A differential deficit in time- versus event-based prospective memory in Parkinson's disease.

Objective: The aim of the current study was to clarify the nature and extent of impairment in time- versus event-based prospective memory in Parkinson's disease (PD). Prospective memory is thought to involve cognitive processes that are mediated by prefrontal systems and are executive in nature. Given that individuals with PD frequently show executive dysfunction, it is important to determine whether these individuals may have deficits in prospective memory that could impact daily functions, such as taking medications. Although it has been reported that individuals with PD evidence impairment in prospective memory, it is still unclear whether they show a greater deficit for time- versus event-based cues. Method: Fifty-four individuals with PD and 34 demographically similar healthy adults were administered a standardized measure of prospective memory that allows for a direct comparison of time-based and event-based cues. In addition, participants were administered a series of standardized measures of retrospective memory and executive functions. Results: Individuals with PD demonstrated impaired prospective memory performance compared to the healthy adults, with a greater impairment demonstrated for the time-based tasks. Time-based prospective memory performance was moderately correlated with measures of executive functioning, but only the Stroop Neuropsychological Screening Test emerged as a unique predictor in a linear regression. Conclusions: Findings are interpreted within the context of McDaniel and Einstein's (2000) multiprocess theory to suggest that individuals with PD experience particular difficulty executing a future intention when the cue to execute the prescribed intention requires higher levels of executive control. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Prospective memory impairment in individuals with Parkinson's disease.

This study investigated prospective memory and its relationship to executive and memory functions in persons with Parkinson's disease (PD). Twenty-three individuals with PD and 25 healthy comparison participants participated in the study. In the prospective memory tasks, participants were asked to execute 3 actions after 20 min (time-based condition) or after a timer ring (event-based condition). A score was computed for the correct recall of the intention to perform the actions (prospective component) and for the correct execution of the actions (retrospective component). Participants with PD also received an extensive neuropsychological test battery. PD participants were less accurate than comparison participants in the prospective component of the time-based but not the event-based task. Individuals with PD were also impaired on the retrospective component of both tasks. In the PD group, a general trend toward significant correlations was found between performance level on the prospective memory component of the time-based task and scores on executive and working memory measures. These results document that prospective memory is impaired in PD possibly in relation to a dysregulation of cognitive functions associated with frontal systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deficient Strategic Control of Verbal Encoding and Retrieval in Individuals With Methamphetamine Dependence.

Methamphetamine (MA) dependence is associated with deficits in episodic verbal memory, but the cognitive mechanisms underlying such impairments are not known. The authors evaluated a component process model of episodic verbal memory in 87 persons with MA dependence (MA+) and 71 demographically similar non-MA-using controls (MA-). Compared with MA- controls, MA+ participants demonstrated deficient overall learning, free recall, and utilization of semantic clustering, as well as higher rates of repetitions and intrusions. No between-groups differences were evident on measures of serial clustering, retention, or recognition discrimination. Taken together, these findings indicate that MA dependence is associated with deficient strategic (i.e., executive) control of verbal encoding and retrieval, which is consistent with the sequelae of MA-related prefronto-striatal circuit neurotoxicity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory in mild Alzheimer's disease and early Parkinson's disease.

Alzheimer's disease (AD) and Parkinson's disease (PD) impair working memory (WM). It is unclear, however, whether the deficits seen early in the course of these diseases are similar. To address this issue, the authors compared the performance of 22 patients with mild AD, 20 patients with early PD and without dementia, and 112 control participants on tests of inhibition, short-term memory, and 2 commonly administered tests of WM. The results suggest that although mild AD and early PD both impair WM, the deficits may be related to the interruption of different processes that contribute to WM performance. Early PD disrupted inhibitory processes, whereas mild AD did not. The WM deficits seen in patients with AD may be secondary to deficits in other cognitive capacities, including semantic memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interference from retrieval cues in Parkinson's disease.

