Dysexecutive functioning in mild cognitive impairment: derailment in temporal gradients

Libon et al. (2010) provided evidence for three statistically determined clusters of patients with mild cognitive impairment (MCI): amnesic (aMCI), dysexecutive (dMCI), and mixed (mxMCI). The current study further examined dysexecutive impairment in MCI using the framework of Fuster's (1997) derailed temporal gradients, that is, declining performance on executive tests over time or test epoch. Temporal gradients were operationally defined by calculating the slope of aggregate letter fluency output across 15-s epochs and accuracy indices for initial, middle, and latter triads from the Wechsler Memory Scale-Mental Control subtest (Boston Revision). For letter fluency, slope was steeper for dMCI compared to aMCI and NC groups. Between-group Mental Control analyses for triad 1 revealed worse dMCI performance than NC participants. On triad 2, dMCI scored lower than aMCI and NCs; on triad 3, mxMCI performed worse versus NCs. Within-group Mental Control analyses yielded equal performance across all triads for aMCI and NC participants. mxMCI scored lower on triad 1 compared to triads 2 and 3. dMCI participants also performed worse on triad 1 compared to triads 2 and 3, but scored higher on triad 3 versus triad 2. These data suggest impaired temporal gradients may provide a useful heuristic for understanding dysexecutive impairment in MCI.     

Mild cognitive impairment in a community sample: The Sydney Memory and Ageing Study

BackgroundMild cognitive impairment (MCI) is associated with an increased dementia risk. This study reports incidence of MCI subtypes, rates of progression to dementia, and stability of MCI classification.MethodsWe examined 873 community-dwelling adults aged 70 to 90 years over 2 years as part of an ongoing population-based longitudinal study, the Sydney Memory and Ageing Study. Neuropsychological testing assessed five cognitive domains, and a diagnosis of no cognitive impairment, MCI, or dementia (follow-up only) was made according to published criteria.ResultsThe incidence of MCI was 104.6 (95% confidence interval: 81.6–127.7) per 1000 person-years, with higher incidence in men (men, 156.8; women, 70.3). Incidence rates for single-domain amnestic, multiple-domain amnestic, single-domain nonamnestic, and multiple-domain nonamnestic MCI were 47.7, 7.9, 45.0, and 3.9 per 1000 person-years, respectively. The 2-year rate of progression from MCI at baseline to dementia was 4.8%, being highest for multidomain amnestic MCI (9.1%). Of those with MCI at baseline, 28.2% reverted to no cognitive impairment at follow-up. Sensitivity analyses by redefining criteria for cognitive impairment did not affect stability of diagnosis, although changing the threshold of domain impairment reduced baseline MCI prevalence from 36.7% to 5.7% and incidence to 23.5, and increased 2-year progression rate from MCI to dementia to 14.3%.ConclusionsIncidence rates for MCI are higher than previously reported, particularly in men and for single-domain MCI; rates for amnestic and nonamnestic MCI were comparable. Multidomain amnestic MCI was the most likely subtype to progress to dementia, but overall, the diagnosis of MCI, particularly single-domain MCI, shows considerable instability.     

Dynamic working memory performance in individuals with single-domain amnestic mild cognitive impairment

Previous studies have observed poorer working memory performance in individuals with amnestic mild cognitive impairment than in healthy older adults. It is unclear, however, whether these difficulties are true only of the multiple-domain clinical subtype in whom poorer executive functioning is common. The current study examined working memory, as measured by the self-ordered pointing task (SOPT) and an n-back task, in healthy older adults and adults with single-domain amnestic mild cognitive impairment (aMCI). Individuals with single-domain aMCI committed more errors and required longer to develop an organizational strategy on the SOPT. The single-domain aMCI group did not differ from healthy older adults on the 1-back or 2-back, but had poorer discrimination on the 3-back task. This is, to our knowledge, the first characterization of dynamic working memory performance in a single-domain aMCI group. These results lend support for the idea that clinical amnestic MCI subtypes may reflect different stages on a continuum of progression to dementia and question whether standardized measures of working memory (span tasks) are sensitive enough to capture subtle changes in performance.     

