[Rehabilitation of prospective memory impairments in pathological aging]. / Prise en charge des troubles de mémoire prospective dans le vieillissement pathologique.

Prospective memory allows us to remember to perform an action in the future in response to environmental cues (event-based) or predetermined times (time-based). It is often impaired in individuals with mild cognitive impairment. These deficits are related to various cognitive functions such as episodic memory and executive functions and are particularly affected in pathological ageing. In this article, we propose a literature review of non-pharmacological interventions with the elderly with MCI and neurodegenerative diseases. This article explores different strategies for managing prospective memory, including cognitive training, mnemonic strategies, and external aids. In all cases, it is important to design personalized interventions that take account of patients' individual characteristics. Research into the long-term effectiveness of these strategies is still limited, and further studies are needed to properly assess their benefits.

Prospective memory, emotions and Alzheimer's disease.

Prospective memory (PM) refers to the ability to implement intended actions in the future. PM is particularly affected in the early stages of Alzheimer's disease (AD). The main objective of this study was to examine the links between PM and emotions in AD, since it has been shown that AD patients generally better memorise information with a positive emotional valence ("age-related positive effect"). Our hypothesis was that prior presentation of cue-action pairs would help subjects recall the prospective tasks to be performed, if these actions were associated with emotional valences. Twenty patients with mild AD and 20 healthy participants were included in this study. The experimental protocol consisted of viewing a video simulating a visit to a shopping centre. After receiving a shopping list, participants had to recall these actions after a given time (time-based) or when passing in front of particular stores (event-based). During the learning phase, actions were associated with positive, negative or neutral cues. We also manipulated the task difficulty by giving weak or strong cue-action links, and by introducing distractors. The results showed that the patients' performance was significantly lower than that of the healthy elderly participants both in event-based and time-based task conditions. However, patients obtained scores similar to those obtained by elderly healthy subjects in "event-based" tasks associated with a positive valence, although only when the link between the cues and the actions was strong. Associating positive stimuli with strongly linked cue-action pairs seems to allow AD patients to compensate for their difficulties in prospective memory. These results open avenues for future research into the rehabilitation of PM disorders in Alzheimer's disease.

[Prospective memory, emotions and Alzheimer's disease]. / Mémoire prospective, émotions et maladie d'Alzheimer.

Prospective memory (PM) refers to the ability to implement intended actions in the future. PM is particularly affected in the early stages of Alzheimer's disease (AD). The main objective of this study was to examine the links between PM and emotions in AD. Since it has been shown that generally AD patients memorize a better information with emotional positive valence ("age-related positive effect"). Our hypothesis was that prior presentation of cue-action pairs to memorize would help to remember the prospective tasks to perform, if these actions were associated with emotional valences. Twenty patients with mild AD and 20 healthy participants were included in this study. The experimental protocol consisted in viewing a video simulating a visit to a shopping center. After receiving a shopping list, participants had to recall these actions after a given time ("time-based") or passing in front of particular stores ("event-based"). During the training, actions were associated with positive, negative or neutral cues. We also manipulated the task difficulty by giving weak or strong cue-action links, and by introducing distractors. The results showed that the patients' performance was significantly lower than that of the healthy elderly participants both in "event-based" and "time-based" task conditions. However, patients obtained scores similar to those obtained by elderly heathy subjects in "event-based" tasks associated with positive valence, and only when the link between the cues and the actions was strong. Associating positive stimuli with strong linked cue-action pairs seems to allow AD patients to compensate their difficulties in prospective memory. These results open avenues of future research for the rehabilitation of PM disorders in Alzheimer's disease.

Emotion effects on implicit and explicit musical memory in normal aging.

