White matter correlates of impulsivity in frontal lobe and their associations with treatment response in first-episode schizophrenia.

Background: It is known that increased impulsivity in schizophrenia patients causes poor treatment outcomes by increasing cost, stigma, hospitalization, treatment challenge, and physical harm. Dysfunction in the prefrontal cortex appears to be involved in the impulsivity associated with schizophrenia; nonetheless, there is a dearth of research on specific white matter alterations in the prefrontal cortex related to impulsivity.

Methods: We enrolled in the present study 119 first-episode schizophrenia patients. We measured their symptom severity at baseline and after eight weeks of treatment, using the positive and negative syndrome scale. We performed neuroimaging analysis using the Tract-Based Spatial Statistics program and by specifying the prefrontal white matter as a region of interest.

Results: In voxel-wise correlational analysis, we observed white matter regions showing significant positive correlations with poor impulse control scores, in both the right dorsolateral prefrontal cortex and the right frontal pole region. The fractional anisotropy values of these areas correlated positively with symptom severity at baseline. Moreover, after eight weeks, treatment non responders showed significantly higher fractional anisotropy values in the same areas.

Conclusions: The results of the present study suggest that white matter tracts in the right dorsolateral prefrontal cortex and the right frontal pole may underlie dysfunctional impulse control and could be potential predictive markers for short-term treatment in patients with first-episode schizophrenia.