Prospective memory in schizophrenia: primary or secondary impairment?

Further clarification of cognitive processes of prospective memory in schizophrenia by comparing eye-tracking and ecologically-valid measurements

The aim of this study is to compare ecologically-valid measure (the Cambridge Prospective Memory Test, CAMPROMPT) and laboratory measure (eye-tracking paradigm) in assessing prospective memory (PM) in individuals with schizophrenia spectrum disorders (SSDs). In addition, eye-tracking indices are used to examine the relationship between PM and other cognitive domains in SSDs patients. Initially, the study sample was formed by 32 SSDs patients and 32 healthy control subjects (HCs) who were matched in sociodemographic profile and the performance on CAMPROMPT. An eye-tracking paradigm was employed to examine the differences in PM accuracy and key cognitive processes (e.g., cue monitoring) between the two groups. Additional 31 patients were then recruited to investigate the relationship between PM cue monitoring, other cognitive functions, and the severity of clinical symptoms within the SSDs group. The monitoring of PM cue was reflected in total fixation time and total fixation counts for distractor words. Cognitive functions were assessed using the Chinese version of the MATRICS Consensus Cognitive Battery (MCCB). The Positive and Negative Syndrome Scale (PANSS) was applied to assess psychopathology. SSDs patients exhibited fewer total fixation counts for distractor words and lower PM accuracy compared to HCs, even though they were priori matched on CAMPROMPT. Correlation analysis within the SSDs group (63 cases) indicated a negative correlation between PM accuracy and PANSS total score, and a positive correlation with working memory and attention/vigilance. Regression analysis within the SSDs group revealed that higher visual learning and lower PANSS total scores independently predicted more total fixation counts on distractor words. Impairment in cue monitoring is a critical factor in the PM deficits in SSDs. The eye-tracking laboratory paradigm has advantages over the ecologically-valid measurement in identifying the failure of cue detection, making it a more sensitive tool for PM deficits in patients with SSDs.

Effects of bilateral repetitive transcranial magnetic stimulation on prospective memory in patients with schizophrenia: A double-blind randomized controlled clinical trial

AIMS

To investigate effects of repetitive transcranial magnetic stimulation (rTMS) on the prospective memory (PM) in patients with schizophrenia (SCZ).

METHODS

Fifty of 71 patients completed this double-blind placebo-controlled randomized trial and compared with 18 healthy controls' (HCs) PM outcomes. Bilateral 20 Hz rTMS to the dorsolateral prefrontal cortex at 90% RMT administered 5 weekdays for 4 weeks for a total of 20 treatments. The Positive and Negative Symptom Scale (PANSS), the Scale for the Assessment of Negative Symptoms (SANS), and PM test were assessed before and after treatment.

RESULTS

Both Event-based PM (EBPM) and Time-based PM (TBPM) scores at baseline were significantly lower in patients with SCZ than that in HCs. After rTMS treatments, the scores of EBPM in patients with SCZ was significantly improved and had no differences from that in HCs, while the scores of TBPM did not improved. The negative symptom scores on PANSS and the scores of almost all subscales and total scores of SANS were significantly improved in both groups.

CONCLUSIONS

Our findings indicated that bilateral high-frequency rTMS treatment can alleviate EBPM but not TBPM in patients with SCZ, as well as improve the negative symptoms.

SIGNIFICANCE

Our results provide one therapeutic option for PM in patients with SCZ.

Prospective memory in early and established psychosis: An Indian perspective

Individuals affected by psychosis often have deficits in several neurocognitive functions. Prospective memory (PM), the ability to remember to do things, is crucial for activities of daily living, social and occupational functioning, but very few studies have attempted to examine this domain of functioning in people with psychosis, particularly in India. A total of 71 patients with psychosis, (both early and established psychosis), and 140 age, gender and education-matched healthy controls were assessed using the Positive and Negative Symptom Scale, Hospital Anxiety and Depression scale, and Addenbrooke's Cognitive Examination. PM was assessed using the Cambridge Prospective Memory Test and the Prospective and Retrospective Memory Questionnaire (PRMQ). Group differences were evaluated using Mann-Whitney U-tests. Significantly greater cognitive deficits, higher anxiety and depression were evident in the psychosis group compared with controls. The psychosis group performed significantly poorer on both time- and event-based tests in CAMPROMPT than controls. These differences remained when controlling for age, education, general cognitive functioning and mood. The subjective measure of PM (PRMQ) did not differentiate the two groups. The PM performance of early and established psychosis patients was similar. Comparisons with cross-cultural data (PRMQ UK norms and CAMPROMPT and PRMQ Chinese data) revealed important differences in PM performance. Individuals with psychosis have significant deficits in both time- and event-based PM. CAMPROMPT emerged as a more sensitive PM measure compared with PRMQ. Results from cross-cultural comparisons underscore the need for cultural contextualization of assessments.

An ecologically sensitive measure of executive cognition (the Breakfast Task) improves prediction of functional outcome in schizophrenia

Previous work has found that the Breakfast Task (BT), a computerized, ecologically informed executive ability measure, is sensitive to group differences in aging, acquired brain injury, and Parkinson's disease. We investigated whether this measure improves the prediction of functional status over and above standard measures of general intellectual ability, relationship perception, life skills, and symptom severity in individuals with schizophrenia. Regression analyses were conducted to evaluate the joint and incremental validity of the BT in predicting functional disability scores on the World Health Organization Disability Assessment Scale (WHODAS 2.0). Analyses with combined patient (n = 25) and control (n = 32) participants showed that participant status (patients versus control) was the only significant predictor of functional outcome. However, in the patient data, the proportion of variance accounted for improved significantly (model R² of 4% vs. 25%) when BT scores were added to a model containing clinical (Brief Psychiatric Rating Scale), social (Relationships Across Domains), intellectual (Wechsler Abbreviated Scale of Intelligence), and life skills (Canadian Objective Assessment of Life Skills) measures. Results suggest that the BT, a tool that captures complex executive functioning, improves the prediction of disability in patients with schizophrenia and has potential assessment applications.

