Prospective, blinded studies of children prenatally exposed to cocaine have not demonstrated significant cognitive impairment. However, prior studies have been limited by the early study age or small sample size. The aim of this preliminary report was to provide information on the cognitive outcome of 6-7 year old children prenatally exposed to cocaine. Subjects are singleton infants born to women extensively screened during pregnancy by research staff for alcohol, cigarette, cocaine and other drug use. As indicated, maternal and infant drug testing was ordered. Cocaine exposure was positive if history of lab was positive. Substance abuse was also quantified. Six years later, families were re-contacted. After informed consent, the child, primary caretaker and, when available, the biologic mother were tested. Child cognition was measured by the Weschler Preschool and Primary Scales of Intelligence (WPPSI). To reduce cultural bias, the triangles subscale of the Kaufman Assessment Battery for Children (K-ABC) was also included. This subtest is a good measure of simultaneous processing. Adult IQ was measured by the WAIS. Drug use since the child's birth was assessed by trained researchers using a structured interview. Results: The study sample consisted of 670 singleton children. Four subjects were known to have expired. Of those remaining, 36% could not be located. Only 8% refused participation. Testing was available for 57% of the sample (Cocaine exposed: N=137). Frequency of prenatal cocaine exposure was available for 314 children and highly correlated with postnatal use in the child's home (r=.35). However, urine testing of 150 children failed to identify any child positive for cocaine at follow-up. In the regression model, after controlling for gestational age, prenatal alcohol and cigarette exposure and the IQ of either the mother (86% cases), father(2%) or primary caretaker (12%), there was no significant relationship between either the binary or quantitative cocaine exposure and any of the child's cognitive scores. Conversely, prenatal alcohol exposure was negatively and significantly related to the WPPSI IQ (r=-.12, p=.023) and the K-ABC subscale approached significance (r=-.10, p=.08). An N of 314 provides sufficient power(.8) with α=.05 to detect a correlation of 0.16. Preliminary results of this NIDA-funded study suggest that cognition was negatively impacted by prenatal alcohol but not cocaine.
