Behavioral effects of low, acute doses of d-amphetamine on the dyadic interaction between mother and infant vervet monkeys (Cercopithecus aethiops) during the first six postnatal months.

Doses of d-amphetamine sulfate (0.1, 0.15, and 0.2 mg/kg body weight) were given to adult monkeys in mother-infant pairs. The fundamental parental care behavior pattern was disrupted and the mother became isolated in a socially withdrawn phase. She did not respond to the calling signals of the infant and showed behavior in which stereotyped self-grooming and/or 'staring' into space were predominant. The reactions of the infant to this amphetamine-induced behavior were different in the two experimental pairs. In group 1 the infant increased its approach--avoidance movements. In group 2 the infant sat very quietly and close in front of the mother. The mother from group 1 reacted to the increased approaches from its infant with active rejection. In both groups the mothers did not react with the typical ventral--ventral grasping to either the infants sitting close or to the social anxiety signals of the infants. In spite of differences in behavior changes induced by amphetamine, the main conclusion is that the mothers totally lost their normal and highly biologic significant interest in their infants.