Understanding specific effects of prenatal alcohol exposure on brain structure in young adults.

Prenatal alcohol exposure (PAE) is associated with various adverse effects on human brain and behavior. Recently, neuroimaging studies have begun to identify PAE effects on specific brain structures. Investigation of such specific PAE effects is important for understanding the teratogenic mechanism of PAE on human brain, which is critical for differentiating PAE from other disorders. In this structural MRI study with young adults, PAE effects on the volumes of automatically segmented cortical and subcortical regions of interest (ROIs) were evaluated both through a group difference approach and a parametric approach. In the group difference approach (comparing among two PAE and a control groups), a disproportionate PAE effect was found in several occipital and temporal regions. This result is inconsistent with previous studies with child samples. Moreover, a gender difference in PAE effect was shown in some cortical ROIs. These findings suggest that sampling and gender may be important factors for interpreting specific PAE effects on human brain. With the parametric approach, it was demonstrated that the higher the PAE level, the smaller the entire brain, the lower the IQ. Several cortical and subcortical ROIs also exhibited a negative correlation between the PAE level and ROI volume. Furthermore, our data showed that the PAE effect on the brain could not be interpreted by the PAE effect on general physical growth until the young adult age. This study provides valuable insight into specific effects of PAE on human brain and suggests important implications for future studies in this field.