Memory and learning for sleep and circadian treatment in serious mental illness treated in a community mental health setting

OBJECTIVE

Existing research has demonstrated that patient memory and learning of treatment contents are poor and poorer learning is associated with worse treatment outcome. Most prior studies have included individuals from only a single diagnostic group, offer limited data on possible contributors to poor memory and learning, and have included small samples recruited in university settings. This study sought to describe patient recall of treatment contents, describe patient learning of treatment contents, examine contributors to patient recall and learning of treatment contents, and examine the association of patient recall and learning of treatment contents with treatment outcome.

METHODS

Adults with serious mental illness and sleep and circadian dysfunction (N = 99) received the Transdiagnostic Intervention for Sleep and Circadian Dysfunction in a community mental health setting. Measures of recall, learning, age, years of education, symptom severity, and treatment outcome were collected at post-treatment and 6-month follow-up.

RESULTS

Recall and learning were poor, fewer years of education was associated with worse recall and learning, and recall and learning were not associated with treatment outcome.

CONCLUSIONS

The findings offer evidence that poor patient memory for, and learning of, treatment contents extends to community settings and are transdiagnostic concerns.

Prospective memory impairment in neurological disorders: implications and management

Prospective memory is a core neurocognitive ability that refers to memory for future intentions, such as remembering to take medications and to switch off appliances. Any breakdown in prospective memory, therefore, has serious implications for the ability to function independently in everyday life. In many neurological disorders, including Parkinson disease and dementia, prospective memory deficits are common even in the earliest stages and typically become more severe with disease progression. Consequently, clinical assessment of prospective memory is of critical importance. This article provides an overview of the various manifestations and neural bases of prospective memory deficits. To facilitate clinical decision-making, validated measures of this construct are identified and their suitability for clinical practice is discussed, focusing in particular on clinical sensitivity and psychometric properties. The article concludes by reviewing the approaches that can be used to rehabilitate different types of prospective memory impairment, and algorithms to guide the evaluation and treatment of these impairments are provided.

Instruments Measuring Prospective Memory: A Systematic and Meta-Analytic Review

OBJECTIVE

To identify the available measures to assess prospective memory (PM) abilities, to describe their content, and to quantitatively summarize the effects of various diseases on PM depending on the type of assessment.

METHOD

Three databases (PsycInfo, PsycArticles and PubMed) were searched up to June 2019 to identify the existing PM measures. The identified PM measures were classified according to the type of assessment: test batteries, single-trial procedures, questionnaires, and experimental procedures. The characteristics and psychometric properties were presented. PM performances were compared between patients with various diseases and controls depending on the type of assessment.

RESULTS

Most of the 16 measures identified evaluated both event- and time-based tasks, were linked to functional outcomes, showed empirical evidences regarding validity and reliability, and provided parallel versions. To a slightly lesser extent, few measures provided normative data, translations/adaptation into another language, cutoff scores for diagnostic purposes, qualitative scoring, parallel version, and external aids during the test. Compared to healthy controls, patients had significantly poorer performances when PM was assessed with experimental procedures. Heterogeneous data precluded the interpretation of a summary effect for test batteries, single-trial procedures, and questionnaires. Planned subgroup analyses indicated consistent PM impairment for patients compared to controls for three test batteries. However, PM complaints did not differ between patients and controls.

CONCLUSIONS

These results suggest that the use of PM test batteries and experimental procedures are relevant for detecting performance variations in diverse clinical populations. Clinical implications and directions for future research are discussed.

The effect of implementation intentions on prospective memory performance in patients with schizophrenia: A multinomial modeling approach

Patients with schizophrenia (SCZ) consistently show prospective memory (PM) impairments, and the technique of implementation intentions has been shown to improve PM performance in these patients. PM is considered to have prospective and retrospective components. However, it remains unclear which component of PM is impaired in patients with SCZ and which component(s) is facilitated by implementation intentions (II). The present study aimed to examine these two issues. Forty-two patients with SCZ and 42 matched healthy controls were randomly assigned to an II group or a typical instruction group. All participants were administered a color-matching PM task. Results showed that, using a multinomial-modeling approach, patients with SCZ exhibited impairment in the retrospective component of PM. In addition, while II improved the prospective PM component in healthy controls, both prospective and retrospective PM components in patients with SCZ were improved. Together, our results shed light on the mechanism of PM impairment in SCZ patients and the mechanism of II in improving PM performance.

Neural correlates of temporal updating and reasoning in association with neuropsychiatric disorders

Here we argue how Hoerl & McCormack's dual system proposal may change the current view about the neural correlates underlying temporal information processing. We also consider that the concept of the dual system may help characterize various timing disabilities in neuropsychiatric disorders from the new perspective.

A potential barrier to adherence? Memory for future intentions is impaired in hemodialysis patients

INTRODUCTION

End-stage renal disease (ESRD) has been associated with a range of cognitive deficits, including impaired retrospective memory and attention. Prospective memory (PM) is memory for future intentions, such as remembering to take medication on time. Prospective memory has not been examined in any ESRD patients; yet, the implications upon diet and medication management could potentially have detrimental effects on patient welfare. This is the first study to examine PM in ESRD patients being treated with hemodialysis (HD).

METHODS

Hemodialysis patients (n = 18) were compared with age-matched and education-matched controls (n = 18) on a boardgame task that emulates a typical week of activities (i.e., grocery shopping, meetings with friends), requiring the participant to remember a series of upcoming tasks. Other measures were also examined, including general cognitive decline, measures of independent living, IQ, and mood.

FINDINGS

Patients recalled significantly fewer upcoming events than the control group, suggesting an impairment of PM. No significant relationship was found between PM performance and any other measures, suggesting the difference between groups is likely due to the effects of ESRD, HD treatment, or some associated comorbidity.

DISCUSSION

This is the first study to demonstrate a PM deficit in patients undergoing HD treatment. This finding contributes to the current knowledge of the cognitive profile of patients undergoing HD while also highlighting the implications that a PM deficit may have on patient quality of life. The finding may go some way to explaining variances in patients' ability to monitor and adhere to medication and dietary regimes and, ultimately, to live independently. The study also highlights the necessity of viewing treatment for ESRD as a holistic process to maximize patient well-being.

Prospective memory in schizophrenia: A meta-analysis of comparative studies

BACKGROUND

Impairment of prospective memory (PM) in schizophrenia has gained increasing attention. This meta-analysis systematically examined PM impairment in schizophrenia.

