A study of performance of delayed intentions in multiple sclerosis

The ability to remember and perform delayed intentions was investigated in a sample of 40 participants with Multiple Sclerosis (MS) and compared to a group of 36 healthy, neurologically intact, control participants. Using a model of task division, performance on both the prospective memory (PM) component (a failure to remember to do something at a specific time) and the retrospective memory (RM) component (a failure to remember the content of the intention) of two "naturalistic" delayed intention experimental tasks were examined. Significantly poorer performance of the MS group in completing one of the delayed intention tasks successfully appeared to be primarily attributable to retrospective memory deficits rather than prospective memory deficits. This proposition was further supported by group differences on RAVLT measures of retrospective memory. By utilising a paradigm that enables the nature of failure in performing delayed intention tasks to be identified, specific strategies for the clinical management of MS cognitive deficits can be developed.     

A Study of Performance of Delayed Intentions in Multiple Sclerosis

The ability to remember and perform delayed intentions was investigated in a sample of 40 participants with Multiple Sclerosis (MS) and compared to a group of 36 healthy, neurologically intact, control participants. Using a model of task division, performance on both the prospective memory (PM) component (a failure to remember to do something at a specific time) and the retrospective memory (RM) component (a failure to remember the content of the intention) of two “naturalistic” delayed intention experimental tasks were examined. Significantly poorer performance of the MS group in completing one of the delayed intention tasks successfully appeared to be primarily attributable to retrospective memory deficits rather than prospective memory deficits. This proposition was further supported by group differences on RAVLT measures of retrospective memory. By utilising a paradigm that enables the nature of failure in performing delayed intention tasks to be identified, specific strategies for the clinical management of MS cognitive deficits can be developed.     

Patients with Parkinson's disease can successfully remember to execute delayed intentions.

The present study investigated prospective memory in patients with Parkinson's disease (PD) and healthy controls. In addition, the influence of task importance on participants' performance was examined. Experimental settings required participants to focus either on the prospective or the ongoing task. The three main findings are (1) PD patients performed as well on a prospective memory task as healthy controls when the focus was laid on the prospective memory task, (2) their prospective memory performance was impaired when the ongoing activity was stressed, and (3) differences in working memory capacity were related to these differential effects. Results indicate that PD patients can perform event-based prospective memory tasks to a normal degree if the prospective task component is prioritized. Data also suggest that a reduced working memory capacity plays an important role in this process. Findings are discussed in terms of conceptual, methodological, and clinical implications.     

Planning and realisation of complex intentions in patients with Parkinson's disease

BACKGROUND: There is some evidence that patients with Parkinson's disease may impaired in prospective memory performance (planning and self initiated realisation of delayed intentions). Little is known about the effect of the disease on distinct phases of prospective memory and the potential mechanisms underlying these effects. OBJECTIVE: To investigate intention formation, intention retention, intention initiation, and intention execution of patients with Parkinson's disease and test for the mediating influence of working memory, inhibition, short term retrospective memory, and divided attention. METHODS: 16 patients with Parkinson's disease and 16 age and education matched normal controls were given a complex event based prospective memory task which differentiates four phases of prospective remembering. In addition, participants completed tasks assessing potential cognitive mediators. RESULTS: On the prospective remembering task, Parkinson patients were impaired in the intention formation phase and showed a trend towards impairment in the intention initiation. In contrast, there were no impairments of retrospective intention retention or the fidelity with which the patients executed their previously developed plan. The group effects were related to interindividual differences in working memory span. CONCLUSIONS: The results suggest that the planning phase of prospective remembering is specifically impaired in Parkinson's disease, and that the impairment is related to working memory deficit. In contrast, even when complex intentions have to be remembered, the retrospective storage of intentions to be performed is not impaired.     

