Attention deficits relate white-matter disturbances in Schizophrenia

1. BackgroundDespite the great importance they have for being addressed by researchers, Attention deficits remained as a fundamental problem in patients suffering schizophrenia (1). Considering broad aspects attention has, multiple brain structures seems to be affected in schizophrenic patients and resulting impaired attention could be investigated by different imaging studies. White matter tracts probably play a significant role in such a complicated and multi-regional task and investigating their structural changes may lead to a betterunderstanding of underlying impaired attention in schizophrenia. This study addressed structural white matter tracts in schizophrenia and their probable relation with different aspects of attentional deficits detected with common standard attention measuring tests. 2. Method 84 native English speaker were selected from participants of Mind Clinical Imaging Consortium (MCIC) (2) which all were aged between 18 and 60, with no history of disorder than schizophrenia. Patients were met DSM- IV criteria for Schizophrenia and all were scanned with a 1.5 Tesla MR scanner to obtain diffusion weighted images (DWIs) and were assessed about attention with Trail Making Test (TMT) and Californiacomputerized Assessment Battery (CalCAP). Acquired DWI images were analyzed using exploreDTI. All images were corrected for eddy current and subject motion distortion. Robust Estimation of Tensors by Outlier Rejection (RESTORE) algorithm was used on previously registered images. Whole brain atlas based tractography were performed and based on prior knowledge (3) 8 tracts of interests were selected for investigations (right and left Superior Longitudinal Fasciculus (SLF), right and left Cingulum, and Splenium and Genu of corpus callosum). Mean fractional anisotropy (FA) and Mean Apparent Diffusion Coefficient (ADC) of mentioned tracts were extracted for statistical analysis. To check for any associations between mean FA and ADC of the fiber tracts, a general linear model was used. Attention test results were assessed separately in a general linear model and FA and ADC of each fiber were the predicting variables. Age, years of education, illness duration, and ethnicity were all included as covariates. Bonferroni and Benjamini-Hochberg methodwas used for each group of regression models for multiple comparison correction.3. Results In primary analysis, 6 of selected tracts were found to have changes related to different attentional functions ( p < 0.05). After Multiple comparison correction of results, 4 of observed relations still stayed statistically significant. TMT-A scores seem to be related with changes in ADC of Genu of carpus callosum (CC) and right cingulum and mean Fractional anisotropy (FA) of Spelenium and TMT-time scores were also related to FA ofGenu of carpus callosum, respectively (p = 0.04563214, 0.04563214, 0.44652134 and 0.07182423 in respect) 4. Conclusions Our study investigated Diffusional changes in patients with schizophrenia considering attention for the first time. Our data sample were statistically big enough to show reduction in FA and ADC of mentioned tracts, which could be interpreted as fiber integrity reduction, is related with worsening of attention in patients. It seems that structural changes in carpus callosum are occurring which is detectable with Diffusion tensor Imaging of the brain in patients suffering schizophrenia with attention deficit. 5. References 1. Barbara A. et al., (1994)