Brain structural and behavioral characterization of long-term effects of prenatal cocaine exposure in adolescents

The purpose of this study was to investigate the potential long-term effects of prenatal cocaine exposure on brain structures and impulsivity using structural MRI, diffusion tensor imaging (DTI) and behavioral measures. The sample included 12-15 years old children participating in a longitudinal study of the effects of prenatal cocaine exposure. Exposure status was determined at birth based on maternal report and meconium toxicology analysis. Forty children (20 cocaine exposed and 20 comparison) born >33 weeks gestational age without prenatal marijuana or opiate exposure participated in the study. The two groups were matched on prenatal alcohol exposure, socioeconomic status, IQ, birth head circumference and gestational age. There were more children with prenatal tobacco exposure in the cocaine group. Structural MRI was analyzed using Fresssurfer. There were no significant differences between the cocaine exposed and comparison groups on subcortical brain structures volumes (caudate, putamen, amygdala, pallidum, thalamus and hippocampus), whole brain volumes (gray matter, white matter) or lobar cortical thickness. Similar findings were observed when these analyses were adjusted for intracranial volume and prenatal tobacco exposure. The mean volumes for these measures indicated larger volumes in the cocaine exposed than in the comparison group and two regions (putamen, p = 0.06; thalamus, p = 0.07) approached statistical significance. The results of the DTI analysis showed no significant differences between exposed and comparison groups in each of 5 subregions of the corpus callosum on measures of fractional anisotropy and mean diffusivity. Similarly, no behavioral differences were detected on the Sensation Seeking Scale for Children or commission errors on the Conners' Continuous Performance Test. Relationships between the neuroimaging findings and measures of impulsivity showed larger caudate related to more commission errors, larger thalamus and white matter related to more sensation seeking in the exposed group but not in the comparison group. Results could suggest that the trend toward increased volumes in the cocaine exposed children is due to delayed or insufficient pruning or functional compensation. The brain-behavior relationships could suggest imposed constraint on development or a diverted maturation pathway in the dopaminergic system specific to prenatal cocaine exposure.