Several studies have suggested that white matter integrity is disrupted in some brain regions in patients with schizophrenia. The purpose of this study was to assess the white matter integrity of the cingulum, uncinate fasciculus, fornix, and corpus callosum using diffusion tensor imaging (DTI). Participants comprised 39 patients with schizophrenia (19 males and 20 females) and 40 age-matched normal controls (20 males and 20 females). We quantitatively assessed the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the anterior cingulum, body of the cingulum, uncinate fasciculus, fornix, and corpus callosum on a tract-specific basis using diffusion tensor tractography (DTT). Group differences in FA and ADC between the patients and normal controls were sought. Additional exploratory analyses of the relationship between the FA or ADC and four clinical parameters (i.e., illness duration, positive symptom scores, negative symptom scores, and medication dosage) were performed. Results were analyzed in gender-combined and gender-separated group comparisons. FA was significantly lower on both sides of the anterior cingulum, uncinate fasciculus, and fornix in the schizophrenia patients irrespective of gender group separation. In the gender-combined analyses, significantly higher ADC values were demonstrated in the schizophrenia patients in both sides of the anterior cingulum, body of the cingulum and uncinate fasciculus, the left fornix, and the corpus callosum, compared with those of the normal controls. In the gender-separated analyses, the male patients showed higher ADC in the left anterior cingulum, the bilateral cingulum bodies, and the bilateral uncinate fasciculi. The female patients showed higher ADC in the right anterior cingulum, the left fornix, and the bilateral uncinate fasciculus. In correlation analyses, a significant negative correlation was found between illness duration and ADC in the right anterior cingulum in the gender-combined analyses. The gender-separated analyses found that the male patients had a significant negative correlation between negative symptom scores and FA in the right fornix, a positive correlation between illness duration and FA in the right anterior cingulum, and a negative correlation between illness duration and FA in the left uncinate fasciculus. Our DTI study showed that the integrity of white matter is disrupted in patients with schizophrenia. The results of our sub-analyses suggest that changes in FA and ADC may be related to negative symptom scores or illness duration.
"White matter integrity has previously been shown to be impaired in patients with more severe negative symptoms. For instance , Kunimatsu et al. found that patients with schizophrenia and a more severe severity of negative symptoms also had decreased FA in the right fornix (Kunimatsu et al., 2012). Similarly, decreased FA values in the right cingulum have been associated with greater severity of negative symptoms (Hazlett et al., 2011). "
"On the other hand, changes in WM integrity may be a fundamental pathophysiological mechanism underlying the clinical presentation of schizophrenia, present before the appearance of clinical symptoms. There are several studies supporting this hypothesis, proposing the change in WM as an endophenotypical feature of the disease (Davis et al., 2003; Camchong, 2009; Abdul-Rahman et al., 2011; Kunimatsu et al., 2012; Kuswanto et al., 2012; Scheel et al., 2012). Together, the data to date strongly suggests that there is an underlying abnormality in the WM tracts of patients with schizophrenia. "
[Show abstract][Hide abstract] ABSTRACT: Background:
White matter abnormality has been recently proposed as a pathophysiological feature of schizophrenia (SZ). However, most of the data available has been gathered from chronic patients, and was therefore possibly confounded by factors such as duration of the disease, and treatment received. The extent and localization of these changes is also not clear.
We examined a population of early stage SZ patients using diffusion tensor imaging (DTI). 77 SZ patients and 60 healthy controls (HCs) were included in the analysis using Tract-Based Spatial Statistics (TBSS). We have also analyzed 250 randomly created subsets of the original cohort, to investigate the relation between the result of TBSS analysis, and the size of the sample studied.
We have found a significant decrease in fractional anisotropy (FA) in the patient group. This change is present in most major white matter (WM) tracts including the corpus callosum, superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus, and posterior thalamic radiation. Furthermore, we identified a clear trend towards an increase in the number and spatial extent of significant voxels reported, with an increasing number of subjects included in the analysis.
Our study shows that FA is significantly decreased in patients at an early stage of schizophrenia, and that the extent of this finding is dependent on the size of studied sample; therefore underpowered studies might produce results with false spatial localization.
Schizophrenia Research 02/2015; 162(1-3). DOI:10.1016/j.schres.2015.01.029 · 3.92 Impact Factor
"Kanaan et al.  suggested a tractography-based analysis (TBA) method [Kunimatsu et al., 2012; Wakana et al., 2004] that analyzes the integrity of a specific tract bundle based on diffusion tractography [Mori and van Zijl, 2002]. However, because the TBA approach invokes tractography , it is operator-dependent and prone to poor reproducibility when less efficient fiber tracking algorithm is used [Tensaouti et al., 2011]. "
A. Saricicek, N. Zorlu, N. Yalin, C. Hidiroglu, B. Cavusoglu, D. Ceylan, E. Ada, Z. Tunca, A. Ozerdem
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