Prenatal cocaine/polydrug exposure and infant performance on an executive functioning task

Executive functioning in cocaine/polydrug (marijuana, alcohol, tobacco) exposed infants was assessed in a single session, occurring between 9.5 and 12.5 months of age. In an A-not-B task, infants searched, after performance-adjusted delays, for an object hidden in a new location. Overall, the cocaine-exposed (CE) infants did not differ from non-CE controls recruited from the same at-risk population. However, comparison of heavier-CE (n = 9) to the combined group of lighter-CE (n = 10) and non-CE (n = 32) infants revealed significant differences on A-not-B performance, as well as on global tests of mental and motor development. Covariates investigated included socioeconomic status, marital status, race, maternal age, years of education, weeks of gestation, birth weight, as well as severity of prenatal marijuana, alcohol, and tobacco exposure. The relationship of heavier-CE status to motor development was mediated by length of gestation, and the relationship of heavier-CE status to mental development was confounded with maternal gestational use of cigarettes. The relationship of heavier-CE status to A-not-B performance remained significant after controlling for potentially confounded variables and mediators, but was not statistically significant after controlling for the variance associated with global mental development.