White matter tract integrity in isolated oral clefts: relationship to cognition and reading skills.

Children with isolated cleft of the lip and/or palate (iCL/P) have been shown to be at risk for impaired reading ability. Structural and functional neuroimaging studies have revealed subtle morphological and functional abnormalities correlated to cognition and reading ability. However, the integrity of white matter tracts and their potential relationship to reading performance in iCL/P is under-studied. The purpose of the present study was to evaluate white matter integrity related to cognition and reading skills among participants with and without iCL/P. Data from two cross-sectional, case/control studies with similar neuropsychological batteries and diffusion tensor imaging (DTI) protocols were combined. The final sample included 210 participants (ages 7 to 27 years). Group and sex differences in fractional anisotropy (FA) values were examined between participants with (n = 105) and without (n = 105) iCL/P. Potential associations between FA values and age, cognition, and reading skills were also evaluated separately by group and sex. Sex effects were prominent in association and projection fibers, and effects of cleft status were found in association fibers and cerebellar regions, with isolated associations to reading skills. Findings provide preliminary understanding of microstructural associations to cognitive and reading performance among children, adolescents, and young adults with iCL/P.