Recognition memory impairment in Parkinson's disease: power and meta-analyses

Recognition subtests for the Repeatable Battery for the Assessment of Neuropsychological Status: Preliminary data in cognitively intact older adults, amnestic Mild Cognitive Impairment, and Alzheimer's disease

Objective: The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) has three delayed recall subtests (list, story, figure), but only one delayed recognition subtest (list). Since comparisons between delayed recall and recognition can be useful in clinical neuropsychology, the current study sought to develop and preliminarily examine two proposed new subtests for Form A of the RBANS, Story Recognition and Figure Recognition. Method: A sample of older adults who were cognitively intact (n = 48) or classified with amnestic Mild Cognitive Impairment (MCI, n = 29) or mild Alzheimer's disease (AD, n = 24) were administered the RBANS and the two new recognition subtests. Results: In the primary analyses, cognitively intact participants performed significantly better than the two memory-impaired groups on all twelve scores (one recall and three recognition [total, hits, false positive errors] for the list, story, and figure). For amnestic MCI and AD participants, they showed statistically comparable scores on 7 of the 12 variables, where those with MCI performed better than those with AD on the other five scores. Across the three groups, effect sizes were large (e.g., Cohen's d = 1.0-2.9). In secondary analyses, all of the List Recall and Recognition scores significantly correlated with one another, and this pattern was observed for all of the Story Recall and Recognition scores and most of the Figure Recall and Recognition scores. Conclusions: Although preliminary, these new recognition scores appear to provide useful information and may improve the sensitivity of the RBANS in identifying cortical/subcortical profiles in clinical and research settings.

Comparison of cognitive performance between patients with Parkinson's disease and dystonia using an intraoperative recognition memory test

Neuroscientific studies on the function of the basal ganglia often examine the behavioral performance of patients with movement disorders, such as Parkinson’s disease (PD) and dystonia (DT), while simultaneously examining the underlying electrophysiological activity during deep brain stimulation surgery. Nevertheless, to date, there have been no studies comparing the cognitive performance of PD and DT patients during surgery. In this study, we assessed the memory function of PD and DT patients with the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE). We also tested their cognitive performance during the surgery using a continuous recognition memory test. The results of the MoCA and MMSE failed to reveal significant differences between the PD and DT patients. Additionally, no significant difference was detected by the intraoperative memory test between the PD and DT patients. The intraoperative memory test scores were highly correlated with the MMSE scores and MoCA scores. Our data suggest that DT patients perform similarly to PD patients in cognitive tests during surgery, and intraoperative memory tests can be used as a quick memory assessment tool during surgery.

Lewy Body Dementias: A Coin with Two Sides?

Lewy body dementias (LBDs) consist of dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), which are clinically similar syndromes that share neuropathological findings with widespread cortical Lewy body deposition, often with a variable degree of concomitant Alzheimer pathology. The objective of this article is to provide an overview of the neuropathological and clinical features, current diagnostic criteria, biomarkers, and management of LBD. Literature research was performed using the PubMed database, and the most pertinent articles were read and are discussed in this paper. The diagnostic criteria for DLB have recently been updated, with the addition of indicative and supportive biomarker information. The time interval of dementia onset relative to parkinsonism remains the major distinction between DLB and PDD, underpinning controversy about whether they are the same illness in a different spectrum of the disease or two separate neurodegenerative disorders. The treatment for LBD is only symptomatic, but the expected progression and prognosis differ between the two entities. Diagnosis in prodromal stages should be of the utmost importance, because implementing early treatment might change the course of the illness if disease-modifying therapies are developed in the future. Thus, the identification of novel biomarkers constitutes an area of active research, with a special focus on α-synuclein markers.

The Modality Effect on Delayed Free Recall in Non-demented Patients With Mild Parkinson's Disease Progression

Background: The modality effect plays the central role in learning and memory functions. Retrieval failure constitutes a common memory impairment that occurs among patients with Parkinson’s disease (PD). However, little knowledge exists about the relation between modality effect and delayed recall impairment in PD. The primary goal of this study was to compare delayed free recall performance between three different memory modalities (verbal, visual, and cross visual-verbal) in a sample of non-demented patients with mild PD progression. The secondary goal was to explore the frequency of deficient performance on the basis of normative comparisons on each of the three delayed free-recall measures.