Association of diabetes with amnestic and nonamnestic mild cognitive impairment

BackgroundType 2 diabetes may increase the risk of amnestic mild cognitive impairment (aMCI) through Alzheimer's disease (AD)-related and vascular pathology and may also increase the risk of nonamnestic MCI (naMCI) through vascular disease mechanisms. We examined the association of type 2 diabetes with mild cognitive impairment (MCI) and MCI subtype (aMCI and naMCI) overall and by sex.MethodsParticipants were Olmsted County, Minnesota residents (70 years and older) enrolled in a prospective, population-based study. At baseline and every 15 months thereafter, participants were evaluated using the Clinical Dementia Rating scale, a neurological evaluation, and neuropsychological testing for a diagnosis of normal cognition, MCI, and dementia by a consensus panel. Type 2 diabetes was ascertained from the medical records of participants at baseline.ResultsOver a median 4.0 years of follow-up, 348 of 1450 subjects developed MCI. Type 2 diabetes was associated (hazard ratio [95% confidence interval]) with MCI (1.39 [1.08–1.79]), aMCI (1.58 [1.17–2.15]; multiple domain: 1.58 [1.01–2.47]; single domain: 1.49 [1.09–2.05]), and the hazard ratio for naMCI was elevated (1.37 [0.84–2.24]). Diabetes was strongly associated with multiple-domain aMCI in men (2.42 [1.31–4.48]) and an elevated risk of multiple domain naMCI in men (2.11 [0.70–6.33]), and with single domain naMCI in women (2.32 [1.04–5.20]).ConclusionsDiabetes was associated with an increased risk of MCI in elderly persons. The association of diabetes with MCI may vary with subtype, number of domains, and sex. Prevention and control of diabetes may reduce the risk of MCI and Alzheimer's disease.     

Verbal serial list learning in mild cognitive impairment: a profile analysis of interference, forgetting, and errors

Using cluster analysis Libon et al. (2010) found three verbal serial list-learning profiles involving delay memory test performance in patients with mild cognitive impairment (MCI). Amnesic MCI (aMCI) patients presented with low scores on delay free recall and recognition tests; mixed MCI (mxMCI) patients scored higher on recognition compared to delay free recall tests; and dysexecutive MCI (dMCI) patients generated relatively intact scores on both delay test conditions. The aim of the current research was to further characterize memory impairment in MCI by examining forgetting/savings, interference from a competing word list, intrusion errors/perseverations, intrusion word frequency, and recognition foils in these three statistically determined MCI groups compared to normal control (NC) participants. The aMCI patients exhibited little savings, generated more highly prototypic intrusion errors, and displayed indiscriminate responding to delayed recognition foils. The mxMCI patients exhibited higher saving scores, fewer and less prototypic intrusion errors, and selectively endorsed recognition foils from the interference list. dMCI patients also selectively endorsed recognition foils from the interference list but performed similarly compared to NC participants. These data suggest the existence of distinct memory impairments in MCI and caution against the routine use of a single memory test score to operationally define MCI.     

Progression to dementia in clinical subtypes of mild cognitive impairment

OBJECTIVE: To examine the outcome among patients diagnosed with different types of mild cognitive impairment (MCI). PATIENTS: A follow-up examination (average follow-up period: 3.49 +/- 2.2 years) was performed in 81 cognitively impaired, non-demented patients aged >55 years at baseline. RESULTS: 8 of 32 patients with amnestic MCI (25%), 22 of 41 patients with multiple-domain MCI (54%), and 3 of 8 patients with single non-memory MCI (37.5%) progressed to dementia. The clinical type of MCI is significantly associated with the likelihood of conversion to dementia. DISCUSSION: When the clinical syndrome of MCI evolves on a neurodegenerative basis, the multiple-domain type of MCI has a less favorable prognosis than the amnestic type and may represent a more advanced prodromal stage of dementia.     

