Learning face-name associations in early-stage dementia: comparing the effects of errorless learning and effortful processing

Some recent studies suggest that errorless learning principles may be beneficial in memory rehabilitation for people with dementia, while others indicate that effortful processing may be more important. The present study compared the effects of four different learning techniques, varying in level of effort required and number of errors elicited, on free recall, cued recall and recognition of novel and previously known associations among people with early-stage dementia. Ten participants with a diagnosis of early-stage Alzheimer's, vascular or mixed dementia learned novel and previously familiar face-name associations with each of four techniques--vanishing cues, forward cues, target selection, and paired associate learning--in a within-subjects design. All conditions produced significant learning for both novel and familiar associations. There were no significant differences between conditions, although mean scores were slightly higher for errorful conditions. Reducing errors did not produce any benefits. Enhancing level of effort had no significant effects for familiar associations, but high-effort conditions were significantly more effective than low-effort conditions in facilitating cued recall of novel associations. The results confirm that memory rehabilitation techniques can produce significant benefits, but do not support the view that error reduction during learning facilitates greater improvement in early-stage dementia. Effort enhancement may be more important, especially when learning novel associations.     

Dual-task performance in demented and nondemented elderly

The present study examined the ability of demented and nondemented elderly subjects to divide their attention between recalling digits and judging the similarity of pairs of letters. Both groups showed substantial decrements in digit recall following distraction by letter matching. To identify the nature of the interference effect, digit recall was scored according to a strict criterion where preservation of the serial order of the digits was required (order-based recall), and a lenient criterion where preservation of digit order was not required (order-free recall). While both groups showed a comparable decrement in order-based recall due to the interfering task, order-free recall virtually eliminated the decrement for the nondemented group whereas substantial interference was still observed in the demented group. These results suggest that letter matching interferes with digit recall in nondemented elderly primarily by disrupting order information. In the case of demented elderly, letter matching disrupts the preservation of item information as well.     

Dual-task performance in demented and nondemented elderly

Abstract

The present study examined the ability of demented and nondemented elderly subjects to divide their attention between recalling digits and judging the similarity of pairs of letters. Both groups showed substantial decrements in digit recall following distraction by letter matching. To identify the nature of the interference effect, digit recall was scored according to a strict criterion where preservation of the serial order of the digits was required (order-based recall), and a lenient criterion where preservation of digit order was not required (order-free recall). While both groups showed a comparable decrement in order-based recall due to the interfering task, order-free recall virtually eliminated the decrement for the nondemented group whereas substantial interference was still observed in the demented group. These results suggest that letter matching interferes with digit recall in nondemented elderly primarily by disrupting order information. In the case of demented elderly, letter matching disrupts the preservation of item information as well.     

Early stage dementia group: an innovative model of support for individuals in the early stages of dementia

Traditionally, supports and services for people diagnosed with Alzheimer's disease have focused on the caregivers. The increase in early diagnosis of Alzheimer's disease has resulted in greater numbers of older adults that have some insight and awareness of their deficits and are capable of dealing with the ramifications of their illness. Yet there are few places to turn for support and education. Circle of Care, a community-based home support agency in Toronto, has developed a support group for individuals with early stage dementia. Comprehensive Rehabilitation and Mental Health Services (COTA), a community-based rehabilitation agency, was invited to provide a co-facilitator for this group. To date, three groups have been held, each one having a fixed membership and meeting for eight sessions of one and a quarter hours. Topics focused on causation, coping with memory problems, loss, grief, and daily living skills. Positive themes emerged to reveal feelings of affirmation, camaraderie, and improved confidence, while feelings of helplessness and frustration were also raised. Implications for future planning and interventions also will be discussed in this paper.     

Cueing effects on semantic and perceptual categorization: ERPs reveal differential effects of validity as a function of processing stage

Valid cueing has been shown to accelerate target identification and improve decision accuracy. However, the precise nature and extent to which biasing influences the successive stages of target processing remain unclear. The present event-related potential (ERP) study used a "hybrid" task that combined features of standard cued-attention and task-switching paradigms in order to explore the effects of expectation on both identification and categorization of centrally presented stimuli. Subjects made semantic judgments (living/nonliving) on word targets ("bunny"), and perceptual judgments (right/left) on arrow targets ("<"). Target expectancy was manipulated using cues that were valid (60 percent of trials), invalid (10 percent), or neutral (30 percent). Invalidly cued targets required task-set switching before categorization could commence, and resulted in RT costs relative to validly or neutrally cued targets. Additional benefits from valid-cueing were only observed for word targets. Invalid cueing of both arrow and word targets modulated early posterior visual potentials (P1/N1) and elicited a subsequent anterior P3a (270 ms). The temporal relationship of these effects suggests that the P3a indexed domain-general task-set switching processes recruited in response to the detection of unexpected perceptual information. Subsequent to the P3a and immediately preceding the behavioral response, validly cued targets elicited enhanced stimulus-specific waveforms (arrows: parietal positivity [P290], words: inferior temporal negativity [late ITN: 400-600 ms]). The degree of neural enhancement relative to the invalid and neutral conditions mirrored the magnitude of corresponding RT benefits, suggesting that these waveforms indexed categorization, decision processes or both. Together, these results suggest that valid cueing increases the neural efficiency of initial stimulus identification, facilitating transmission of information to subsequent categorization stages, where increased neural activity leads to behavioral benefits.     

