"After controlling for confounding variables, prenatal cocaine exposure was not associated with lower full-scale, verbal, or performance IQ scores at age 4 years, but did predict significant deficits in specific cognitive skills underlying intellectual functioning and attenuated the incidence of IQ scores above the normative mean, even for children in better home environments. Further, higher concentrations of cocaine metabolites in infant meconium were significantly related to lower verbal IQ and arithmetic scores. Importantly, however, the quality of the caregiving environment appeared to have substantial compensatory effects on cocaine-exposed children placed in adoptive or foster care. Cocaine-exposed children placed in adoptive care achieved performance similar to nonexposed children living in less stimulating, lower socioeconomic status home environments. Indeed, environmental intervention through foster or adoptive care was associated with a lower likelihood of mental retardation among cocaine-exposed children, despite heavier drug exposure."
Singer, L. T., Minnes, S., Short, E., Arendt, R., Farkas, K., Lewis, B., Klein, N., Russ, S., Min, M. O., & Kirchner, H. L. (2004). Cognitive outcomes of preschool children with prenatal cocaine exposure. JAMA, 291(20), 2448–2456. doi.org/10.1001/jama.291.20.2448