Method: A total of 71 non-demented patients with mild PD progression were recruited for the administration of the Montreal Cognitive Assessment (MoCA), the Rey Auditory Verbal Learning Test (RAVLT), the Rey Osterrieth Complex Figure Test (ROCFT), and the Greek Version of Face-Name Associative Memory Examination (GR-FNAME12).

Results: The percentages of deficient-performances for the three delayed free recall measures were 45.1% (32/71), 39.4% (28/71) and 31% (22/71) for the GR-FNAME12, ROFCT and RAVLT, respectively. The results indicated no significant difference between performances of the GR-FNAME12 and ROCFT, both of which were significantly lower than performance on the RAVLT.

Conclusions: In conclusion, delayed free recall appears to be more severely affected in the cross visual-verbal and visual memory modalities than in verbal-memory modalities in the early phase of PD progression.

Melatonin attenuates hLRRK2-induced long-term memory deficit in a Drosophila model of Parkinson's disease

As the most common genetic cause of Parkinson's disease (PD), the role of human leucine-rich repeat kinase 2 (hLRRK2) in the efficacy of PD treatment is a focus of study. Our previous study demonstrated that mushroom body (MB) expression of hLRRK2 in Drosophila could recapitulate the clinical feature of sleep disturbances observed in PD patients, and melatonin (MT) treatment could attenuate the hLRRK2-induced sleep disorders and synaptic dysfunction, suggesting the therapeutic potential of MT in PD patients carrying hLRRK2 mutations; however, no further study into the impacts on memory deficit was conducted. Therefore, in the current paper, the study of the effects of MT on hLRRK2 flies was continued, to determine its potential role in the improvement of memory deficit in PD. To achieve this, the Drosophila learning and memory phases, including short- and long-term memory, were recorded; furthermore, the effect of MT on calcium channel activity during neurotransmission was detected using electrophysiology patch clamp recordings. It was demonstrated that MT treatment reversed hLRRK2-induced long-term memory deficits in Drosophila; furthermore, MT reduced MB calcium channel activities. These findings suggest that MT may exerts therapeutic effects on the long-term memory of PD patients via calcium channel modulation, thus providing indication of its potential to maintain cognitive function in PD patients.

Partial lesion of the nigrostriatal dopamine pathway in rats impairs egocentric learning but not spatial learning or behavioral flexibility

Degeneration of the nigrostriatal dopaminergic system in Parkinson's disease (PD) causes motor dysfunction and cognitive impairment, but the etiology of the cognitive deficits remains unclear. The present study investigated the behavioral effects of partial lesions of the nigrostriatal dopamine (DA) pathway. Rats received bilateral infusions of either 6-hydroxydopamine (6-OHDA) or vehicle into the dorsolateral striatum and were tested in spatial and procedural learning tasks. Compared with intact rats, DA-depleted rats were impaired when the first task they learned required egocentric responses. Intact rats that received prior training on a spatial task were impaired while learning a subsequent body-turn task, suggesting that prior spatial training may compete with egocentric learning in intact but not DA-depleted rats. Spatial discrimination, reversal learning, and switching between allocentric and egocentric strategies were similar in both groups. The results suggest that DA loss that is not associated with gross motor pathology temporarily impairs egocentric, but not allocentric, learning or subsequent behavioral flexibility. (PsycINFO Database Record

Memory for gist and detail information in patients with Parkinson's disease

OBJECTIVE

Memory formation is proposed to be a dual process that involves the simultaneous memorisation of both detailed information (item-specific memory) and gist information (gist memory). Memory deficits have been reported in patients with Parkinson's disease (PD); however, few studies have explicitly addressed the nature of these deficits. To obtain a detailed understanding of memory dysfunction in patients with PD, it is of crucial importance to establish whether item-specific memory and gist memory performance are impaired. The aim of this study is to explore whether gist memory and item-specific memory performance are still intact in patients with PD, as well as to determine which psychological mechanisms are responsible for memory formation.

