Yes/No Versus Forced-Choice Recognition Memory in Mild Cognitive Impairment and Alzheimer's Disease: Patterns of Impairment and Associations with Dementia Severity

Memory tests are sensitive to early identification of Alzheimer's disease (AD) but less useful as the disease advances. However, assessing particular types of recognition memory may better characterize dementia severity in later stages of AD. We sought to examine patterns of recognition memory deficits in individuals with AD and mild cognitive impairment (MCI). Memory performance and global cognition data were collected from participants with AD (n?=?37), MCI (n?=?37), and cognitively intact older adults (normal controls, NC; n?=?35). One-way analyses of variance (ANOVAs) examined differences between groups on yes/no and forced-choice recognition measures. Individuals with amnestic MCI performed worse than NC and nonamnestic MCI participants on yes/no recognition, but were comparable on forced-choice recognition. AD patients were more impaired across yes/no and forced-choice recognition tasks. Individuals with mild AD (≥120 Dementia Rating Scale, DRS) performed better than those with moderate-to-severe AD (<120 DRS) on forced-choice recognition, but were equally impaired on yes/no recognition. There were differences in the relationships between learning, recall, and recognition performance across groups. Although yes/no recognition testing may be sensitive to MCI, forced-choice procedures may provide utility in assessing severity of anterograde amnesia in later stages of AD. Implications for assessment of insufficient effort and malingering are also discussed.     

Diagnostic differentiation of mild cognitive impairment due to Alzheimer's disease using a hippocampus‐dependent test of spatial memory

The hippocampus is one of the earliest brain regions affected in Alzheimer's disease (AD) and tests of hippocampal function have the potential to detect AD in its earliest stages. Given that the hippocampus is critically involved in allocentric spatial memory, this study applied a short test of spatial memory, the 4 Mountains Test (4MT), to determine whether test performance can differentiate mild cognitive impairment (MCI) patients with and without CSF biomarker evidence of underlying AD and whether the test can distinguish patients with MCI and mild AD dementia when applied in different cultural settings. Healthy controls (HC), patients with MCI, and mild AD dementia were recruited from study sites in UK and Italy. Study numbers were: HC (UK 20, Italy 10), MCI (UK 21, Italy 14), and AD (UK 11, Italy 9). Nineteen UK MCI patients were grouped into CSF biomarker‐positive (MCI+, n = 10) and biomarker‐negative (MCI–, n = 9) subgroups. Behavioral data were correlated with hippocampal volume and cortical thickness of the precuneus and posterior cingulate gyrus. Spatial memory was impaired in both UK and Italy MCI and AD patients. Test performance additionally differentiated between MCI+ and MCI– subgroups (P = 0.001). A 4MT score of ≤8/15 was associated with 100% sensitivity and 90% specificity for detection of early AD (MCI+ and mild AD dementia) in the UK population, and with 100% sensitivity and 50% specificity for detection of MCI and AD in the Italy sample. 4MT performance correlated with hippocampal volume in the UK population and cortical thickness of the precuneus in both study populations. In conclusion, performance on a hippocampus‐sensitive test of spatial memory differentiates MCI due to AD with high diagnostic sensitivity and specificity. The observation that similar diagnostic sensitivity was obtained in two separate study populations, allied to the scalability and usability of the test in community memory clinics, supports future application of the 4MT in the diagnosis of pre‐dementia due to AD. © 2015 Wiley Periodicals, Inc.     