Maze test performance and reported driving ability in early dementia

A battery of standard neuropsychological tests examining various features of executive function, attention, and visual perception was administered to 27 subjects with questionable to mild dementia and compared to a 4-point caregiver rating scale of driving ability. Based on the results of this study, a computerized maze task, employing 10 mazes, was administered to a second sample of 40 normal elders and questionable to moderately demented drivers. Comparison was made to the same caregiver rating scale as well as to crash frequency. In the first study of neuropsychological tests, errors on Porteus Mazes emerged as the only significant predictor of driving ability in a stepwise regression analysis. In the follow-up study employing the computerized mazes, all 10 mazes were significantly related to driving ability ratings. Computerized tests of maze performance offer promise as a screening tool to identify potential driving impairment among cognitively impaired elderly and demented drivers.     

Blood cells cholinesterase activity in early stage Alzheimer's disease and vascular dementia

Blood acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities have been studied as markers for Alzheimer's disease (AD), but their usefulness as a disease marker is controversial. To determine cholinesterase (ChE) activity during AD progression and whether ChE changes associate to other dementias, ChE activity was measured in lymphocytes, erythrocytes and platelets. Subjects underwent extensive medical and neuropsychological examination. Both early-AD and AD patients had lower AChE activity in lymphocytes compared to control subjects (p < 0.0001). In contrast, erythrocyte AChE activity was higher in patients with vascular dementia (p = 0.004). Low ChE activity in lymphocytes was the best discriminator for AD. Because it was already low at very early stages of AD, ChE could be helpful as an early biomarker of differential diagnosis for the follow-up of patients during their early stages of cognitive impairment before a clinical dementia is established.     

Assessing early to late stage dementia: the TSI and BANS-S scales in the nursing-home

BACKGROUND: The traditional assessment tools for dementia, such as the MMSE, have only limited ability to follow subjects with severe dementia because they show a floor effect. Specific observational and performance-based instruments were recently developed. OBJECTIVES: To directly compare an observational scale to a performance-based instrument in moderate to severe dementia. METHODS: We compared a slightly modified version of the performance-based Test for Severe Impairment (mTSI) to the observer-based Bedford Alzheimer Nursing Severity Scale (BANS-S). Both scales were administered, together with the Mini-Mental State Examination (MMSE) and the Clinical Dementia Rating scale (CDR), to a nursing-home sample of 130 women suffering from different types of dementia (CDR range:1-4; MMSE range:0-18), defined according to DSM-IV criteria. Mean age was 86.9 +/- 7.3 years and mean education was 2.7 +/- 1.1 years. RESULTS: The BANS-S could be applied to all patients, the mTSI to 87 subjects (66.9%). Mean mTSI score decreased progressively from CDR stage 2 to CDR stage 4, whereas no difference was detectable between CDR stages 1 and 2. By contrast, the BANS-S was not significantly different for CDR stages 1 to 3, and the mean BANS-S score worsened only in CDR stage 4. Results were similar for AD and non AD dementia. Both scales were independent from age and education and their test-retest and inter-rater reliabilities were satisfactory. CONCLUSION: The mTSI looks promising in the moderate-to-severe range, whereas the BANS-S seems more useful in the very late stage of dementia. However, neither scale was optimal and additional instruments should be tested in future studies.     

Abnormal amino acid metabolism in patients with early stage Alzheimer dementia

Summary. Plasma levels of several amino acids were studied in 14 patients with early stage probable Alzheimer's disease (AD) and 17 age-matched controls. In the AD patients a possible relationship between amino acid levels and behavioural symptomatology was also investigated. We found significantly reduced levels of tryptophan and methionine in plasma samples from the AD patients compared to the control subjects. Moreover, plasma tyrosine/large neutral amino acids (LNAA) ratio and the ratio of plasma taurine and the product of the plasma levels of methionine and serine (TSM-ratio) were significantly increased in the AD patients in comparison with the controls. However, no difference was found in plasma tryptophan/LNAA ratio and in homocysteine levels between both groups. Concerning the behavioural symptomatology no significant correlation was found between the Reisberg Behave AD scale and plasma amino acid levels or ratios. The reported findings suggest that abnormal amino acid metabolism is present in the early stages of AD. We hypothesize that this abnormality could play a role in the pathogenesis of behavioural changes occurring in later stages of AD. Accepted February 2, 1998; received November 11, 1997     

