Artificial grammar learning in Alzheimer’s disease

Patients with early Alzheimer’s disease (AD) exhibit impaired declarative memory although some forms of nondeclarative memory are intact. Performance on perceptual nondeclarative memory tasks is often preserved in AD, whereas conceptual nondeclarative memory is often impaired. A conceptual nondeclarative learning task that has been studied in amnesic patients is the artificial grammar learning (AGL) task. Healthy participants and patients with impaired declarative memory both acquire information about an underlying rule structure in this task and exhibit the ability to identify rule-conforming items, despite the subjective experience of guessing at the response. In this study, 12 patients diagnosed with early AD were tested on the AGL task and a matched recognition task. The patients were able to reliably distinguish rule-conforming items from others, indicating successful AGL. Performance of the AD patients was impaired, relative to controls, on a similar recognition task, although they were found to use information about the grammaticality of study items in an attempt to improve their recognition performance. The AD patients showed a dissociation similar to that seen in anterograde amnesia: impaired recognition memory in conjunction with successful AGL. This finding suggests that the brain areas that support AGL are not compromised early in the course of AD. In addition, the nondeclarative memory of the AD patients acquired during AGL appeared to influence their performance on a declarative memory task, suggesting an interaction between this nondeclarative memory task and declarative memory.     

Memories defining the self in Alzheimer’s disease

ABSTRACT

There is a debate over the extent to which personal identity or the self is preserved in patients with Alzheimer’s disease (AD). Autobiographical memory deficits at early stages of AD could contribute to altering patients’ self. However, the nature of the relationship between autobiographical memory deficits and the self in AD has not been much investigated experimentally. In the present study, we aimed to investigate the integrative meaning of self-defining memories (SDMs) in early stages of AD and to analyse its relationship with the self-concept. The results showed that, when compared to the control group, AD patients less frequently extracted meaning from their SDMs and the meaning was less frequently tied to the self. Patients exhibited some altered aspects of the self-concept (i.e., complexity and strength), though some other components still persisted (i.e., valence and certainty). Correlation analyses showed that the impaired integrative meaning in the AD group was correlated with some changes in self-concept. We suggest that integrative meaning may act as a bridge between autobiographical memories and the self-concept, with reduced integration abilities appearing as a potential mechanism for the deterioration of the self-concept in AD.     

Anosognosia in Alzheimer’s disease – The petrified self

This paper reviews the literature concerning the neural correlates of the self, the relationship between self and memory and the profile of memory impairments in Alzheimer’s disease (AD) and explores the relationship between the preservation of the self and anosognosia in this condition. It concludes that a potential explanation for anosognosia in AD is a lack of updating of personal information due to the memory impairments characteristic of this disease. We put forward the hypothesis that anosognosia is due in part to the “petrified self.”     

Normal McCollough effect in Alzheimer’s disease and global amnesia

The McCollough effect (ME), a long-lasting, pattern-contingent aftereffect in normal human vision, was examined in persons with known deficits in memory. We induced MEs in 11 subjects, 5 patients with various severities of Alzheimer’s disease (AD), H.M. (a patient who has global amnesia due to bilateral medial temporal lobectomy and who has been studied for 35 years since his operation), and 5 control subjects. H.M. and the AD patients showed MEs of strength and duration comparable to those of the control subjects. These results demonstrate a dissociation between learning mechanisms that mediate recall and recognition versus mechanisms that mediate the ME. Furthermore, knowledge about the sites of neuropathology in H.M. and in AD are consistent with other sources of evidence implicating early visual areas, especially V1, as a critical locus of the ME.     

Speech rhythm alterations in Spanish-speaking individuals with Alzheimer’s disease

Rhythm is the speech property related to the temporal organization of sounds. Considerable evidence is now available for suggesting that dementia of Alzheimer’s type is associated with impairments in speech rhythm. The aim of this study is to assess the use of an automatic computerized system for measuring speech rhythm characteristics in an oral reading task performed by 45 patients with Alzheimer’s disease (AD) compared with those same characteristics among 82 healthy older adults without a diagnosis of dementia, and matched by age, sex and cultural background. Ranges of rhythmic-metric and clinical measurements were applied. The results show rhythmic differences between the groups, with higher variability of syllabic intervals in AD patients. Signal processing algorithms applied to oral reading recordings prove to be capable of differentiating between AD patients and older adults without dementia with an accuracy of 87% (specificity 81.7%, sensitivity 82.2%), based on the standard deviation of the duration of syllabic intervals. Experimental results show that the syllabic variability measurements extracted from the speech signal can be used to distinguish between older adults without a diagnosis of dementia and those with AD, and may be useful as a tool for the objective study and quantification of speech deficits in AD.     

