Prospective Memory and Traumatic Brain Injury: A Review

Factors Influencing Objective and Subjective Prospective Memory Measures in Traumatic Brain Injury

OBJECTIVE

To accurately assess prospective memory (PM) functioning in patients who sustained a traumatic brain injury (TBI), it is important to use both subjective (questionnaires) and objective (tests) measures. However, which factors have the most significant effect on each PM measure remains unknown. This observational study aims to verify whether TBI severity or psychological status has the most influence on patients' objective and subjective PM measures.

METHOD

Fifteen healthy control (HC) participants (n = 15), 19 patients with a mild TBI (n = 19) and 30 patients with a moderate-to-severe TBI (n = 30) were recruited during the post-acute phase. For almost every participant, a relative was also recruited (n = 62). The Test écologique de mémoire prospective (TEMP), an objective computerized PM measure consisting of naturalistic stimuli, was administered to all participants along with anxiety (BAI) and depression inventories (BDI). Participants and their relatives also completed a questionnaire, the comprehensive assessment of PM (CAPM), a subjective PM measure assessing everyday failures.

RESULTS

Results on the objective PM measure were predicted by TBI severity, while psychological symptoms (BAI and BDI) predicted scores on the subjective PM measure. In addition, relatives in the moderate-to-severe TBI group reported more PM failures on the subjective measure and their perception was significantly correlated with results on the objective PM measure, which was not the case for the other two groups of relatives.

CONCLUSIONS

Objective PM measures are related to TBI severity and appear more robust against the influence of psychological factors than subjective PM measures.

Time-Based and Event-Based Prospective Memory in Mild Cognitive Impairment and Alzheimer's Disease Patients: A Systematic Review and Meta-analysis

Prospective memory (PM) is the ability to remember to perform planned actions in a future moment and it is of fundamental importance for an independent and autonomous lifestyle from development to late adulthood. Deficits in episodic memory and executive functions, which are involved in PM are characteristic features of mild cognitive impairment (MCI) and Alzheimer's disease (AD). Considering that the number of older adults is drastically increasing over the next decades, it is of great interest to understand how PM decline in healthy older adults and patients with different degree of cognitive decline. The present meta-analysis included 46 studies investigating PM performance in AD patients (17 studies) and people with MCI (24 studies); 5 studies included both clinical conditions in the same article. The 46 studies contributed a total of 63 independent samples and 129 effect sizes from 4668 participants (2115 patients and 2553 controls). Unlike previous reviews of the literature, our results with a larger and updated sample of studies confirmed lower PM abilities in AD compared to MCI and controls, although we did not observe conclusive differences between event-based and time-based PM in patients. Surprisingly, PM deficits shown by MCI and AD patients have decreased across years, in parallel to a reduction of the evidence of publication bias and an increase in the number of observations per task. We propose the use of more reliable research designs as one plausible explanation for the reduction of PM impairments.

Supporting People with Acquired Brain Injury to Use a Reminding App; Narrow-deep vs. Broad-shallow User Interfaces

People with memory impairments following an acquired brain injury stand to benefit from smartphone apps as memory aids. Due, in part, to usability issues they use smartphone-based reminding less than the general population. Evidence suggests this group may benefit from user interface (UI) designs with more screens with less information per screen (narrow-deep UI) rather than fewer screens with more information per screen (broad-shallow UI). This study compared the difference in speed, accuracy, guidance needed, and task load for 32 people with acquired brain injury when setting reminders using narrow-deep and broad-shallow UI. They were also given cognitive assessments (measuring selective attention, executive functioning, and overall executive and memory ability) and interviewed about their UI preference. There was a significant difference in accuracy; participants were less accurate (they made two more errors on average for every three reminders set) using a broad-shallow compared to narrow-deep UI. The reason for this difference was that participants omitted more information when using broad-shallow UI. There were no differences in speed, guidance required, and overall task-load. Participants with better selective attention and more experience with smartphones benefited the most from narrow-deep UI compared to broad-shallow UI. Most participants preferred one UI over the other. Those who preferred narrow-deep found it easier to use, that they missed less information and liked having one piece of information at a time. Those who preferred broad-shallow found it easier to review the information and felt less likely to lose track. The findings can inform that implementation of UI choices to make apps more accessible for those with cognitive impairments.