Objective: Existing studies on memory interference in Parkinson's disease (PD) patients have provided mixed results and it is unknown whether PD patients have problems in overcoming interference from retrieval cues. We investigated this issue by using a part-list cuing paradigm. In this paradigm, after the study of a list of items, the presentation of some of these items as retrieval cues hinders the recall of the remaining ones. Method: We tested PD patients' (n = 19) and control participants' (n = 16) episodic memory in the presence and absence of part-list cues, using initial-letter probes, and following either weak or strong serial associative encoding of list items. Results: Both PD patients and control participants showed a comparable and significant part-list cuing effect after weak associative encoding (13% vs. 12% decrease in retrieval in part-list cuing vs. no part-list cuing -control- conditions in PD patients and control participants, respectively), denoting a similar effect of cue-driven interference in the two populations when a serial retrieval strategy is hard to develop. However, only PD patients showed a significant part-list cuing effect after strong associative encoding (20% vs. 5% decrease in retrieval in patients and controls, respectively). Conclusions: When encoding promotes the development of an effective serial retrieval strategy, the presentation of part-list cues has a specifically disruptive effect in PD patients. This indicates problems in strategic retrieval, probably related to PD patients' increased tendency to rely on external cues. Findings in control conditions suggest that less effective encoding may have contributed to PD patients' memory performance. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A meta-analysis of performance on simple span and more complex working memory tasks in Parkinson's disease.

The working memory (WM) concept has stimulated substantial research since Baddeley and Hitch advanced their model in 1974. There has also been growing interest in WM in Parkinson's disease (PD) where the brain structures considered important for WM are often compromised. However, it remains unclear how and to what degree WM is affected in PD. The authors used meta-analysis to clarify the research findings on WM in PD. The results confirmed that people with PD are impaired on tests of WM. This impairment is small for verbal span but moderate on complex verbal and both simple and complex visuospatial tasks. These data do not support the belief that WM impairment in PD is solely at the level of the central executive. However, our findings support the notion that impairment is more pronounced for visuospatial than verbal WM. A number of different interpretations of these results are discussed. It remains to be established what these statistically significant differences mean in terms of clinically significant levels of impairment in WM. Another important methodological issue that demands greater consideration in this area is that of sampling and the generalizability of results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Metamemory and prospective memory in Parkinson's disease.

Objective: Metamemory is integral for strategizing about memory intentions. This study investigated the prospective memory (PM) deficit in Parkinson's disease (PD) from a metamemory viewpoint, with the aim of examining whether metamemory deficits might contribute to PM deficits in PD. Method: Sixteen patients with PD and 16 healthy older adult controls completed a time-based PM task (initiating a key press at two specified times during an ongoing task), and an event-based PM task (initiating a key press in response to animal words during an ongoing task). To measure metamemory participants were asked to predict and postdict their memory performance before and after completing the tasks, as well as complete a self-report questionnaire regarding their everyday memory function. Results: The PD group had no impairment, relative to controls, on the event-based task, but had prospective (initiating the key press) and retrospective (recalling the instructions) impairments on the time-based task. The PD group also had metamemory impairments on the time-based task; they were inaccurate at predicting their performance before doing the task but, became accurate when making postdictions. This suggests impaired metamemory knowledge but preserved metamemory monitoring. There were no group differences regarding PD patients' self-reported PM performance on the questionnaire. Conclusions: These results reinforce previous findings that PM impairments in PD are dependent on task type. Several accounts of PM failures in time-based tasks are presented, in particular, ways in which mnemonic and metacognitive deficits may contribute to the difficulties observed on the time-based task. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Spatial and object working memory deficits in Parkinson's disease are due to impairment in different underlying processes.