SETTING

Two hospitals in northern Taiwan.

PARTICIPANTS

Thirty-nine patients with PD and 28 normal controls were recruited. Each participant received a gist-based recognition test following the Deese-Roediger-McDermott paradigm, as well as neuropsychological tests and measures of clinical characteristics.

RESULTS

Gist memory was impaired in patients with advanced-stage disease (Hoehn and Yahr (H&Y) stage: III) (F2,64=3.58, p=0.033), whereas item-specific memory was preserved throughout all disease stages. Correlation analysis showed that item-specific memory was related to executive functions in normal controls and early-stage patients with PD (H&Y stage: I-II); however, item-specific memory was related to episodic memory, rather than to executive functions, in advanced-stage patients with PD. Moreover, gist memory was related to episodic memory, but only in early-stage patients with PD.

CONCLUSIONS

We discovered that impaired gist memory is found in advanced-stage, but not in early-stage, patients with PD. Our findings suggest that the techniques used to take advantage of the relatively preserved gist memory in early-stage patients with PD, as well as the preserved item-specific memory in patients with PD of all stages, could be useful for memory rehabilitation programmes.

Homotaurine in Parkinson's disease

Homotaurine is a natural compound of red algae, which has been demonstrated to have a neuroprotective effect and has been evaluated as a possible therapeutic agent for Alzheimer's disease. This was a single blind, randomized, controlled study to evaluate the safety and efficacy of homotaurine in patients with Parkinson's disease (PD) and cognitive impairment. Patients were evaluated at baseline and 6 months later. Assessments included, the evaluation of: motor and non-motor conditions and complications (Unified Parkinson's Disease Rating Scale, UPDRS); disability and quality of life; depression; excessive daytime sleepiness and fatigue. An extensive neuropsychological tests battery was administered evaluating specific cognitive domains: memory, phonemic verbal fluency, executive functions and selective visual attention. After baseline testing, patients were allocated to one of the two groups: (A) treatment group: patients treated with homotaurine 100 mg; (B) control group: patients not treated with homotaurine. Forty-seven patients were evaluated at baseline, 24 (51 %) completed the study (PD-homotaurine: n = 11; 44 % and PD-controls: n = 13; 59 %); discontinuation rate was similar across subjects (p = 1.0). Intention to treat analyses to evaluate homotaurine safety showed mild side effects (gastrointestinal upsetting) in 3 patients. Per protocol analyses of homotaurine efficacy showed no difference between groups. Within group analyses showed that PD-homotaurine patients had better score at UPDRS-I at the end of the study compared to baseline (p = 0.017) and at Epworth Sleepiness Scale (p = 0.01). No other differences were found. No significant difference arose for the PD-ctrl group. Homotaurine is a safe drug. Our data suggest a beneficial effect of homotaurine on excessive sleepiness. Future studies are encouraged to confirm this promising role of homotaurine in promoting the sleep/awake cycle in patients with PD.

Structural MRI Correlates of Episodic Memory Processes in Parkinson's Disease Without Mild Cognitive Impairment

BACKGROUND

Changes in episodic memory are common early in Parkinson's disease (PD) and may be a risk factor for future cognitive decline. Although medial temporal lobe (MTL) memory and frontostriatal (FS) executive systems are thought to play different roles in distinct components of episodic memory impairment in PD, no study has investigated whether different aspects of memory functioning are differentially associated with MTL and FS volumes in nondemented patients without mild cognitive impairment (PD-woMCI).

OBJECTIVES

The present study investigated MRI markers of different facets of memory functioning in 48 PD-woMCI patients and 42 controls.

METHODS

Regional volumes were measured in structures comprising the MTL and FS systems and then correlated with key indices of memory from the California Verbal Learning Test.