Validation of the Prospective Memory Concerns Questionnaire (PMCQ)

Prospective memory (PM), the ability to remember to complete intended tasks, is essential for successfully completing activities of daily living. PM impairments are common in people with neuropathology such as acquired brain injury and dementia. These PM impairments affect individuals’ capabilities in key aspects of daily living including their health, safety, and independence. The Prospective Memory Concerns Questionnaire (PMCQ) was designed as a self-report measure to understand individuals’ concerns about their memory. This questionnaire may help identify issues with PM which in turn may assist clinicians in the targeted implementation of memory compensation strategies. The PMCQ was developed using Rasch and classical test methodologies, with subscales measuring frequency of forgetting behaviors, memory concerns, and retrieval failures. The current study aimed to confirm the factor structure of the PMCQ for use in adults in the general population. The study also aimed to examine relationships between the PMCQ and naturalistic performance-based measures of PM to determine how the self-report PMCQ could be used in conjunction with performance-based measures. A community dwelling sample of 558 adults completed the PMCQ, an event-based naturalistic PM task, and time-based naturalistic PM task. Confirmatory factor analyses (CFAs) indicated that a higher order model with three subscales containing 35 items produced acceptable fit [RMSEA = 0.056 (90% CI 0.054, 0.060), SRMR = 0.062, CFI = 0.915, TLI = 0.909] The PMCQ demonstrated good internal consistency (total α = 0.95, subscales: α = 0.88–0.89). The Forgetting Behaviors subscale significantly correlated with performance on the event-based naturalistic PM task (r = −0.14, p < 0.01). The Memory Concerns and Retrieval Failures subscales did not correlate significantly with performance-based PM tasks. These findings suggest that the PMCQ may be best suited for assessing individuals’ concerns about their forgetting behaviors and identifying appropriate compensation strategies or support services. It is recommended that the PMCQ be used alongside performance-based PM tasks and other cognitive measures to comprehensively assess PM. It was concluded that the PMCQ is a suitable measure for use in adults in the general population. Further validation research of the PMCQ in general population and clinical samples will determine the measures’ sensitivity and specificity in identifying PM impairments.

The Assessment and Prediction of Prospective Memory after Stroke

OBJECTIVE

Prospective memory (PM) is the memory used when intentions are to be carried out in the future. Little research has been conducted examining PM after stroke. This study aimed to determine if PM is impaired after stroke through comparison of individuals with stroke to healthy controls. Additionally, it aimed to explore the predictors of PM performance post-stroke.

METHOD

Twenty-eight individuals with stroke and 27 neurologically healthy controls completed the Cambridge Prospective Memory Test (CAMPROMPT), 2 self-report PM questionnaires, and multiple cognitive measures.

RESULTS

Individuals with stroke performed significantly lower on both event- and time-based PM than controls on the CAMPROMPT, indicating PM impairment. Event-based PM after stroke was significantly predicted by age, retrospective memory (RM), and global cognitive function, whereas time-based PM was only predicted by the metacognitive skill of note-taking. Age and note-taking predicted time-based PM for controls, whereas only age predicted event-based PM for control participants.

CONCLUSIONS

The findings of this study have helped to confirm that PM impairment does exist after stroke, particularly when using a standardised PM measure. Furthermore, PM impairment may be predicted by variables, such as age, strategy use, RM, and cognitive ability.

Designing ApplTree: usable scheduling software for people with cognitive impairments

BACKGROUND

Smartphone reminding applications can help overcome memory difficulties experienced by people with acquired brain injury (ABI). Cognitive difficulties with memory and attention make entering reminders into a device, and remembering to set reminders, challenging for this group. ApplTree is a reminding app with features that aim to address challenges. One app feature was push notifications (asking "Do you need to set any reminders?") to support people to initiate use of the app to set reminders. Another app feature was a customisable user interface design to support attention and short term memory during reminder setting.