METHODS

Both English (PubMed, PsycINFO, EMBASE, and Cochrane Library) and Chinese (WanFang, Chinese Biomedical and China Journal Net databases) databases were systematically searched from their inception until August 14, 2017. Case-control studies of PM in schizophrenia were included. Standardized mean differences (SMDs) and their 95% confidence interval (CI) were calculated using the random-effects model.

RESULTS

Twenty-nine case-control studies (n = 2492) were included in the analyses. The overall and three subtypes of PM were compared between patients with schizophrenia (n = 1284) and healthy controls (n = 1208). Compared to healthy controls, patients performed significantly poorer in overall (SMD = -1.125), time-based (SMD = -1.155), event-based (SMD = -1.068), and activity-based PM (SMD = -0.563). Subgroup analyses revealed significant differences between older and younger patients (SMD = -1.398 vs. -0.763), higher male predominance and no sex predominance (SMD = -1.679 vs. -0.800), lower and higher education level (SMD = -1.373 vs.-0.637), chronic and first-episode patients (SMD = -1.237 vs. -0.641) and between eco-valid and dual-task laboratory measurements (SMD = -1.542 vs. -0.725) regarding overall PM. Meta-regression analysis showed that higher negative symptom score was significantly associated with more severe overall PM impairment in patients (P = 0.022).

CONCLUSIONS

In this meta-analysis the overall PM and all its subtypes, particularly the time-based PM, were significantly impaired in schizophrenia.

A comparison of different types of prospective memory reminders in schizophrenia

People with schizophrenia often experience difficulties with prospective memory (PM), but few empirical studies have directly compared the effectiveness of different types of reminders in remediating these difficulties. In the present study, two distinct types of reminders were compared to a standard (no reminder) condition in outpatients with schizophrenia (n = 30) and controls (n = 30). Using an adapted version of the well-validated laboratory PM measure, Virtual Week, participants were asked to complete three different conditions (counterbalanced), in which they were (i) provided with access to self-initiated reminders, (ii) provided with experimenter-initiated reminders, and (iii) completed a standard (no-reminder) condition. Both groups benefited from the provision of reminders, but self-initiated reminders were the most beneficial, particularly for time-based tasks. These data align with a broader literature that shows PM can be enhanced by the use of reminders. However, it extends this literature in an important way by showing that these benefits are equivalent for people with schizophrenia, and may be greatest where access to reminders is self-initiated. The implications of these data for the development of rehabilitative interventions are discussed.

Reinforcing the prospective remembering of children with autism spectrum disorder

Prospective memory is remembering to carry out a behavior on a particular occasion or at a specific time in the future. This form of remembering is critical for the daily functioning of children with autism spectrum disorder (ASD) and their functional independence from caregivers. We used a single-subject design to investigate whether reinforcement increased the accuracy of prospective remembering in the context of a computerized board game, Virtual Week, of four 6- to 7-year-old children diagnosed with ASD. Reinforcement increased accuracy for all participants compared to baseline performance and effects were maintained after reinforcement was discontinued for three of four children. This is the first study of which we are aware to use a reinforcement-based behavioral intervention to improve the prospective remembering of children with ASD. Limitations and areas for future research are discussed.

Mild cognitive impairment and prospective memory: translating the evidence into neuropsychological practice

OBJECTIVE

There has been a recent rapid development of research characterizing prospective memory performance in mild cognitive impairment (MCI) in older age. However, this body of literature remains largely separated from routine clinical practice in neuropsychology. Furthermore, there is emerging evidence of effective interventions to improve prospective memory performance. Therefore, our objective in this article was to offer a clinical neuropsychological perspective on the existing research in order to facilitate the translation of the evidence-base into clinical practice.

METHOD

By conducting a critical review of the existing research related to prospective memory and MCI, we highlight how this data can be introduced into clinical practice, either within diagnostic assessment or clinical management.

CONCLUSIONS

Prospective memory is impaired in older adults with MCI, with a pattern of performance that helps with differential diagnosis from healthy aging. Clinical neuropsychologists are encouraged to add prospective memory assessment to their toolbox for diagnostic evaluation of clients with MCI. Preliminary findings of prospective memory interventions in MCI are promising, but more work is required to determine how different approaches translate to increasing independence in everyday life.

Prospective Memory Performance in Persons With Schizophrenia and Bipolar Disorder and Healthy Persons

PURPOSE

There is a paucity of studies comparing prospective memory (PM) impairment between persons with schizophrenia and bipolar disorder. The aim of this study was to directly compare PM performances of these two groups and healthy controls.

DESIGN AND METHODS

A total of 44 persons with schizophrenia and 76 with bipolar disorder, and 44 healthy controls formed the study sample.

FINDINGS

Patients were found to be impaired in PM relative to controls and the two patient groups showed similar level of PM performance after controlling confounding sociodemographic and clinical variables.

PRACTICE IMPLICATIONS

The findings add to the evidence concerning the neurocognitive similarity between cohorts of schizophrenia and bipolar disorder with respect to PM. Rehabilitative effort in PM remedies for both patient groups is warranted.

Prospective memory deficits in patients with depression: A meta-analysis

BACKGROUND

Prospective memory (PM) can be impaired in patients with psychiatric disorders including depression. This meta-analysis systematically examined PM in patients with depression.

METHODS

The meta-analysis was conducted according to the guidelines from Strengthening the Reporting of Observational studies in Epidemiology (STROBE). Case-control studies on PM in patients with depression were included. Standardized mean differences (SMDs) and 95% confidence interval (CI) were calculated using random effect models.

RESULTS

Ten case-control studies (n = 596) comparing patients with depression (n = 299) with healthy controls (n = 297) were included in the analyses. Compared with healthy controls, patients with depression had significant impairment in event-based PM (EBPM) [8 trials, n = 436; SMD: -0.87 (95%CI: -1.43, -0.31), P = 0.002; I² = 87%]. Significance was observed after removing two outlier trials [SMD: -0.44 (95%CI: -0.69, -0.20), P = 0.0004; I² = 23%] and also in 8 out of the 13 subgroup analyses. Similarly, time-based PM (TBPM) was significantly impaired in patients with depression [4 trials, n = 239; SMD: -0.89 (95%CI: -1.46, -0.31), P = 0.003; I² = 78%] when compared with healthy controls.

