Monoamine oxidase and homovanillic acid in boys with predispositions to substance abuse.

Both dopaminergic dysregulation and abnormalities in monoamine oxidase (MAO) have been postulated as etiological factors in substance abuse. This study assessed whether MAO activity differed in sons of substance-abusing fathers compared with sons of nonsubstance-abusing fathers. It also assessed the levels of homovanillic acid (HVA), the metabolite of dopamine, and MAO in a group of substance-using/-abusing boys compared with peers without this history in the same setting. Sixty-five boys admitted to a residential center were evaluated on blood tests for HVA and MAO, and on a series of diagnostic instruments and questionnaires designed to elicit information about parental substance abuse and about the subject's own substance use/abuse. The results indicated tentatively that younger (< 12.0 years) sons of substance-abusing fathers had higher levels of MAO than younger sons of nonsubstance-abusing fathers. Levels of MAO in older (> or = 12.0 years) sons of substance-abusing and nonsubstance-abusing fathers did not differ. Boys with histories of significant use/abuse of substances themselves had significantly higher MAO levels and significantly lower HVA levels than peers of the same age without substance use/abuse histories.