Prospective memory and mesial temporal epilepsy associated with hippocampal sclerosis

Episodic memory impairment is commonly observed in patients with epilepsy associated with mesial temporal sclerosis (MTS). Prospective memory (PM) is a set cognitive abilities that allow future performance of a present intention, in response to time- or event-based evocation cues, that trigger the intended action at the appropriate time. PM has not been evaluated in mesial temporal sclerosis. We evaluated the role of right and left hippocampal lesions on performance in both the retrospective and prospective PM components in patients with epilepsy secondary to mesial temporal sclerosis and correlated with performance in traditional neuropsychological tests, as well as with self-perception of memory impairment. We tested the hypotheses that a hippocampal lesion impacts on the prospective components of PM, and that a left-sided lesion had a greater impact on performance in the prospective component of PM than a right-sided lesion. We evaluated PM in 26 patients with right MTS, 22 left MTS patients, and 26 age-gender and education matched controls. The prospective component of PM was impaired in both patient groups, with both a lesion (patients performed significantly worse in the PM battery) and laterality effect (left MTS patients performed significantly worse than right MTS patients in the PM battery). Performance in the prospective component of the PM battery correlated with long-term delay performance in episodic verbal memory and self-perception of memory impairment in the left MTS group. The retrospective component was impaired in left MTS patients. Impaired performance was not accounted for solely by depression, anxiety or an antiepileptic drug effect. We conclude that mesial temporal lobe structures, including the hippocampus, play an important role in both the prospective and retrospective components of PM processes in tasks involving long delay intervals.     

Program

Abstract

Sixty-four individuals were given the Learning and Memory Battery (LAMB), which consists of a series of retrospective learning tasks. Embedded within the LAMB was a prospective memory task, requiring individuals to respond with a different word or phrase (target response) each time one of the LAMB subtests was introduced. The impact of retrospective memory, as well as age, on prospective memory was examined. An age-associated decrease in performance occurred on both the prospective and retrospective memory tests. The decreased ability of the older subjects to spontaneously recall target words on the prospective memory task was due to a failure to retrieve previously learned information rather than a failure to learn the target words. The results of a stepwise multiple regression analysis, in which age was forced into the equation first, showed a significant relationship between prospective and retrospective memory. The clinical implications of the results were discussed.     

Neural activity associated with the realization of a delayed intention

This study examines neural activity associated with the realization of a delayed intention within the context of the noticing+search model of prospective memory (PM) using event-related brain potentials (ERPs). The noticing+search model proposes that PM is supported by two related processes, noticing (the detection of a PM cue in the environment) and search (the retrieval of an intention from memory). In two experiments participants performed a PM task that permitted the dissociation of the noticing and search processes. Noticing was associated a phasic negativity over the occipital-parietal region (N320) and search was associated with a sustained modulation (slow-wave) reflecting a negativity over the right frontal region and a broadly distributed positivity over the parietal region. The amplitude of the N320 was greater when the PM cue was associated with an intention than when the cue was irrelevant to task performance, leading to the proposal that noticing may be accomplished through the attentional modulation of neural systems which support processing of the defining features of the PM cue. The topography of the slow-wave resembled that of modulations of the ERP associated with the recollection of information in studies of retrospective memory leading to the suggestion that similar neural processes may support the recovery of information from memory in both prospective and retrospective memory tasks.     

Age-related differences in the neural correlates of remembering time-based intentions

The present study used event-related potentials (ERPs) to explore the effect of age on the neural correlates of monitoring processes involved in time-based prospective memory. In both younger and older adults, the addition of a time-based prospective memory task to an ongoing task led to a sustained ERP activity broadly distributed over the scalp. Older adults, however, did not exhibit the slow wave activity observed in younger adults over prefrontal regions, which is considered to be associated with retrieval mode. This finding indicates that age-related decline in intention maintenance might be one source of the impaired prospective memory performance displayed by older adults. An 'anterior shift' in scalp distribution of the P3 was observed in older adults, and was related to lower levels of accuracy in prospective memory performance. This relationship suggests that possible factors responsible for age-related decline in prospective memory performance include the decreased efficiency of executive/frontal functions as well as the reduced amount of resources available for the prospective memory task.     

Prospective memory assessment in acute mild traumatic brain injury

Abstract

Objective: Prospective memory (PM) is the ability to remember to perform an intention at the appropriate time in the future. It is of primary importance for daily living, and its disruption may impact functional autonomy. To date, few studies have examined PM during the acute phase of mild traumatic brain injury (mTBI), despite the high prevalence of this neurological condition and its potential impact on cognition.