METHODS

In a mixed-methods user study, five people with self or other reported memory impairment following ABI used ApplTree for at least 4 months. They received push notifications for at least 2 months and no push notifications for at least 2 months. Monthly participant interviews provided insight into user interface preference, app use, and push notification acceptability.

RESULTS

Receiving four Push notifications per day doubled number of daily reminders set and four of the five participants found receiving them to be acceptable. This long-term field study uncovered issues relevant for clinicians and designers, including insights into the potential benefits of different user interface designs, the impact of family members on app use, and the importance of perceived need influencing use and acceptance.

CONCLUSIONS

Feedback provided insight into future considerations when designing reminding apps and using them in neuropsychological rehabilitation. This work highlights the benefit of user-led research into accessible design and use of assistive technologies.IMPLICATIONS FOR REHABILITATION"Unsolicited" push prompts are an easy to implement feature of reminding technology that is useful and acceptable for people with ABI in community rehabilitation.Observations provide insights about how people with ABI make use of reminding apps over time. This can inform those designing apps or providing reminding technology as part of neuropsychological rehabilitation.Participants differed on their preference of the two user-interface designs available in ApplTree. This highlights an area for future research because currently available reminding apps have a broad-shallow design which may not always be appropriate for people with ABI.

Self-reported prospective memory after stroke

Prospective Memory (PM) is the memory for completing future intentions. This study aimed to compare self-reported PM of individuals with stroke to healthy controls, to determine if PM is impaired after stroke. Additionally, self-reported PM for individuals with stroke was compared to significant-other reports, ascertaining a level of self-awareness of PM function. Twenty-eight individuals with stroke, 25 significant-others, and 27 healthy controls completed the Brief Assessment of PM (BAPM) and the Prospective and Retrospective Memory Questionnaire (PRMQ) as part of a larger study. Individuals with stroke reported significantly more Basic Activities of Daily Living (BADL) PM failures compared to controls on Part A of the BAPM. On Part B, individuals with stroke reported BADL PM failures to be less problematic/important than controls, suggesting a lack of self-awareness into the consequences of PM failure. Individuals with stroke also reported significantly more PM and RM failures compared to controls on the PRMQ. No significant differences were found between individuals with stroke and their significant-others on both the BAPM and PRMQ. Results of this study helped to clarify the previous research and highlighted that individuals with stroke reported more PM failures than controls but underestimated the importance of such memory lapses.

Comparing different tests to detect early manifestation of prospective memory decline in aging

Objective: Prospective memory (PM) is the ability to remember to perform future intentions. Previous studies have demonstrated that, compared to a younger cohort, healthy older adults have impairments in PM. Considering the importance of early detection of age-related PM decline, the present study aims to compare the performance of healthy older adults using three well-known PM tests commonly used in clinical settings.Method: In the present study, we tested 70 older adults (65-95 years old) using the Cambridge Prospective Memory Test (CAMPROMPT), the Memory for Intentions Screening Test (MIST) and the Royal Prince Alfred Prospective Memory Test (RPA-ProMem). In order to compare performance across tests and the interaction between age and cues, we performed a linear mixed model with random intercept and random slopes. Moreover, additional mixed models with random intercept were run for analyzing the additional information provided by MIST and RPA-ProMem regarding delay responses, response modality effects and type of errors committed.Results: Our data showed a drop in PM performance as age increased detected by all three tests. Furthermore, CAMPROMPT was the most sensitive test to identify differences in PM for event-and time-based cues, at least for participants with 65-77 years old. When data were analyzed in term of delay responses, participants were more accurate for 2 min delay (MIST) and 30 in delay (RPA-ProMem). Participants were less accurate when response modality was "verbal" compared to "action" (MIST) and made more PM errors as age increased.Conclusions: Overall, the study provides important information regarding age-related PM decline and can help researchers as well as clinicians in deciding the preferred test to evaluate PM performance.

