Distinct and shared cognitive functions mediate event- and time-based prospective memory impairment in normal ageing

The overall aim of the current thesis was to explore three key components of future-oriented thinking, namely episodic future thinking (EFT), episodic foresight, and prospective memory (PM), in middle childhood. The developmental literature examining each of these future-oriented abilities has generally focused on their emergence in the preschool years, with less known about how these abilities present in middle childhood. In addition, research investigating what cognitive mechanisms may drive these abilities in this age band is limited and findings of those studies that have been conducted are inconsistent. Lastly, the literature has predominantly examined EFT, episodic foresight, and PM in isolation, and research has only just begun to explore interrelations between these future-oriented constructs. The first empirical study therefore aimed to investigate whether EFT ability was associated with age and to examine what cognitive mechanisms may contribute to this skill. The second empirical study aimed to examine, for the first time, whether episodic foresight was associated with age across middle childhood. A second aim of this study was to provide the first investigation of the cognitive mechanisms that may contribute to episodic foresight in this age group, with the particular interest in whether EFT contributed to episodic foresight. The final empirical study aimed to explore whether age was associated with children’s PM performance across event-based and time-based PM tasks. An additional aim of this study was to explore the cognitive abilities that contribute to children’s performance on both event-based and time-based PM tasks, with a particular interest in the contribution of EFT. A single sample of 80 children aged 8 to 12 years were recruited for this research project. Study 1 indicated greater EFT ability was associated with age, consistent with some of the limited studies previously conducted with this age group. Study 1 also demonstrated strong evidence regarding the contribution from episodic memory to children’s EFT and a lack of contribution from executive functions. Study 2 was the first study to examine episodic foresight beyond the preschool years. Results of this study provided the first evidence of an association between age and better episodic foresight performance across the ages of 8 to 12 years. In addition, Study 2 identified age and IQ as significant contributors to successful episodic foresight performance, while retrospective memory, executive functions, and EFT were not found to contribute. The lack of contribution from EFT may have been due to the specific form of episodic foresight task used in this study, which did not require a specific scenario to be envisaged. Further research is now required to investigate whether EFT contributes to other types of episodic foresight task that involve clear scenarios that can be envisaged. The results of Study 3 indicated age was significantly correlated with performance on both event-based and time-based PM tasks. The findings also clearly revealed age, retrospective memory, and EFT were significant contributors to event-based PM performance, while retrospective memory was the only significant contributor to time-based PM performance. Furthermore, the results clearly demonstrated a lack of contribution from executive functions to performance on both task types. Importantly, Study 3 demonstrated that EFT selectively contributed to children’s event-based PM performance. This finding is consistent with the only other study in this age band and used a more comprehensive set of predictors than this previous study. The current research provided novel insights into the profile of children’s future-oriented thinking across the middle childhood period. The findings regarding age-related improvements in EFT, episodic foresight, and PM help to bridge the gap in understanding of the development of these abilities between their emergence in the preschool years and their presentation later in development. Longitudinal research that extends from early childhood to adulthood is now needed to provide a thorough understanding of the developmental trajectory of these abilities across the lifespan. In addition, the current research revealed a clear pattern of results regarding the cognitive mechanisms that contribute to each of these abilities, providing some clarity to the previously mixed findings in the children’s future oriented-thinking literature. Results regarding the inter-relationships between the future-oriented constructs also provided an important extension to current understanding of future-oriented thinking as a broader taxonomy. Furthermore, the current findings bring attention to the need for further theoretical distinction between different forms of episodic foresight and the cognitive processes that contribute to this skill. Overall, the findings from the current thesis have important implications for children’s daily living. In particular, greater understanding of future-oriented thinking in the middle childhood period gained from this thesis may assist in fostering the development of these abilities early in life. This in turn will enable parents and teachers to create reasonable expectations regarding children’s capacity to use these skills in their everyday functioning, thereby maximising success and minimising failure.