CONCLUSIONS

This meta-analysis showed that both TBPM and EBPM appeared to be impaired in patients with depression.

Impaired cue identification and intention retrieval underlie prospective memory deficits in patients with first-episode schizophrenia

OBJECTIVE

Schizophrenia is associated with impairment in prospective memory, the ability to remember to carry out an intended action in the future. It has been established that cue identification (detection of the cue event signaling that an intended action should be performed) and intention retrieval (retrieval of an intention from long-term memory following the recognition of a prospective cue) are two important processes underlying prospective memory. The purpose of this study was to examine prospective memory deficit and underlying cognitive processes in patients with first-episode schizophrenia.

METHODS

This study examined cue identification and intention retrieval components of event-based prospective memory using a dual-task paradigm in 30 patients with first-episode schizophrenia and 30 healthy controls. All participants were also administered a set of tests assessing working memory and retrospective memory.

RESULTS

Both cue identification and intention retrieval were impaired in patients with first-episode schizophrenia compared with healthy controls ( ps < 0.05), with a large effect size for cue identification (Cohen's d = 0.98) and a medium effect size for intention retrieval (Cohen's d = 0.62). After controlling for working memory and retrospective memory, the difference in cue identification between patients and healthy controls remained significant. However, the difference in intention retrieval between the two groups was no longer significant. In addition, there was a significant inverse relationship between cue identification and negative symptoms ( r = -0.446, p = 0.013) in the patient group.

CONCLUSION

These findings suggest that both cue identification and intention retrieval in event-based prospective memory are impaired in patients with first-episode schizophrenia. Cue identification and intention retrieval could be potentially used as biomarkers for early detection and treatment prognosis of schizophrenia. In addition, addressing cue identification deficit through cognitive enhancement training may potentially improve negative symptoms as well.

Longitudinal changes in prospective memory and their clinical correlates at 1-year follow-up in first-episode schizophrenia

This study aimed to investigate prospective memory (PM) and the association with clinical factors at 1-year follow-up in first-episode schizophrenia (FES). Thirty-two FES patients recruited from a university-affiliated psychiatric hospital in Beijing and 17 healthy community controls (HCs) were included. Time- and event-based PM (TBPM and EBPM) performances were measured with the Chinese version of the Cambridge Prospective Memory Test (C-CAMPROMPT) at baseline and at one-year follow-up. A number of other neurocognitive tests were also administered. Remission was determined at the endpoint according to the PANSS score ≤ 3 for selected items. Repeated measures analysis of variance revealed a significant interaction between time (baseline vs. endpoint) and group (FES vs. HCs) for EBPM (F(1, 44) = 8.8, p = 0.005) and for all neurocognitive components. Paired samples t-tests showed significant improvement in EBPM in FES (13.1±3.7 vs. 10.3±4.8; t = 3.065, p = 0.004), compared to HCs (15.7±3.6 vs. 16.5±2.3; t = -1.248, p = 0.230). A remission rate of 59.4% was found in the FES group. Analysis of covariance revealed that remitters performed significantly better on EBPM (14.9±2.6 vs. 10.4±3.6; F(1, 25) = 12.2, p = 0.002) than non-remitters at study endpoint. The association between EBPM and 12-month clinical improvement in FES suggests that EBPM may be a potential neurocognitive marker for the effectiveness of standard pharmacotherapy. Furthermore, the findings also imply that PM may not be strictly a trait-related endophenotype as indicated in previous studies.

Effects of Episodic Future Thinking and Self-Projection on Children's Prospective Memory Performance

The present study is the first to investigate the benefits of episodic future thinking (EFT) at encoding on prospective memory (PM) in preschool (age: M = 66.34 months, SD = 3.28) and primary school children (age: M = 88.36 months, SD = 3.12). A second aim was to examine if self-projection influences the possible effects of EFT instructions. PM was assessed using a standard PM paradigm in children with a picture-naming task as the ongoing activity in which the PM task was embedded. Further, two first- and two second-order ToM tasks were administered as indicator of children’s self-projection abilities. Forty-one preschoolers and 39 school-aged children were recruited. Half of the participants in each age group were instructed to use EFT as a strategy to encode the PM task, while the others received standard PM instructions. Results revealed a significant age effect, with school-aged children significantly outperforming preschoolers and a significant effect of encoding condition with overall better performance when receiving EFT instructions compared to the standard encoding condition. Even though the interaction between age group and encoding condition was not significant, planned comparisons revealed first evidence that compared to the younger age group, older children’s PM benefitted more from EFT instructions during intention encoding. Moreover, results showed that although self-projection had a significant impact on PM performance, it did not influence the effects of EFT instructions. Overall, results indicate that children can use EFT encoding strategies to improve their PM performance once EFT abilities are sufficiently developed. Further, they provide first evidence that in addition to executive functions, which have already been shown to influence the development of PM across childhood, self-projection seems to be another key mechanism underlying this development.

Preserved Intention Maintenance and Impaired Execution of Prospective Memory Responses in Schizophrenia: Evidence from an Event-based Prospective Memory Study

Executive system dysfunction and impaired prospective memory (PM) are widely documented in schizophrenia. However, it is not yet clarified which components of PM function are impaired in this disorder. Two plausible target components are the maintenance of delayed intentions and the execution of PM responses. Furthermore, it is debated whether the impaired performance on frequently used executive tasks is associated with deficit in PM functions. The aim of our study was twofold. First, we aimed to investigate the specific processes involved in event-based PM function, mainly focusing on difference between maintenance of intention and execution of PM responses. Second, we aimed to unfold the possible connections between executive functions, clinical symptoms, and PM performance. An event-based PM paradigm was applied with three main conditions: baseline (with no expectation of PM stimuli, and without PM stimuli), expectation condition (participants were told that PM stimuli might occur, though none actually did), and execution condition (participants were told that PM stimuli might occur, and PM stimuli did occur). This procedure allowed us to separately investigate performances associated with intention maintenance and execution of PM responses. We assessed working memory and set-shifting executive functions by memory span tasks and by the Wisconsin Card Sorting Test (WCST), respectively. Twenty patients diagnosed with schizophrenia and 20 healthy control subjects (matched according to age and education) took part in the study. It was hypothesized that patients would manifest different levels of performance in the expectation and execution conditions of the PM task. Our results confirmed that the difference between baseline performance and performance in the execution condition (execution cost) was significantly larger for participants diagnosed with schizophrenia in comparison with matched healthy control group. However, this difference was not observed in the expectation condition. The PM performance in the execution condition was correlated with impaired executive functions in schizophrenia. Specifically, the size of execution cost positively correlated with percent of perseverative errors committed on WCST by the patient group. Our results suggest that maintenance of delayed intentions is unimpaired in schizophrenia, whereas the impairment in execution of PM responses is associated with set-shifting deficit.