A review of prospective memory in individuals with acquired brain injury

OBJECTIVE

Prospective memory (PM) deficits have emerged as an important predictor of difficulty in daily life for individuals with acquired brain injury (BI). This review examines the variables that have been found to influence PM performance in this population. In addition, current methods of assessment are reviewed with a focus on clinical measures. Finally, cognitive rehabilitation therapies are reviewed, including compensatory, restorative and metacognitive approaches.

METHOD

Preferred reporting items for systematic reviews and meta-analyses guidelines were used to identify studies. Studies were added that were identified from the reference lists of these.

RESULTS

Research has begun to elucidate the contributing variables to PM deficits after BI, such as attention, executive function and retrospective memory components. Imaging studies have identified prefrontal deficits, especially in the region of BA10 as contributing to these deficits. There are now several clinical measures available with good psychometric properties. Rehabilitation techniques have mostly focused on compensatory strategies, but, in addition, some restorative and metacognitive approaches have shown preliminary promise.

CONCLUSIONS

PM deficits are a common and important deficit after BI. Clinical evaluation is recommended and further understanding of rehabilitation techniques is needed.

Prospective memory 7 years after severe childhood traumatic brain injury - the TGE 2 prospective longitudinal study

OBJECTIVE

To investigate the long-term outcome in prospective memory (PM), seven years after childhood severe traumatic brain injury (TBI), in a prospective longitudinal cohort.

PARTICIPANTS

76 young individuals (aged 7-22 years): 39 patients with a severe accidental TBI included prospectively seven years earlier, aged 0-15 years at injury, and 37 controls individually matched on age, gender and parental education.

MAIN OUTCOME MEASURES

Three novel short PM tasks varying in the delay, motivation and context (ecological versus paper and pencil task).

RESULTS

Individuals with severe TBI showed significantly poorer PM than matched controls in the two low-motivation PM tasks: (1) the ecological long-delay task consisting of sending a letter on a rainy day (p=0.047, odds ratio = 2.6); (2) the non-ecological short-delay task consisting of taking off post-its while identifying facial emotions (p=0.004, r=0.34). Differences in PM on the high motivation were not significant. PM is impaired several years post severe TBI.

The efficacy of prospective memory rehabilitation plus metacognitive skills training for adults with traumatic brain injury: study protocol for a randomized controlled trial

BACKGROUND

Impairment of prospective memory (PM) is common following traumatic brain injury (TBI) and negatively impacts on independent living. Compensatory approaches to PM rehabilitation have been found to minimize the impact of PM impairment in adults with TBI; however, poor self-awareness after TBI poses a major barrier to the generalization of compensatory strategies in daily life. Metacognitive skills training (MST) is a cognitive rehabilitation approach that aims to facilitate the development of self-awareness in adults with TBI. This paper describes the protocol of a study that aims to evaluate the efficacy of a MST approach to compensatory PM rehabilitation for improving everyday PM performance and psychosocial outcomes after TBI.

METHODS/DESIGN

This randomized controlled trial has three treatment groups: compensatory training plus metacognitive skills training (COMP-MST), compensatory training only (COMP), and waitlist control. Participants in the COMP-MST and COMP groups will complete a 6-week intervention consisting of six 2-h weekly training sessions. Each 1.5-h session will involve compensatory strategy training and 0.5 h will incorporate either MST (COMP-MST group) or filler activity as an active control (COMP group). Participants in the waitlist group receive care as usual for 6 weeks, followed by the COMP-MST intervention. Based on the sample size estimate, 90 participants with moderate to severe TBI will be randomized into the three groups using a stratified sampling approach. The primary outcomes include measures of PM performance in everyday life and level of psychosocial reintegration. Secondary outcomes include measures of PM function on psychometric testing, strategy use, self-awareness, and level of support needs following TBI. Blinded assessments will be conducted pre and post intervention, and at 3-month and 6-month follow-ups.

