Prenatal Cocaine Exposure: Drug and Environmental Effects at 9 Years

Objective

To assess school-age cognitive and achievement outcomes in children with prenatal cocaine exposure, controlling for confounding drug and environmental factors.

Study design

At age 9 years, 371 children (192 cocaine exposure [CE]; 179 non–cocaine exposure [NCE]) were assessed for IQ and school achievement in a longitudinal, prospective study from birth. An extensive number of confounding variables were controlled, including quality of caregiving environment, polydrug exposure, blood lead level, iron-deficiency anemia (IDA), and foster/adoptive care.

Results

Prenatal cocaine exposure predicted poorer perceptual reasoning IQ, with a linear relationship of the concentration of the cocaine metabolite benzoylecgonine to the degree of impairment. Effects were mediated through birth head circumference, indicating a relationship with fetal brain growth. Negative effects of alcohol, lead, and marijuana exposure and positive effects of the home environment were additive. The CE children in foster/adoptive care had better home environments and lower lead levels. School achievement was not affected.

Conclusions

Persistent teratologic effects of CE on specific cognitive functions and additive effects of alcohol, lead, and marijuana exposure; IDA; and the home environment were identified. Documenting environmental factors in behavioral teratology studies is important, because in this sample, CE was associated with better home environment and lower environmental risk in a substantial number of children.

Abbreviations: CE, Cocaine exposure, CI, Confidence interval, df, Degrees of freedom, Hb, Hemoglobin, HOME, Home Observation of the Environment, IDA, Iron-deficiency anemia, MANCOVA, Multivariate analysis of covariance, MANOVA, Multivariate analyses of variance, MCV, Mean corpuscular volume, NCE, Non–cocaine exposure, OR, Odds ratio, PPVT-R, Peabody Picture Vocabulary Scale–Revised, SE, Standard error, SF, Serum ferritin, TS, Transferrin saturation, WAIS-R, Wechsler Adult Intelligence Scale–Revised, WISC-IV, Wechsler Intelligence Scale for Children–Fourth Edition, WJTOA-III, Woodcock-Johnson–III Tests of Achievement