Mother-infant interaction in rhesus monkeys treated clinically with delta-9-tetrahydrocannabinol.

Behavior was studied in 15 rhesus monkeys mother-infant pairs, 5 of whom were exposed to delta-9-tetrahydrocannabinol continuously throughout gestation and the nursing period via drug treatment of mother (2.4 mg/kg/day). The drug-exposed mother-infant pairs were similar to nontreated controls in the amount and types displayed at 10 and 90 days of age, and adequate maternal care was demonstrated by all mothers. Drug-exposed pairs, however, showed no increase in interaction patterns that signal the onset of mother-infant independence at about 3 months of age. This finding suggests that mother-infant attachment may be a behavioral system that is particularly sensitive to modification by perinatal exposure to psychoactive drugs.