Normal aging affects explicit memory while leaving implicit memory relatively spared. Normal aging also modifies how emotions are processed and experienced, with increasing evidence that older adults (OAs) focus more on positive information than younger adults (YAs). The aim of the present study was to investigate how age-related changes in emotion processing influence explicit and implicit memory. We used emotional melodies that differed in terms of valence (positive or negative) and arousal (high or low). Implicit memory was assessed with a preference task exploiting exposure effects, and explicit memory with a recognition task. Results indicated that effects of valence and arousal interacted to modulate both implicit and explicit memory in YAs. In OAs, recognition was poorer than in YAs; however, recognition of positive and high-arousal (happy) studied melodies was comparable. Insofar as socioemotional selectivity theory (SST) predicts a preservation of the recognition of positive information, our findings are not fully consistent with the extension of this theory to positive melodies since recognition of low-arousal (peaceful) studied melodies was poorer in OAs. In the preference task, YAs showed stronger exposure effects than OAs, suggesting an age-related decline of implicit memory. This impairment is smaller than the one observed for explicit memory (recognition), extending to the musical domain the dissociation between explicit memory decline and implicit memory relative preservation in aging. Finally, the disproportionate preference for positive material seen in OAs did not translate into stronger exposure effects for positive material suggesting no age-related emotional bias in implicit memory. (PsycINFO Database Record

The positivity bias in aging: Motivation or degradation?

The question of an emotional memory enhancement in aging, and of a positivity bias in particular, has been the subject of numerous empirical studies in the last decade. However, the roots of such positive preference are not yet well established. Partisans of a motivation-based perspective contend with those arguing that positivity is related to a cognitive or neural degradation. The aim of this study was to introduce some elements concerning positivity effect in aging. We compared immediate (i.e., immediate recall) versus delayed (i.e., delayed recall and recognition) emotional memory performance in 38 young adults, 39 old adults, 37 very old adults, and 41 Alzheimer's disease patients. Moreover, we manipulated the encoding instruction: Either participants received no particular processing instruction, or they had to process the material in a semantic way. The results indicated that the positivity bias is most likely to occur in individuals whose cognitive functions are preserved, after long retention delay, and in experimental conditions that do not constrain encoding. We concluded by highlighting that although these findings seem to be better in line with the motivation, rather than the degradation, perspective, they do not fully support either theory. (PsycINFO Database Record

Intermittent theta burst stimulation over left BA10 enhances virtual reality-based prospective memory in healthy aged subjects.

Prospective memory (PM) refers to a complex cognitive ability that underpins the delayed execution of previously formulated intentions. PM performance declines early in normal aging and this process is accentuated in Alzheimer's disease. The left frontopolar cortex (BA10) has been consistently assigned a major role in PM functioning, but whether it can be noninvasively modulated to enhance PM performance in aged people has not been addressed so far. Here, we investigated the effects of modulating left BA10 by means of theta burst stimulation (TBS), using either excitatory (intermittent TBS), inhibitory (continuous TBS) or control (vertex) TBS in healthy aged subjects. The behavioral effects were assessed using a reliable and ecological virtual reality PM task that included both event- and time-based retrievals. As compared with vertex stimulation, event-based PM performance significantly improved after excitatory stimulation, whereas inhibitory stimulation had no significant effect. Additionally, and across the different types of stimulation, performance for congruent links between the event-based PM cue and the action to be performed was significantly better as compared with incongruent links. In conclusion, intermittent TBS might provide a relevant interventional strategy to counteract the decline of cognitive functions and memory abilities in normal aging.

The role of saccade preparation in lateralized word recognition: evidence for the attentional bias theory.

Words presented to the right visual field (RVF) are recognized more readily than those presented to the left visual field (LVF). Whereas the attentional bias theory proposes an explanation in terms of attentional imbalance between visual fields, the attentional advantage theory assumes that words presented to the RVF are processed automatically while LVF words need attention. In this study, we exploited coupling between attention and saccadic eye movements to orient spatial attention to one or the other visual field. The first experiment compared conditions wherein participants had to remain fixated centrally or had to make a saccade to the visual field in which subsequent verbal stimuli were displayed. The orienting of attention by saccade preparation improved performance in a lexical decision task in both the LVF and the RVF. In the second experiment, participants had to make a saccade either to the visual field where verbal stimuli were presented subsequently or to the opposite side. For RVF as well as for LVF presentation, saccade preparation toward the opposite side decreased performance compared to the same side condition. These results are better explained by the attentional bias theory, and are discussed in the light of a new attentional theory dissociating two major components of attention, namely preparation and selection.

