Associations between intraindividual reaction time variability and prospective memory performance in patients with schizophrenia and healthy controls.

Introduction: Patients with schizophrenia exhibit prospective memory (PM) impairment. Intraindividual reaction time variability (IIRTV) is an index of attentional control that is required for PM. This study examined the differences in IIRTV between patients with schizophrenia and healthy controls and the relationship between IIRTV and PM performance.Method: Thirty-nine patients with schizophrenia and forty-two healthy controls were recruited to complete a PM task and the Sustained Attention to Response Task. IIRTV was calculated as the coefficient of variation (mean/SD) of reaction time over correctly responded trials in these tasks.Results: Patients with schizophrenia showed lower PM accuracy and increased IIRTV, while the associations between PM accuracy and IIRTV were significant in healthy controls but not in patients with schizophrenia.Conclusion: These findings suggest impaired PM and relationship between PM and attentional control in patients with schizophrenia.

Schizophrenia patients with poor clinical insight report less subjective memory problems.

This study aimed to explore the relationships among clinical insight, subjective memory complaints, and objective memory performance in patients with schizophrenia. We recruited 205 patients with schizophrenia and 221 healthy controls in this study. The participants were administered a subjective-report scale on memory (the Prospective and Retrospective Memory Questionnaire), and several objective memory tasks measuring verbal memory, visual memory, and working memory. Clinical insight was measured with an item in the Positive and Negative Syndrome Scale. We found that when patients with schizophrenia were divided into subgroups with good and poor insight, both subgroups showed impairment in memory performance compared with controls. The schizophrenia patients with good insight reported similar memory complaints as controls whereas patients with poor insight reported less memory complaints than did the controls. These findings suggest that clinical insight may be related to subjective memory complaints, but not objective memory performance.

The general facilitation effect of implementation intentions on prospective memory performance in patients with schizophrenia.

INTRODUCTION: Prospective memory (PM) refers to remembering to execute a planned intention in the future. It can be divided into event- and time-based, according to the nature of the PM cue. Event-based PM cues can be classified as focal or non-focal. Patients with schizophrenia (SCZ) have been found to be impaired in both event- and time-based PM. PM has been found to be improved by implementation intentions, which is an encoding strategy in the format of "if X then Y". This study examined the effect of implementation intentions on a non-focal event-based and a time-based PM task in patients with SCZ. METHODS: Forty-two patients with SCZ and 42 healthy controls were allocated to either an implementation intention or a control PM instruction condition and were asked to complete two PM tasks. RESULTS: Implementation intentions was found to improve performance in both the non-focal event-based and time-based PM tasks in patients with SCZ and healthy controls, with no costs to the ongoing task. The improvement in time-based PM performance in the implementation intentions condition was partially mediated by the frequency of clock checking behaviour. CONCLUSIONS: Implementation intentions can facilitate PM performance in patients with SCZ and has the potential to be used as a clinical intervention tool.

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

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.

The effect and mechanisms of implementation intention in improving prospective memory performance in schizophrenia patients.

People with schizophrenia (SCZ) have been shown to have prospective memory (PM) deficits. PM refers to the ability to remember to perform delayed intentions in the future and plays an important role in everyday independent functioning in SCZ. To date, few studies have investigated methods to improve PM in SCZ. This study aimed to examine whether implementation intention can improve PM performance and to explore its underlying mechanisms. Fifty people with SCZ and 50 demographically matched healthy controls (HC) participated in this study. Participants were randomly assigned to an implementation intention condition or a control instruction condition. Participants were required to make PM responses when PM cue words appeared while they were undertaking an ongoing task with two levels of cognitive load (1-back or 2-back). Results showed that people with SCZ were impaired in PM, and implementation intention improved PM performances for both SCZ and HC. Implementation intention improved PM performance in SCZ in both the low and the high cognitive load conditions without ongoing task cost, suggesting that implementation intention improved PM remembering in an automatic way. These results indicate that implementation intention may be a beneficial technique for improving PM performances in people with SCZ.

The effect of implementation intention on prospective memory: a systematic and meta-analytic review.

Prospective memory (PM) refers to remembering to perform a planned action at a future time. Implementation intention is an encoding method in the form of "if situation Y is encountered, then I will initiate the goal-directed behavior X". It has been applied to improve PM performances. The present study conducted a systematic and meta-analytic review on the effect and mechanism of implementation intention on PM. In the meta-analysis, 36 comparisons were included. The results showed that for healthy young adults, the overall effect of implementation intention in improving PM performances was significant with a medium effect size (d = 0.445). The combined verbal and imagery form of implementation intention had a relatively larger effect size (d = 0.590). For older adults, implementation intention had a medium to large effect size on their PM performances (d = 0.680). As for the mechanism, implementation intention seemed to reduce ongoing task performances in young adults as reflected by longer reaction time (d = 0.224) though the effect size was small. The present study supports the positive effect of implementation intention on PM. The mechanism and potential implications of this promising strategy especially for clinical/sub-clinical people are discussed.