAO is known to show deviations from normal in various somatic disorders and to interplay with the intracellularly active MAO. In humans two forms of SSAO a circulating form in plasma and a membrane-bound form are involved in monoaminergic metabolism. METHODS: We analyzed serum levels of SSAO in 27 children meeting ICD-10 criteria of Hyperkinetic Disorder (F90) or DSM-IV criteria of ADHD combined type by HPLC method and fluorimetric detection. A group of 42 healthy volunteers within the same age range (7.0 – 14.0 years) served as controls. RESULTS: No significant differences between children with ADHD (SSAO activity M = 773, SD = 217 mU/l) and healthy controls (SSAO activity M = 775, SD = 256 mU/l) in SSAO serum levels were found (F = 2.18; p > 0.14). Further, stimulant medication status had no influence on the result (F = 2.52; p > 0.11). CONCLUSION: There is no evidence for a deviation of SSAO serum activity in ADHD. Hence, extracellularly acting SSAO does not seem to be a promising factor for further research in ADHD. But progress in knowledge of its physiologic role and of the relationship between the membrane-bound and the circulating serum form may open new avenues for research on SSAO in ADHD.