Cognitive Outcomes of Preschool Children With Prenatal Cocaine Exposure
- Lynn T. Singer, PhD;
- Sonia Minnes, PhD;
- Elizabeth Short, PhD;
- Robert Arendt, PhD;
- Kathleen Farkas, PhD;
- Barbara Lewis, PhD;
- Nancy Klein, PhD;
- Sandra Russ, PhD;
- Meeyoung O. Min, PhD;
- H. Lester Kirchner, PhD
- Author Affiliations: Departments of General Medical Sciences and Pediatrics, School of Medicine (Drs Singer, Minnes, Lewis, Min, and Kirchner), Mandel School of Applied Social Sciences (Dr Farkas), and the Department of Psychology (Drs Short and Russ), Case Western Reserve University, Cleveland, Ohio; Department of Education, Cleveland State University (Dr Klein), Cleveland, Ohio; and Department of Pediatrics, The Ohio State University (Dr Arendt), Columbus.
Abstract
Context Because of methodological limitations, the results of the few prospective studies assessing long-term cognitive effects of prenatal cocaine exposure are inconsistent.
Objective To assess effects of prenatal cocaine exposure and quality of caregiving environment on 4-year cognitive outcomes.
Design Longitudinal, prospective, masked comparison cohort study from birth (September 1994-June 1996) to 4 years.
Setting Research laboratory of a US urban county teaching hospital.
Participants A total of 415 consecutively enrolled infants identified from a high-risk population screened for drug use through clinical interview, urine, and meconium screens. Ninety-three percent retention for surviving participants at 4 years of age resulted in 376 children (190 cocaine-exposed and 186 nonexposed).
Main Outcome Measure The Wechsler Preschool and Primary Scales of Intelligence-Revised.
Results After control for covariates, prenatal cocaine exposure was not related to lower full-scale IQ (cocaine exposed [80.7] vs nonexposed [82.9]; P = .09) scores or summary verbal (cocaine exposed [79.9] vs nonexposed [81.9]; P = .11) or performance (cocaine exposed [85.5] vs nonexposed [87.5]; P = .18) IQ scores at age 4 years. However, prenatal cocaine exposure was related to small but significant deficits on several subscales (mean [SE]): visual-spatial skills (cocaine exposed [7.3 (0.22)] vs nonexposed [8.2 (0.22)]; P = .01), general knowledge (cocaine exposed [6.1 (0.18)] vs nonexposed [6.7 (0.17)]; P = .04), and arithmetic skills (cocaine exposed [6.2 (0.20)] vs nonexposed [6.8 (0.20)]; P = .05). Prenatal cocaine exposure was also associated with a lower likelihood of achievement of IQ above normative means (odds ratio, 0.26 [95% confidence interval, 0.10-0.65]; P = .004). The quality of the caregiving environment was the strongest independent predictor of outcomes. Cocaine-exposed children placed in nonrelative foster or adoptive care lived in homes with more stimulating environments and had caregivers with better vocabulary scores, and they attained full-scale and performance IQ scores (83 and 87, respectively) similar to nonexposed children in biological maternal or relative care (full-scale IQ, 82; performance IQ, 88) and higher than cocaine-exposed children in biological maternal or relative care (full-scale IQ, 79; performance IQ, 84).
Conclusions Prenatal cocaine exposure was not associated with lower full-scale, verbal, or performance IQ scores but was associated with an increased risk for specific cognitive impairments and lower likelihood of IQ above the normative mean at 4 years. A better home environment was associated with IQ scores for cocaine-exposed children that are similar to scores in nonexposed children.
