Monoamine metabolites in 'leftover' newborn human cerebrospinal fluid--a potential resource for biobehavioral research.

Although variations in monoamine neurotransmission have been implicated in a variety of psychopathologic outcomes in man, little is known about how monoamines influence or are affected by developmental processes early in childhood. In this study, assays for 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) were obtained from leftover cerebrospinal fluid (CSF) of 119 human newborns. The levels of these monoamine metabolites were in keeping with pre-existing 'normative' data from two small previously published studies. The levels were largely unaffected by variations in the infants' physiologic condition at the time of lumbar puncture, and exhibited evidence for circadian rhythms. Among 32 infants (8 neurologically normal, 24 neurologically compromised) for whom more than one CSF sample was obtained during the first year of life, the correlations between baseline and follow-up measurements for 5-HIAA and HVA were on the order of 0.75. Correlations between twins (four sets) were significantly higher than those between unrelated individuals for 5-HIAA and HVA. At 9-month follow-up, neurologically normal infants in the lower extreme 15% of the distribution for 5-HIAA exhibited a trend toward lower scores for sociability on the Colorado Childhood Temperament Inventory (maternal report) than their counterparts at the upper extreme of the 5-HIAA distribution. Leftover CSF is a readily available resource for measurements of monoamine metabolites (and possibly other CSF constituents) in population-based samples of human newborns.