White Matter Microstructural Differences in Youth With Classical Congenital Adrenal Hyperplasia.

CONTEXT: Gray matter morphology in the prefrontal cortex and subcortical regions, including the hippocampus and amygdala, are affected in youth with classical congenital adrenal hyperplasia (CAH). It remains unclear if white matter connecting these aforementioned brain regions is compromised in youth with CAH. OBJECTIVE: To examine brain white matter microstructure in youth with CAH compared to controls. DESIGN: A cross-sectional sample of 23 youths with CAH due to 21-hydroxylase deficiency (12.9 ±â€…3.5 year; 61% female) and 33 healthy controls (13.1 ±â€…2.8 year; 61% female) with 3T multishell diffusion-weighted magnetic resonance brain scans. MAIN OUTCOME MEASURES: Complementary modeling approaches, including diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI), to examine in vivo white matter microstructure in six white matter tracts that innervate the prefrontal and subcortical regions. RESULTS: DTI showed CAH youth had lower fractional anisotropy in both the fornix and stria terminalis and higher mean diffusivity in the fornix compared to controls. NODDI modeling revealed that CAH youth have a significantly higher orientation dispersion index in the stria terminalis compared to controls. White matter microstructural integrity was associated with smaller hippocampal and amygdala volumes in CAH youth. CONCLUSIONS: These patterns of microstructure reflect less restricted water diffusion likely due to less coherency in oriented microstructure. These results suggest that white matter microstructural integrity in the fornix and stria terminalis is compromised and may be an additional related brain phenotype alongside affected hippocampus and amygdala neurocircuitry in individuals with CAH.