Validation of the Test Your Memory (F-TYM Test) in a French Memory Clinic Population

The Test Your Memory (TYM) test has been proposed for screening dementia. We present a French version and its validation in memory clinics. F-TYM was administered to 201 patients with memory complaints visiting five secondary referral hospital centers. Final diagnosis was dementia in 34%, amnestic mild cognitive impairment (MCI) in 32%, non-amnestic MCI in 11%, absence of cognitive disorder in 23% and F-TYM scores were respectively (M ± SD) 30.9 ± 7.6, 40.5 ± 6.3, 44.3 ± 4.5 and 43.5 ± 6.6 (p < .0001). F-TYM showed high correlation with MMSE (r = .78), excellent internal consistency, no effect of educational level, sex, or mood but a significant effect of age (p = .004). A F-TYM score ≤ 39 had 0.90 sensitivity and 0.70 specificity for diagnosis of dementia. F-TYM was unable to discriminate MCI and patients without cognitive disorders. F-TYM could be proposed for screening of dementia in patients with memory complaints.     

Cognitive Impairment Questionnaire (CIMP‐QUEST): reported topographic symptoms in MCI and dementia

Åstrand R, Rolstad S, Wallin A. Cognitive Impairment Questionnaire (CIMP‐QUEST): reported topographic symptoms in MCI and dementia.
Acta Neurol Scand: 2010: 121: 384–391.
© 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Objective – The Cognitive Impairment Questionnaire (CIMP‐QUEST) is an instrument based on information obtained by key informants to identify symptoms of dementia and dementia‐like disorders. The questionnaire consists of three subscales reflecting impairment in parietal‐temporal (PT), frontal (F) and subcortical (SC) brain regions. The questionnaire includes a memory scale and lists non‐cognitive symptoms. The reliability and validity of the questionnaire were examined in 131 patients with mild cognitive impairment (MCI) or mild dementia at a university‐based memory unit. Methods/Results – Cronbach alpha for all subscales was calculated at r = 0.90. Factor analysis supported the tri‐dimensionality of CIMP‐QUEST’s brain region‐oriented construct. Test–retest reliability for a subgroup of cognitively stable MCI‐patients (n = 25) was found to be r = 0.83 (P = 0.0005). The correlation between the score on the cognitive subscales (PT + F + M) and Informant Questionnaire on Cognitive Decline in the Elderly was r = 0.83 (P = 0.0005, n = 123). The memory subscale correlated significantly with episodic memory tests, the PT subscale with visuospatial and language‐oriented tests, and the SC and F subscales with tests of attention, psychomotor tempo and executive function. Conclusions – CIMP‐QUEST has high reliability and validity, and provides information about cognitive impairment and brain region‐oriented symptomatology in patients with MCI and mild dementia.     

Cognition in MCI and Alzheimer’s Disease: Baseline Data from a Longitudinal Study of the NTB

Baseline data are summarized from a study examining the psychometric properties of the Neuropsychological Test Battery (NTB) and its subtests, and correlating the NTB with other cognitive and functional assessments. A multicenter, longitudinal, non-interventional study included mild to moderate Alzheimer’s disease (AD, n = 196), mild cognitive impairment (MCI, n = 70), or normal cognition participants (NC, n = 75). The NTB, other cognitive assessment tools, functional/behavioral questionnaires, and health outcome assessments were administered. At baseline composite NTB, NTB memory, and NTB executive function z-scores were significantly lower for participants with AD compared with MCI, and for participants with MCI compared with NC. The composite NTB z-score had high test–retest reliability between screening and baseline. The results of this study suggest that NTB exhibits good reliability in patients with mild to moderate AD and MCI.     

Frontal atrophy as a marker for dementia conversion in Parkinson's disease with mild cognitive impairment

This study aimed to investigate the cortical neural correlates of dementia conversion in Parkinson's disease with mild cognitive impairment (PD‐MCI). We classified 112 patients with drug‐naïve early stage PD meeting criteria for PD‐MCI into either PD with dementia (PDD) converters (n = 34) or nonconverters (n = 78), depending on whether they developed dementia within 4 years of PD diagnosis. Cortical thickness analyses were performed in 34 PDD converters and 34 matched nonconverters. Additionally, a linear discriminant analysis was performed to distinguish PDD converters from nonconverters using cortical thickness of the regions that differed between the two groups. The PDD converters had higher frequencies of multiple domain MCI and amnestic MCI with storage failure, and poorer cognitive performances on frontal/executive, memory, and language function domains than did the nonconverters. Cortical thinning extending from the posterior cortical area into the frontal region was observed in PDD converters relative to nonconverters. The discriminant analysis showed that the prediction model with two cortical thickness variables in the right medial superior frontal and left olfactory cortices optimally distinguished PDD converters from nonconverters. Our data suggest that cortical thinning in the frontal areas including the olfactory cortex is a marker for early dementia conversion in PD‐MCI.     