RESULTS

In PD-woMCI patients, memory was impaired only for verbal learning, which was not associated with executive, attention/working memory, or visuospatial functioning. Despite an absence of cortical atrophy, smaller right MTL volumes in patients were associated with poorer verbal learning, long delayed free recall, long delayed cued recall, and recognition memory hits and false positives. Smaller right pars triangularis (inferior frontal) volumes were also associated with poorer long delayed cued recall and recognition memory hits. These relationships were not found in controls.

CONCLUSIONS

The findings indicate that MTL volumes are sensitive to subtle changes in almost all facets of memory in PD-woMCI, whereas FS volumes are sensitive only to memory performances in cued-testing formats.

Neuropsychologic assessment in collaborative Parkinson's disease research: a proposal from the National Institute of Neurological Disorders and Stroke Morris K. Udall Centers of Excellence for Parkinson's Disease Research at the University of Pennsylvania and the University of Washington

Cognitive impairment (CI) and behavioral disturbances can be the earliest symptoms of Parkinson's disease (PD), ultimately afflict the vast majority of PD patients, and increase caregiver burden. Our two Morris K. Udall Centers of Excellence for Parkinson's Disease Research were supported by the National Institute of Neurological Disorders and Stroke (NINDS) in an effort to recommend a comprehensive yet practical approach to cognitive and behavioral assessment to further collaborative research. We recommend a stepwise approach with two levels of standardized evaluation to establish a common battery, as well as an alternative testing recommendation for severely impaired subjects, and review supplemental tests that may be useful in specific research settings. Our flexible approach may be applied to studies with varying emphasis on cognition and behavior, does not place undue burden on participants or resources, and has a high degree of compatibility with existing test batteries to promote collaboration.

Damage to the lateral prefrontal cortex impairs familiarity but not recollection

Frontal lobe lesions impair recognition memory but it is unclear whether the deficits arise from impaired recollection, impaired familiarity, or both. In the current study, recognition memory for verbal materials was examined in patients with damage to the left or right lateral prefrontal cortex. Words were incidentally encoded under semantic or phonological orienting conditions, and recognition memory was tested using a 6-point confidence procedure. Receiver operating characteristics (ROCs) were examined in order to measure the contributions of recollection and familiarity to recognition memory. In both encoding conditions, lateral prefrontal cortex damage led to a deficit in familiarity but not recollection. Similar deficits were observed in left and right hemisphere patients. The results indicate that the lateral prefrontal cortex plays a critical role in the monitoring or decision processes required for accurate familiarity-based recognition responses.

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.

Impaired verbal memory in Parkinson disease: relationship to prefrontal dysfunction and somatosensory discrimination

Objective

To study the neurocognitive profile and its relationship to prefrontal dysfunction in non-demented Parkinson's disease (PD) with deficient haptic perception.

Methods

Twelve right-handed patients with PD and 12 healthy control subjects underwent thorough neuropsychological testing including Rey complex figure, Rey auditory verbal and figural learning test, figural and verbal fluency, and Stroop test. Test scores reflecting significant differences between patients and healthy subjects were correlated with the individual expression coefficients of one principal component, obtained in a principal component analysis of an oxygen-15-labeled water PET study exploring somatosensory discrimination that differentiated between the two groups and involved prefrontal cortices.

Results

We found significantly decreased total scores for the verbal learning trials and verbal delayed free recall in PD patients compared with normal volunteers. Further analysis of these parameters using Spearman's ranking correlation showed a significantly negative correlation of deficient verbal recall with expression coefficients of the principal component whose image showed a subcortical-cortical network, including right dorsolateral-prefrontal cortex, in PD patients.

Conclusion

PD patients with disrupted right dorsolateral prefrontal cortex function and associated diminished somatosensory discrimination are impaired also in verbal memory functions. A negative correlation between delayed verbal free recall and PET activation in a network including the prefrontal cortices suggests that verbal cues and accordingly declarative memory processes may be operative in PD during activities that demand sustained attention such as somatosensory discrimination. Verbal cues may be compensatory in nature and help to non-specifically enhance focused attention in the presence of a functionally disrupted prefrontal cortex.