Objective: Prospective memory (PM) is the ability to remember to carry out an intended action. Working memory is the ability to store information in mind while processing potentially distracting information. The few previous studies of PM in autism spectrum disorder (ASD) have yielded inconsistent findings. Studies of working memory ability in ASD have suggested a selective impairment of “visual working memory.” However, it remains unclear whether any such impairment is the result of diminished (domain-specific; visual/verbal) storage capacity or diminished (domain-general) processing capacity. We aim to clarify these issues and explore the relation between PM and working memory in ASD. Method: Seventeen adults with ASD and 17 age- and IQ-matched comparison participants completed experimental measures of both event-based (perform action x when event y occurs) and time-based (perform action a at time b) PM, plus a self-report measure of PM skills. Participants also completed a working memory test battery. Results: Participants with ASD self-reported diminished PM skill, and showed diminished performance on the time-based, but not event-based, PM task. On the working memory test battery, visual but not verbal storage capacity was diminished among participants with ASD, as was processing ability. Whereas visual storage was associated with event-based PM task performance among comparison participants, verbal storage was associated among ASD participants. Conclusions: ASD appears to involve a selective deficit in time-based PM and a selective difficulty with aspects of working memory that depend on the storage of visual information. However, event-based PM may be achieved through compensatory strategies in ASD.

Cognitive correlates of prospective memory in dystonia

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

Objective To investigate the event-based prospective memory(EBPM)and time-based prospective memory(TBPM)in the inpatients with abstinent alcoho1 dependence and the relationships between prospective memory and symptoms. Methods 32 male patients with alcoho1 dependence and 30 normal controls matched by age, education, HAMD and HAMA were assessed with a neuropsychological battery of tests including EBPM and TBPM tasks. Results A statistically significant in EBPM was observed between patients with alcoho1 dependence and normal controls (3.91±0.69 vs. 4.47±0.63, t=-3.348, P<0.01) and the same result in TBPM (3.28±0.77 vs. 4.20±0.66, t=-5.032, P<0.01). The positively correlation was showed between the duration of abstinence and EBPM (r=0.444, P<0.05), as well as TBPM (r=0.423, P<0.05) in the patients. Conclusion The results suggest abstinent alcoho1 dependence patients impairs both EBPM and TBPM. PM shows correlated with duration of abstinence moderately in the patients. Key words: Alcohol dependence; Prospective memory; Neuropsychology

Whilst the deleterious effects of alcohol on retrospective remembering have been widely documented, no study has yet objectively determined alcohol's effects on prospective memory (PM)--remembering to do something in the future. With this aim, the present study determined the acute effects of alcohol upon PM using a laboratory measure that simulates the PM tasks in everyday life--'Virtual Week'--both (a) in its standard form with regular, irregular, event-based and time-based PM tasks; and (b) an adapted version which enabled exploration of how future event simulation at encoding impacted upon subsequent PM. Forty healthy volunteers were administered 0.6 g/kg ethanol or a matched placebo in a double-blind fashion and completed the two versions of Virtual Week along with prose recall (to tap retrospective memory) and an executive function task. Alcohol acutely produced global impairments across all (regular, irregular, event-based and time-based) PM tasks. It also produced impairments of episodic memory which positively correlated with PM performance of irregular tasks. Future-event simulation tended to enhance PM in the placebo but not in the alcohol group. These findings on an objective measure of PM suggest that 4-5 units of alcohol will compromise PM abilities in everyday life.

Prospective memory (PM) impairment in recreational drug users has been documented in recent years. However, most studies on the effects of drugs on PM contain several methodological challenges, such as small sample size (< 100 participants), unrepresentative sample type (e.g., student or patient), short abstinence period (< 7days), and lack of control of potential confounds (e.g., sleep and IQ). The present study investigated the possible consequences of recreational drug use on prospective memory, using self-report and lab-based prospective memory measures while overcoming the methodological challenges. The sample was composed of 47 non-users (27 females, age range from 18 to 50 +) and 53 drug users (21 females, age range from 18 to 50 +). Recreational drug users reported significantly more deficits in the long-term episodic, short-term habitual, and internally cued PM failures subscales of the Prospective Memory Questionnaire. However, these deficits were eliminated after controlling for covariates (e.g., age, sleep quality, general health, alcohol usage). Recreational drug users also performed worse than non-users in the short-term, long-term, event-based, and time-based PM subscales of the Royal Prince Alfred Prospective Memory Test. These results remained significant after controlling for the covariates. Drug users demonstrated greater impairments on time-based and long-term PM tasks thought to be linked with executive functioning. Taken together, the present study provides further support for recreational drug-related deficits in PM and highlights a dissociation between self-report and lab-based PM measures.