Adiponectin in plasma and cerebrospinal fluid in MCI and Alzheimer’s disease

Background and purpose: Life style‐related disorders such as hypertension, diabetes, dyslipidemia, and obesity are reported to be a great risk of dementia. Adipocytokines released from adipose tissue are thought to modulate some brain functions including memory and cognition. We here analysed adiponectin, one of the most important adipocytokines, in plasma and cerebrospinal fluid (CSF) from cognitive normal controls (NC), mild cognitive impairment (MCI) subjects, and patients with Alzheimer’s disease (AD) and discussed if/how adiponectin could relate to the pathogenesis of AD. Methods: Normal controls (n = 28), MCI (n = 18), and AD (n = 27) subjects were recruited at Tohoku University Hospital. The diagnosis of AD was based on NINCDS‐ADRDA criteria. All the blood and CSF samples were obtained from each fasted subject. Adiponectin was assayed using a sandwich ELISA system. Results: The levels of adiponectin between in plasma and in CSF showed a positive correlation. Plasma adiponectin was significantly higher in MCI and AD compared to NC, whereas CSF adiponectin was significantly higher in MCI compared to NC. Conclusion: It is possible that the level of adiponectin in plasma reflects its level in CSF. The tendency to have higher adiponectin in plasma and CSF from MCI and AD suggests that this molecule plays a critical role in the onset of AD.     

Prospective memory on a novel clinical task in older adults with mild cognitive impairment and subjective cognitive decline

Despite the relevance of prospective memory to everyday functioning and the ability to live independently, prospective memory tasks are rarely incorporated into clinical evaluations of older adults. We investigated the validity and clinical utility of a recently developed measure, the Royal Prince Alfred Prospective Memory Test (RPA-ProMem), in a demographically diverse, non-demented, community-dwelling sample of 257 older adults (mean age = 80.78?years, 67.7% female) with amnestic mild cognitive impairment (aMCI, n = 18), nonamestic mild cognitive impairment (naMCI, n = 38), subjective cognitive decline (SCD, n = 83) despite intact performance on traditional episodic memory tests, and healthy controls (HC, n = 118). Those with aMCI and naMCI performed significantly worse than controls on the RPA-ProMem and its subtasks (time-based, event-based, short-term, long-term). Also, those with SCD scored significantly lower than controls on long-term, more naturalistic subtasks. Additional results supported the validity and inter-rater reliability of the RPA-ProMem and demonstrated a relation between test scores and informant reports of real-world functioning. The RPA-ProMem may help detect subtle cognitive changes manifested by individuals in the earliest stages of dementia, which may be difficult to capture with traditional episodic memory tests. Also, assessment of prospective memory can help guide the development of cognitive interventions for older adults at risk for dementia.     

Prevalence and cognitive performances of clinical dementia rating 0.5 and mild cognitive impairment in Japan. The Tajiri project

The borderline zone condition between normal aging and dementia is a major issue of concern. Although the term mild cognitive impairment (MCI) is popular, its prevalence and neuropsychological features have not been fully investigated. We investigated the prevalence and neuropsychological features for Clinical Dementia Rating (CDR) 0.5 and MCI. For normal aging, the effects of age and educational level on cognitive performance were examined. We examined 1501 older residents (46.8%) in Tajiri 65 years of age and older. They performed the Cognitive Abilities Screening Instrument (CASI). Depressive scores and subjective memory complaints were also evaluated. There was no age effect but an educational effect on cognitive performance in healthy adults. We found the overall prevalence of CDR 0.5 to be 30.2%, whereas that of MCI was only 4.9%. All CASI domains were deteriorated except for long-term memory and visual construction in the CDR 0.5 participants compared with healthy adults, suggesting that CDR 0.5 is similar to very mild Alzheimer disease. Memory complaints' data suggested that it would be better to exclude memory complaints from the MCI criteria. We considered that the concept of CDR 0.5 would be more applicable to community residents rather than that of the MCI.     

