A Nonhuman Primate Model of Excessive Alcohol Intake

Abstract

Developmental, biochemical, and behavioral concomitants of voluntary excessive alcohol consumption were investigated using a nonhuman primate model. Studies were designed to investigate potential neurobiological and behavioral parallels of Cloninger’s subtypes of type I and type II alcoholism in nonhuman primates. The studies have shown that a subpopulation of primates chronically consume intoxicating amounts of alcohol. Subjects that chronically consume intoxicating amounts of alcohol often exhibit neurobiological and behavioral features that were predicted by Cloninger’s model for subtypes of alcoholism among humans. Investigations showed that behavior patterns and biological indices that characterize high anxiety, whether constitutionally or stress induced, were correlated with high rates of alcohol consumption, consistent with predictions for type I alcoholism. Early untoward rearing experiences that increased anxiety increased the probability that subjects would chronically drink alco h olto intoxication. Investigations of type II-like alcohol consumption patterns focused on subjects with low central nervous system (CNS) serotonin functioning [as measured by reduced cerebrospinal fluid (CSF) concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA)]. CSF 5-HIAA in infancy was shown to be a relatively stable neurobiological trait across development into adulthood. An individual CSF 5-HIAA concentration in infancy was shown to be a consequence of paternal and maternal genetic influences. Early parental neglect reduced CSF 5-HIAA concentrations. Low CSF 5-HIAA and CNS norepinephrine functioning were shown to predict excessive alcohol consumption in adolescence. Behaviorally, subjects with low CSF 5-HIAA demonstrated impaired impulse control, which resulted in excessive and inappropriate aggression, infrequent and inept social behaviors, low social status, social isolation and expulsion from social groups at an early age, and high rates of early mortality. With some exceptions, these findings were consistent with predictions from Cloninger’s type II model of excessive alcohol consumption among men who exhibit impaired impulse control and violent and antisocial behaviors.