Method: Twenty mTBI patients (time since injury ranged from 45 to 73?days) and 15 healthy control participants performed the Ecological Test of Prospective Memory (TEMP), a simulated errand task in which participants were required to execute 10 event-based (EB) and five time-based (TB) tasks. The TEMP separately evaluates PM phases as well as prospective and retrospective components in event- and time-based conditions. Participants also completed a neuropsychological test battery. Correlations were performed between cognitive composite scores and the TEMP.

Results: mTBI patients experienced difficulty in learning the content of intentions, retrieving these intentions in the time-based condition (prospective component) and recalling the associated actions in the event- and time-based conditions (retrospective component). Retrospective memory composite score was correlated with the learning and retention phases of the TEMP, whereas attention/working memory and executive composite scores were correlated with the time-based condition and performance on the ongoing task.

Conclusion: These results suggest the presence of global PM impairment during the acute phase of mTBI, as well as impairment of retrospective memory, attention/working memory, and executive functions, which are key components for PM performance.     

Prospective and retrospective components in the memory for actions to be performed in patients with severe closed-head injury.

This study investigated the basic mechanisms of the impairment of memory for actions to be performed in a group of 16 chronic survivors of severe closed-head injury (CHI). The experimental paradigm allowed discrimination between the deficit in spontaneously remembering the intention at the appropriate moment (prospective component of the task) and the deficit in remembering the specific actions to perform (retrospective component). The experimental procedure also contrasted a condition in which the time expiration was marked by the ringing of a timer (event-based condition) and one in which the time expiration was not marked by any event and the patient had to monitor the passing of time and completely self-activate the recall of the intention (time-based condition). Two other experimental manipulations were concerned with the duration of the delay interval from the examiner's instructions to the time expiration (10 vs. 45 min) and the fact that the three actions to be performed could be functionally related or not. With respect to a group of 16 normal controls, the patients with CHI were impaired in both the prospective and retrospective components of the memory for actions. Although an impairment of episodic memory is a plausible explanation for the poor retrieval of specific actions to perform, it is unlikely that this deficit played a major role in the CHI patient's reduced accuracy in spontaneously recalling the intention when the event occurred or the time expired. Instead, reduced frequency and less strategic utilization of time monitoring and/or self-reminding likely played a significant role in this sense.     

Prospective memory in multiple sclerosis.

There is considerable evidence that multiple sclerosis (MS) is associated with impaired retrospective memory. However, although preliminary evidence suggests that prospective memory is also affected by the disorder, the degree and nature of the impairment remains to be clarified. Twenty participants with MS were compared with 20 matched controls on Virtual Week, a measure of prospective memory that closely represents the types of prospective memory tasks that actually occur in everyday life, and provides an opportunity to investigate the different sorts of prospective memory failures that occur. The results indicated that irrespective of the specific prospective memory task demands, MS participants' performance was significantly impaired relative to controls. MS deficits could not be attributed to problems with retrospective memory because MS participants in the present study did not differ significantly from controls on measures of long- and short-term memory, and significant impairment was observed on a prospective memory task, which imposed only minimal demands on retrospective memory. These results therefore suggest that individuals with MS may experience general difficulties with prospective memory. The practical and theoretical implications of these findings are discussed.     

The Influence of the Stroop Interference Effect on an Event-based Prospective Memory Task in Alzheimer's Disease Patients

Background : Prospective memory is known as the memory of a plan to carry out an intended action in the future. Although it is associated with many activities in everyday life, to date there have been no well controlled laboratory studies of prospective memory in patients with Alzheimer's dementia (AD). In this study, we investigated the ability of prospective memory in AD subjects using an event-based prospective memory task in which prospective remembering is triggered by a specific external cue.
Methods : Using a personal computer, we conducted event-based prospective memory tasks embedded in the Stroop task. The concurrent cognitive task such as the Stroop task was called the ongoing task. In the event-based prospective memory task, subjects were required to react by pressing a mouse key whenever a stimulus during the Stroop task (identification of the name of a color printed in black, of the correct color of a colored circle, or the name of a color printed in an incorrect color) appeared in a larger-than-normal size. This target stimulus was designed to appear eight times in each condition, i.e., word condition, color condition, and incorrect-color condition, during the Stroop task.
Results : Normal elderly people showed good event-based prospective memory performance across all three conditions in the Stroop task. In contrast, AD subjects performed poorly in the event-based prospective memory task under the incorrect-color condition in the Stroop task.
Conclusion : This study indicated that an ongoing concurrent task with a high attention demand affects the performance of event-based prospective memory in AD subjects. The performance of event-based prospective memory in AD subjects was more sensitive to the Stroop interference effect observed in the ongoing task than in normal elderly people. The breakdown of this event-based prospective memory may reflect the limited attention capacity of AD subjects.     