Time-based but not event-based prospective memory remains impaired one year after the onset of schizophrenia: A prospective study

BACKGROUND

Prospective memory (PM) deficits have been consistently found in people with schizophrenia. Although there is evidence to suggest that PM deficits may be putative markers for schizophrenia, no longitudinal study has investigated the persistence of PM deficits.

AIMS

We examined whether PM deficits persist after the onset of schizophrenia, and compared the trajectories of time- and event-based PM performance 12 months after illness onset. We also examined whether the association between PM and clinical symptoms changes over time 12 months after illness onset.

METHOD

We recruited 58 individuals with first-episode schizophrenia for a 12-month follow-up study. Comparison participants were 37 healthy individuals who were matched in terms of demographics and intelligence with the patient group. PM functions and clinical symptoms were measured at baseline, the sixth month, and the twelfth month, using a computerized PM task and the Positive and Negative Syndrome Scale.

RESULTS

People with schizophrenia showed a gradual improvement in both time- and event-based PM 12 months after illness onset. However, compared to event-based PM, deficit in time-based PM persisted and was relatively stable. At baseline, PM functions were not associated with clinical symptoms. However, an association between time-based PM and PANSS positive and general symptoms emerged 12 months after the onset of schizophrenia.

CONCLUSION

People with first-episode schizophrenia exhibit persistent time-based PM deficit. Our findings support that PM deficit, in particular, time-based deficit, may be a putative neuropsychological marker of schizophrenia.

Event-related brain potential correlates of prospective memory in symptomatically remitted male patients with schizophrenia

Prospective memory (PM) refers to the ability to remember to perform intended actions in the future. Although PM deficits are a prominent impairment in schizophrenia, little is still known about the nature of PM in symptomatically remitted patients with schizophrenia. To address this issue, event-related brain potentials (ERPs) were recorded from 20 symptomatically remitted patients with schizophrenia and 20 healthy controls during an event-based PM paradigm. Behavioral results showed that symptomatically remitted patients with schizophrenia performed poorly on the PM task compared with healthy controls. On the neural level, the N300, a component of the ERPs related to PM cue detection, was reliable across these two groups, suggesting a degree of functional recovery of processes supporting cue detection in patients with symptomatically remitted schizophrenia. By contrast, the amplitude of the prospective positivity, a component of the ERPs related to PM intention retrieval, was significantly attenuated in symptomatically remitted schizophrenia patients relative to healthy controls. Furthermore, a significant positive correlation between the amplitude of the prospective positivity and accuracy on the PM task was found in those patients, indicating that patients’ poor performance on this task may result from the failure to recover PM cue-induced intention from memory. These results provide evidence for the existence of altered PM processing in patients with symptomatically remitted schizophrenia, which is characterized by a selective deficit in retrospective component (intention retrieval) of PM. Therefore, these findings shed new light on the neurophysiological processes underlying PM in schizophrenia patients during clinical remission.

Forming implementation intentions improves prospective memory in early psychosis

The study examined whether individuals with early psychosis are impaired in prospective memory (PM), that is, remembering to execute a planned intention in the future, and whether implementation intentions can improve their PM performance. Thirty participants with early psychosis and 33 healthy controls were randomly allocated to either an implementation intentions or control condition and completed a computerised event-based PM task. Participants were also administered two standardised tests of PM and an abbreviated IQ test. Results demonstrated that individuals with early psychosis showed PM deficits relative to healthy controls on the computerised PM task and on some standardised measures of PM. The PM performance of the early psychosis group benefited from forming implementation intentions. Implementation intentions was concluded to be an effective strategy for improving PM performance in individuals with early psychosis.

Checking Behaviours, Prospective Memory and Executive Functions

Explanations implicating memory in the causes and severity of checking symptoms have focused primarily on retrospective memory, and relatively little attention has been paid to prospective memory. Limited research has examined the relationship between prospective memory and executive functions. We assessed whether impairments in prospective memory and executive function predict checking symptoms in a sample of 106 adults. Checking symptoms were assessed using the Padua Inventory Washington State University Revision (PI-WSUR). All participants completed the prospective memory questionnaire (PMQ) and four computerised executive function tasks from the CANTAB, measuring inhibition, planning, attention set-shifting and working memory. Prospective memory and inhibition predicted checking symptom severity. Importantly, there were no correlations between internally cued prospective memory and inhibition or between prospective memory aiding strategies and inhibition. These variables appear to have an independent role in checking. The current findings highlight prospective memory and inhibition as key contributors to the checking symptom profile and provide the first evidence that these cognitive processes may independently contribute to checking symptoms. These findings have implications for a model in which memory performance is thought to be secondary to impairments in executive functions.

Prospective memory impairment in chronic heart failure

Although cognitive deficits are common in patients with chronic heart failure (CHF), no study to date has investigated whether these deficits extend to the capacity to execute delayed intentions (prospective memory, PM). This is a surprising omission given the critical role PM plays in correctly implementing many important CHF self-care behaviors. The present study aimed to provide the first empirical assessment of PM function in people with CHF. The key dependent measure was a laboratory measure of PM that closely simulates PM tasks in daily life - Virtual Week. A group comparison design was used, with 30 CHF patients compared to 30 demographically matched controls. Background measures assessing executive functions, working memory, and verbal memory were also administered. The CHF group exhibited significant PM impairment, with difficulties generalizing across different types of PM tasks (event, time, regular, irregular). The CHF group also had moderate deficits on several of the background cognitive measures. Given the level of impairment remained consistent even on tasks that imposed minimal demands on memory for task content, CHF-related difficulties most likely reflects problems with the prospective component. However, exploratory analyses suggest that difficulties with retrospective memory and global cognition (but not executive control), also contribute to the PM difficulties seen in this group. The implications of these data are discussed, and in particular, it is argued that problems with PM may help explain why patient engagement in CHF self-care behaviors is often poor.