DISCUSSION

This study seeks to determine the efficacy of COMP-MST for improving and maintaining everyday PM performance and level of psychosocial integration in adults with moderate to severe TBI. The findings will advance theoretical understanding of the role of self-awareness in compensatory PM rehabilitation and skills generalization. COMP-MST has the potential to reduce the cost of rehabilitation and lifestyle support following TBI because the intervention could enhance generalization success and lifelong application of PM compensatory strategies.

TRIAL REGISTRATION

New Zealand Clinical Trials Registry, ACTRN12615000996561 . Registered on 23 September 2015; retrospectively registered 2 months after commencement.

Prospective Memory After Stroke: A Scoping Review

The aim of this paper was to review the limited, but growing, literature on prospective memory (PM) following stroke using a scoping study methodology. Multiple databases were systematically searched and yielded 11 studies that were classified as observational (n = 7) or intervention studies (n = 4) and reviewed for quality. PM impairment after stroke was more commonly identified using behavioural measures compared to self-report measures. There were mixed findings regarding the extent and nature of PM impairment poststroke; however, more studies reported impairment for time-based PM, compared to both event- and activity-based PM. Studies examining rehabilitative techniques for PM resulted in mixed findings and were limited as most were case studies of poor methodological quality. Overall previous research in this area was limited as most studies were often underpowered due to small sample sizes, or used single-item measures which may not be robust enough to reliably measure PM impairment. Additionally, the methods used to measure PM were varied and many studies did not control for retrospective memory impairment, which could impact the results, as PM has both a retrospective (remembering both the action and when it needs to be completed) and prospective component (remembering to perform the action when appropriate). In conclusion, PM impairment is apparent poststroke, specifically for time-based PM. However, more research is needed to determine why PM impairment occurs, and how it can be improved.

Spanish Version of the Prospective and Retrospective Memory Questionnaire (PRMQ-S)

The concept of prospective memory is relatively recent. Thus, it is necessary to have instruments to assess it, in interaction with retrospective memory. The Prospective and Retrospective Memory Questionnaire (PRMQ; Smith et al., 2000) is an instrument that has been effectively used for assessment in several languages. Nevertheless, there is still no Spanish adaptation. The aim of this study was to translate the PRMQ and obtain information about its psychometric properties. A back translation process was applied to the PRMQ. The resulting PRMQ-S was self-administered to 520 subjects after applying the pilot test. Confirmatory factor analysis (CFA) was used to test competing models of its latent structure. Internal consistency was evaluated using Cronbach's alpha. The results showed an adequate internal consistency of the total scale and the Prospective and Retrospective scales were: .89, .84 and .76, respectively. The factor structure was compared with the original study. Our results suggested a disagreement with the tripartite model defended by the authors of the PRMQ. Since there is a high correlation between two factors in the bi-factor model, and the tripartite model showed non-significant loadings to the two specific factors, we recommend that the PRMQ-S be used as one general memory score. We demonstrated adequate psychometric properties of the PRMQ-S if it is used as unique measurement of memory failures. These results are relevant due to the need for a short and accurate instrument in our language that explores memory failures, which has a major impact on the activities of daily living.

Everyday Memory for Everyday Tasks: Prospective Memory as an Outcome Measure Following TBI in Older Adults

Traumatic brain injury in older adults is an increasing problem in our aging community. Traditional functional outcome measures, such as return to work or academic achievement, as used with younger samples following traumatic brain injury are of limited use for older people. Although challenging to assess reliably, evaluation of prospective memory is gradually being included in outcome assessments following traumatic brain injury in younger samples and may be a useful index of cognitive competence in everyday life when assessing older adults following traumatic brain injury.

