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Background: Previous MRI studies of healthy children have reported age-related white matter (WM) changes in language and motor areas of the brain. The authors investigated WM development in healthy adolescent males through age-associated changes in fractional anisotropy (FA), radial (lambda( perpendicular)) and axial (lambda(||)) diffusivity., Methods: Twenty-four healthy adolescent males (mean age=16.6, SD=2.5 years) were divided into two groups with an age split of 16.9 years and underwent a whole-brain voxelwise analysis., Results: At a threshold of p<0.001 and extent threshold of 100 contiguous voxels, several clusters with increased FA and axial diffusivity and no differences in radial diffusivity were observed in older adolescents compared to the younger adolescents in the left arcuate fasciculus, bilateral posterior internal capsule/thalamic radiation, bilateral prefrontal gyrus, right superior temporal gyrus, and posterior corpus callosum. Increased FA and lambda(||) of several clusters along the arcuate fasciculus significantly correlated with a test of language and semantic memory., Conclusions: These results suggest ongoing maturational changes especially in the arcuate fasiculus during late adolescence. Increased FA and lambda(||) with no changes in radial diffusivity may reflect a developmental pattern of reduced tortuousity toward more straightened fibers and/or increased axonal fiber organization during late adolescence.

Objective: To investigate abnormalities in the structural integrity of brain white matter as suggested by diffusion tensor imaging in adolescents with early-onset schizophrenia (onset of psychosis by age 18)., Method: Twenty-six patients with schizophrenia and 34 age- and gender-matched healthy volunteers received diffusion tensor imaging and structural magnetic resonance imaging examinations. Fractional anisotropy maps were compared between groups in the white matter using a voxelwise analysis after intersubject registration to Talairach space., Results: Compared with healthy volunteers, patients demonstrated lower fractional anisotropy values in the left anterior cingulate region in close proximity to the caudate nucleus (95% confidence interval of schizophrenic-healthy: -66 to -20). Using regression analysis, the rate of change in fractional anisotropy differed significantly between groups in this region across the age span examined (10-20 years), after adjusting for group differences in premorbid intellectual capacity and parental socioeconomic status. There were no areas of significantly higher fractional anisotropy in patients compared with healthy volunteers., Conclusions: These data suggest that early-onset schizophrenia is associated with a disruption in the structural integrity of white matter tracts in the anterior cingulate region. These structural abnormalities may contribute to the deficits in motivation, attention, memory, and higher executive functions in adolescents with schizophrenia.