Association between social functioning and prefrontal cortex function during a verbal fluency task in schizophrenia: A near-infrared spectroscopic study

Aim: Impaired social functioning is a common characteristic of patients with schizophrenia. Social functioning requires the complex operation of various executive functions. Deficits in the prefrontal cortex (PFC) have been implicated in executive dysfunction. Here we aimed to clarify the relation between subjectively and objectively assessed social functioning, and their associations with PFC function in patients with schizophrenia. Methods: Twenty-three patients and 22 age- and sex-matched healthy controls (HC) were assessed. In the schizophrenia group, self- and caregiver-rated social functioning were measured using the Specific Level of Functioning Assessment (SLOF). The hemodynamic responses elicited by a verbal fluency task (VFT) in three regions of interest in the frontotemporal area were measured using multi-channel near-infrared spectroscopy (NIRS). We also investigated psychiatric symptoms, neurocognition, and cognitive insight to assess possible confounding factors. Results: Significant positive correlations were found between self- and caregiver-rated SLOF composite scores and three subdomain scores. Self- and caregiver-rated SLOF composite scores were significantly associated with dorsolateral PFC and frontopolar cortex (DLPFC/FPC) activation during the VFT. Psychiatric symptoms, global functioning, neurocognition, and cognitive insight were not associated with NIRS signals. General psychopathology was associated with NIRS signals in the ventrolateral PFC and the anterior temporal cortex. DLPFC and FPC activity may be associated with social functioning in patients with schizophrenia. Conclusion: Our results suggest that the two distinct assessments of social functioning were significantly correlated. Moreover, DLPFC and FPC function was strongly associated with social functioning and the ability to carry out daily life in patients with schizophrenia.