The early stage of vascular dementia: significance of a complete therapeutic program

THEORY: Mild manifestations of vascular dementia are relatively widespread among the old-age population. Drug therapy for this disorder is insufficiently effective at present, making it necessary to improve the treatment of such patients by means of an adequate psychotherapeutic and rehabilitation program. AIMS: To assess the role of psychotherapeutic and rehabilitation measures in improving outcome in the early stage of vascular dementia. METHODS: The test and control cohorts (each n = 95) were matched for characteristics found to be significant for outcome of treatment (the relevant predictors were found using Multiple Regression Analysis). The cohorts differed in the amount of the psychotherapy and rehabilitation received. To assess the effects of treatment the SCAG scale and a special scale for evaluating the level of activity in the household were used. RESULTS: In the test cohort the patients' condition improved significantly compared with the controls. Even in case of only slight therapeutic reduction of psychopathologic symptoms the systematic use of psychotherapeutic and rehabilitation methods favoured preserving a certain level of activity in the household and for some patients even improving it. CONCLUSIONS: The results of therapy at the early stage of vascular dementia to a great extent depend on carrying out a full-scale psychotherapeutic and rehabilitation program. The positive significance of the latter is connected not only with improvement of clinical indices but also with direct optimizing the every day life activity level.     

事件相关电位和脑电图在痴呆早期诊断中的意义

目的 研究血管性痴呆（vascular dementia,VD）患者ERP和EEG的变化特征,并与神经心理学及痴呆程度进行相关性分析。方法 测定68例VD患者及37例健康志愿者的事件相关电位（ERP：N100,P300）、脑电图（EEG）,同时采用MMSE进行认知功能评定,并进行相关性分析。结果 68例VD组患者的P300潜伏期明显延长,波幅明显降低,与正常对照组比较有明显差异性（P〈0.01,P〈0.05）,N100潜伏期。波幅变化不是很大（P〉0.05）,脑电图异常率,VD组94%,正常对照组18%,2组比较有明显差异性（P〈0.01）。VD组患者ERP异常程度与EEG异常程度经相关性分析无相关性。VD组MMSE与正常对照组比较有明显差异（P〈0.05）,VD组MMSE评分与P300PL呈负相关（r=-0.57,P〈0.05）,与P300AMP呈正相关（r=0.37,P〉0.05）。结论 ERP与认知功能存在明显相关性,提示了ERP是反映其认知功能障碍程度的客观指标之一,可作为检测高危人群普查的手段之一,ERP在判断认知功能方面敏感于其他检查手段,客观性强。     

Diagnostic classification of arterial spin labeling and structural MRI in presenile early stage dementia

Because hypoperfusion of brain tissue precedes atrophy in dementia, the detection of dementia may be advanced by the use of perfusion information. Such information can be obtained noninvasively with arterial spin labeling (ASL), a relatively new MR technique quantifying cerebral blood flow (CBF). Using ASL and structural MRI, we evaluated diagnostic classification in 32 prospectively included presenile early stage dementia patients and 32 healthy controls. Patients were suspected of Alzheimer's disease (AD) or frontotemporal dementia. Classification was based on CBF as perfusion marker, gray matter (GM) volume as atrophy marker, and their combination. These markers were each examined using six feature extraction methods: a voxel‐wise method and a region of interest (ROI)‐wise approach using five ROI‐sets in the GM. These ROI‐sets ranged in number from 72 brain regions to a single ROI for the entire supratentorial brain. Classification was performed with a linear support vector machine classifier. For validation of the classification method on the basis of GM features, a reference dataset from the AD Neuroimaging Initiative database was used consisting of AD patients and healthy controls. In our early stage dementia population, the voxelwise feature‐extraction approach achieved more accurate results (area under the curve (AUC) range = 86 ? 91%) than all other approaches (AUC = 57 ? 84%). Used in isolation, CBF quantified with ASL was a good diagnostic marker for dementia. However, our findings indicated only little added diagnostic value when combining ASL with the structural MRI data (AUC = 91%), which did not significantly improve over accuracy of structural MRI atrophy marker by itself. Hum Brain Mapp 35:4916–4931, 2014. © 2014 Wiley Periodicals, Inc .     

