Schizophrenia Spectrum Disorders Show Reduced Specificity and Less Positive Events in Mental Time Travel

Abstract

Mental time travel refers to the ability to recall past events and to imagine possible future events. Schizophrenia (SCZ) patients have problems in remembering specific personal experiences in the past and imagining what will happen in the future. This study aimed to examine episodic past and future thinking in SCZ spectrum disorders including SCZ patients and individuals with schizotypal personality disorder (SPD) proneness who are at risk for developing SCZ. Thirty-two SCZ patients, 30 SPD proneness individuals, and 33 healthy controls participated in the study. The Sentence Completion for Events from the Past Test (SCEPT) and the Sentence Completion for Events in the Future Test were used to measure past and future thinking abilities. Results showed that SCZ patients showed significantly reduced specificity in recalling past and imagining future events, they generated less proportion of specific and extended events compared to healthy controls. SPD proneness individuals only generated less extended events compared to healthy controls. The reduced specificity was mainly manifested in imagining future events. Both SCZ patients and SPD proneness individuals generated less positive events than controls. These results suggest that mental time travel impairments in SCZ spectrum disorders and have implications for understanding their cognitive and emotional deficits.

Differential associations between impaired autobiographical memory recall and future thinking in people with and without schizophrenia

“…People with schizophrenia were found to have a broad deficit in their ability to generate future events compared to healthy controls who did not have psychiatric diagnoses, with problems generating both positive and negative future events, compared to controls. These findings are in line with some previous evidence (Goodby & MacLeod, ; Raffard et al ., ) but contrast with another investigation which found evidence of a between‐group difference for positive but not negative events (Chen et al ., ). Participants in the latter investigation recalled so few negative events that this may have restricted the researchers’ ability to examine between‐group differences.…”

“…The present investigation replicated and extended upon studies comparing the ability to generate future events between people with and without schizophrenia (Chen et al ., ; D'Argembeau et al ., ; de Oliveira et al ., ; Huddy, Drake, & Wykes, ; Raffard et al ., , ). People with schizophrenia were found to have a broad deficit in their ability to generate future events compared to healthy controls who did not have psychiatric diagnoses, with problems generating both positive and negative future events, compared to controls.…”

“…In particular, it remains unclear whether people with psychotic symptoms or schizophrenia, compared to healthy controls without psychiatric diagnoses, have difficulty generating positive and negative future events (Goodby & MacLeod, ; Raffard, Esposito, Boulenger, & Van der Linden, ) or whether the deficit is specific to positive events (Chen et al ., ). Also, although future thinking impairments may be explained by impairments in autobiographical memory (Kwan, Carson, Addis, & Rosenbaum, ; Schacter, Addis, & Buckner, ), studies of schizophrenia have shown mixed findings regarding the association between past and future thinking abilities, or have not reported correlations specifically within the clinical group, instead conflating them with diagnoses‐free control participants (Chen et al ., ; D'Argembeau, Raffard, & Van der Linden, ). The present investigation provides further evidence regarding the nature of future thinking impairments in schizophrenia and associations with autobiographical memory abilities.…”

“…In the only study to examine between‐group differences in past and future thinking abilities and the association between these abilities, healthy control participants showed a positive correlation between identity/self‐related connections in their past and future narratives, and yet this correlation was not significant for participants with schizophrenia (Allé et al ., ). Other studies in this area have mostly combined groups of people with and without schizophrenia when reporting correlations between autobiographical memory and future thinking abilities (Chen et al ., ; D'Argembeau et al ., ), perhaps due to limited sample sizes within each group ( N = 16–32). It is possible that in more highly powered studies, group differences may emerge when correlating other aspects of past and future thinking, such as whether the ability to retrieve past events is related to the ability to generate future events.…”

“…In particular, we examine the correlations between future thinking and participants’ illness duration and also the severity of their symptoms, measured in terms of their scores on the Positive and Negative Syndrome Scale (PANSS). Although several studies have explored this latter association before, these studies have yielded mixed findings, perhaps due to their limited sample sizes (Chen et al ., ; D'Argembeau et al ., ; Raffard et al ., ), and so further clarification is needed. Participants with more severe depression and schizophrenia symptoms were expected to show worse future thinking abilities.…”