Impaired empathic abilities and reduced white matter integrity in schizophrenia.

Empathic abilities are impaired in schizophrenia. Although the pathology of schizophrenia is thought to involve disrupted white matter integrity, the relationship between empathic disabilities and altered white matter in the disorder remains unclear. The present study tested associations between empathic disabilities and white matter integrity in order to investigate the neural basis of impaired empathy in schizophrenia. Sixty-nine patients with schizophrenia and 69 age-, gender-, handedness-, education- and IQ level-matched healthy controls underwent diffusion-weighted imaging. Empathic abilities were assessed using the Interpersonal Reactivity Index (IRI). Using tract-based spatial statistics (TBSS), the associations between empathic abilities and white matter fractional anisotropy (FA), a measure of white matter integrity, were examined in the patient group within brain areas that showed a significant FA reduction compared with the controls. The patients with schizophrenia reported lower perspective taking and higher personal distress according to the IRI. The patients showed a significant FA reduction in bilateral deep white matter in the frontal, temporal, parietal and occipital lobes, a large portion of the corpus callosum, and the corona radiata. In schizophrenia patients, fantasy subscales positively correlated with FA in the left inferior fronto-occipital fasciculi and anterior thalamic radiation, and personal distress subscales negatively correlated with FA in the splenium of the corpus callosum. These results suggest that disrupted white matter integrity in these regions constitutes a pathology underpinning specific components of empathic disabilities in schizophrenia, highlighting that different aspects of empathic impairments in the disorder would have, at least partially, distinct neuropathological bases.

Fujino J ，Takahashi H ，Miyata J ，Sugihara G ，Kubota M ，Sasamoto A ，Fujiwara H ，Aso T ，Fukuyama H ，Murai T ... -  《-》

Reduced white matter integrity and cognitive deficit in never-medicated chronic schizophrenia: a diffusion tensor study using TBSS.

Disrupted white matter (WM) integrity is the pathological hallmark of schizophrenia. Previous studies have reported the cognitive deficits that are associated with WM disruption in schizophrenia with anti-psychiatric treatment. However, no study has yet revealed the correlation between cognition and WM abnormalities in never-medicated chronic schizophrenia. We used the diffusion tensor imaging (DTI) with tract-based spatial statistics (TBSS) approach to investigate the whole-brain difference in the WM fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) values between 17 schizophrenia patients and 17 healthy controls matched in age, gender and education level. Patients' cognition was assessed through the MATRICS Consensus Cognitive Battery (MCCB). We explored the association between WM reduction and cognitive, clinical characteristics (severity of clinical symptoms, age, age of onset, illness duration). Voxel-wise statistics revealed that schizophrenia patients showed significant FA reduction in left inferior longitudinal fasciculus (ILF) and left inferior fronto-occipital fasciculus (IFOF), and no difference in MD, AD or RD as compared to healthy subjects. Furthermore, in the patients group, lower FA value of the left ILF and left IFOF significantly correlated with worse processing speed, as well as verbal learning and visual learning abilities. There was no correlation between the FA value and the severity of clinical symptoms, age, and age of onset or illness duration. Our results provide evidence to support that the disconnection of WM pathways may contribute to the pathophysiology of schizophrenia and suggest that the disturbance of left ILF and left IFOF integrity may contribute to cognitive deficits in schizophrenia, independent of effects of antipsychotic medication.

Liu X ，Lai Y ，Wang X ，Hao C ，Chen L ，Zhou Z ，Yu X ，Hong N ... -  《-》

Alexithymia and reduced white matter integrity in schizophrenia: a diffusion tensor imaging study on impaired emotional self-awareness.

Alexithymia is characterized by deficits in emotional self-awareness. A number of previous studies have revealed impaired emotional self-awareness in schizophrenia. Although the pathology of schizophrenia is thought to involve disrupted white matter integrity, its relationship with alexithymia remains unclear. The present study investigated associations between alexithymia and white matter integrity, to seek the neural basis of impaired emotional self-awareness in schizophrenia. Forty-four patients with schizophrenia and 44 age-, gender- and predicted IQ level-matched healthy controls underwent diffusion-weighted imaging. Alexithymia was assessed using the 20-item Toronto Alexithymia Scale (TAS-20). We applied tract-based spatial statistics to investigate the correlation between the TAS-20 total score and white matter fractional anisotropy (FA). TAS-20 scores were significantly higher in patients than in controls. In the patient group only, FA was negatively correlated with the TAS-20 total score in the corpus callosum, mostly the left part of the superior and inferior longitudinal fasciculi, the inferior occipito-frontal fasciculus, the anterior and posterior thalamic radiation, and the precuneus white matter. These results suggest that schizophrenia is associated with alexithymia, and that reduced white matter integrity within these regions constitutes an important pathology underlying impaired self-emotional awareness in schizophrenia.

Kubota M ，Miyata J ，Sasamoto A ，Kawada R ，Fujimoto S ，Tanaka Y ，Sawamoto N ，Fukuyama H ，Takahashi H ，Murai T ... -  《-》

Effect of clozapine on white matter integrity in patients with schizophrenia: a diffusion tensor imaging study.

Several diffusion tensor imaging (DTI) studies have reported disturbed white matter integrity in various brain regions in patients with schizophrenia, whereas only a few studied the effect of antipsychotics on DTI measures. The aim of this study was to investigate the effect of 12 weeks of clozapine treatment on DTI findings in patients with schizophrenia, and to compare the findings with those in unaffected controls. The study included 16 patients with schizophrenia who were assessed with the Positive and Negative Syndrome Scale, a neurocognitive test battery, and DTI at baseline and 12 weeks after the initiation of clozapine treatment. Eight unaffected controls were assessed once with the neurocognitive test battery and DTI. Voxel-wise analysis of DTI data was performed via tract-based spatial statistics (TBSS). Compared with the control group, the patient group exhibited lower fractional anisotropy (FA) in 16 brain regions, including the bilateral superior longitudinal fasciculi, inferior fronto-occipital fasciculi, superior and inferior parietal lobules, cingulate bundles, cerebellum, middle cerebellar peduncles, and left inferior longitudinal fasciculus, whereas the patients had higher FA in six regions, including the right parahippocampus, left anterior thalamic radiation, and right posterior limb of the internal capsule before clozapine treatment. After 12 weeks of treatment with clozapine, white matter FA was increased in widespread brain regions. In two of the regions where FA had initially been lower in patients compared with controls (left inferior fronto-occipital fasciculus and superior parietal lobule), clozapine appeared to increase FA. An improvement in semantic fluency was correlated with the increase in FA value in the left inferior fronto-occipital fasciculus. An increase in FA following 12 weeks of treatment with clozapine suggests that this treatment alters white matter microstructural integrity in patients with schizophrenia previously treated with typical and/or atypical antipsychotics and, in some locations, reverses a previous deficit.

Ozcelik-Eroglu E ，Ertugrul A ，Oguz KK ，Has AC ，Karahan S ，Yazici MK ... -  《-》

Tract-specific analysis of white matter integrity disruption in schizophrenia.

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.

Kunimatsu N ，Aoki S ，Kunimatsu A ，Abe O ，Yamada H ，Masutani Y ，Kasai K ，Yamasue H ，Ohtomo K ... -  《PSYCHIATRY RESEARCH》