Differences in white matter microstructure in first-episode schizophrenia spectrum disorders vs healthy volunteers and their association with cognition.

OBJECTIVE: Both cognitive impairment and alterations in white matter tissue microstructure are well recognised in schizophrenia. We investigated whether differences in white matter microstructure underpin cognitive impairments in patients with first-episode schizophrenia spectrum disorders when controlling for multiple confounding factors. METHODS: We employed a cross-sectional study design and compared fractional anisotropy (FA) between individuals diagnosed with first- episode schizophrenia spectrum disorders (FES) (n = 68) and matched healthy controls (n = 120). We conducted multiple analyses of covariance (ANCOVAs) to compare the mean FA values for patients and controls across 27 white matter tracts. We conducted exploratory correlation analyses to determine if white matter tract differences were associated with global cognitive impairment as well as deficits across seven cognitive domains. RESULTS: We found widespread reductions in FA in patients compared to controls, after controlling for confounding variables, such as age, biological sex, education, substances, and childhood adversities. We found a significant positive correlation between the attention/vigilance domain and the splenium of the corpus collosum and external capsule after correction for multiple comparisons. In the control group we found no significant correlations between FA and cognition. CONCLUSION: Our findings provide a neurobiological basis for attentional cognitive deficits in schizophrenia, highlighting a potential role for the splenium of the corpus collosum and external capsule.

Cognitive-perceptual deficits and symptom correlates in first-episode schizophrenia.

BACKGROUND: Thought disorder and visual-perceptual deficits have been well documented, but their relationships with clinical symptoms and cognitive function remain unclear. Cognitive-perceptual deficits may underscore clinical symptoms in schizophrenia patients. AIM: This study aimed to explore how thought disorder and form perception are related with clinical symptoms and cognitive dysfunction in first-episode schizophrenia. SETTING: Forty-two patients with a first-episode of schizophrenia, schizophreniform or schizoaffective disorder were recruited from community clinics and state hospitals in the Cape Town area. METHODS: Patients were assessed at baseline with the Rorschach Perceptual Thinking Index (PTI), the Positive and Negative Syndrome Scale (PANSS) and the MATRICS Cognitive Consensus Battery (MCCB). Spearman correlational analyses were conducted to investigate relationships between PTI scores, PANSS factor analysis-derived domain scores and MCCB composite and subscale scores. Multiple regression models explored these relationships further. RESULTS: Unexpectedly, poor form perception (X- %) was inversely correlated with the severity of PANSS positive symptoms (r = -0.42, p = 0.02). Good form perception (XA%) correlated significantly with speed of processing (r = 0.59, p < 0.01), working memory (r = 0.48, p < 0.01) and visual learning (r = 0.55, p < 0.01). PTI measures of thought disorder did not correlate significantly with PANSS symptom scores or cognitive performance. CONCLUSIONS: Form perception is associated with positive symptoms and impairment in executive function during acute psychosis. These findings suggest that there may be clinical value in including sensory-perceptual processing tasks in cognitive remediation and social cognitive training programmes for schizophrenia patients.