Frontotemporal neural systems supporting semantic processing in Alzheimer’s disease

We hypothesized that semantic memory for object concepts involves both representations of visual feature knowledge in modality-specific association cortex and heteromodal regions that are important for integrating and organizing this semantic knowledge so that it can be used in a flexible, contextually appropriate manner. We examined this hypothesis in an fMRI study of mild Alzheimer’s disease (AD). Participants were presented with pairs of printed words and asked whether the words matched on a given visual–perceptual feature (e.g., guitar, violin: SHAPE). The stimuli probed natural kinds and manufactured objects, and the judgments involved shape or color. We found activation of bilateral ventral temporal cortex and left dorsolateral prefrontal cortex during semantic judgments, with AD patients showing less activation of these regions than healthy seniors. Moreover, AD patients showed less ventral temporal activation than did healthy seniors for manufactured objects, but not for natural kinds. We also used diffusion-weighted MRI of white matter to examine fractional anisotropy (FA). Patients with AD showed significantly reduced FA in the superior longitudinal fasciculus and inferior frontal-occipital fasciculus, which carry projections linking temporal and frontal regions of this semantic network. Our results are consistent with the hypothesis that semantic memory is supported in part by a large-scale neural network involving modality-specific association cortex, heteromodal association cortex, and projections between these regions. The semantic deficit in AD thus arises from gray matter disease that affects the representation of feature knowledge and processing its content, as well as white matter disease that interrupts the integrated functioning of this large-scale network.     

Memory for Music in Alzheimer’s Disease: Unforgettable?

The notion that memory for music can be preserved in patients with Alzheimer’s Disease (AD) has been raised by a number of case studies. In this paper, we review the current research examining musical memory in patients with AD. In keeping with models of memory described in the non-musical domain, we propose that various forms of musical memory exist, and may be differentially impaired in AD, reflecting the pattern of neuropathological changes associated with the condition. Our synthesis of this literature reveals a dissociation between explicit and implicit musical memory functions. Implicit, specifically procedural musical memory, or the ability to play a musical instrument, can be spared in musicians with AD. In contrast, explicit musical memory, or the recognition of familiar or unfamiliar melodies, is typically impaired. Thus, the notion that music is unforgettable in AD is not wholly supported. Rather, it appears that the ability to play a musical instrument may be unforgettable in some musicians with AD.     

Targeted training of the decision rule benefits rule-guided behavior in Parkinson’s disease

The impact of Parkinson’s disease (PD) on rule-guided behavior has received considerable attention in cognitive neuroscience. The majority of research has used PD as a model of dysfunction in frontostriatal networks, but very few attempts have been made to investigate the possibility of adapting common experimental techniques in an effort to identify the conditions that are most likely to facilitate successful performance. The present study investigated a targeted training paradigm designed to facilitate rule learning and application using rule-based categorization as a model task. Participants received targeted training in which there was no selective-attention demand (i.e., stimuli varied along a single, relevant dimension) or nontargeted training in which there was selective-attention demand (i.e., stimuli varied along a relevant dimension as well as an irrelevant dimension). Following training, all participants were tested on a rule-based task with selective-attention demand. During the test phase, PD patients who received targeted training performed similarly to control participants and outperformed patients who did not receive targeted training. As a preliminary test of the generalizability of the benefit of targeted training, a subset of the PD patients were tested on the Wisconsin card sorting task (WCST). PD patients who received targeted training outperformed PD patients who did not receive targeted training on several WCST performance measures. These data further characterize the contribution of frontostriatal circuitry to rule-guided behavior. Importantly, these data also suggest that PD patient impairment, on selective-attention-demanding tasks of rule-guided behavior, is not inevitable and highlight the potential benefit of targeted training.     

Very Early Decline in Recognition Memory for Odors in Alzheimer’s Disease

When in the progression of Alzheimer’s disease (AD) a decline in detection sensitivity and recognition memory for odors begins, and whether a fast progression in dementia is related to a fast loss in odor sensitivity, was determined by studying 78 patients with probable AD, categorized as very mild, mild, or moderate in degree of dementia, and 78 controls. Taste and vision were studied for comparison. Whereas the earliest decline in odor sensitivity and visual memory was found in mild patients, a decline in odor memory was found in the very mild patients. Similar taste thresholds in the four groups suggest that the poor odor detectability in AD was not related to task demands in threshold testing. A fast progression in dementia was also found to be related to a fast loss in odor sensitivity. The findings imply that memory-based olfactory tests may contribute to early diagnosis of AD.     

