The naming deficit in early Alzheimer's and vascular dementia

Prevalence of low scores on language tests as a potential factor in misdiagnosis of cognitive impairment in a Spanish-speaking adult population

Objective: In this study, the prevalence of low scores for two neuropsychological tests of language has been determined.Methods: In total, N = 5218 healthy adults from 11 countries in Latin America (LA) were administered the Boston Naming Test (BNT) and the Verbal Fluency Test (VFT) as part of a comprehensive neuropsychological evaluation. Z-scores were calculated for BNT Total score, and phonological (letters F, A, S, M) and semantic (Animals, Fruits). Scores were adjusted for age, age², sex, education, and interaction variables if significant for the given country. Each Z-score was converted to a percentile for each of the seven test-scores. Each participant was categorized based on his/her number of low scoring tests in specific percentile cutoff groups (25th, 16th, 10th, 5th, and 2nd).Results: Between 53% (Paraguay) and 71% (Mexico) of the sample had at least 1-score below the 25th percentile, and between 41% (Paraguay) and 55% (Cuba) scored below the 16th percentile. Between 27% (Paraguay) and 39% (Peru) scored below the 10th percentile on at least 1-score, and between 17% (Chile) and 23% (Argentina) scored below the 5th percentile.Conclusions: Clinicians should use these data to reduce false-positive diagnoses and to improve the neuropsychological assessments in Spanish-speaking individuals from LA countries.

[Collation of word retrieval disorders in patients with Alzheimer's dementia]

BACKGROUND

One of the first symptoms of Alzheimer's disease (AD) is word retrieval deficits. A systematic evaluation of word retrieval deficits can have an important predictive value for developing Alzheimer's disease.

OBJECTIVE

Is the test for finding word retrieval deficits (word finding = WoFi) able to detect deficits in word retrieval and does it correlate with other dementia tests?

METHODS

A word retrieval test called WoFi was developed. It is an instrument that tests word retrieval deficits based on 50 questions. A maximum of 100 points can be scored.

RESULTS

The control group scored significantly better than the AD group. Using a cut-off score of 84 points WoFi could discriminate controls from subjects with a sensitivity of 95% and a specificity of 92%.

CONCLUSION

The use of WoFi was able to test for word retrieval deficits. Application required less than 15 min and test instructions are very simple. This instrument might be useful in telehealth.

Diminished neural network dynamics in amnestic mild cognitive impairment

Mild cognitive impairment (MCI) is widely regarded as an intermediate stage between typical aging and dementia, with nearly 50% of patients with amnestic MCI (aMCI) converting to Alzheimer's dementia (AD) within 30 months of follow-up (Fischer et al., 2007). The growing literature using resting-state functional magnetic resonance imaging reveals both increased and decreased connectivity in individuals with MCI and connectivity loss between the anterior and posterior components of the default mode network (DMN) throughout the course of the disease progression (Hillary et al., 2015; Sheline & Raichle, 2013; Tijms et al., 2013). In this paper, we use dynamic connectivity modeling and graph theory to identify unique brain "states," or temporal patterns of connectivity across distributed networks, to distinguish individuals with aMCI from healthy older adults (HOAs). We enrolled 44 individuals diagnosed with aMCI and 33 HOAs of comparable age and education. Our results indicated that individuals with aMCI spent significantly more time in one state in particular, whereas neural network analysis in the HOA sample revealed approximately equivalent representation across four distinct states. Among individuals with aMCI, spending a higher proportion of time in the dominant state relative to a state where participants exhibited high cost (a measure combining connectivity and distance), predicted better language performance and less perseveration. This is the first report to examine neural network dynamics in individuals with aMCI.

Effects of Education on Differential Item Functioning on the 15-Item Modified Korean Version of the Boston Naming Test

OBJECTIVE

Education is expected to have an effect on differential item functioning (DIF) on the 15-item Modified Boston Naming Test in the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet (BNT-KC). However, no study has examined DIF in the BNT-KC.

METHODS

We used the item response theory to investigate the impact of education on the DIF in the BNT-KC among elderly individuals with or without dementia (n=720). A two-parameter item response model was used to determine the difficulty and discrimination parameters of each item. The Benjamini-Hochberg procedure was used to address the risk of Type I errors on multiple testing.

RESULTS

Four items, "mermaid," "acorn," "compass," and "pomegranate" continued to demonstrate DIF after controlling for multiple comparisons. Those with low education levels were more likely to error on "mermaid" and "compass," while those with high education levels were more likely to error on "acorn" and "pomegranate." "Hand" and "red pepper" were too easily identified to be used for detecting dementia patients. "Monk's hat" and "pomegranate" were less discriminating than other items, limiting their usefulness in clinical setting.

CONCLUSION

These findings may provide useful information for the development of a revised version of the BNT-KC to help clinicians make diagnostic decisions more accurately.

Treatment effects in multiple cognitive domains in Alzheimer's disease: a two-year cohort study

Introduction

Despite widespread use of second-generation cholinesterase inhibitors for the symptomatic treatment of Alzheimer’s disease (AD), little is known about the long term effects of cholinergic treatment on global cognitive function and potential specific effects in different cognitive domains. The objectives of this study were to determine the association between cholinergic treatment and global cognitive function over one and two years in a cohort of patients with mild or moderate AD and identify potential differences in domain-specific cognitive outcomes within this cohort.