Characteristics of prospective memory deficits in HIV-seropositive substance-dependent individuals: preliminary observations

The construct of "prospective memory" (PM) refers to a type of episodic memory for a future intention or "remembering what one must do." This function has been proposed as a candidate mechanism underlying behaviors of critical importance in HIV disease, including adherence with medication regimens and continued engagement in risk behavior. We administered tasks of time-based and event-based prospective memory and control tasks of retrospective and working memory to 31 HIV-seropositive and 35 HIV-seronegative substance-dependent individuals (SDIs). We found that compared with HIV- controls HIV+ participants showed deficits in time-based but not event-based PM. Retrospective, but not working, memory performance correlated significantly with time-based PM performance. In addition, performance on the time-based PM task was a significant predictor of scores on a self-report measure of risky sexual and injection practices. These preliminary data provide new and unique findings regarding the components of executive function mediated by prefrontal cortical systems that are impaired among HIV+ SDIs and their relevance to "real-world" behaviors.     

Odor recognition memory is not independently impaired in Parkinson’s disease

The results of previous studies in small groups of Parkinson’s disease (PD) patients are inconclusive with regard to the presence of an odor recognition memory impairment in PD. The aim of the present study was to investigate odor recognition memory in PD in a larger group of patients. Odor recognition memory and detection thresholds were assessed using components of the “Sniffin’ Sticks” test battery in 55 non-demented PD patients (Hoehn and Yahr stages I–III) and 50 control subjects of comparable age and sex. PD patients performed slightly but significantly worse than control subjects on the odor recognition memory task. After correction for odor detection scores, however, the difference in odor recognition memory performance between PD patients and controls was no longer statistically significant. These data indicate that odor recognition memory is not independently impaired in PD patients.     

Metamemory for faces following frontal lobe damage.

Previous research has provided evidence of metamemory impairments in patients with frontal lobe damage on verbal episodic memory tasks. In the present study, we employed metamemory paradigms to investigate whether patients with frontal lesions show monitoring deficits on semantic memory tasks involving facial stimuli. Patients with frontal lobe damage and healthy control subjects made memory decisions to famous faces in a retrospective confidence judgment task and in a prospective feeling-of-knowing (FOK) task. Results indicated that frontal patients performed worse than controls on the retrospective confidence task, but there were no differences between the groups on the FOK task. These findings suggest that metamemory deficits in frontal patients are not confined to specific stimulus domains (words vs. faces) or memory systems (episodic vs. semantic). In addition, the dissociation between retrospective confidence judgments and FOK accuracy documented in this study and also in a recent report by Schnyer et al. suggesting that metamemory should not be considered a unitary function with a single neuroanatomic substrate.     

Failure of Prospective Memory after Acquired Brain Damage: Preliminary Investigation and Suggestions for Future Directions

Abstract

This paper investigates the premise that the greater frequency of errors after acquired brain damage will facilitate identification of essential components of successful prospective memory. It examines performance by patients with recent acquired non-progressive brain damage and age-matched control subjects on two experimental measures of prospective memory. A significant difference between patients and control subjects arises mainly from performance on a time-based prospective memory task. Results from patients on tests of time- and event-based prospective memory are compared with scores on tests of episodic memory and executive skills. A relationship is identified between event-based prospective memory and retrospective episodic memory but not between time-based prospective memory and executive skills. Premorbid intelligence and current mood state are identified as variables that should be considered when investigating prospective memory under experimental conditions.     