Working memory maintenance processes for visual-spatial and visual-object information were evaluated in patients with Parkinson's disease (PD). PD patients and controls performed a working memory task with two conditions that differed only in the aspect of the stimuli that the participant was instructed to remember: their locations or shapes. Maintenance processes were investigated by measuring accuracy over 1-s, 5-s, and 10-s delays. Results indicated that patients were impaired in maintaining object information over the delay. In contrast, the patients showed impairment on the spatial condition only when the to-be-remembered stimulus was highly similar in location to the probe, but this impairment was equivalent across the delays, suggesting that this deficit was not due to maintenance impairment. These results suggest that deficits in working memory for spatial and object information are mediated by distinct cognitive processes in nondemented patients with PD and may differ in their pathophysiological basis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory encoding and retrieval in frontotemporal dementia and Alzheimer's disease.

Memory encoding and retrieval strategies were assessed in patients with behavior-executive variant frontotemporal dementia (FTD), language variant FTD, and Alzheimer's disease (AD) using verbal and visuospatial supraspan learning tests. FTD patients obtained higher free recall, cued recall, and recognition scores than AD patients. Comparison of free recall scores with cued recall and recognition scores was similar in the 3 dementia groups. Groups did not differ in semantic clustering strategies during learning, but serial-order recall was more common in FTD patients. These data do not support the idea that FTD patients' poor memory is due to a selective retrieval disorder, though FTD patients may fail to implement sophisticated organizational strategies during learning. FTD patients' retained capacity for encoding new information into long-term declarative memory is likely due to relatively spared medial temporal lobe involvement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Manipulation of working memory information is impaired in Parkinson's disease and related to working memory capacity.

It has been suggested that in patients with Parkinson's disease (PD), difficulties in the manipulation of information, which result in problems in executive tasks, are related to a reduction of working memory capacity (J. D. E. Gabrieli, J. Singh, G. T. Stebbins, & C. G. Goetz, 1996). The present study selectively varied the manipulation demand irrespective of the maintenance requirement. In a group of 14 PD patients, performance declined overproportionally with the increasing task demand and was significantly correlated with a measure of working memory capacity. These results suggest that the complexity of working memory processing may decisively contribute to the exhaustion of resources in PD patients. Increasing complexity may either affect their manipulation ability directly or impede the management of inhibitory control requirements inherent to the task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal knowledge, working memory, and processing speed as predictors of verbal learning in older adults.

The present study aimed at modeling individual differences in a verbal learning task by means of a latent structured growth curve approach based on an exponential function that yielded 3 parameters: initial recall, learning rate, and asymptotic performance. Three cognitive variables—speed of information processing, verbal knowledge, working memory—and the participant's age were included in the model in order to explain individual differences in the learning parameters. The data come from the second wave of the Zurich Longitudinal Study on Cognitive Aging (D. Zimprich, Martin, et al., 2008) comprising 334 participants ranging in age from 66 to 81 years (M = 74.43, SD = 4.41). Among the logistic, the Gompertz, and the hyperbolic function, the exponential function described the data best. Reliable individual differences were found in all 3 learning parameters. The cognitive predictor variables affected the verbal learning parameters differentially: All 3 predictors affected positively initial recall, the asymptotic performance increased with better working memory and faster processing speed, and the learning rate was positively associated with verbal knowledge only. Age did not affect the learning parameters but correlated negatively with working memory and processing speed. The finding of large and reliable individual differences in learning is seen as evidence that the potential for positive change, or plasticity in adulthood is maintained and that it is worthwhile to enhance the determinants of learning or learning itself. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The dynamics of memory retrieval in older adulthood.

One of the most robust findings in cognitive aging is that of a significant decline in self-initiated recall from episodic memory. In laboratory studies this deficit can be seen in significant age differences in word-list free recall. In this article, the authors focus on free recall of categorized word lists where one observes "response bursting" in the form of a rapid output of within-category items with longer delays between categories. Age differences appear primarily in between category latencies, results that are consistent with a relative sparing of semantic memory combined with an age-deficit in episodic retrieval. When adjusted for differences in overall mnemonic ability, it is demonstrated that the relationship between organization and learning remains invariant with normal aging. The authors argue that the locus of the age deficit in free recall lies at the level of temporal coding of items and the use of temporal associations to guide recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding modality can affect memory accuracy via retrieval orientation.

