Plasma-free homovanillic acid: within- and across-day stability in children and adults with Tourette's syndrome

Homovanillic acid and dopamine-beta-hydroxylase in male youth: relationships with paternal substance abuse and antisocial behavior

Recent research suggests that dopaminergic/noradrenergic system dysfunction may be associated with substance abuse and/or antisocial behavior. In order to determine whether male youth of fathers with these disorders would manifest differences in these systems when compared with youth of nonsubstance-abusing or nonantisocial fathers, levels of homovanillic acid (HVA), the metabolite of dopamine (DA) and dopamine-beta-hydroxylase (DBH), the enzyme facilitating the conversion of dopamine to norepineprhine, were studied in offspring blood samples. The subjects were 65 male youth aged 6-15 years admitted to a residential center because of behavioral disorders. Parental substance abuse and antisocial behavior were assessed through interviews, rating scales, and/or chart review. HVA and DBH were determined from blood samples obtained after admission. The findings indicated that youth of substance-abusing fathers had significantly greater levels of HVA than yough of nonsubstance-abusing fathers. Younger (< 12.0 years) boys of antisocial fathers had significantly lower DBH activity than comparably aged youth of nonantisocial fathers. The results suggest that common generational links in substance abuse and antisocial behavior in males may be associated with detectable biological parameters in susceptible youth.

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.

Morning variations of plasma homovanillic acid in untreated schizophrenic patients

Plasma concentrations of homovanillic acid were determined in samples obtained at 8.30 a.m. and 12.30 p.m. from 29 untreated schizophrenic patients, 14 males and 15 females. When the earlier samples were compared with the later, a significant decrease in mean plasma homovanillic acid level was observed, but only in the male patients. The morning fall was observed in 10 of 14 male patients and 6 of the 15 female patients. This morning rhythm in plasma homovanillic acid concentration may mask the putative rises in plasma homovanillic acid provoked by neuroleptic administration and may explain some of the observed differences between findings in studies involving the assessment of this metabolite.

Biodevelopmental aspects of conduct disorder in boys

The association between biochemical parameters and conduct disorder (CD) was studied in 22 boys admitted to a residential center. Three-methoxy-4-hydroxyphenylglycol (MHPG) levels were significantly higher in prepubertal CD youth than in pubertal/post pubertal CD youth. Homovanillic acid (HVA) levels were significantly lower in CD youth under age 12.0 years than in non CD youth under age 12.0 years. The implications of these biodevelopmental findings in the study of CD are discussed.

Neurochemical study of dopamine functioning in autistic and normal subjects

Plasma prolactin (PRL) and homovanillic acid (HVA) levels, and urinary HVA and dopamine (DA) excretion, were measured in groups of unmedicated autistics, medicated autistics, and normal controls. No significant differences were found between unmedicated autistics and normal controls in plasma PRL and HVA levels. Excretion rates of urinary HVA and DA were also similar in the unmedicated autistic and normal subjects. Plasma PRL and HVA, as well as urinary HVA excretion, were significantly increased in the autistics on neuroleptic medication compared to the unmedicated autistics. A significant correlation (r = 0.46, p = less than 0.05) was observed between dose of neuroleptics and plasma PRL values; the correlation (r = 0.42) between neuroleptic dose and plasma HVA levels approached significance (p = 0.06). In contrast, no differences were observed in urinary DA excretion between medicated and unmedicated autistics. In general, the findings indicate that peripheral indices of dopamine functioning are normal in autistic subjects.

Plasma MHPG: within- and across-day stability in children and adults with Tourette's syndrome

Within- and across-day stability of unconjugated plasma 3-methoxy-4-hydroxyphenethyleneglycol (pMHPG, the major metabolite of norepinephrine) levels were assessed in several subgroups of 47 primarily child and adolescent subjects with Tourette's syndrome (TS). Mean morning pMHPG levels remained stable over a 20-min period from 8:30 to 8:50 AM at 3.5 +/- 0.8 ng/ml. However, the mean intraindividual fluctuation in pMHPG levels over 20 min was +/- 12%. Mean pMHPG levels remained stable in the morning from 8:00-8:30 AM to noon. However, an 11% decrease (p less than 0.01) in mean pMHPG levels was observed in the afternoon between noon and 3:00-4:00 PM. Monitored on consecutive days, mean morning pMHPG levels fell 12% (p less than 0.002). The afternoon and across-day falls in pMHPG levels observed in this study of primarily children and adolescents with TS have not been observed in studies of adult control subjects. The results suggest that the design of research protocols involving children and adolescents that use pMHPG should take into consideration the effects of time, both within- and across-day, in pMHPG levels.