Subcortical grey matter changes in untreated,early stage Parkinson's disease without dementia

BackgroundPrevious MRI studies have investigated cortical or subcortical grey matter changes in patients with Parkinson's disease (PD), yielding inconsistent findings between the studies. We therefore sought to determine whether focal cortical or subcortical grey matter changes may be present from the early disease stage.MethodsWe recruited 49 untreated, early stage PD patients without dementia and 53 control subjects. Voxel-based morphometry was used to evaluate cortical grey matter changes, and automated volumetry and shape analysis were used to assess volume changes and shape deformation of the subcortical grey matter structures, respectively.ResultsVoxel-based morphometry showed neither reductions nor increases in grey matter volume in patients compared to controls. Compared to controls, PD patients had significant reductions in adjusted volumes of putamen, nucleus accumbens, and hippocampus (corrected p < 0.05). Vertex-based shape analysis showed regionally contracted area on the posterolateral and ventromedial putamen bilaterally in PD patients (corrected p < 0.05). No correlations were found between cortical and subcortical grey matter and clinical variables representing disease duration and severity.ConclusionsOur results suggest that untreated, early stage PD without dementia is associated with volume reduction and shape deformation of subcortical grey matter, but not with cortical grey matter reduction. Our findings of structural changes in the posterolateral putamen and ventromedial putamen/nucleus accumbens could provide neuroanatomical basis for the involvement of motor and limbic striatum, further implicating motor and non-motor symptoms in PD, respectively. Early hippocampal involvement might be related to the risk for developing dementia in PD patients.     

Individual differences in prefrontal cortical activation on the Tower of London planning task: implication for effortful processing

Solving challenging ('effortful') problems is known to involve the dorsal and dorsolateral prefrontal cortex in normal volunteers, although there is considerable individual variation. In this functional magnetic resonance imaging study, we show that healthy subjects with different levels of performance in the Tower of London planning task exhibit different patterns of brain activation. All subjects exhibited significant bilateral activation in the dorsolateral prefrontal cortex, the anterior and posterior cingulate areas and the parietal cortex. However, 'standard performers' (performance < 70% correct) and 'superior performers' (performance >70% correct) differed in the patterns of activation exhibited. Superior performers showed a significantly more spatially extended activation in the left dorsolateral prefrontal cortex than did standard performers, whereas the latter group tended to show increased activation of the anterior cingulate region.     

Everyday action in dementia: evidence for differential deficits in Alzheimer's disease versus subcortical vascular dementia.

The relationship between dementia diagnosis and everyday action (e.g., meal preparation, grooming) is not well understood. This study examines differences between individuals diagnosed with vascular dementia (VaD; n = 25) versus Alzheimer's disease (AD; n = 23) on the Naturalistic Action Test (NAT; Schwartz et al., 2003), a performance-based measure that includes three tasks of increasing complexity. The percentage of task steps accomplished, number of errors, and performance times were recorded for each task. While the groups did not differ in dementia severity or overall impairment on the NAT, the VaD group committed more errors (3.3 vs. 1.6, p = 02). The VaD group also accomplished significantly fewer steps when salient distractor objects were present (74.0% vs. 91.3%, p < .01). Correlations between NAT variables and neuropsychological tests suggest the executive control deficits associated with VaD may contribute to specific action difficulties, such as distractor interference and inefficient, error-prone action on complex tasks. In AD, everyday action may be negatively influenced by episodic memory failures. Thus, dementia diagnosis has relevance to everyday function.     

非痴呆早期帕金森病患者脑白质微结构的改变

目的分析非痴呆早期帕金森病(Parkinson’s Disease,PD)患者脑白质微结构的变化,为早期诊断提供依据。方法共纳入非痴呆早期PD患者32例、对照组20例,两组性别、年龄和受教育年相匹配(P>0.05)。采用GE Signa HDxt America 3.0 T核磁共振进行弥散张量成像(Diffusion Tensor Imaging,DTI)扫描。在AW4.4workstation工作站上运用the Functool image analysis软件包进行图像后处理,采用圆形感兴趣区(rigion-of-interest,ROI)对不同脑区白质纤维进行部分各向异性(fractional anisotropy,FA)值测量,比较两组相应脑白质区域的FA值的差异。结果非痴呆早期PD患者的一些脑白质区域,如双侧颞叶、左侧前扣带束和胼胝体压部的FA值较对照组降低(P<0.05)。结论 PD患者在疾病早期即出现较广泛的脑白质微结构改变,可能是其一些非运动症状的基础;采用DTI评估PD脑白质微结构的改变可能有助于早期诊断。     

Predictive and sensory integration begins at an early stage of visual processing

Brain activity was measured by magnetoencephalography to investigate the spatiotemporal stage of visual processing at which predictive and sensory integration begins. We examined the consequences of a visual mismatch between preliminary prediction and incoming stimulus. Following auditory cues (1000- and 1250-Hz tones) for prediction, congruent and incongruent images, pictures of two musical keys, were presented to volunteers. When they predicted visual inputs on the basis of preceding auditory cues, we detected a mismatch signal for predictive-sensory incongruities in the striate and extrastriate areas for 100-200 ms after image presentation. As this signal reflects a compatibility analysis, we propose that the integration process begins in these areas approximately 100 ms after image presentation.