Credence for conclusions: a brief for Jeffrey’s rule

Synthese - Some arguments are good; others are not. How can we tell the difference? This article advances three proposals as a partial answer to this question. The proposals are keyed to arguments...     

Recognition of familiar and unfamiliar melodies in normal aging and Alzheimer’s disease

We tested normal young and elderly adults and elderly Alzheimer’s disease (AD) patients on recognition memory for tunes. In Experiment 1, AD patients and age-matched controls received a study list and an old/new recognition test of highly familiar, traditional tunes, followed by a study list and test of novel tunes. The controls performed better than did the AD patients. The controls showed the “mirror effect” of increased hits and reduced false alarms for traditional versus novel tunes, whereas the patients false-alarmed as often to traditional tunes as to novel tunes. Experiment 2 compared young adults and healthy elderly persons using a similar design. Performance was lower in the elderly group, but both younger and older subjects showed the mirror effect. Experiment 3 produced confusion between preexperimental familiarity and intraexperimental familiarity by mixing traditional and novel tunes in the study lists and tests. Here, the subjects in both age groups resembled the patients of Experiment 1 in failing to show the mirror effect. Older subjects again performed more poorly, and they differed qualitatively from younger subjects in setting stricter criteria for more nameable tunes. Distinguishing different sources of global familiarity is a factor in tune recognition, and the data suggest that this type of source monitoring is impaired in AD and involves different strategies in younger and older adults.     

Five weeks of immersive reminiscence therapy improves autobiographical memory in Alzheimer’s disease

ABSTRACT

We examined the effects of a new Immersive Reminiscence Therapy (IRT) programme on cognitive function, including autobiographical memory, in a sample Alzheimer’s disease (AD) patients. A total of 43 AD patients with mild to moderate disease severity were randomly assigned to either an intervention group (n?=?22, MMMSE?=?20.77), or a control group (n?=?21, MMMSE?=?19.24). The intervention group received one weekly group-based session of IRT for five weeks in an authentic 1950s style museum environment, matching the time of the participants’ youth. IRT included semi-structured conversations about the past. The control group received standard care. We assessed performance on cognitive function and autobiographical memory at baseline and post-intervention. Five weeks of IRT enhanced subsequent autobiographical memory performance, when participants were cued by concrete objects dated to their youth. Object-cued memories reported post intervention included a significantly higher degree of episodic details and higher word counts. The intervention showed no effect on the Autobiographical Memory Interview or word-cued recall. Global cognitive function and semantic autobiographical memory performance increased across time for both groups. Our findings demonstrate that immersion into a setting, rich on concrete cues dated to the participants’ youth can improve autobiographical remembering.     

Construct and concurrent validity of the Cambridge neuropsychological automated tests in Portuguese older adults without neuropsychiatric diagnoses and with Alzheimer’s disease dementia

We aimed to analyze the construct and concurrent validity of the Rapid Visual Information Processing (RVP), Paired Associates Learning (PAL), Reaction Time (RTI), and Spatial Working Memory (SWM) tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB®). Inclusion criteria were checked in a first session. The CANTAB and additional pencil-and-paper tests were administered within 1 week. The participants (aged 69–96 years) were 137 Portuguese adults without neuropsychiatric diagnoses and 37 adults with mild-to-moderate Alzheimer’s disease dementia. Comparisons were made between the CANTAB tests and between these tests and the Rey Complex Figure Test (RCFT), Verbal Fluency (VF) test, and some Wechsler Memory Scale-III and Wechsler Adult Intelligence Scale-III subtests. Most intra-test correlations were stronger than the CANTAB inter-test correlations. The RVP correlated more with VF animals (.44), the PAL with RCFT immediate recall (–.52), the RTI with RVP mean latency (.42), and the SWM with Spatial Span backward (–.39).     