Eye tracking during a visual paired comparison task as a predictor of early dementia

The authors present findings from a behavioral task (visual paired comparison) using infrared eye-tracking that could potentially be useful in predicting the onset of Alzheimer's disease. Delay intervals of 2 seconds and 2 minutes were used between the initial viewing of a picture and when the picture was displayed alongside a novel picture. Eye-tracking revealed that at the 2-second delay, 6 patients with mild cognitive impairment, 15 matched control participants (normal control), and 4 neurological control participants with Parkinson's disease performed comparably, viewing the novel picture greater than 71% of the time. When the delay increased to 2 minutes, patients with mild cognitive impairment viewed the novel picture only 53% of the time (P < .05), while control participants and participants with Parkinson's disease remained above 70%. These findings demonstrate the usefulness of this task for assessing normal as well as impaired memory function.

Profile of cognitive impairment in dementia associated with Parkinson's disease compared with Alzheimer's disease

OBJECTIVE

To compare the profile of cognitive impairment in Alzheimer's disease (AD) with dementia associated with Parkinson's disease (PDD).

METHODS

Neuropsychological assessment was performed in 488 patients with PDD and 488 patients with AD using the Mini-Mental State Examination (MMSE) and the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog). Logistic regression analysis was used to investigate whether the diagnosis could be accurately predicted from the cognitive profile. Additionally, the cognitive profiles were compared with a normative group using standardised effect sizes (Cohen's d).

RESULTS

Diagnosis was predicted from the cognitive profile, with an overall accuracy of 74.7%. Poor performance of the AD patients on the orientation test in ADAS-cog best discriminated between the groups, followed by poor performance of the PDD patients on the attentional task in MMSE. Both groups showed memory impairment, AD patients performing worse than PDD patients.

CONCLUSION

The cognitive profile in PDD differs significantly from that in AD. Performance on tests of orientation and attention are best in differentiating the groups.

A new measure of visual location learning and memory: development and psychometric properties for the Brown Location Test (BLT)

There are a variety of well-established neuropsychological tests that are helpful in identifying global and specific verbal memory deficits. In contrast, tests of visual memory have produced less consistent results likely due in part to confounding variables such as verbal encodability, administration difficulties, and insufficient differentiation of among types of visual memory. The Brown Location Test (BLT) was designed to specifically measure visual memory for location of identical objects (dots) and address limitations found in commonly employed visual memory tests. This paper describes the empirical basis for the BLT and reports the psychometric properties of the test. Results indicate good internal and alternate form reliabilities. Factor analysis of a brief test battery confirmed that BLT performance is generally independent of verbal memory and global intellectual abilities. BLT performance declined with age, but there was no association between performance and gender, education, or intellectual functioning. In view of the favorable psychometric properties observed during preliminary studies, additional normative and validation studies in healthy and patient populations are warranted.

Basal ganglia and dopamine contributions to probabilistic category learning

Studies of the medial temporal lobe and basal ganglia memory systems have recently been extended towards understanding the neural systems contributing to category learning. The basal ganglia, in particular, have been linked to probabilistic category learning in humans. A separate parallel literature in systems neuroscience has emerged, indicating a role for the basal ganglia and related dopamine inputs in reward prediction and feedback processing. Here, we review behavioral, neuropsychological, functional neuroimaging, and computational studies of basal ganglia and dopamine contributions to learning in humans. Collectively, these studies implicate the basal ganglia in incremental, feedback-based learning that involves integrating information across multiple experiences. The medial temporal lobes, by contrast, contribute to rapid encoding of relations between stimuli and support flexible generalization of learning to novel contexts and stimuli. By breaking down our understanding of the cognitive and neural mechanisms contributing to different aspects of learning, recent studies are providing insight into how, and when, these different processes support learning, how they may interact with each other, and the consequence of different forms of learning for the representation of knowledge.