A Meta‐Analysis of fMRI Activation Differences during Episodic Memory in Alzheimer's Disease and Mild Cognitive Impairment

Functional MRI (fMRI) has the potential to be used as a tool to detect biomarkers related to classifying Alzheimer's disease (AD) and its prodromal stage, mild cognitive impairment (MCI). Previous meta‐analyses suggest that during episodic memory tasks, MCI patients exhibit hyperactivation in the medial temporal lobe (MTL) while AD patients exhibit hypoactivation, compared to healthy older adults (HOAs). However, these previous studies have methodological weaknesses that limit the generalizability of the results. This quantitative meta‐analysis re‐examines the activation associated with episodic memory in AD and MCI as compared to cognitively normal populations to assess these commonly cited activation differences. A whole‐brain activation likelihood estimation based meta‐analysis was conducted on fMRI studies that examined episodic memory in HOA (n = 200), MCI (n = 131), and AD populations (n = 89; total n = 409). Diffuse activation was exhibited in the HOA sample, while activation was more limited in the clinical populations. Additionally, the HOA sample showed more activation in the right hippocampus compared to the AD sample. The MCI studies showed greater activation in the cerebellum compared to the HOA sample, potentially indicating a compensatory mechanism for verbal encoding. MTL hypoactivation in the AD sample is consistent with previous studies, but more evidence of MCI hyperactivation is needed before considering MTL activation as an early biomarker for the AD disease process.     

Identifying mild cognitive impairment at baseline in the Ginkgo Evaluation of Memory (GEM) study

Objectives: To identify, characterize and compare the frequency of mild cognitive impairment (MCI) subtypes at baseline in a large, late-life cohort (n = 3063) recruited into a dementia prevention trial.

Method: A retrospective, data-algorithmic approach was used to classify participants as cognitively normal or MCI with corresponding subtype (e.g. amnestic vs. non-amnestic, single domain vs. multiple domain) based on a comprehensive battery of neuropsychological test scores, with and without Clinical Dementia Rating (CDR) global score included in the algorithm.

Results: Overall, 15.7% of cases (n = 480) were classified as MCI. Amnestic MCI was characterized as unilateral memory impairment (i.e. only verbal or only visual memory impaired) or bilateral memory impairment (i.e. both verbal and visual memory impaired). All forms of amnestic MCI were almost twice as frequent as non-amnestic MCI (10.0% vs. 5.7%). Removing the CDR = 0.5 (‘questionable dementia’) criterion resulted in a near doubling of the overall MCI frequency to 28.1%.

Conclusion: Combining CDR and cognitive test data to classify participants as MCI resulted in overall MCI and amnestic MCI frequencies consistent with other large community-based studies, most of which relied on the ‘gold standard’ of individual case review and diagnostic consensus. The present data-driven approach may prove to be an effective alternative for use in future large-scale dementia prevention trials.     

Detection of mild cognitive impairment in a community‐dwelling population using quantitative,multiparametric MRI‐based classification

