Background: Reports from clinical and experimental (animal) research converge on the suggestion that prenatal exposure to alcohol, cocaine, or marijuana undermines executive functioning (EF) and its neurological underpinnings. However, large, adequately controlled, prospective studies of alcohol and marijuana effects on EF have reported conflicting findings, and there have been no such studies of cocaine exposure.
Methods: EF was investigated in a cohort (n = 316) of 4-year-old children the majority of whose mothers had used varying combinations of cocaine, alcohol, and marijuana during pregnancy. With use of postpartum maternal report and biological assay, children were assigned to overlapping prenatal cocaine-exposed, alcohol-exposed, and marijuana-exposed groups and to complementary control groups. The postnatal environmental assessment included measures of maternal intellectual and psychosocial functioning, current drug or alcohol use, and home environment.
Results: The children in the alcohol-exposed group had worse tapping-inhibition performance than children in the non-alcohol-exposed group, and this effect persisted when potential confounding environmental variables, other drug variables, and concurrent verbal intelligence were controlled for.
Conclusions: Prenatal alcohol is predictive of decreased EF in early childhood that could not be attributed to environmental factors. The results are discussed in terms of the age and overall high-risk status of the children.