The effect of response modality on immediate serial recall in dementia of the Alzheimer type.

OBJECTIVE: Contrary to traditional models of verbal short-term memory (STM), psycholinguistic accounts assume that temporary retention of verbal materials is an intrinsic property of word processing. Therefore, memory performance will depend on the nature of the STM tasks, which vary according to the linguistic representations they engage. The aim of this study was to explore the effect of response modality on verbal STM performance in individuals with dementia of the Alzheimer Type (DAT), and its relationship with the patients' word-processing deficits. METHOD: Twenty individuals with mild DAT and 20 controls were tested on an immediate serial recall (ISR) task using the same items across two response modalities (oral and picture pointing) and completed a detailed language assessment. RESULTS: When scoring of ISR performance was based on item memory regardless of item order, a response modality effect was found for all participants, indicating that they recalled more items with picture pointing than with oral response. However, this effect was less marked in patients than in controls, resulting in an interaction. Interestingly, when recall of both item and order was considered, results indicated similar performance between response modalities in controls, whereas performance was worse for pointing than for oral response in patients. Picture-naming performance was also reduced in patients relative to controls. However, in the word-to-picture matching task, a similar pattern of responses was found between groups for incorrectly named pictures of the same items. CONCLUSION: The finding of a response modality effect in item memory for all participants is compatible with the assumption that semantic influences are greater in picture pointing than in oral response, as predicted by psycholinguistic models. Furthermore, patients' performance was modulated by their word-processing deficits, showing a reduced advantage relative to controls. Overall, the response modality effect observed in this study for item memory suggests that verbal STM performance is intrinsically linked with word processing capacities in both healthy controls and individuals with mild DAT, supporting psycholinguistic models of STM.

Recollection training and transfer effects in Alzheimer's disease: effectiveness of the repetition-lag procedure.

OBJECTIVE: This study was designed to extend the use of a memory training technique, known as the repetition-lag procedure, to Alzheimer patients. The specificity of this procedure is to target the process of recollection for improvement. METHOD: A group of 12 patients were trained individually for 6h. The training procedure consisted of a series of yes/no recognition tasks in which some words were repeated throughout the test list across gradually increasing delays. Their performance was evaluated on pre-and-post tests and compared with a recognition practice group and a no contact control group. RESULTS: Initially, recollection training patients only performed accurately when the delay between repetitions consisted of one intervening word, but by the end of training their performance increased up to four-word intervals. Interestingly, these benefits generalized to other measures of memory, such as working memory, visual memory and source recognition. CONCLUSIONS: Effectiveness of the repetition-lag procedure in Alzheimer's disease is discussed.

Abnormal temporal dynamics of visual attention in Alzheimer's disease and in dementia with Lewy bodies.