Early and accurate mild cognitive impairment (MCI) detection within a heterogeneous, nonclinical population is needed to improve care for persons at risk of developing dementia. Magnetic resonance imaging (MRI)‐based classification may aid early diagnosis of MCI, but has only been applied within clinical cohorts. We aimed to determine the generalizability of MRI‐based classification probability scores to detect MCI on an individual basis within a general population. To determine classification probability scores, an AD, mild‐AD, and moderate‐AD detection model were created with anatomical and diffusion MRI measures calculated from a clinical Alzheimer's Disease (AD) cohort and subsequently applied to a population‐based cohort with 48 MCI and 617 normal aging subjects. Each model's ability to detect MCI was quantified using area under the receiver operating characteristic curve (AUC) and compared with an MCI detection model trained and applied to the population‐based cohort. The AD‐model and mild‐AD identified MCI from controls better than chance level (AUC = 0.600, p = 0.025; AUC = 0.619, p = 0.008). In contrast, the moderate‐AD‐model was not able to separate MCI from normal aging (AUC = 0.567, p = 0.147). The MCI‐model was able to separate MCI from controls better than chance (p = 0.014) with mean AUC values comparable with the AD‐model (AUC = 0.611, p = 1.0). Within our population‐based cohort, classification models detected MCI better than chance. Nevertheless, classification performance rates were moderate and may be insufficient to facilitate robust MRI‐based MCI detection on an individual basis. Our data indicate that multiparametric MRI‐based classification algorithms, that are effective in clinical cohorts, may not straightforwardly translate to applications in a general population.     

Quality of life in patients with mild cognitive impairment

Background: Quality of life (QoL) is affected in patients with dementia, but it is not clear whether it is already disturbed in more initial phases of cognitive decline, like Mild Cognitive Impairment (MCI).

Aim: Compare the QoL in MCI patients with controls without cognitive impairment, and ascertain whether there are differences in the reports of QoL made by the subjects and by their informants.

Methods: Two hundred participants were enrolled, divided into MCI patients (n?=?50), MCI informants (n?=?50), recruited from a memory clinic and a dementia outpatient clinic, and controls (n?=?50) and controls informants (n?=?50), recruited in a family practice clinic. QoL was assessed with the QoL in Alzheimer disease (QOL-AD) scale.

Results: The total scores of the QOL-AD questionnaire were 32.1?±?6.9 for MCI patients self-report, 27.2?±?6.7 for MCI patients in the opinion of their informants, 35.3?±?4.9 for controls self-report and 35.6?±?4.9 for controls in the opinion of their informants. MCI patients had lower QOL-AD scores than controls. The QoL reported by patients with MCI was more favorable than the opinion of their informants.

Conclusion: The QoL is affected at early stages of cognitive decline. The QoL reported by patients with MCI is better than the opinion of their informants, similarly to what is known in Alzheimer's disease patients. QoL appears to be an important domain to be evaluated in aging studies.     

Spontaneous oscillatory markers of cognitive status in two forms of dementia

Abnormal oscillatory brain activity in dementia may indicate incipient neuronal/synaptic dysfunction, rather than frank structural atrophy. Leveraging a potential link between the degree of abnormal oscillatory activity and cognitive symptom severity, one could localize brain regions in a diseased but pre‐atrophic state, which may be more amenable to interventions. In the current study, we evaluated the relationships among cognitive deficits, regional volumetric changes, and resting‐state magnetoencephalography abnormalities in patients with mild cognitive impairment (MCI; N = 10; age: 75.9 ± 7.3) or primary progressive aphasia (PPA; N = 12; 69.7 ± 8.0), and compared them to normal aging [young (N = 18; 24.6 ± 3.5), older controls (N = 24; 67.2 ± 9.7]. Whole‐brain source‐level resting‐state estimates of relative oscillatory power in the delta (1–4 Hz), theta (4–7 Hz), alpha (8–12 Hz), and beta (15–30 Hz) bands were combined with gray matter volumes and cognitive scores to examine between‐group differences and brain–behavior correlations. Language and executive function (EF) abilities were impaired in patients with PPA, while episodic memory was impaired in MCI. Widespread oscillatory speeding and volumetric shrinkage was associated with normal aging, whereas the trajectory in PPA indicated widespread oscillatory slowing with additional volumetric reductions. Increases in delta and decreases in alpha power uniquely predicted group membership to PPA. Beyond volumetric reductions, more delta predicted poorer memory. In patients with MCI, no consistent group difference among oscillatory measures was found. The contributions of delta/alpha power on memory abilities were larger than volumetric differences. Spontaneous oscillatory abnormalities in association with cognitive symptom severity can serve as a marker of neuronal dysfunction in dementia, providing targets for promising treatments.     