Problems in remembering to carry out future actions in first-episode schizophrenia: primary or secondary impairment?

Prospective memory (PM) is the ability to remember to carry out intended actions in the future. Empirical evidence suggests that PM deficits exist in individuals with chronic schizophrenia. However, it is unclear whether PM deficits in first-episode schizophrenia exist independently from other neuropsychological deficits. Moreover, prior research using patients with first-episode has been limited to small inpatient samples. We aimed to clarify the nature and extent of PM deficits in individuals with first-episode schizophrenia, using a large outpatient sample. Participants were 91 clinically stable outpatients with first-episode schizophrenia and 83 healthy controls. PM was assessed using both a subjective self-reported checklist and a laboratory-based task capturing time- and event-based PM. A battery assessing verbal and visuo-spatial working memory, as well as executive functions was also administered. ANOVA analyses showed that patients with first-episode schizophrenia performed significantly poorer than healthy controls in time- and event-based PM. Stepwise linear regression analyses suggested that cognitive flexibility predicted time- and event-based PM; and working memory predicted event-based PM. Subgroup analyses showed that "cognitive-preserved" patients with first-episode schizophrenia tended to perform poorer in time-based PM deficit than healthy controls who were matched in IQ and other neuropsychological functions. Overall, our results provide substantial evidence to support that time-based PM deficits in first-episode schizophrenia are apparent and not entirely attributable to other neuropsychological deficits. PM may constitute a neuropsychological marker for schizophrenia.

Prospective memory performance in non-psychotic first-degree relatives of patients with schizophrenia: a controlled study

Objective

We aimed at investigating prospective memory and its socio-demographic and neurocognitive correlates in non-psychotic, first-degree relatives (FDRs) of patients with schizophrenia compared to patients with first episode schizophrenia (FES), and healthy controls (HCs).

Methods

Forty-seven FES patients, 50 non-psychotic FDRs (23 offspring and 27 siblings) of patients with chronic schizophrenia (unrelated to the FES group) and 51 HCs were studied. The Chinese version of the Cambridge Prospective Memory Test (C-CAMPROMPT) was used to measure time-based prospective memory (TBPM) and event-based prospective memory (EBPM) performance. Other cognitive functions (involving respective memory and executive functions) were evaluated with standardized tests.

Results

After controlling for basic demographic characteristics including age, gender and educational level, there was a significant difference between FDRs, FES and HCs with respect to both TBPM (F_(2,142) = 10.4, p<0.001) and EBPM (F_(2,142) = 10.8, p<0.001). Multiple linear regression analyses revealed that lower scores of the Hopkins Verbal Learning Test-Revised (HVLT-R) and the STROOP Word-Color Test (SWCT) contributed to TBPM impairment, while lower educational level and higher scores of the Color Trails Test-2 (CTT-2) contributed to EBPM deficit in FDRs.

Conclusions

FDRs share similar but attenuated prospective memory impairments with schizophrenia patients, suggesting that prospective memory deficits may represent an endophenotype of schizophrenia.

Prospective memory impairment in long-term opiate users

RATIONALE

Opiate use is associated with a range of neurological and cognitive deficits. However, to date, no studies have assessed whether these cognitive deficits extend to the ability to perform intended actions in the future (i.e. prospective memory). Reduced ability in this area might be anticipated due to impaired executive functions and episodic memory associated with long-term opiate use.

OBJECTIVES

The main objectives of this study are to assess the performance of long-term opiate users on a laboratory measure of prospective memory which closely simulates the types of prospective memory tasks encountered in everyday life ('Virtual Week') and to investigate the extent to which prospective memory performance is related to executive functions and episodic memory ability.

METHODS

Twenty-six long-term heroin users enrolled in an opiate substitution program, and 30 controls with no previous history of drug use were tested on Virtual Week. Retrospective memory and executive functions were also assessed.

RESULTS

Long-term opiate users were significantly impaired on prospective memory performance compared with controls (p = 0.002, η(2) p = 0.17), and these deficits did not vary as a function of prospective memory task type (regular, irregular, event, time). The findings also suggest that retrospective memory difficulties contribute to the prospective memory difficulties seen in opiate users (r s  = 0.78, p < 0.001) but that executive dysfunction is less influential.

CONCLUSIONS

Prospective memory is sensitive to long-term opiate use. Importantly, opiate users suffer from generalised deficits in prospective memory, regardless of the task demands, which may have significant implications for day-to-day functioning. These results may therefore contribute to the development of clinical intervention strategies to reduce the negative impact of prospective memory failures in daily life.

Prospective memory in schizophrenia: a review

The wide range of psychological and cognitive symptoms associated with schizophrenia can often affect the level of independence that individuals with schizophrenia can achieve in their lives. Prospective memory (PM), or memory associated with future intentions, has been proposed as a useful indicator of select independent living skills. Currently, there is limited research with regards to prospective memory in schizophrenia. The current review systematically summarizes the literature focusing on prospective memory in schizophrenia and concludes that individuals with schizophrenia exhibited both an impairment in PM when compared to healthy controls and a general lack of awareness regarding these deficits. The existing research also suggests that PM deficits are not related to chronicity of illness or medications associated with schizophrenia. Limited findings suggest that PM deficits in individuals with schizophrenia may be associated with the ability to live independently and instrumental activities of daily living.

Altered gene expression in the dorsolateral prefrontal cortex of individuals with schizophrenia

The underlying pathology of schizophrenia (SZ) is likely as heterogeneous as its symptomatology. A variety of cortical and subcortical regions, including the prefrontal cortex, have been implicated in its pathology, and a number of genes have been identified as risk factors for disease development. We used in situ hybridization (ISH) to examine the expression of 58 genes in the dorsolateral prefrontal cortex (DLPFC, comprised of Brodmann areas 9 and 46) from 19 individuals with a premorbid diagnosis of SZ and 33 control individuals. Genes were selected based on: (1) previous identification as risk factors for SZ; (2) cell type markers or (3) laminar markers. Cell density and staining intensity were compared in the DLPFC, as well as separately in Brodmann areas 9 and 46. The expression patterns of a variety of genes, many of which are associated with the GABAergic system, were altered in SZ when compared with controls. Additional genes, including C8orf79 and NR4A2, showed alterations in cell density or staining intensity between the groups, highlighting the need for additional studies. Alterations were, with only a few exceptions, limited to Brodmann area 9, suggesting regional specificity of pathology in the DLPFC. Our results agree with previous studies on the GABAergic involvement in SZ, and suggest that areas 9 and 46 may be differentially affected in the disease. This study also highlights additional genes that may be altered in SZ, and indicates that these potentially interesting genes can be identified by ISH and high-throughput image analysis techniques.