Gray matter atrophy patterns of mild cognitive impairment subtypes

Mild cognitive impairment (MCI) is a heterogeneous neurocognitive disorder that can be classified into various subtypes. The present study aims to examine the gray matter (GM) atrophy patterns of MCI subtypes in comparison with a cognitively healthy group. Participants, including 135 MCI subjects and 120 cognitively healthy controls, were drawn from the Sydney Memory and Ageing Study. The MCI subjects were first categorized into amnestic (aMCI) and non-amnestic (naMCI) subtypes, which were then divided into single-domain (aMCI-SD and naMCI-SD) and multiple-domain subtypes (aMCI-MD and naMCI-MD). Furthermore, naMCI-SD was divided into three subgroups (language, processing speed, and executive function) according to individual cognitive impairment. Voxel-wise GM volumes were then compared between MCI subtypes and controls. The aMCI group had significantly lower GM volumes in the bilateral hippocampi and temporal cortices than the controls. This was mainly due to GM reduction of aMCI-MD but not aMCI-SD, as the latter did not show any significant GM reduction. GM reduction of naMCI and its two subdivisions was shown in widespread brain regions compared to controls. GM volumes of the multiple-domain subtypes (aMCI-MD and naMCI-MD) were lower than their single-domain counterparts (aMCI-SD and naMCI-SD) in the frontal and temporal lobes, respectively. Moreover, the language subgroup of naMCI-SD showed GM reduction in the frontal and temporal lobes compared to controls. MCI subtypes displayed specific patterns of GM atrophy that appear to be related to their various clinical presentations, which implies that underlying mechanisms of MCI subtypes are different.     

Predictors of independence in instrumental activities of daily living: Amnestic versus nonamnestic MCI

Introduction: Individuals with mild cognitive impairment (MCI) demonstrate deficits in instrumental activities of daily living (IADL) that place them at high risk for progression to dementia. The cognitive profiles, IADL deficits, and risk of progression differ between MCI subgroups of amnestic (aMCI) and nonamnestic MCI (naMCI), though many studies of functional impairment have not examined these subgroups separately. This study aims to determine whether common neuropsychological measures, as well as the related concept of patient anosognosia, are associated with IADL functioning differently in aMCI compared to naMCI. Method: Seventy-one individuals were identified as naMCI, and 99 individuals were identified as aMCI based on neuropsychological evaluation. Controlling for age, gender, and education, we examined whether performance on neuropsychological tests predicted informant-rated IADL dysfunction. We also investigated the ability of patient awareness, as rated by clinicians and informants, to predict informant-rated IADL dysfunction within MCI subgroups. Results: Better performance in cognitive domains of attention/processing speed and executive functioning predicted IADL independence in aMCI, but not in naMCI. Exploratory analysis with a subset of these individuals revealed that after accounting for an estimate of cerebrovascular burden, better performance in Delayed Memory predicted IADL independence in the naMCI group, but not in the aMCI group. Lastly, informant, but not clinician, ratings of patient awareness predicted IADL independence within the aMCI group only. Conclusion: Neuropsychological performance on tests of attention/processing speed and executive functioning may be better able to predict cognitive contributions to IADL dysfunction specifically in aMCI. After controlling for vascular burden, memory deficits may be the earliest cognitive indication of IADL dysfunction in naMCI. These results suggest that executive functions and memory, in addition to patient’s awareness of deficits, differentially predict early IADL dysfunction in subgroups of MCI and can be used to formulate patient prognosis and recommendations on a more individualized basis.     

The profile of executive functioning in amnestic mild cognitive impairment: disproportionate deficits in inhibitory control

Amnestic mild cognitive impairment (aMCI) represents a group of individuals who are highly likely to develop Alzheimer's disease (AD). Although aMCI is typically conceptualized as involving predominantly deficits in episodic memory, recent studies have demonstrated that deficits in executive functioning may also be present, and thorough categorization of cognitive functioning in MCI may improve early diagnosis and treatment of AD. We first provide an extensive review of neuropsychology studies that examined executive functioning in MCI. We then present data on executive functioning across multiple sub-domains (divided attention, working memory, inhibitory control, verbal fluency, and planning) in 40 aMCI patients (single or multiple domain) and 32 normal elderly controls (NECs). MCI patients performed significantly worse than NECs in all 5 sub-domains, and there was impairment (>1.0 SD below the mean of NECs) in all sub-domains. Impairment on each test was frequent, with 100% of MCI patients exhibiting a deficit in at least one sub-domain of executive functioning. Inhibitory control was the most frequently and severely impaired. These results indicate that executive dysfunction in multiple sub-domains is common in aMCI and highlights the importance of a comprehensive neuropsychological evaluation for fully characterizing the nature and extent of cognitive deficits in MCI.     