Boston Naming Test automatic credits inflate scores of nonaphasic mild dementia patients

Introduction: The Boston Naming Test (BNT), a 60-item test of confrontation naming, may be administered either from Item 1 or Item 30, depending on assumptions of performance. If the BNT is administered from Item 30, 29 automatic credits are given for preceding items, allowing identical norms for either administration. We aimed to compare effects of automatic credits. Method: We compared effects of automatic credits in the Gothenburg Mild Cognitive Impairment Study, first between normal controls (n = 23) and patients (n = 259), and then between the same patients grouped by stage of impairment: subjective cognitive impairment (SCI, n = 75), mild cognitive impairment (MCI, n = 117), or mild dementia (n = 67). Results: Automatic credits added to all groups. Both administrations from Item 1 and those from Item 30 discriminated between controls (n = 23) and all patients (n = 259), as well as between the above stages of impairment. However, neither administration discriminated between normal controls and SCI patients. When earned scores were compared, with scores counted from Item 30 plus 29 automatic credits, mild dementia patients on average received a 3.4-credit boost. This equals 82% of the standard deviation of Tallberg’s Swedish norms [Brain and Language, 94(1), 19–31 (2005)] or 117% of our normal controls’ standard deviation. Conclusions: In our homogenous material, administration of BNT from Item 30 distinguished between stages of deterioration as well as administration from Item 1. In line with recent literature, we also find BNT results skewed. Thus, for clinical accuracy, we recommend use of cumulative percentages, careful consideration of education and demographic factors, and, most importantly, never to mix forms of administrations with and without automatic credits. While BNT automatic credits diminish accuracy on all levels, they inflate scores significantly for nonaphasic mild dementia patients.     

Neuropsychological markers of mild cognitive impairment: A clinic based study from urban India

Background:

Mild cognitive impairment (MCI) is a transitional stage between normal aging and dementia. Persons with MCI are at higher risk to develop dementia. Identifying MCI from normal aging has become a priority area of research. Neuropsychological assessment could help to identify these high risk individuals.

Objective:

To examine clinical utility and diagnostic accuracy of neuropsychological measures in identifying MCI.

Materials and Methods:

This is a cross-sectional study of 42 participants (22 patients with MCI and 20 normal controls [NC]) between the age of 60 and 80 years. All participants were screened for dementia and later a detailed neuropsychological assessment was carried out.

Results:

Persons with MCI performed significantly poorer than NC on word list (immediate and delayed recall), story recall test, stick construction delayed recall, fluency and Go/No-Go test. Measures of episodic memory especially word list delayed recall had the highest discriminating power compared with measures of semantic memory and executive functioning.

Conclusion:

Word list learning with delayed recall component is a possible candidate for detecting MCI from normal aging.     

Repetition priming in mild cognitive impairment and mild dementia: Impact of educational attainment

Objective: To examine the role of education on repetition priming performances in healthy aging, mild cognitive impairment (MCI), and mild dementia.

Method: A total of 72 participants (healthy = 27, with MCI = 28, with mild dementia = 17) took part in the present study. Priming was assessed using the Word Stem Completion Test, and delayed and recognition memory was assessed using the Rey Auditory Verbal Learning Test. A multinomial regression analysis was used to examine whether years of education moderated priming and declarative memory performances in predicting group membership.

Results: Priming performances discriminated between individuals with MCI and mild dementia but not between MCI and healthy. Additionally, this effect was most salient in individuals with low levels of education. Education did not moderate explicit memory performances in predicting group membership.

Conclusion: Little is known about the impact of education on priming in verbal memory. Our findings indicate that formal years of education impact priming performances in MCI and individuals with mild dementia, which may have implications for designing interventions targeting “intact” cognitive abilities in these groups.     

