Investigation of the cortical activity during episodic future thinking in schizophrenia: A functional near-infrared spectroscopy study.

Episodic future thinking (EFT) refers to mental simulation of possible future events, a process that mostly depends on episodic memory (EM). EFT impairment in schizophrenia was proposed to disturb continuity in self-functioning. Schizophrenia patients are also impaired in EM as well as executive functions (EFs). In the present study, we aimed to clarify the relationship between EFT and memory functions in schizophrenia by assessing (a) whether a group of individuals with schizophrenia (schizophrenia group [SG]) who have relatively intact long-term memory functions differ from healthy controls (control group [CG]) in terms of EFT performance, and (b) whether such difference is biologically represented in terms of cortical activity. We also aimed to clarify the role of EFs in EFT in 3 task conditions: past remembering with a single cue (PR), future imagination with a single cue (FI-1C), and future imagination with 3 given cues (FI-3C). Cortical activity was monitored by functional near-infrared spectroscopy. Although the two groups showed a comparable performance in the PR, the SG performed worse than the CG in the two future-imagination conditions. In the CG, mental flexibility predicted EFT, and EM predicted PR. No such relationship was observed in the SG. In the CG only, activity was higher in the FI-1C than the PR in the middle and superior temporal cortices. In the SG, activity in the rostral prefrontal cortex (rPFC) was negatively correlated with performance in FI-3C. These results suggest that EFT is still observed but not associated with EFs in individuals with schizophrenia having relatively intact memory functions. Altered activity in the rPFC may be associated with EFT impairment in schizophrenia. (PsycInfo Database Record (c) 2020 APA, all rights reserved).