Predictive validity and diagnostic stability of mild cognitive impairment subtypes

BackgroundMild cognitive impairment (MCI) is subclassified into four subtypes by the presence of impairment in the memory domain (amnestic vs nonamnestic) and the number of impaired cognitive domains (single vs multiple). However, predictive validity for outcomes of these criteria and the diagnostic stability of the subtypes are questionable.MethodsWe investigated the outcomes of 140 patients with MCI who participated in the baseline study of the Korean Longitudinal Study on Health and Aging and completed the 18-month follow-up evaluation (mean duration of follow-up = 1.57 ± 0.24 years). We evaluated the predictive validity of the criteria using multinomial logistic regression analyses, and the diagnostic stability of MCI subtypes using annual conversion rates between subtypes.ResultsCompared with the single-domain type (MCIs), the multiple-domain type (MCIm) had a lower chance of reversion to normal cognition (MCIm = 10.94%, MCIs = 43.42%) and higher risk of conversion to dementia (MCIm = 23.44%, MCIs = 5.26%). The difference in the reversion rate between the multiple- and single-domain type was statistically significant (odds ratio = 0.233, 95% confidence interval = 0.070–0.771, P = .017). However, neither the chance of reversion nor the risk of conversion was different between amnestic and nonamnestic subtypes. Among the 81 participants who neither converted to dementia nor reverted to normal cognition, 39 converted to different subtype (annual conversion rate = 17.74%).ConclusionsThe number of impaired cognitive domains, but not the presence of memory impairment, predicted poor outcomes in people with MCI. However, MCI subtype was diagnostically unstable.     

Neuropsychological subtypes of incident mild cognitive impairment in the Mayo Clinic Study of Aging

IntroductionWe evaluated whether incident mild cognitive impairment (MCI) subtypes could be empirically derived in the Mayo Clinic Study of Aging.MethodsWe performed cluster analysis on neuropsychological data from 506 participants with incident MCI.ResultsThe 3-cluster solution resulted in (1) amnestic, (2) dysexecutive, (3) dysnomic subtypes. The 4-cluster solution produced these same three groups and a fourth group with subtle cognitive impairment (SCI). The SCI cluster was a subset of the amnestic cluster and distinct from well-matched cognitively unimpaired participants based on memory and global z-score area under the receiver operating characteristic curve analyses and probability of progression to MCI/dementia.DiscussionWe empirically identified three neuropsychological subtypes of MCI that share some features with MCI subtypes identified in the Alzheimer's Disease Neuroimaging Initiative. The fourth subtype with SCI in the Mayo Clinic Study of Aging differed from the fourth cluster-derived normal group in Alzheimer's Disease Neuroimaging Initiative and could represent a group to target with early interventions.     

Subtype of mild cognitive impairment and progression to dementia and death

BACKGROUND: Mild cognitive impairment (MCI) represents a common cognitive state between normal cognitive aging and dementia. There is limited information about the heterogeneity of MCI and how this heterogeneity may influence the clinical course of MCI. We determined the longitudinal course of subtypes of MCI and assessed the rate of progression to dementia and to death. METHODS: As part of the Alzheimer's Disease Research Centers of California, we studied 327 patients with MCI (250 with amnestic MCI, 34 with single nonmemory MCI, and 43 with multiple domain MCI) who were followed longitudinally. We determined if subtype of MCI was independently associated with time to dementia diagnosis and time to death using Cox proportional hazard models, and type of dementia using Fisher's exact test. RESULTS: Mean age of the patients with MCI was 72.9 +/- 9.3 years and mean Mini-Mental State Examination score was 25.7 +/- 4.3. After a mean follow-up of 3.1 years, 199 (65%) progressed to dementia and 80 (24%) died. After multivariate adjustment, compared to those with amnestic MCI, patients with single nonmemory or multiple subtype MCI were less likely to receive a diagnosis of dementia (HR = 0.60; 95% CI 0.35-1.05 and HR = 0.71; 95% CI 0.44-1.14) but more likely to die (HR = 2.57; 95% CI 1.13-5.84 and HR = 1.73; 95% CI 0.72-4.18), but these results were of borderline statistical significance. There were significant differences in the type of dementia diagnosed across MCI subtypes (p = 0.006). Among the patients who progressed to Alzheimer's disease, 76% had prior amnestic MCI; of the patients who progressed to vascular dementia, 50% had prior amnestic MCI; all patients who progressed to a frontal dementia syndrome had single nonmemory MCI previously. CONCLUSIONS: The majority of patients with MCI progressed to dementia and a significant proportion died. Subtype of MCI may influence rates of progression to death and to dementia and has a major influence on subsequent type of dementia diagnosis.     