Methods

A cohort of patients meeting the revised National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria for mild or moderate AD, including patients both on treatment with a cholinesterase inhibitor and untreated controls (treated = 65, untreated = 65), were recruited from the Cognitive Neurology Clinic at Sunnybrook Health Sciences Centre, as part of the Sunnybrook Dementia Study. Patients were followed for one to two years and underwent standardized neuropsychological assessments to evaluate global and domain-specific cognitive function. Associations between cholinesterase inhibitor use and global and domain-specific cognitive outcome measures at one and two years of follow-up were estimated using mixed model linear regression, adjusting for age, education, and baseline mini mental state examination (MMSE).

Results

At one year, treated patients showed significantly less decline in global cognitive function, and treatment and time effects across tests of executive and visuospatial function. At two years, there was a significant trend towards less decline in global cognition for treated patients. Moreover, treated patients showed significant treatment and time effects across tests of executive functioning, memory, and visuospatial function.

Conclusions

The present study offers two important contributions to knowledge of the effectiveness of cholinesterase inhibitor treatment in patients with mild-moderate AD: 1) that second-generation cholinesterase inhibitors demonstrate long-term effectiveness for reducing global cognitive decline over one to two years of follow-up, and 2) that decline in function for cognitive domains, including executive function, memory, and visuospatial skill that are primarily mediated by frontal networks and by the cholinergic system, rather than memory, may be slowed by treatment targeting the cholinergic system.

Auditory confrontation naming in Alzheimer's disease

Naming is a fundamental aspect of language and is virtually always assessed with visual confrontation tests. Tests of the ability to name objects by their characteristic sounds would be particularly useful in the assessment of visually impaired patients, and may be particularly sensitive in Alzheimer's disease (AD). We developed an auditory naming task, requiring the identification of the source of environmental sounds (i.e., animal calls, musical instruments, vehicles) and multiple-choice recognition of those not identified. In two separate studies mild-to-moderate AD patients performed more poorly than cognitively normal elderly on the auditory naming task. This task was also more difficult than two versions of a comparable visual naming task, and correlated more highly with Mini-Mental State Exam score. Internal consistency reliability was acceptable, although ROC analysis revealed auditory naming to be slightly less successful than visual confrontation naming in discriminating AD patients from normal participants. Nonetheless, our auditory naming task may prove useful in research and clinical practice, especially with visually impaired patients.

Quantitative tractography metrics of white matter integrity in diffusion-tensor MRI

We present new quantitative diffusion-tensor imaging (DTI) tractography-based metrics for assessing cerebral white matter integrity. These metrics extend prior work in this area. Tractography models of cerebral white matter were produced from each subject's DTI data. The models are a set of curves (e.g., "streamtubes") derived from DTI data that represent the underlying topography of the cerebral white matter. Nine metrics were calculated in whole brain tractography models and in three "tracts-of-interest": transcallosal fibers and the left and right cingulum bundles. The metrics included the number of streamtubes and several other based on the summed length of streamtubes, including some that were weighted by scalar anisotropy metrics and normalized for estimated intracranial volume. We then tested whether patients with subcortical ischemic vascular disease (i.e., vascular cognitive impairment or VCI) vs. healthy controls (HC) differed on the metrics. The metrics were significantly lower in the VCI group in whole brain and in transcallosal fibers but not in the left or right cingulum bundles. The metrics correlated significantly with cognitive functions known to be impacted by white matter abnormalities (e.g., processing speed) but not with those more strongly impacted by cortical disease (e.g., naming). These new metrics help bridge the gap between DTI tractography and scalar analytical methods and provide a potential means for examining group differences in white matter integrity in specific tracts-of-interest.

Forgetting in dementia with and without subcortical lacunes

Alzheimer's disease (AD) and subcortical ischemic vascular disease (SIVD) are common causes of dementia, often co-occur, and can present quite similarly, making differential diagnosis clinically challenging. This study tested the hypothesis that patients with SIVD retain information better than AD patients. Participants were 35 dementia patients with subcortical lacunes (SIVD group), 27 dementia patients without lacunar infarction (AD group), and 56 normal controls. Results indicated that despite comparable levels of initial acquisition, AD patients showed more rapid forgetting. Further analysis indicated that memory patterns within the SIVD group were heterogeneous, with some participants exhibiting rapid forgetting and some exhibiting good retention. SIVD participants with good retention showed a trend for greater executive impairments relative to SIVD participants with rapid forgetting and AD participants. Results suggest that rapid forgetting in SIVD may imply concomitant AD, whereas the dementia in patients with good retention may be purely vascular in origin. Three SIVD patients with rapid forgetting followed to autopsy all had AD pathology, further supporting the link between memory patterns and AD.

Defining the Diagnosis of Vascular Dementia

Vascular dementia (VaD) is a heterogeneous term that has evolved to describe the behavioral syndromes associated with a variety of clinical and neuropathologic changes. As such, the VaD literature lacks a clear consensus regarding the neuropsychological and other constituent characteristics associated with various cerebrovascular changes. We address the issues articulated by Paul and colleagues (Paul, Garrett, & Cohen, 2003), by offering four recommendations to refine the clinical assessment and diagnostic decision-making process of individuals with suspected cerebrovascular changes: (a) Describing the nature of vascular changes may facilitate predictions regarding the neuropsychological profile of subtypes of VaD; (b) employ a process approach to assessment, measuring cognitive constructs in addition to test scores to describe the neuropsychological profiles of types of VaD; (c) integrate direct MRI observations of the brain and other collateral data in the diagnostic process; and (d) consider using "vascular cognitive impairment, no dementia" for suspected prodromal VaD.