Although attentional control processes are disproportionately impaired in dementia with Lewy bodies (DLB) compared with dementia of the Alzheimer type (DAT), previous studies have not compared directly the temporal dynamics of visual attention in DLB and DAT. We examined the magnitude of the attentional blink (AB) effect in these patients, to determine the degree to which each patient group exhibited a deficit in selecting and processing visual stimuli presented in rapid succession. Eighteen DAT, 15 DLB patients, and 33 elderly controls were tested in a rapid serial visual presentation task. Participants were asked to report 1 (single-target condition) or 2 target letters (dual-target condition) embedded in a sequence of digit distracters. The temporal dynamics of visual attention was examined by varying the number of intervening distracters between the 2 targets in the dual-target condition and by estimating the attentional blink effect as the decline in the ability to report the second target correctly after successfully identifying the first. Patients with DLB performed significantly worse than patients with DAT and controls in both the single and dual-targets conditions. In contrast, DAT patients showed a selective impairment in the dual-target condition as compared with controls. As predicted, we found that both patients with DAT and DLB showed a more pronounced and protracted attentional blink than controls, indicating a reduced ability to re-engage attention on the second target. Furthermore, when DAT and DLB patients were able to report the second target, they frequently failed to identify the first, an effect that was absent in elderly controls and particularly large and long-lasting in DLB patients. This study suggests that both DLB and DAT patients show abnormal temporal dynamics of visual selective attention, presumably due to a greater intertarget competition for limited processing capacity. More generally, these findings reinforce the notion that deficits of attentional control processes are more severe in DLB patients as compared with DAT patients.

[Contribution of various MRI techniques to the characterization of Mild cognitive impairment]. / Apport de l'IRM à la caractérisation du MCI.

Mild cognitive impairment (MCI) is considered as a strong risk factor for Alzheimer's disease (AD) or other dementia syndromes. Since the last decade, numerous publications have been aimed to characterize early detectable brain changes in vivo, using more and more efficient neuroimaging techniques. This review is devoted to the brain damages detectable in MCI patients according to the MRI techniques available to date. The greatest number of studies, using structural and functional imaging, report many abnormalities principally located in the medial temporal lobe. They show, especially in this region, cortical atrophy, reduction of glucose metabolism, decrease in regional cerebral blood flew and biochemical changes. Moreover, progresses in the functional methods allow to detect brain activity during memory tasks, trying to specify whether this activity increases or decreases according to the task and the severity of cognitive impairment. The contribution of each RMI technique (morphologic, metabolic, and functional) is addressed in order to reveal how relevant they are to distinguish subjects with MCI from patients with early AD. Furthermore, their relevance to discriminate between MCI with different degrees of cognitive deficit and their power to predict the risk of conversion to AD is discussed. Finally, we review the main assumptions made to explain the underlying mechanisms of cognitive decline and present evidences in favor of dynamic compensatory processes, existence of cognitive reserve and disconnection processes. Many neuroimaging data support the pattern of installation and evolution of brain damages found in AD, reinforcing the idea that a part of amnesic MCI is probably a prodromal state of AD.

Episodic memory and organizational strategy in free recall in unipolar depression: the role of cognitive support and executive functions.

Executive functioning and memory impairment have been demonstrated in adults with depression. Executive functions and memory are related, mainly when the memory tasks require controlled processes (attentional resource demanding processes)--that is, when a low cognitive support (external aid) is provided. A cross-sectional study was carried out on 45 participants: 21 with depression, and 24 healthy controls matched for age, verbal ability, education level, and anxiety score. Cognitive support was manipulated by providing a categorized word list at encoding, presented either clustered (high cognitive support) or randomized (low cognitive support) to both depressed and healthy adults. The number of words recalled was calculated, and an index of clustering was computed to assess organizational strategies. Participants were also administered cognitive tests (executive functions, cognitive speed, and categorical fluency) to explore the mediators of organizational strategies. Depressed participants had greater difficulty recalling and organizing the words, but the differences between the two groups were reduced for both measures when high cognitive support was provided at encoding. Healthy adults performed better on all cognitive tests. Statistical analyses revealed that in the depressed group, executive functions were the only variable associated with clustering and only when low cognitive support was provided. These findings support the view that the decrement in executive function due to depression may lead to impairment in organization when this mnemonic strategy has to be self-initiated.

[Assessment of episodic memory in illiterate elderly]. / Evaluation des capacités de mémoire épisodique de sujets âgés illettrés.