Predictive value of prospective memory for remission in first-episode schizophrenia

PURPOSE

The study examined the rate of remission in individuals experiencing a first episode of schizophrenia (FES) in China and explored predictors of remission in the acute phase of the illness.

DESIGN AND METHODS

Fifty-five FES patients were randomly treated with risperidone, olanzapine, or aripiprazole at therapeutic doses for 8 weeks, and their clinical profiles and cognition were assessed using standardized assessment instruments at entry and the end of the study.

FINDINGS

Of the 55 patients, 30 (54.5%) remitted by the end of the 8-week study. In univariate analyses, shorter duration of untreated psychosis, higher scores on both the time-based prospective memory (TBPM) and event-based prospective memory tasks and the Hopkins Verbal Learning Test-revised, and less severe negative symptoms were significantly associated with remission. In stepwise multiple logistic regression analyses, only higher scores on the TBPM significantly predicted remission. Individuals having higher scores reflecting better TBPM at baseline were more likely to achieve remission after 8 weeks of optimized antipsychotic treatment.

PRACTICE IMPLICATIONS

TPBM may be useful in helping clinicians identify those FES patients most likely to achieve a favorable treatment response.

A Virtual Week study of prospective memory function in autism spectrum disorders

Prospective memory (PM) refers to the implementation of delayed intentions, a cognitive ability that plays a critical role in daily life because of its involvement in goal-directed behavior and consequently the development and maintenance of independence. Emerging evidence indicates that PM may be disrupted in autism spectrum disorders (ASDs), potentially contributing to the functional difficulties that characterize this group. However, the degree, nature, and specificity of ASD-related impairment remains poorly understood. In the current study, children between 8 and 12 years of age who were diagnosed with ASDs (n=30) were compared with typically developing children (n=30) on a child-appropriate version of the Virtual Week board game. This measure provides an opportunity to investigate the different sorts of PM failures that occur. The ASD group showed significant PM impairment on measures of time-based (but not event-based) prospective remembering. However, only a subtle difference emerged between regular and irregular PM tasks, and group differences were consistent across these tasks. Because regular and irregular tasks differentially load retrospective memory, these data imply that the PM difficulties seen in ASDs may primarily reflect a monitoring deficit and not an encoding and memory storage deficit. PM performance was poorer under conditions of high ongoing task absorption, but the magnitude of this effect did not vary as a function of group. In both groups, time-based (but not event-based) PM difficulties were associated with functional outcomes in daily life, but only an inconsistent association with executive control emerged.

Assessment of prospective memory in schizophrenia using the Chinese version of the Cambridge Prospective Memory Test: a controlled study

INTRODUCTION

Data on the psychometric assessment of prospective memory (PM) are limited. The Cambridge Prospective Memory Test (CAMPROMPT) and its Chinese version (CAMPROMPT-C) have been applied to a variety of clinical conditions except for chronic schizophrenia. This controlled study explored the clinical utility of the CAMPROMPT-C in patients with schizophrenia by comparing their PM performance with that of normal controls.

METHODS

Forty-four schizophrenia patients and 44 normal controls formed the study sample. Sociodemographic characteristics, PM, retrospective memory, and intelligence were measured in all subjects. Patients' psychopathology was rated with a standardized instrument.

RESULTS

Patients performed worse than normal controls on both the sum and subscale scores of the CAMPROMPT-C. Patients had comparable performances in PM subtypes. Bivariate analyses revealed that education level, intelligence, and retrospective memory were associated with PM functions.

DISCUSSION

The study supports the clinical utility of the CAMPROMPT-C in chronic schizophrenia and corroborated the significant relationship between PM and education, intelligence, and retrospective memory.

Improving Outcome of Psychosocial Treatments by Enhancing Memory and Learning

Mental disorders are prevalent and can lead to significant impairment. Some progress has been made toward establishing treatments; however, effect sizes are small to moderate, gains may not persist, and many patients derive no benefit. Our goal is to highlight the potential for empirically supported psychosocial treatments to be improved by incorporating insights from cognitive psychology and research on education. Our central question is: If it were possible to improve memory for the content of sessions of psychosocial treatments, would outcome substantially improve? We leverage insights from scientific knowledge on learning and memory to derive strategies for transdiagnostic and transtreatment cognitive support interventions. These strategies can be applied within and between sessions and to interventions delivered via computer, the Internet, and text message. Additional novel pathways to improving memory include improving sleep, engaging in exercise, and using imagery. Given that memory processes change across the lifespan, services to children and older adults may benefit from different types and amounts of cognitive support.

Prospective memory in schizophrenia: relationship to medication management skills, neurocognition, and symptoms in individuals with schizophrenia

OBJECTIVE

Impaired adherence to medication regimens is a serious concern for individuals with schizophrenia linked to relapse and poorer outcomes. One possible reason for poor adherence to medication is poor ability to remember future intentions, labeled prospective memory skills. It has been demonstrated in several studies that individuals with schizophrenia have impairments in prospective memory that are linked to everyday life skills. However, there have been no studies, to our knowledge, examining the relationship of a clinical measure of prospective memory to medication management skills, a key element of successful adherence.

METHODS

In this Study 41 individuals with schizophrenia and 25 healthy adults were administered a standardized test battery that included measures of prospective memory, medication management skills, neurocognition, and symptoms.

RESULTS

Individuals with schizophrenia demonstrated impairments in prospective memory (both time and event-based) relative to healthy controls. Performance on the test of prospective memory was correlated with the standardized measure of medication management in individuals with schizophrenia. Moreover, the test of prospective memory predicted skills in medication adherence even after measures of neurocognition were accounted for.