Computerized assessment of syntactic complexity in Alzheimer’s disease: a case study of Iris Murdoch’s writing

Currently, the majority of investigations of linguistic manifestations of neurodegenerative disorders such as Alzheimer’s disease are conducted based on manual linguistic analysis. Grammatical complexity is one of the language use characteristics sensitive to the effects of Alzheimer’s disease and is difficult to operationalize and measure using manual approaches. In the current study, we demonstrate the application of computational linguistic methods to automate the analysis of grammatical complexity. We implemented the Computerized Linguistic Analysis System (CLAS) based on the Stanford syntactic parser (Klein and Manning, Pattern Recognition, 38(9), 1407–1419, 2005) for longitudinal analysis of changes in syntactic complexity in language affected by neurodegenerative disorders. We manually validated CLAS scoring and used it to analyze writings of Iris Murdoch, a renowned Irish author diagnosed with Alzheimer’s disease. We found clear patterns of decline in grammatical complexity consistent with previous analyses of Murdoch’s writing conducted by Garrard, Maloney, Hodges, and Patterson (Brain, 128(250–260, 2005). CLAS is a fully automated system that may be used to derive objective and reproducible measures of syntactic complexity in language production and can be particularly useful in longitudinal studies with large volumes of language samples.     

Talkativeness in Cognitively Normal Women at Genetic Risk for Alzheimer’s Disease

Previous research has suggested a correlation between some linguistic patterns and the risk for Alzheimer’s disease (AD). There is increasing clinical need to identify factors that can be used alone or in combination to predict the onset of AD. The purpose of the present study was to explore the association of language skills and genetic risk for Alzheimer’s disease. Oral and written language samples of cognitively normal women with a susceptibility gene for AD (ApoE e4) were compared to those of noncarriers on measures of grammatical complexity, topic relevance, and talkativeness by observers unaware of participant genotypes. Participants included 29 ApoE e4 carriers 49-73 years of age, and 29 e4 noncarriers 48-76 years of age, most of whom had a first-degree relative with AD. Carriers and noncarriers were group matched for age, educational level, and estimated IQ. Participant groups did not differ significantly in language complexity or topic relevance. However, the ApoE e4 group was significantly more talkative than the noncarrier group (p < .05).     

Gaze tracking patterns on different types of traffic risk in early-stage Alzheimer’s disease

Many fatal accidents are caused by the driver’s inability, upon the occurrence of sudden events, to detect hazards in time, an ability that is based on the driver’s eye movement patterns, the detection of involved persons, events, objects, as well as the length of time spent on noticing same. This study intends to compare risk perception and decision-making in high-risk traffic situations between individuals with AD and controls by exploring gaze tracking and hazard detection patterns. The study included 16 individuals with early-stage AD and 26 controls. During the experiment, participants underwent several vision and cognitive tests and watched twelve videos of high-risk traffic situations while their eye movement patterns were being recorded by the eye tracking device, in order to understand how cognitive abilities affect eye movement patterns during high-risk traffic situations. The results revealed poorer cognitive abilities and diminished risk perception in individuals with AD compared with the controls and thus an inability to predict potential accidents. In terms of high-risk traffic situations involving pedestrians, traffic violations by others and view-blocking events, a significant difference in gaze patterns was found between individuals with AD and healthy seniors. The contribution of this study is in elaborating the effect of different traffic event type and specific cognitive abilities on traffic risk-detection in individuals with AD. The results of this study may aid in the formulation of driver licensing policies and the design of traffic scenarios; they also elucidate the driving behaviors of individuals with AD.     

Macro-event recognition in healthy ageing,Alzheimer’s disease,and mild cognitive impairment

Event perception and cognition is integral to our everyday experience and functional ability. A commonly reported complaint in Alzheimer’s disease (AD) is the inability to follow narratives – be it textual, conversational, video, or pictures. This phenomenon has received little systematic research so far. In the current study, we developed a novel paradigm to examine macro-event recognition in individuals with AD in the early stage and its preceding stage of mild cognitive impairment (MCI) in comparison with cognitively healthy older adults, using pictures depicting events. In Experiment 1, we examined participants’ ability to integrate pictorially depicted sub-events into macro-events. The pictures were presented in a scrambled order, and participants were expected to arrange them in the temporally and causally appropriate sequence, as dictated by the macro-event schema. Additionally, we investigated the effect of cueing the appropriate event schema by providing a word cue (verb). In Experiment 2, macro-event recognition was examined again using a cognitively less taxing paradigm, where pictures depicting sub-events were presented in correct order, but staggered, and recognition speed was measured. We observed significant deficits in the AD and MCI groups’ performance compared with the cognitively healthy older adults, across both experiments, suggesting event perception and cognition is impaired early in the course of AD. There was no effect of cueing on the performance of any of the groups. The theoretical and clinical implications of these findings are discussed.