Prospective memory impairment and executive dysfunction in prefrontal lobe damaged patients: is there a causal relationship?

Relationship Between Future Thinking and Prospective Memory in Alzheimer's Disease

Background

Future thinking and prospective memory are two cognitive processes oriented toward the future and reliant on the ability to envision oneself in future scenarios.

Objective

We explored the connection between future thinking and prospective memory in individuals with Alzheimer's disease (AD).

Methods

We invited both AD participants and control participants to engage in event-based prospective memory tasks (e.g., "please hand me this stopwatch when I inform you there are 10 minutes remaining") and time-based prospective memory tasks (e.g., "close the book you are working on in five minutes"). Additionally, we asked participants to engage in a future thinking task where they imagined upcoming events.

Results

Analysis revealed that AD participants exhibited lower performance in both prospective memory tasks and future thinking compared to the control group. Importantly, we identified significant positive correlations between the performance on event- and time-based prospective memory tasks and future thinking abilities among AD participants.

Conclusions

These findings underscore the connection between the decline in both prospective memory domains and the ability to envision future events in individuals with AD. Our results also shed light on the challenges AD individuals face when trying to project themselves into the future to mentally pre-experience upcoming events.

Microstructural Correlates and Laterality Effect of Prospective Memory in Non-Demented Adults with Memory Complaints

BACKGROUND

An increasing number of studies suggest the importance of prospective memory (ProM) due to its functional relevance and sensitivity to neuropathology. However, its relevant neural substrates have not been sufficiently explored.

OBJECTIVES

The present study aimed to investigate the relationship between structural connectivity and both objective and subjective ProM measures in a group of non-demented people with subjective memory complaints, and to examine the potential of ProM measures to detect the difference between subjective cognitive decline (SCD) and mild cognitive impairment (MCI) in the pre-dementia stage.

METHOD

Thirty-sevennon-dementedparticipants aged above 50 years were recruited from an outpatient Neurology Clinic; 13 of them fulfilled the criteria of MCI and 24 of SCD. All subjects received comprehensive neuropsychological tests, including the adapted version of the Cambridge Prospective Memory Test, as well as the Taiwan version of the Prospective and Retrospective Memory Questionnaire. The diffusion tensor imaging technique with tract-based spatial statistics was applied to measure cerebral microstructural changes.

RESULTS

Time-based ProM performance was significantly correlated with microstructural integrity of the right superior longitudinal fasciculus, while the event-based one was associated with that of the left superior longitudinal fasciculus and the genu of the corpus callosum among all participants and in the SCD group. After controlling for age, the correlation remained significant between event-based ProM performance and the left superior longitudinal fasciculus among all participants and in the MCI group, as well as between event-based ProM performance and the genu among all participants. Although self-reported ProM failures in real life was associated with fiber disruption of the left superior longitudinal fasciculus among all participants and within the MCI group, an inverse relationship was also observed with that of the corpus callosum in the SCD group even after controlling for age. As compared to the SCD group, people with MCI performed significantly worse on time-based ProM tasks and reported more ProM failures in daily life.

CONCLUSIONS

ProM was related to the integrity of interhemispheric commissural fibers and association fibers that connect the frontal lobe with posterior regions, with a task-specific laterality effect. Time-based ProM tasks and self-reported ProM questionnaire may be sensitive to early pathological cognitive deterioration, while the concomitant aging process and individual awareness level may respectively confound the results of evaluation.

Prospective memory under acute stress: The role of (output) monitoring and ongoing-task demands

Prospective memory (PM) refers to the ability to postpone retrieval and execution of intended actions until the appropriate situation (PM cue) has come, while engaging in other ongoing activities or tasks. In everyday live we often perform PM tasks in stressful situations. While it has been shown that acute stress does not impair PM-cue identification and intention retrieval, little is known about acute stress effects on PM performance and memory for having performed an action (output monitoring) under varying ongoing-task demands. Here we investigated this in eighty healthy participants who performed event-based PM tasks during low- and high-demanding ongoing working memory tasks after having undergone either a standardized stress induction (Maastricht Acute Stress Test) or a standardized control protocol. Successful stress induction in the stress group compared to the no-stress group was confirmed by increased salivary cortisol, an indicator of stress-related hypothalamus-pituitaryadrenal axis activity, throughout the event-based PM tasks. Nevertheless, not-only PM-cue identification but also output monitoring remained fully intact after stress induction. The absence of these effects was independent of ongoing-task demands. Nonetheless, we replicated recent findings of a stress-induced reduction in performance cost of monitoring for PM-cue occurrences. Taken together our findings suggest that acute stress alters PM monitoring by enhancing selective attention, decreasing PM response thresholds or by shifting performance towards more automatic processes in PM, while not affecting PM-cue identification and output monitoring.

