ABSTRACT
OBJECTIVES: Diffuse tensor imaging (DTI) was applied to explore the difference in regional distribution and extent of white matter (WM) abnormalities in boys with Attention-deficit/hyperactivity disorder (ADHD) versus boys with comorbid ADHD and tic disorders. METHODS: Fifteen boys with ADHD (mean age 9.3+/-1.8), 24 ADHD boys with chronic tic disorder or Tourette's disorder (9.9+/-1.2) and 9 age-, gender-matched controls (9.2+/-1.8) received DTI assessments. Fractional Anisotropy (FA) maps of WM were compared between groups with a voxel-wise analysis after intersubject registration to MNI space. RESULTS: Both groups, ADHD group and ADHD with tic disorder group, commonly showed decreased FA than healthy control group in left cerebellar middle peduncle and right frontal lobe, increased FA in right middle occipital WM. In the common areas of left cerebellar middle peduncle and right middle occipital WM, comorbid group showed broader areas of significant FA. The comorbid group also showed increased FA in right cerebellar peduncle, additionally. CONCLUSION: The findings in ADHD group support previous ADHD hypothesis of the functional abnormalities in corticocerebellar circuit, and suggest that ADHD might have more complicated pathology of neuronal circuit including occipital visual system. The comorbid group showed common areas of overlapping but more extensive abnormalities and also had additional WM abnormalities. ADHD with chronic tic disorders may represent a severe form of ADHD with additional regions of abnormal connectivity.