Research indicates that false memory is lower following visual than auditory study, potentially because visual information is more distinctive. In the present study we tested the extent to which retrieval orientation can cause a modality effect on memory accuracy. Participants studied unrelated words in different modalities, followed by criterial recollection tests that selectively oriented retrieval toward one study modality at a time. Memory errors were lower when oriented toward visual than toward auditory information, thereby generalizing the modality effect to an explicit source memory task. Moreover, these effects persisted independent of the test presentation modality, indicating that retrieval orientation overrode the potential cuing properties of the test stimulus. An independent manipulation check confirmed that visual recollections were subjectively experienced as more distinctive than auditory recollections. These results suggest that retrieval orientation is sufficient to cause a modality effect on memory accuracy by focusing monitoring processes on the recollection of studied features that are diagnostic of prior presentation. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Stress facilitates consolidation of verbal memory for a film but does not affect retrieval.

The effect of psychosocial stress on distinct memory processes was investigated in 157 college students using a brief film, which enabled comparison of verbal and visual memory by using a single complex stimulus. Participants were stressed either following stimuli presentation (consolidation) or before testing 48 hr later (retrieval) and were compared with no-stress controls. Salivary cortisol was measured before and 20 min after stress. The consolidation group significantly outperformed controls on total and verbal film scores. Stress did not impair retrieval relative to controls. Exploratory analyses revealed a significant correlation between cortisol and verbal scores across all groups (r = .18). Results provide the first evidence of a facilitative effect of a stressor on verbal memory, but failed to replicate retrieval findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Study of Verbal Working Memory in Patients With Parkinson's Disease.

The authors examined the nature of the working memory deficit in persons with Parkinson's disease (PD). Three hypotheses were tested: a limited storage capacity, an impaired executive component, and a reduction of psychomotor speed. Verbal working memory was assessed in 14 PD patients without dementia and 14 matched control participants. Participants were administered a classical verbal span test, working memory tasks that required either updating or manipulation capacities, and motor and psychomotor speed tasks. Patients' performance was comparable to that of control participants on the verbal span test. However, results on the working memory tasks indicated a deficit in manipulation with normal updating capacities. Motor and psychomotor slowing were found in the patient group, but slowing could not fully account for the impairment observed in the manipulation task. Results indicated that there is a genuine but selective working memory impairment in patients with PD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory profiling with paired associate learning in Alzheimer's disease, mild cognitive impairment, and healthy aging.

Mild cognitive impairment (MCI) is associated with increased risk of developing Alzheimer's disease (AD), but up to 40% of cases do not develop AD. Examining a case's specific memory profile may help distinguish which MCI cases will progress to AD: An encoding profile is suggestive of incipient AD, whereas a retrieval profile suggests an alternative etiology. Paired associate learning (PAL) tasks are sensitive for preclinical and early detection of AD, but existing tasks do not enable memory profiling. We developed a novel PAL task enabling the differentiation of memory profiles in 19 people with AD, 17 people with amnestic MCI, and 33 normal elderly controls. Unexpectedly, the AD group demonstrated a retrieval profile for PAL using yes-no recognition, although an encoding profile was evident for forced-choice recognition and for the California Verbal Learning Test--Second Edition (Delis, Kramer, Kaplan, & Ober, 2000). There was considerable heterogeneity within the AD and MCI groups as well as intraindividual discordance for memory profiles. The findings challenge the clinical application of memory profiling in the differential diagnosis of AD, and, by extension, question its potential application in the assessment of MCI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adjustments of conflict monitoring in Parkinson's disease.