High openness and high extroversion are linked with better time-based prospective memory in multiple sclerosis

BACKGROUND

Prospective memory (PM) deficits are often reported in multiple sclerosis (MS), but their relationship with neuropsychological characteristics and personality traits remains to be explored.

OBJECTIVE

To systematically investigate both time-based and event-based PM abilities in a sample of MS without clinically relevant disability or global cognitive decline and to explore cognitive, neuropsychiatric characteristics and personality traits associated with PM deficits.

METHODS

Thirty-three patients with MS and 33 healthy individuals were enrolled in the study. All participants underwent a standardized measure of PM to evaluate both time-based and event-based PM. Moreover, patients with MS completed the Brief Repeatable Battery to assess cognitive functioning, the Beck Depression Inventory-II and the Dimensional Apathy Scale to assess neuropsychiatric characteristics, and the NEO Personality Inventory-3 to assess personality traits.

RESULTS

Individuals with MS demonstrated impaired time-based PM compared to healthy individuals. The regression analysis showed that poor performance in time-based PM was significantly related to lower extroversion and openness traits, whereas poor performance in event-based PM was significantly related to lower visuospatial memory abilities.

CONCLUSIONS

Low levels of openness and extroversion traits are associated with a greater risk of developing time-based PM deficit. Therefore, personality assessment and behavioural interventions should be encouraged in MS clinical practice.

Negative Prospective Memory in Alzheimer's Disease: "Do Not Perform That Action"

Relatively to "standard" prospective memory, i.e., remembering to perform a future action, little is known about negative prospective memory, i.e., remembering not to perform a future action. This study investigated the latter ability in Alzheimer's disease (AD). AD participants and healthy older adults were asked to click on the keyboard or not to click on it when a cue word was encountered. Results showed more omissions (i.e., forgetting to click the keyboard when the instruction was to do so) in AD participants than in healthy older adults, suggesting a prospective memory deficit. Interestingly, more commissions (i.e., clicking the keyboard when the instruction was not to do so) were also observed in AD participants than in healthy older adults. Similar levels of commissions and omissions were observed in AD participants and in healthy older adults. Also, commissions and omissions were correlated with performance on an inhibition assessment task. Our findings reveal that AD is characterized by not only difficulty in the retrieval of recent information, but also difficulty to inhibit no-longer appropriate stimulus-response associations previously learned, suggesting a specific deficit of negative prospective memory in AD.

Time-based prospective memory functioning in mild cognitive impairment associated with Parkinson's disease: relationship with autonomous management of daily living commitments

OBJECTIVE

Prospective memory (PM), that is, the ability to keep in memory and carry out intentions in the future, is reported to be impaired in individuals with Parkinson's disease (PD). PM failure may be also associated with reduced daily living functioning in these patients. Little is known, however, about the relationship between mild cognitive impairment (MCI) and time-based PM functioning in PD patients and the possible impact of PM deficits on patients' autonomy in daily living. Here we aimed to investigate whether MCI associated with PD affects time-based PM. We also wished to determine whether PM impairment accounts for reduced autonomous management of medication in these patients.

METHOD

The study included 48 PD patients with MCI, 33 PD patients without cognitive disorders (PDN) and 20 healthy controls. The time-based PM procedure required that subjects perform an action after a fixed time. The PM procedure was incorporated in the standard neuropsychological assessment. One score was computed for the ability to retrieve the intention (prospective component) and one for remembering the action to be executed (retrospective component). The Pill Questionnaire was administered to assess the ability to manage medication.

RESULTS

PD patients with MCI performed less accurately in the PM procedure than HC and tended to perform poorer than PDN. Moreover, in PD patients with MCI, accuracy on the prospective component of the PM task and performance on the Modified Card Sorting Test significantly predicted the ability to manage medication.

CONCLUSIONS

RESULTS document that reduced efficiency of time-based PM processes in PD is specifically related to the presence of MCI. The same data indicate that PM weakness may be associated with impaired daily living functioning and decreased autonomy.