Associations between white matter micro- and macro-structure and attention in 6-7-year-old children with low to moderate prenatal alcohol exposure.

Heavy prenatal alcohol exposure is associated with changes to the brain’s white matter, which may underpin attention problems observed in this population. Less is known about the effect of low to moderate exposure. This study investigated white matter correlates of attention in children with low to moderate levels of prenatal alcohol exposure and controls whose mothers abstained from alcohol. We also examined whether associations differed between alcohol exposure in trimester one only or throughout pregnancy. A total of 129 children aged 6-7-years from the prospective Asking Questions about Alcohol in pregnancy (AQUA) cohort (trimester one alcohol exposure n = 47; exposure throughout pregnancy n = 45; controls n = 37) participated in a brain magnetic resonance imaging study. Fixel-based analysis was performed on diffusion weighted images to investigate associations between whole brain white matter micro- and macro-structure and attention (focus, shift, sustain, hyperactivity and inattention). In controls, better focused attention and less hyperactivity were associated with greater macrostructural cross-sectional area of the corticospinal tract and cerebellar white matter, respectively. Greater microstructural fiber density in the splenium of the corpus callosum was associated with more inattention in the children with trimester one alcohol exposure, which persisted when adjusted for any binge drinking episodes prior to pregnancy recognition. Subtle differences in the association between white matter and attention were found between controls and prenatal exposure groups, where associations were stronger in controls. While further exploration is needed, preliminary findings in 6-7-year-old children suggest that low to moderate prenatal alcohol exposure affects white matter fibers that subserve attention skills.