Objective To investigate the event-based prospective memory(EBPM)and time-based prospective memory(TBPM)in schizophrenia patients with concomitant metabolism syndrome, and to provide theory basis for early intervention and treatment. Methods According to inclusion standard, 50 schizophrenia patients with concomitant metabolism syndrome and 50 schizophrenia patients without metabolism syndrome matched in age, gender and education were assessed with a neuropsychological battery of tests including EBPM and TBPM tasks. Results In the EBPM task, there was significant difference between schizophrenia patients with and without metabolism syndrome (3.46±0.91 vs 3.86±0.81, t=-2.326, P=0.022). A statistically significant difference in TBPM was observed between schizophrenia patients with and without metabolism syndrome (3.02±1.12 vs 3.78±0.89, t=-3.770, P=0.000). Conclusion The schizophrenia patients with metabolism syndrome have severer prospective memory impairment than those without metabolism syndrome. Key words: Metabolism syndrome; Schizophrenia; Prospective Memory

Prospective memory refers to the ability to remember to do something in the future. To date, little is known about prospective memory deficits in bipolar disorder (BD) in remission (euthymia). This study examined the nature and correlates of prospective memory in these patients. Forty-seven euthymic BD patients and 47 matched healthy controls formed the study sample. Socio-demographic and basic clinical characteristics, prospective memory (Cambridge Prospective Memory Test [CAMPROMPT]), retrospective memory (immediate Logical Memory subtests of the Wechsler Memory Scales-Revised [WMS-R]), IQ (Raven's Progressive Matrices) and executive functioning (Wisconsin Card Sorting Test) were measured in all participants; patients' symptoms were rated with the 17-item Hamilton Depression Rating Scale and the 11-item Young Mania Rating Scale. Patients performed significantly worse on time-based prospective memory compared to controls. Multivariate analyses revealed that patients' lower score on Raven's Progressive Matrices significantly contributed to poor performance on time-based prospective memory, whereas lower scores on WMS-R Logical Memory subtest contributed to poor performance on event-based prospective memory; in controls, lower education level and older age significantly contributed to poor performance on time-based and event-based prospective memory, respectively. Prospective memory deficits persist in remitted BD patients suggesting that prospective memory impairment constitutes a trait deficit in BD.

Background While event-based prospective memory refers to enacting intending action in response to a specific event or cue (“e.g., When I tell you there are 10 minutes left, please give me this stopwatch”), time-based prospective memory refers to enacting intending action in relation to a specific time (“In 10 minutes time, please ask me for a pencil”). Relative to event-based prospective memory, little is known about time-based prospective memory in Korsakoff’s syndrome (KS). Method We used behavioral tasks to investigate event- and time-based prospective memory as well as episodic memory and executive function in patients with KS and control participants. Results Analysis demonstrated lower event- and time-based prospective memory in patients with KS than in control participants. Interestingly, we found lower time-based than event-based prospective memory in patients with KS. Further, significant correlations were observed between prospective memory and episodic memory and executive function in the patients. Conclusions Prospective memory is important for everyday life tasks, and failures of prospective memory can endanger patients’ safety. One clinical implication of our findings is the importance of including an evaluation of prospective memory in cognitive evaluation of KS.

Prospective memory and quality of life in older and younger autistic adults.

Amnestic mild cognitive impairment (aMCI) is associated with neuropathological changes in medial-temporal and frontal-system structures. By definition, retrospective memory is mildly impaired in aMCI. We examined whether prospective memory (PM) is also impaired, in particular time-based PM, which requires considerable self-initiation and inhibition. We administered time- and event-based PM tasks to 42 healthy older adults, 45 individuals with aMCI, and 24 individuals with Alzheimer's disease (AD). The healthy group performed better than the aMCI group, and the aMCI group performed better than the AD group on both PM tasks. Importantly, the aMCI group performed more poorly on the time- than event-based task, whereas the other groups performed comparably on both tasks. Findings suggest that PM, particularly time-based PM, is sensitive to the earliest cognitive changes associated with aMCI, possibly reflecting decreased self-initiation, attention switching, and/or inhibition on memory tasks because of early involvement of the frontal system.

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

What impact does a state of alcohol hangover have upon everyday prospective memory and does this differ for men and women

Frontal lobe involvement in a task of time-based prospective memory