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.