Predicting Compliance With Treatment Following Stroke: A New Model of Adherence Following Rehabilitation

Background and purpose: Adherence to medication is fundamental to optimal health recovery yet compliance to medication rates are lower than 50% in most studies. This study aimed to investigate the correlates of adherence in stroke patients. Method: Twenty-six stroke patients and 29 amputee patients who had completed a rehabilitation program at Melbourne Rehabilitation Centre were investigated. Medical adherence was determined from computed adherence metrics based on pill counts and subjective reports of patient knowledge of medication use. Model components that were believed to contribute to poor adherence, included emotional and cognitive dysfunction, beliefs about medication, and social support. These factors were assessed by patient and partner self-rating questionnaires. Results: Stroke patients showed a lower level of adherence compared to amputee patients. Cognitive and emotional dysfunction, beliefs about medication, and the level of care were significantly associated with low adherence to medicine regimes in stroke patients. Level of cognitive impairment and emotional impairment were significantly associated with low adherence to medicines in amputee patients. Emotional dysfunction was the best predictor of poor adherence in both patient groups. Conclusion: The findings are in keeping with past adherence studies with other patient groups and support the position that emotional, cognitive, and social factors are important factors in adherence. The specific nonadherence profile for this brain-damaged group is modeled and the application for outpatients following rehabilitation is discussed.

Traumatic Brain Injury and Prospective Memory in a Virtual Shopping Trip Task: Does It Matter Who Generates the Prospective Memory Target?

The current study aimed to investigate prospective memory in traumatic brain injury by using a laboratory-based but naturalistic style assessment task. The objective was to determine if performance differed when the prospective memory targets were self-generated or experimenter-generated (a generation effect). Sixteen people who had sustained a traumatic brain injury and had received rehabilitation were compared to 16 healthy age-matched control participants on a naturalistic virtual measure of shopping and prospective memory. Results demonstrated that the traumatic brain group was less accurate in overall prospective remembering performance than the control group but there was a lack of difference between the self- and experimenter-generated prospective memory targets for both participant groups. Both retrospective memory and executive attention of working memory were associated with prospective memory performance in the naturalistic task. The findings of the study suggest that the generation effect commonly observed in retrospective memory performance may not impact performance in prospective memory.

Effect of Cognitive Demand on Prospective Memory in Individuals with Traumatic Brain Injury

This study aimed to evaluate the influence of cognitive demand on prospective-memory in individuals with traumatic brain injury (TBI) using a dual-task paradigm. Fourteen individuals with severe TBI and 14 matched controls were required to undertake two tasks. A lexical-decision task was used as an ongoing task and had two levels of cognitive demand (viz., low and high). The event-based prospective-memory task involved performing a specific action whenever a target stimulus appeared during the ongoing task. The Letter-Number Sequencing Test, the Tower of London and the Controlled Oral Word Association Test were also administered to assess the relationship between prefrontal lobe functions and prospective memory. As hypothesised, participants in the TBI group performed more poorly than participants in the control group on the prospective-memory task in the high but not in the low demand condition. There were significant correlations between prospective-memory task performance and scores on the Letter-Number Sequencing Test and the Controlled Oral Word Association Test. These findings help to clarify the nature of prospective-memory impairment in individuals with TBI and support the involvement of prefrontal processes in prospective remembering.

Effect of type of cue, type of response, time delay and two different ongoing tasks on prospective memory functioning after acquired brain injury

Failures of prospective memory (PM) are one of the most frequent, and least studied, sequelae of brain injury. PM, also referred to as memory for intentions, is the ability to remember to carry out a future task. Successful completion of a PM task requires the ability to monitor time, keep the action to be performed periodically in awareness, remember the task to be performed, and initiate the action. Although PM has been shown to be a common difficulty after brain injury, it remains unknown which aspects of performance are impaired. In this study, the performance of 25 individuals with brain injury and that of 25 healthy participants were measured separately on the following variables: time until completion of the task, difficulty of the ongoing task being performed while waiting, whether the task to be performed is an action or is verbal, and whether the cue to perform the task is the passing of a particular amount of time (e.g., 10 minutes) or is an external cue (e.g., an alarm sounding). Individuals with brain injury demonstrated impairment compared to healthy adults on virtually all variables. PM performance was also compared to a battery of standard neuropsychological measures of attention, memory, and executive functions, and to self-report measures of PM functioning, in order to determine the underlying cognitive deficits responsible for poor PM performance, if any. PM performance was correlated with measures of executive functioning but not to self-report measures of PM functioning. Implications are discussed in terms of cognitive rehabilitation recommendations.