Assessing cognitive functions in illiterate people is a difficult task because most of the neuropsychological tests exploring episodic memory have been validated in formally educated people, are based on verbal material and, therefore, require a good knowledge of language. Two episodic memory tests (TNI93 and TMA93) designed to be used for cognitive impairment screening in illiterate people have been designed, then validated in a multicultural low-educated population. Four hundred and thirty seven subjects aged 60 and over, living in the Seine-Saint-Denis district, received a medical check up offered by the National Health Service and their episodic memory performance was examined with these screening tests. The performance obtained on these tests depends both on age and educational level, as expected. Normative data for screening purpose in population with low education and/or not fluent with the language of the examiner are presented.

[Prospective memory in normal aging and Alzheimer's disease]. / La mémoire prospective au cours du vieillissement normal et dans la maladie d'Alzheimer.

Remembering to implement intented activities such as remembering to take medications is referred to as prospective memory (PM). Studies on aging and PM show important variations in the magnitude of the effect of age. One explanation, derived from the multiprocess framework, proposes that age differences depend on retrieval processing. It is thought to be automatic for event-based PM tasks by contrast to self-initiated processing for time-based PM tasks. Older adults generally perform worse than younger ones in laboratory tasks. PM tasks show pronounced age-related deficits, particularly in tasks demanding high level of controlled strategies (e.g. in time-based tasks versus in event-based tasks or, in low salience cue condition versus high salience cue condition in event-based tasks). However, age differences in PM tasks settings differ substantially across studies: some of them show that older adults perform as well as younger ones in event-based PM tasks, especially in ecological ones. Developmental psychologists have investigated this topic, and suggested that several factors could potentially be responsible for the age-related differences observed in MP. These differences could be related to the characteristics of PM cues (e.g. the strength of the association between PM cues and intended actions), the complexity or demands of the ongoing task, or the involvement of planning processes, in other words, the involvement of executive functions. PM deficits are important in mild Alzheimer's disease, even more important than episodic memory or executive functions deficits. This article presents a critical review of cognitive and neuropsychological studies that examined whether these factors or other partly mediate the older adults deficits in prospective memory, which are more important than those observed in episodic memory. The variability of results between studies points to the concept complexity.

Effects of the dopamine agonist piribedil on prefrontal temporal cortical network function in normal aging as assessed by verbal fluency.

Normal aging has been associated with impaired performance in verbal fluency suggesting a prefrontal temporal cortical network (PFTCN) deficiency. In this study, we investigated the effects of a 2-month treatment period with a dopaminergic agonist (DA) on PFTCN function. Forty healthy, elderly volunteers were assessed on semantic and phonemic verbal fluency after two months of a placebo or a DA treatment (i.e. piribedil 50 mg/day) in a double-blind crossover design. Protocols were scored considering clustering, (i.e. production of words within semantic or phonemic categories, depending on the integrity of temporal lobe), and switching (i.e. the ability to shift between clusters, depending on frontal lobe functioning). Results revealed no significant main effect of the DA treatment on either verbal fluency variables but showed a significant interaction with working memory capacities, with high-capacity span subjects improving phonemic switching on DA whereas low-capacity span subjects performed more poorly on the drug than off. These data are consistent with the literature and confirm the crucial link between working memory capacities and dopamine agonist effects. The present study also provides evidence that pharmacological remediation of age-related cognitive decline has to be taken into consideration.

Verbal memory performance of patients with a first depressive episode and patients with unipolar and bipolar recurrent depression.

Depression is usually associated with episodic memory impairment. The main clinical features of depression associated with that memory impairment are not clearly defined. The main goal of that study was to assess the role of the diagnostic subtypes and the number of depressive episodes on the memory performance of acute unipolar (UP) and bipolar (BP) depressed patients.Twenty-three patients with a first major depressive episode (FE), 28 patients meeting DSM-IV criteria for UP recurrent depression (UR) and 18 BP patients with recurrent depression were compared with 88 healthy subjects on a verbal episodic memory task. Patients suffering from a first depressive episode did not show verbal memory impairment as compared to normal controls. Unlike FE patients, UR and BP patients exhibited verbal memory deficits with impaired free recall and normal cued recall and recognition. The memory deficits of the UR and BP patients was present in the first free recall trial. Depressed patients improved their memory performance across the three trials of the task at the same rate than normal controls. Our results suggest that the number of depressive episodes has a negative influence on verbal memory performance of acute depressed patients. The effects of the repetition of the depressive episodes are not modulated by the subtypes of depression and may reflect sensitization to the cognitive impact of depression associated with increasing prefrontal dysfunction.