Mild cognitive impairment: animal models

Mild cognitive impairment (MCI) is an aspect of cognitive aging that is considered to be a transitional state between normal aging and the dementia into which it may convert. Appropriate animal models are necessary in order to understand the pathogenic mechanisms of MCI and develop drugs for its treatment. In this review, we identify the features that should characterize an animal model of MCI, namely old age, subtle memory impairment, mild neuropathological changes, and changes in the cholinergic system, and the age at which these features can be detected in laboratory animals. These features should occur in aging animals with normal motor activity and feeding behavior. The animal models may be middle-aged rats and mice, rats with brain ischemia, transgenic mice overexpressing amyloid precursor protein and presenilin 1 (tested at an early stage), or aging monkeys. Memory deficits can be detected by selecting appropriately difficult behavioral tasks, and the deficits can be associated with neuropathological alterations. The reviewed literature demonstrates that, under certain conditions, these animal species can be considered to be MCI models, and that cognitive impairment in these models responds to drug treatment.     

Complex discourse production in mild cognitive impairment: Detecting subtle changes

Background: Mild cognitive impairment (MCI) is characterised by memory impairment that is greater than would be expected for an individual's age and educational background. Differentiating MCI from normal cognition in ageing is a compelling social, clinical, and scientific concern. Of those with MCI, 50% progress to Alzheimer's dementia within 5 years, while many individuals remain stable or return to normal functioning. Importantly, early identification of MCI has important implications for speech‐language pathology intervention.

Aims: The purpose of this study was to investigate whether performance on a complex elicited discourse production task differentiated individuals with MCI from those with normal cognition. The variables of interest were discourse length, complexity, and quality.

Methods & Procedures: Eight individuals with MCI and eight age‐ and gender‐matched controls were tested with the Mini‐Mental State Exam (MMSE), Logical Memory Subtest (LMS) of the Weschsler Memory Scale, and the Boston Naming Test (BNT). For the experimental task, each participant provided a complex, elicited discourse sample that was unconstrained in terms of discourse genre, in response to verbal instructions.

Outcomes & Results: The MMSE and LMS scores differentiated the groups in the expected direction, with the control group outperforming the MCI group. The groups performed comparably on the BNT. Performance on the experimental discourse production task distinguished the groups on measures of length and quality, but not in syntactic complexity.

Conclusions: These findings suggest that performance on a complex elicited discourse production task uncovers subtle differences in the abilities of individuals with MCI, such that measures of length and quality differentiated them from individuals with normal cognition.     

Clustering and switching during a semantic verbal fluency test contribute to differential diagnosis of cognitive impairment

The verbal fluency test (VFT) can be dissociated into "clustering" (generating words within subcategories) and "switching" (shifting between clusters), which may be valuable in differential diagnosis. In the current study, we investigated the validity of VFT in the differential diagnosis of Alzheimer’s disease (AD, n = 65), vascular dementia (VaD, n = 65), mild cognitive impairment (MCI, n = 92), and vascular cognitive impairment without dementia (VCIND, n = 76) relative to cognitively normal senior controls (NC, n = 374). We found that in the NC group, the total correct score was significantly correlated with age and education; males generated more subcategories; cluster size increased with education, and subcategory and switching decreased with age. A significantly progressive advantage was observed in VFT scores in the sequence NC > MCI/VCIND > AD/VaD, and this significantly discriminated dementia patients from the other groups. AD patients performed better in all four VFT scores than VaD patients. Subcategory and switching scores significantly distinguished AD from VaD patients (AD > VaD; mean difference, 0.50 for subcategory, P <0.05; 0.71 for switching, P <0.05). MCI patients scored higher than VCIND patients, but the difference did not reach statistical significance. These results suggest that semantic VFT is useful for the detection of MCI and VCIND, and in the differential diagnosis of cognitive impairment.