Prospective memory in patients with closed head injury: a review

This paper aimed to review the limited, but growing literature on prospective memory (PM) following closed head injury (CHI). Search of two commonly used databases yielded studies that could be classified as: self- or other-report of PM deficits; behavioral PM measures in adults with CHI, behavioral PM measures in children and adolescents with CHI, and treatment of PM in adults with CHI. The methodology and findings of these studies were critically reviewed and discussed. Because of the small number of studies, meta-analysis was only conducted for studies that used behavioral PM measures in adults to integrate findings. PM deficits were found to be commonly reported by patients with CHI and their significant others and they could be identified using behavioral measures in adults, children and adolescents with CHI. However, more work is needed to clarify the nature and mechanisms of these deficits. Although some promising results have been reported by studies that evaluated PM treatment, most studies lack tight experimental control and used only a small number of participants. The paper concluded with some suggestions for future research.

Validation of a new measure of prospective memory: the Royal Prince Alfred Prospective Memory Test

Prospective memory problems are common in patients with brain injury, but appropriate measures are limited. The reliability and validity of the newly designed Royal Prince Alfred Prospective Memory Test (RPA-ProMem), which has three alternate versions, was investigated in 20 healthy volunteers and 20 neurological patients with everyday prospective memory problems. The RPA-ProMem was found to be easy to score reliably (inter-rater reliability = .90) and its three versions were well matched (delayed alternate-form reliability = .71). Test validity and sensitivity to patient deficits were also supported. This new measure of prospective memory should be particularly useful in situations that require repeated assessments, such as evaluation of rehabilitation efforts.

Meta-analysis of prospective memory in schizophrenia: nature, extent, and correlates

Prospective memory (PM) is the ability to remember to carry out an intended action in the future and it is an important function for everyday living. Studies have found that the neural basis of PM is located mainly in the prefrontal lobes (particularly in Brodmann Area 10) and patients with schizophrenia have functional deficits in this area. The present study provided a meta-analytic review of PM performances in patients with schizophrenia in 11 studies. A total of 485 patients with schizophrenia and 409 controls were included. Results showed that patients with schizophrenia exhibited impairments in all time- (d=-1.33), event- (d=-0.827), and activity-based (d=-0.729) PM, with time-based PM more impaired than event-based PM. In addition, PM was found to be significantly correlated with negative symptoms (r=-0.18), general psychopathology (r=-0.168), medication dosage (r=-0.119), duration of illness (r=-0.131), age (r=-0.23), education (r=0.249), IQ (r=0.439) and premorbid IQ (r=0.356). It has theoretical and clinical implications. Theoretically, the results indicate time-based PM involves more initiation than event-based PM. Clinically, the results indicate patients on high dose of antipsychotic medication and with long duration of illness need special attention from care givers for PM problems.

Prospective memory in schizophrenia: further clarification of nature of impairment

Prospective memory (PM) refers to the ability to execute a delayed intention and is different from retrospective memory (RM) in its nature and underlying mechanism (e.g., intention formation, maintenance, detection of PM cue and intention execution). Although preliminary studies have found PM impairment in patients with schizophrenia, the nature and magnitude of this problem in this clinical group is not yet fully known. The current study aimed to further clarify the nature of this impairment in schizophrenia. Fifty-four patients with schizophrenia and fifty-four healthy volunteers matched on demographic variables, IQ and executive functions took part in the study. Time-, event-, and activity-based PM tasks and a set of neurocognitive tests were administered to the participants. Results showed that patients with schizophrenia performed significantly worse on all sub-types of PM tasks, even after controlling for neurocognitive functions such as working memory, verbal memory, visual memory, and executive function. These findings suggest PM deficit is a primary deficit rather than a secondary consequence of neurocognitive impairments in schizophrenia. Analysis found that PM deficits may be mainly due to the impairment of the cue detection and intention retrieval stage.