CONCLUSIONS

This suggests that prospective memory may play a key role in medication management skills and thus should be a target of cognitive remediation programs.

Prospective memory in Parkinson disease during a virtual week: effects of both prospective and retrospective demands

OBJECTIVE

This study investigated the effect of Parkinson's disease (PD) on event-based prospective memory tasks with varying demand on (1) the amount of strategic attentional monitoring required for intention retrieval (prospective component), and (2) the retrospective memory processes required to remember the contents of the intention or the entire constellation of prospective memory tasks.

METHOD

Twenty-four older adults with PD and 28 healthy older adults performed the computerized Virtual Week task, a multi-intention prospective memory paradigm that simulates everyday prospective memory tasks. The Virtual Week included regular (low retrospective memory demand) and irregular (high retrospective memory demand) prospective memory tasks with cues that were focal (low strategic monitoring demand) or less focal (high strategic monitoring demand) to the ongoing activity.

RESULTS

For the regular prospective memory tasks, PD participants were impaired when the prospective memory cues were less focal. For the irregular prospective memory tasks, PD participants were impaired regardless of prospective memory cue type. PD participants also had impaired retrospective memory for irregular tasks, which was associated with worse prospective memory for these tasks during the Virtual Week.

CONCLUSIONS

When retrospective memory demands are minimized, prospective memory in PD can be supported by cues that reduce the executive control demands of intention retrieval. However, PD-related deficits in self-initiated encoding or planning processes have strong negative effects on the performance of prospective memory tasks, with increased retrospective memory demand.

Prospective memory and chronic heart failure

Background

Patients with chronic heart failure (CHF) experience a number of debilitating symptoms, which impact on activities of daily living and result in poor quality of life. Prospective memory, which is defined as memory to carry out future intentions, has not been investigated in this group. However, emerging evidence suggests CHF patients have difficulties with cognitive processes related to prospective memory. Self-care, which partly relies on prospective memory, is essential in symptom management and preventing acute clinical deterioration. This study aims to measure prospective memory in CHF patients, and examine the relationship between prospective memory and CHF self-care.

Methods/Design

A comprehensive neuropsychological assessment will be conducted to assess a range of cognitive functions and psychopathology. The primary focus will be an assessment of prospective memory using a well-established behavioral measure; Virtual Week. Thirty CHF patients attending a nurse-led management program will be recruited from three hospital sites in Melbourne, Australia and their self-care behaviors will be assessed using the Self-care Chronic Heart Failure Index (SCHFI), a validated self-report tool. An additional 30 healthy controls, matched on age, gender, and IQ will be recruited from the general community.

Discussion

This is a group comparison study that will provide an evaluation of the prospective memory abilities of CHF patients. The findings of this research will provide insight into whether prospective memory may be hindering patients’ ability to perform adequate self-care.

Do adults with autism spectrum disorders compensate in naturalistic prospective memory tasks?

The present study is the first to directly compare event- and time-based prospective memory in Autism Spectrum Disorders (ASD) using a contextual task mirroring real life demands of prospective memory. Twenty-five individuals with ASD and 25 age- and ability-matched controls completed the Dresden Breakfast task which required participants to prepare breakfast following a set of rules and time restrictions. Overall, adults with ASD had less correct time- and event-based prospective memory responses in comparison to controls, which is consistent with previous research in children with ASD. Moreover, ASD participants completed fewer tasks, followed rules less closely, and monitored the elapsing time less closely than controls. Individuals with ASD seem not to be compensating in naturalistic prospective memory tasks.

Prospective memory performance in patients with drug-naïve, first-episode psychosis

Schizophrenia is associated with an impairment of prospective memory (PM) which refers to the ability to remember to carry out an intended action in the future. However, most of these studies were limited to chronic samples. The current study examined the event-based PM and time-based PM using a dual-task paradigm in 22 drug-naïve, first-episode psychosis (FEP) patients and 23 healthy controls. Results indicated that FEP patients performed significantly poorer than healthy controls in both event-based and time-based PM. However, the significant difference in time-based PM disappeared after controlling for working memory. Correlation analysis indicated that both types of PM did not correlate with positive symptoms or negative symptoms, duration of illness, or duration of untreated psychosis. However, time-based PM was correlated with the general psychopathology subscale of the PANSS. Taken together, these findings suggest that PM deficits are present in drug-naïve FEP patients; impairment of event-based PM appears to occur independently, whereas time-based PM impairment may be, in part, a secondary consequence of a working memory deficit.

Prospective memory in schizophrenia and schizotypy

INTRODUCTION

Most evidence suggests that schizophrenia is associated with pervasive prospective memory (PM) impairment that does not vary as a function of task demands. However, a central tenet of the Multiprocess Framework is that PM involves both automatic and strategic processes, and that their relative prominence varies as a function of PM task characteristics, such as target-cue saliency.

METHODS

Participants with schizophrenia (n = 30), matched controls (n = 29), low schizotypes (n = 35), and high schizotypes (n = 36) were administered a PM measure in which saliency was manipulated. To further clarify the relationship between PM and schizotypy, high and low schizotypies were additionally assessed on Virtual Week, a laboratory measure which has documented sensitivity to schizophrenia-related impairment.

RESULTS

Relative to controls, participants with schizophrenia exhibited PM difficulties, but the magnitude of this deficit did not vary as a function of target-cue saliency. High and low schizotypes did not differ on any PM test parameter.

CONCLUSIONS

These data are consistent with other evidence showing that schizophrenia is characterised by generalised PM impairment. However, the absence of any schizotypy effects on PM does not support the recent suggestion that PM may represent an endophenotype for schizophrenia.

Prospective memory, emotional valence, and multiple sclerosis

Cognitive impairments in multiple sclerosis (MS) extend to tasks demanding prospective memory (PM): remembering to perform an intended act during ongoing activity. This study investigated whether emotional content influenced the effects of MS on PM, following evidence that emotional valence can influence other aspects of memory. Thirty participants with MS were compared to 30 controls on a PM task, Virtual Week, in which emotion was manipulated. People with MS showed a consistent deficit in PM performance across manipulations of task and valence. Results indicated that emotionally positive tasks improved the PM performance of MS participants, with implications for rehabilitation.