Prevalence of mild cognitive impairment subtypes in patients attending a memory outpatient clinic—comparison of two modes of mild cognitive impairment classification. Results of the Vienna Conversion to Dementia Study

BackgroundEarly detection of dementia is becoming more and more important owing to the advent of pharmacologic treatment.ObjectiveThe goals of this study were to establish prevalence of mild cognitive impairment (MCI) subtypes in an outpatient memory clinic cohort using two different modes of MCI determination.DesignConsecutive patients complaining of cognitive problems who came to the memory outpatient clinic for assessment of a possible cognitive disorder were included in the study.SettingAcademic medical center.ParticipantsSix hundred eighty consecutive patients complaining about cognitive problems who came to the memory outpatient clinic for assessment of a possible cognitive disorder and fulfilled the inclusion criteria were included in the study. For 676 patients, sufficient data for MCI classification were available.ResultsCategorizing MCI patients into MCI subtypes according to the minimum mode of MCI classification revealed the following results: 106 patients (15.7%) were categorized as cognitively healthy, whereas 570 patients (84.3%) met the criteria for MCI. MCI patients were subtyped as amnestic mild cognitive impairment (aMCI) single domain (31 patients; 4.6%), aMCI multiple domain (226 patients; 33.4%), non-aMCI single domain (125 patients; 18.5%), and non-aMCI multiple domain (188 patients; 27.8%). Categorizing MCI patients into MCI subtypes according to the mean mode of MCI classification revealed the following results: 409 patients (60.5%) were categorized as cognitively healthy, whereas 267 patients (39.5%) met the criteria for MCI. MCI patients were subtyped as aMCI single domain (47 patients; 6.9%), aMCI multiple domain (57 patients; 8.5%), non-aMCI single domain (97 patients; 14.3%), and non-aMCI multiple domain (66 patients; 9.8%).ConclusionMCI diagnosis frequencies are substantially affected by the criteria used for estimation of MCI. The effect of modifying the presence of impairment on a single cognitive measure versus the presence of impairment on a mean composite score of a certain domain differed considerably, ranging from 39.5% to 84.3%, indicating the importance of the development of guidelines for operationalizing MCI.     

Mild cognitive impairment: disparity of incidence and prevalence estimates

BackgroundThe purpose of conducting this study was to identify areas of concordance and sources of variation for the published rates of prevalence and incidence associated with various definitions for mild cognitive impairment (MCI).MethodsThe study used systematic review of studies published in English since 1984. Studies were identified by searching MEDLINE and EMBASE databases. Population-based observational studies of incidence or prevalence of MCI and related terms were eligible for inclusion.ResultsA total of 3,705 citations were identified, and 42 were accepted for inclusion; 35 included data on prevalence and 13 on incidence. The following four terms predominated: age-associated memory impairment (AAMI); cognitive impairment no dementia (CIND); MCI; and amnestic MCI (aMCI). Within each term, the operational definition varied. Substantial variation was observed for both incidence (MCI: 21.5–71.3; aMCI: 8.5–25.9 per 1,000 person-years) and prevalence of each definition of cognitive impairment (AAMI 3.6%–38.4%; CIND 5.1%–35.9%; MCI 3%–42%; aMCI 0.5%–31.9%). CIND and MCI showed increasing prevalence among older age groups, whereas age-specific rates of aMCI were lower and without any apparent age relationship.ConclusionsPrevalence and incidence estimates associated with MCI vary greatly both between definitions and within a definition across the 42 publications. These wide differences pose a significant challenge to our understanding of the social burden of this disease. Enhancement and standardization of operational definitions of the subtypes of cognitive impairment could improve estimates of disease burden and provide a mechanism to assist in the identification of individuals at risk for future Alzheimer’s disease and other dementias.     