Predictors of prospective memory in adults with traumatic brain injury

Previous studies have established that prospective memory is commonly affected following traumatic brain injury (TBI). This study examines whether demographic factors, injury severity and site, executive function, and metacognitive factors predict prospective memory performance in adults with TBI, using a cross-sectional multivariate correlational model. Prospective memory of 44 adults (mean age = 30 years) with severe TBI was measured by the Cambridge Prospective Memory Test (CAMPROMPT) time-based and event-based scores. Using stepwise multiple regression, the time-based score was predicted by the Controlled Oral Word Association Test (COWAT) Animals subtest score, length of post-traumatic amnesia (PTA) and use of note-taking on the CAMPROMPT. The event-based score was predicted by length of PTA and COWAT Animals score. Therefore, patients with longer periods of PTA and executive function impairment may be expected to display poorer prospective memory. Note-taking was associated with improved performance on time-based prospective memory tasks.

Reliability and normative data for the comprehensive assessment of prospective memory (CAPM)

The Comprehensive Assessment of Prospective Memory (CAPM) is a questionnaire designed to evaluate frequency of prospective memory (PM) failures in people with brain injury. The aims of this study were to investigate the psychometric properties of the CAPM, including test-retest reliability and internal consistency, and to establish normative data by comparing CAPM scores between groups on the basis of sex, age, and education. Data were collected on 95 people aged 15-60 years living in the community, with no history of brain injury, using the CAPM. The results showed that the test-retest reliability and internal consistency for the CAPM were within acceptable ranges, indicating that the CAPM provides a stable and homogenous measure of an individual's self-report of PM failures. Normative data are presented in two age groups based on the significant difference found between the age groups 15-30 years and 31-60 years. These established norms can be used to describe perceived or observed behaviours indicative of PM failure in patients with brain injury by comparing CAPM ratings from significant others with the norms. The CAPM questionnaire provides researchers or clinicians with a stable and reliable assessment option that specifically focuses on PM for individuals with brain injury.

Traumatic brain injury and prospective memory: Influence of task complexity

A quantitative review indicated that prospective memory impairment is a consistent feature of traumatic brain injury (TBI). However, evidence also suggests that manipulations that increase demands on controlled attentional processes moderate the magnitude of observed deficits. A total of 16 TBI participants were compared with 15 matched controls on a task in which the number of prospective target events was manipulated. This manipulation was of interest because two competing models make different predictions as to its effect on controlled attentional processes. In the context of Smith and Bayen's (2004) preparatory attentional processes and memory processes (PAM) model increasing the number of target events should increase requirements for controlled attentional processing. In contrast, McDaniel and Einstein's (2000) multiprocess framework assumes that distinct target events presented in focal awareness of the processing activities required for the ongoing task are likely to depend on automatic processes. This latter model therefore leads to the prediction that increasing the number of target events should not increase demands upon controlled attentional processes. Consistent with McDaniel and Einstein's (2000) multiprocess framework, TBI patients were significantly and comparably impaired on the one- and the four-target-event conditions relative to controls. Further, TBI deficits could not be attributed to increased difficulty with the retrospective component of the prospective memory task. The practical and theoretical implications of these results are discussed.

Prospective memory in adults with traumatic brain injury: An analysis of perceived reasons for remembering and forgetting

Reasons for prospective remembering and forgetting after traumatic brain injury (TBI) were investigated using Ellis' (1996) five phases of prospective memory as a framework. Participants were 38 individuals with severe TBI and 34 controls. Participants self-rated their perceived reasons for prospective remembering and forgetting using section C of the Comprehensive Assessment of Prospective Memory (CAPM). Significant others also rated participants using the same scale. Analyses were conducted to examine the effect of group membership (TBI or control) on reported reasons for prospective remembering and forgetting. Findings highlighted the TBI group's difficulties with encoding, performance interval, and execution phases of prospective remembering.