Implicit and explicit emotional memory for melodies in Alzheimer's disease and depression.

The present study investigates the impact of emotional deficits on implicit and explicit memory for musical stimuli in patients with Alzheimer's disease and elderly depressed patients. Results showed that unlike Alzheimer's patients, depressed patients were unable to develop a positive affective bias of judgment for previously heard melodies.

Qualitative analysis of verbal fluency in depression.

The aim of this study was to analyze qualitative aspects of verbal fluency in depression. Phonemic and semantic output was scored for word clustering and switching between clusters in depressed patients and normal control subjects. Depressed patients (n=25) and normal control subjects (n=19) were administered both phonemic and semantic fluency tasks. All patients were also evaluated with executive card sorting tests. Patients with depression produced fewer words on the semantic fluency task than controls and showed normal performance on the phonemic fluency tasks. The deficit on semantic fluency of depressed patients was related to a reduced number of switches with normal cluster sizes. The number of switches in depression was associated with a reduced ability to shift mental set on card sorting tests, suggesting that verbal fluency impairment reflects general executive problems in depression.

[Explicit and implicit memory for emotional stimuli in depressed elderly and Alzheimer's disease]. / Mémoire explicite et implicite pour des stimuli émotionnels dans la dépression du sujet âgé et la maladie d'Alzheimer.

It is well known that emotional events are better recalled than neutral events. It indicates that memory is affected by the emotional content of stimuli. Since psychiatric and neurodegenerative diseases produce qualitatively and quantitively different memory and emotional disorders, a better understanding of their relations should improve our knowledge about memory and emotion interaction. We present here a review of recent studies that examined the effects of emotions on episodic (explicit) memory and on perceptual and conceptual priming (implicit memory) in depression and in Alzheimer's disease. Several studies of memory in depressed patients reported a tendency toward recall of negatively toned material indicating the existence of a bias toward processing of mood-congruent information. On the other hand, an enhancement of memory performance is observed in Alzheimer's disease when positive and negative stimuli are used.

Influence of age and executive functioning on verbal memory of inpatients with depression.

BACKGROUND: Despite many studies demonstrating memory and executive impairments in young and old depressed patients, the relationships between age, executive functioning and memory have not been evaluated in depression. The aim of this study was to investigate if older patients were more vulnerable than younger patients to the impact of depression on memory and if the differences between young and old depressed could be related to executive functioning. METHODS: Forty-nine inpatients, with unipolar and bipolar depression, ranging in age from 19 to 72 years were compared with 70 controls on a verbal memory task. Age cut-off of 45 years was used as a categorical variable to divide subjects into subgroups. A subset of patients (n=41) was also evaluated with the modified version of the Wisconsin Card Sorting Test and separated into a non-dysexecutive group and a group of patients with mild-executive impairment. RESULTS: Depressed patients exhibited memory deficits with a pattern of memory failure -- impaired free recall and normal cued recall and recognition -- interpreted as a retrieval problem. Both age and executive function influenced memory performance in depression, however neither group x age interaction nor age x executive status interaction were significant. Multiple regression analysis showed that free recall scores were related to age and psychomotor retardation in depressed patients. CONCLUSION: Age and executive functioning have different influences on the memory performance of depressed patients. Our findings support an 'executive memory decline hypothesis' in young as well as old depressed patients. The memory deficits in depression may be associated with both trait and state factors and raise questions about the long-term cognitive functioning of patients with recurrent affective disorders.