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S056-3

Disorder-Specific Alteration in White Matter Structural Property in Adults with
Autism Spectrum Disorders Relative to Adults with ADHD and Adult Controls

Huey-Ling Chiang1, Yu-Jen Chen2, Susan Shur-Fen Gau3, Wen-Yih Isaac Tseng2

1Department of Psychiatry, Far Eastern Memorial Hospital, Taiwan 2Center for Optoelectronic Medicine, National
Taiwan University College of Medicine, Taiwan 3Department of Psychiatry, National Taiwan University Hospital
and College of Medicine, Taiwan

Background/Objective: Autism spectrum disorder (ASD) and attention-deficit hyperactivity
disorder (ADHD) are two common neurodevelopmental disorders. These two disorders are not only
often comorbid, but also have overlapped behavioral and cognitive abnormalities. A key question is
whether these shared phenotypes are based on common or different underlying neuropathologies.
Therefore, this study aims to examine the disorder-specific alterations in white matter structural
property.

Method: The three comparison groups included 23 male adults with ASD (age: 21.4±3.1),32 male
adults with ADHD (age: 23.4±3.3) and 29 age-matched healthy male controls (age: 22.4±3.3). They
were assessed by the Conners’ continuous performance test (attention performance) and the
Cambridge Neuropsychological Test Automated Battery (executive functions) and scanned by MRI.
After acquisition of the diffusion spectrum imaging (DSI), whole brain tractography was
reconstructed by a tract-based automatic analysis (TBAA), and generalized fractional anisotropy
(GFA) values were computed to indicate tract-specific white matter property.

Result: There are significant differences (FDR adjusted p-value < 0.05) in the GFA values among
the three groups in six identified fiber tracts: right arcuate fascilucus, right cingulum (hippocampal
part), anterior commissure, and three callosal fibers (ventrolateral prefrontal cortex part, precentral
part, superior temporal part). Post-hoc analyses revealed that adults with ASD, compared with adults
with ADHD, had significant lower GFA in these fiber tracts. There was no significant difference in
the GFA of any of the white matter tracts between adults with ADHD and healthy male controls. The
GFA values of some of the fiber tracts were positively associated with attention performance and
executive functions, and these three groups showed differential association patterns.

Conclusion: This study highlights the disorder-specific alteration of white matter tracts in adults
with ASD. Future studies in patients with other age range and both genders using DSI and other
imaging modalities are needed to elucidate disorder-specific brain structural biomarkers for these
two disorders.