Objective: In Stroop-like tasks, the detection of conflict triggers adjustments of cognitive control to reduce conflict in subsequent trials. The present study tested the hypothesis of an impaired modulation of conflict monitoring in Parkinson's disease (PD). Method: 18 PD patients and 18 healthy control (HC) participants performed a Stroop-like task in 2 conditions differing in terms of incongruent/congruent stimuli ratio. Results: HC participants demonstrated a sustained modulation of interference effect, the interference effect being decreased when the proportion of incongruent stimuli was high. A trial-by-trial analysis also showed that in the HC group, processing an incongruent stimulus reduced interference in the subsequent trial. Unlike controls, PD patients did not demonstrate any transient or sustained reduction of the interference effect. Conclusion: Within the framework of recent models, these results can be interpreted as an impairment of a proactive mode of cognitive control in patients with PD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The differential effects of stress on memory consolidation and retrieval: A potential involvement of reconsolidation? Theoretical comment on Beckner et al. (2006).

Previous experiments in the field of stress and memory have suggested a facilitative effect of stress hormones on the consolidation of information but an impairing effect on the retrieval of information. In the article "Stress Facilitates Consolidation of Verbal Memory for a Film but Does Not Affect Retrieval," V. E. Beckner, D. M. Tucker, Y. Delville, and D. C. Mohr (2006) (see record 2006-07279-002) report that exposure to an anticipatory psychological stress enhances consolidation, although it has no impact on the retrieval of previously learned information. This finding is discussed around the importance of the environmental context in which stress is applied and memory is measured. Here, the authors raise the possibility that the enhancing effects of stress on consolidation as reported by Beckner et al. may be explained by the fact that stress can act as a reactivation cue, leading to a 2nd round of consolidation, a process called reconsolidation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of Verbal Semantic Impairment in Left Hemisphere Epilepsy.

Fifty-two patients with partial epilepsy of left (n=30) or right (n=22) hemisphere origin were compared with 23 healthy subjects to explore the characteristics and mechanisms of verbal semantic deficits. Picture Naming, Picture Pointing, and the Semantic Questionnaire assessed semantic retrieval, comprehension, and judgment, respectively. In comparison with the controls and right hemisphere patients, the left hemisphere patients showed impairments on Picture Naming and the Semantic Questionnaire. On Picture Naming, the left hemisphere patients made significant omissions and intracategorical errors; on the Semantic Questionnaire, they made errors at superordinate and subordinate levels of information, they made more errors in relation to living than nonliving things, and there were significant associations between their Picture Naming and Semantic Questionnaire scores. In this population, the mixed profiles of semantic deficits suggests the coexistence of altered retrieval and information loss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The independent influence of apathy and depression on cognitive functioning in Parkinson's disease.

Objective: The purpose of the present study was to examine the independent influence of symptoms of depression and apathy, two of the most common neuropsychiatric symptoms in Parkinson's disease (PD), on executive functioning and memory in PD patients using measures designed to discriminate between these symptoms. Method: Participants included 68 nondemented, idiopathic PD patients, ages 56–82 years. The Apathy Evaluation Scale—Self-Rating and select items of the Beck Depression Inventory II were used to assess symptoms of apathy and depression, respectively. Cognitive function was assessed using the Wisconsin Card Sorting Test and Hopkins Verbal Learning Test—Revised. Correlations and hierarchical regressions were conducted to investigate the relationships between apathy, depression, and cognitive function. Hierarchical regression analyses were conducted to evaluate the degree of influence of depression and apathy on cognitive function. Results: Results revealed that symptoms of apathy, but not depression, were significantly and negatively associated with executive functioning. Immediate memory was significantly and negatively associated with both apathy and depression. However, apathy accounted for additional variance in memory performance after controlling for depression at a level approaching significance. Conclusions: Apathy is not only associated with cognitive impairment, but also with impaired daily functioning, caregiver burden and distress, medication noncompliance, and increased mortality. Differentiating apathy and depression, understanding their unique effects, and appropriately identifying apathy symptoms in patients have robust implications for the development of neuropsychological models of these effects in PD as well as practical implications in guiding improvements to patient care and enhancing quality of life in patients and caregivers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)