Magnetic resonance imaging: A biomarker for cognitive impairment in Parkinson's disease?

Dementia is a frequent and disabling complication of Parkinson's disease (PD). Clinicians and researchers lack a biomarker capable of tracking the structural and functional changes that underlie the evolution of cognitive dysfunction in PD. Magnetic resonance imaging (MRI) has been adopted as a biomarker in natural history and interventional studies of Alzheimer's disease (AD) and amnestic mild cognitive impairment (MCI), but its utility as a biomarker for PD and Parkinson's disease dementia (PDD) is unclear. In this review, the authors summarize the studies that have used MRI to investigate cognitive decline in PD, outline limitations of those studies, and suggest directions for future research. PD dementia is associated with extensive cortical atrophy, which may be quantified with structural MRI. More promisingly, patterns of atrophy may be present in those who have PD with MCI (PD‐MCI). Subcortical white matter tract degeneration is detectable early in the disease with diffusion tensor imaging and may precede changes observed on conventional structural MRI. Although less well studied, other MR techniques, such as functional MRI, MR perfusion imaging with arterial spin labeling, and MR spectroscopy, have demonstrated differences in activation and metabolism between PD and PDD. In this review, the ability to compare studies was limited by the heterogeneity of study populations, cognitive testing methods, and imaging protocols. Future work should adopt agreed scan protocols, should be adequately powered, and should use carefully phenotyped patients to fully maximize the contribution of MRI as a biomarker for PDD. © 2013 Movement Disorder Society     

Cognitive profiles in Alzheimer's disease and in mild cognitive impairment of different etiologies

There has been increasing interest in determining whether amnestic, nonamnestic and multiple-domain subtypes of mild cognitive impairment (MCI) reflect different disease etiologies. In this study, we examined the extent to which cognitive profiles of nondemented patients with MCI diagnosed with prodromal Alzheimer's disease (AD) differed from those MCI patients diagnosed with vascular disease. We also compared these diagnostic groups to mildly demented patients diagnosed with AD and normal elderly controls. Results indicate that a majority of both MCI-AD and MCI-vascular patients experienced amnestic features and that multiple-domain was the most common presentation. MCI-AD and MCI-vascular groups did not differ on neuropsychological measures tapping memory, language, visuospatial skills/praxis or executive function. Further both MCI groups could be distinguished from dementia patients with regards to performance on measures of memory but not on non-memory measures. Considerable variability was observed in the degree of memory impairment among MCI patients with scores as much as 6 standard deviations below expected mean values. MCI-AD and MCI-vascular patients frequently exhibit both common and overlapping amnestic and nonamnestic features. The implication of these findings for future clinical research is discussed.     

Crise suicidaire et maladie d’Alzheimer débutante : intérêt d’une analyse neuropsychologique détaillée

IntroductionThe role of Alzheimer's disease as a risk factor for suicide is unclear. The aim of this study was to understand neuropsychological component of the suicidal crisis in Alzheimer's disease.MethodUsing an extensive neuropsychological battery, different aspects of cognitive inhibition were particularly examined: Access to relevant information (using the Reading with distraction task), suppression of no longer relevant information (Trail Making Test, Rule Shift Cards), and restraint of cognitive resources to relevant information (Stroop test, Hayling Sentence Completion test, Go/No-Go). One female Alzheimer depressed case was assessed before and after a suicide attempt.ResultsTen days after the patient's suicide attempt, dementia was still moderate with a MMSE score at 21/30 but with a worsening of executive functions (FAB at 8/18) in the context of depression and suicide. The Hamilton-Depression Rating Scale was at 24 (maximal score at 52), and the Cornell Scale for Depression was at 21 (maximal score at 38). Suicidal intent was moderate with a score of 9 on the Beck Suicide Intent Scale (maximal score at 25). The patient did not present a delirium, psychotic symptoms, or anosognosia. Her episodic memory was altered as shown by her semantic performance on verbal fluency (naming 12 animals in 120 seconds) and on lexical fluency (naming 8 words beginning with the letter P). Initially preserved, executive function declined during a suicidal crisis in a context of depression in Alzheimer's disease case. Neuropsychological testing confirmed a dysexecutive syndrome (FAS at 8/18), with an impairment in her conceptualization capacity (MCST) and a deficit in cognitive inhibition and its access (reading task in the presence of distractors), deletion (TMT) and restraint (Stroop, Go/No-Go, Hayling) functions. Computed tomography has shown no signs of intracranial expansive process.ConclusionAssessing predictors of suicide and means of completion in patients with dementia may help the development of interventions to reduce risk of suicide among the growing population of individuals with dementia. Because of Alzheimer's-related cognitive inhibition impairment, identification and intervention addressing the complex issues of depression, executive dysfunction and dementia may help clinicians to mitigate the risk of suicide in patients with Alzheimer's disease.     

