A nonhuman primate model of type II excessive alcohol consumption? Part 1. Low cerebrospinal fluid 5-hydroxyindoleacetic acid concentrations and diminished social competence correlate with excessive alcohol consumption.

Developmental, biochemical, and behavioral concomitants of excessive alcohol consumption were investigated using a nonhuman primate model. The variables of interest were: (1) interindividual stability of cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) from infancy to adulthood, (2) effect of parental deprivation early in life on adult CSF 5-HIAA concentrations; (3) correlations between CSF 5-HIAA and 3-methoxy-4-hydroxyphenylglycol (MHPG) concentrations and alcohol consumption; and (4) correlation between the frequency of competent social behaviors and alcohol consumption. Twenty-nine rhesus macaques were reared for their first 6 months either with their mothers or without adults in peer-only conditions. At 6 and 50 months of age, each subject underwent a series of four, 4-day social separations. Cisternal CSF was sampled before and during the first and last separations; concomitantly, observational data were collected on social dominance behavior in the home-cage. When they reached 50 months of age, the monkeys were provided free access to a palatable alcohol solution daily for 1-hr periods before, during, and after the social separations. Before and after the 50-month separations, data were collected on all types of social behavior in the home-cage. Results showed that peer-reared subjects consumed more alcohol than mother-reared subjects during baseline conditions. Mother-reared subjects, however, increased their rates of consumption to equal peer-reared subjects' rates of consumption during the conditions of a social separation stressor. Peer-reared subjects also exhibited lower CSF 5-HIAA concentrations in infancy and adulthood than their mother-reared counterparts. With rearing condition held constant, interindividual differences in CSF 5-HIAA, MHPG, and homovanillic acid were stable from infancy to adulthood, and high rates of alcohol were consumed by the young adult monkeys with low CSF 5-HIAA and MHPG concentrations, particularly when the CSF was obtained during the social separations. High rates of alcohol consumption were also observed in subjects with infrequent social interactions and less competent social behaviors. In contrast to the human data, we found no gender differences in rates of alcohol consumption, nor in the correlations between alcohol consumption and the other variables. With some exceptions, findings from the study are generally consistent with predictions from Cloninger's type II model of excessive alcohol consumption in men with low CSF 5-HIAA, who also exhibit impaired impulse control and violent and antisocial behaviors.