Prospective memory impairment as an early indicator of dementia

Abstract

Theoretical accounts of the cognitive processes involved in prospective memory imply that performance on such tasks will be more vulnerable than retrospective memory tests to the early stages of dementia. This hypothesis is examined in elderly subjects from a general population sample which includes demented subjects. We report the findings on three tests of prospective memory from the Rivermead Behavioural Memory Test (Wilson et al., 1985) and compare it with measures of retrospective memory for recently acquired information. In contrast to retrospective memory where subjects with minimal dementia perform at a level intermediate between normals and more demented subjects, the subjects with minimal dementia perform as poorly as more demented subjects on the prospective memory tests. These findings provide evidence that prospective memory tasks are particularly sensitive to the early stages of dementia. Covariance analysis and the pattern of intercorrelations found between prospective and retrospective memory lead to alternative hypotheses about the cognitive processes involved in prospective memory and the way in which they break down.     

Implicit and explicit memory in Alzheimer's disease and Parkinson's disease

Several tasks examined implicit and explicit memory in demographically matched samples of Alzheimer's (AD) and Parkinson's disease (PD) patients, and healthy elderly subjects. A fragmented pictures test, word stem-completion repetition priming, and a pursuit-rotor tracking task, followed by explicit memory tests, were given. AD patients were impaired on all explicit tests and on word stem-completion priming, but were intact on pursuit-rotor tracking and the skill learning (SL) component of the fragmented pictures test. PD patients were significantly better than AD patients on all explicit memory tests, but were selectively impaired on the SL component of the fragmented pictures test. Finally, a mirror-reading test was given to the PD patients and control subjects, with no significant differences found in performances between the two groups. Results are discussed in terms of hypothetical cognitive processes and brain circuits underlying different implicit and explicit memory domains.     

Deficits in prospective memory following damage to the prefrontal cortex

Neuropsychological investigations of prospective memory (PM), representing memory of future intentions or plans, have evolved over the past two decades. The broadly accepted divisions involved in PM consist of a prospective memory component (PMC), a process for remembering to remember, and a retrospective memory component, a process for remembering the content of the intended action. Previous functional neuroimaing studies have provided some evidence that the rostral prefrontal cortex (BA10) is one of areas that is critical for prospective remembering. However, the question of whether damage to part of the prefrontal cortex affects attenuated performance for PMC remains unresolved. In this study, 74 participants with traumatic brain injury (TBI) including focal damage to frontal or temporal lobe areas were administered thirteen standard neuropsychological tests and the PM task. To identify influential areas contributing to PM performance, discriminant function analysis was conducted. The results indicated that the following three areas are highly contributory to PM performance: the right dorsolateral prefrontal cortex; the right ventromedial prefrontal cortex; and the left dorsomedial prefrontal cortex. Comparing differences in neuropsychological test scores showed that orientation scores were significantly higher in the greater PM performance group, suggesting that PMC represents an integrated memory function associated with awareness of current status. These data contribute to our understanding of the neural substrates and functional characteristics of the PMC.     

Cognitive processes involved in delayed non-matching-to-sample performance in Parkinson''s disease

Visual recognition memory was assessed in terms of delay duration, memory load and amount of interference(s) in non-demented patients with Parkinson's disease (PD) using an automated delayed non-matching-to-sample (DNMS) task with trial-unique stimuli. Special attention was focused on the different cognitive functions engaged by these patients in solving this recognition memory task. Thirteen patients with PD, carefully selected according to their stable regimen and anticholinergic medication, were compared to 12 controls matched by age and educational level. Besides the DNMS task, a neuropsychological battery that included tasks carefully selected according to processes potentially required to perform the DNMS task (e.g. attention, executive functions, visual discrimination and motor speed) was administered to the subjects. As compared with controls, patients with PD showed a deficit on most DNMS subscores, except those requiring the least cognitive load. The correlative analysis between the DNMS and other neuropsychological tasks suggests involvement of long-term memory mainly in the DNMS performance for the control group, contrasting with a major involvement of executive functions for the patients with PD. These data indicate that visual recognition memory impairment in non-demented patients with PD is largely due to an executive dysfunction, notably in working memory. Several hypotheses are proposed concerning the neuronal substrates underlying the impairment on the visual DNMS task in PD.