Deficits in facial emotion processing in mild cognitive impairment

BACKGROUND: Patients with Alzheimer disease consistently demonstrate impaired performance on tests of facial emotion processing. However, it remains unclear how early in the neurodegenerative process these deficits emerge. METHODS: We approached this question by examining facial emotional processing in a 'pre-dementia' condition, amnestic mild cognitive impairment (MCI). Nine single-domain amnestic MCI subjects, 14 multiple-domain amnestic MCI subjects (MCI-MD), and 68 normal control subjects were assessed with the Florida Affect Battery. RESULTS: After adjustment for age and gender, analyses of performance across the facial affect processing subtests of the Florida Affect Battery demonstrated intact performance in the single-domain MCI group but significantly impaired performance in the MCI-MD group, particularly on a test of facial affect discrimination. Within the MCI-MD group, men performed disproportionately worse than women. Performance on facial affect discriminations in the MCI-MD group correlated most robustly with performance on tests of frontal/executive function. CONCLUSION: These data suggest that facial emotion processing can be impaired in MCI prior to the more marked cognitive deficits seen with clinically diagnosed Alzheimer disease.     

Olfactory screening test in mild cognitive impairment

Abstract Mild cognitive impairment (MCI) is a transient status between physiologic ageing and dementia. Each year more than 12% of subjects with MCI develop Alzheimer’s disease. This study evaluated the presence of an olfactory deficit in amnesic MCI (aMCI) patients. Twenty–nine patients diagnosed with aMCI and a homogeneous control group of 29 subjects were enrolled in the study. Olfactory function was assessed by the Sniffin’ Sticks Screening Test (SSST) and the Mini Mental State Examination, the Clinical Dementia Rating, the Geriatric Depression Scale and the Mental Deterioration Battery were used to evaluate the neurocognitive status. aMCI patients showed a significant impairment of their olfactory identification compared to controls (SSST score: 8.3±2.1 vs. 10.8±0.9; p<0.001). These results suggest that olfactory tests should be part of the diagnostic armamentarium of pre–clinical dementia. A long–term follow up might confirm the olfactory identification function as an early and reliable marker in the diagnosis of pre–clinical dementia.     

Can a novel computerized cognitive screening test provide additional information for early detection of Alzheimer's disease?

BackgroundVirtual reality testing of everyday activities is a novel type of computerized assessment that measures cognitive, executive, and motor performance as a screening tool for early dementia. This study used a virtual reality day-out task (VR-DOT) environment to evaluate its predictive value in patients with mild cognitive impairment (MCI).MethodsOne hundred thirty-four patients with MCI were selected and compared with 75 healthy control subjects. Participants received an initial assessment that included VR-DOT, a neuropsychological evaluation, magnetic resonance imaging (MRI) scan, and event-related potentials (ERPs). After 12 months, participants were assessed again with MRI, ERP, VR-DOT, and neuropsychological tests.ResultsAt the end of the study, we differentiated two subgroups of patients with MCI according to their clinical evolution from baseline to follow-up: 56 MCI progressors and 78 MCI nonprogressors. VR-DOT performance profiles correlated strongly with existing predictive biomarkers, especially the ERP and MRI biomarkers of cortical thickness.ConclusionsCompared with ERP, MRI, or neuropsychological tests alone, the VR-DOT could provide additional predictive information in a low-cost, computerized, and noninvasive way.