Mild cognitive impairment: a concept in evolution

Polymorphic variation in CHAT gene modulates general cognitive ability: An association study with random student cohort

The choline O-acetyltransferase (CHAT) gene has been associated with various human disorders that involve cognitive impairment or deficiency. However, the influence of disease-associated variants of CHAT on normal individuals remains dubious. Here we demonstrated the impact of CHAT sequence variants (G-120A) on general human cognitive ability in a cohort of 750 Chinese undergraduate students. A multiple choice questionnaire was used to obtain basic demographic information, such as parents' occupations and education levels. We also administered and scored the Raven's Standard Progressive Matrices (RSPM). A one-way analysis of variance (ANOVA) and Kruskal-Wallis test (K-W) revealed a significant association between sequence polymorphisms of G-120A and individuals' Raven score (p=0.031 for ANOVA and p=0.026 for K-W tests). Moreover, further hierarchical analysis showed a similar trend in the association between G-120A variants and Raven scores only in the female subjects (p=0.008 for ANOVA and p=0.024 for K-W tests) but not in the male subjects. The results of a multiple linear regression confirmed that after we controlled gender, age, birthplace and other non-genetic factors, CHAT G-120A polymorphisms still significantly influenced individual Raven scores (B=-0.70, SE=0.28, t=-2.50, p=0.013). Our results demonstrated that sequence variants of CHAT were associated with human cognitive ability in not only patients with psychiatric disorders but also normal healthy individuals. However, some issues remained indeterminable, such as gender differences and the extent of the influence on individuals' general cognitive abilities; thus, the further research using an independent random sample was required.

Independent and Interactive Influences of the APOE Genotype and Beta-Amyloid Burden on Cognitive Function in Mild Cognitive Impairment

This study aimed to investigate the independent and interactive influences of apolipoprotein E (APOE) ε4 and beta-amyloid (Aβ) on multiple cognitive domains in a large group of cognitively normal (CN) individuals and patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Participants were included if clinical and cognitive assessments, amyloid imaging, and APOE genotype were all available from the Alzheimer's Disease Neuroimaging Initiative database (CN = 324, MCI = 502, AD = 182). Individuals with one or two copies of ε4 were designated as APOE ε4 carriers (ε4+); individuals with no ε4 were designated as APOE ε4 non-carriers (ε4-). Based on mean florbetapir standard uptake value ratios, participants were classified as Aβ burden-positive (Aβ+) or Aβ burden-negative (Aβ-). In MCI, APOE ε4 effects were predominantly observed on frontal executive function, with ε4+ participants exhibiting poorer performances; Aβ positivity had no influence on this effect. Aβ effects were observed on global cognition, memory, and visuospatial ability, with Aβ+ participants exhibiting poorer performances. Measures of frontal executive function were not influenced by Aβ. Interactive effects of APOE ε4+ and Aβ were observed on global cognition and verbal recognition memory. Aβ, not APOE ε4+, influenced clinical severity and functional status. The influences of APOE ε4+ and Aβ on cognitive function were minimal in CN and AD. In conclusion, we provide further evidence of both independent and interactive influences of APOE ε4+ and Aβ on cognitive function in MCI, with APOE ε4+ and Aβ showing dissociable effects on executive and non-executive functions, respectively.

Cerebrospinal fluid inflammatory markers in amnestic mild cognitive impairment

AIMS

Inflammatory processes might play a significant role at the pathophysiology of Alzheimer's disease (AD). Neuroinflammation is characterized by activation of microglia and the release of inflammatory cytokines, such as interleukin (IL)-1β, IL-6 and tumor necrosis factor-α. Although, it is unknown what the real contribution of these inflammatory markers in the development of AD is. The purpose of the present study was to assess the possible relationship between inflammatory markers in the cerebrospinal fluid (CSF) of amnestic mild cognitive impairment patients (aMCI), aged 60 years or older, and compare with aged healthy controls.

METHODS

We examined concentrations of IL-1β, IL-6 and tumor necrosis factor-α in the CSF of aMCI patients and controls by enzyme immunoassay. aMCI diagnoses were based on anamnesis and Petersen criteria, corroborated by the Clinical Dementia Rating. Cognitive function was assessed by neuropsychological tests.

RESULTS

CSF levels of IL-1β (13.735 vs 22.932 pg/mL; P < 0.001) and tumor necrosis factor-α (1.913 vs 2.627 pg/mL; P = 0.002), but not IL-6 (4.178 vs 5.689 pg/mL; P = 0.106), were significantly reduced in the aMCI samples as compared with controls. Individuals with IL-1β < 17 pg/mL were at a 7.2 (CI 1.5-36; P: 0.016) increased odds of aMCI. There was a positive correlation between IL-1β levels and the Consortium to Establish a Registry for Alzheimer's Disease word list score (r_s  = 0.299; P = 0.046). Linear regression analysis showed that IL-1β levels might explain 13.7% (β = 24.545; P = 0.012) of the variance on this Consortium to Establish a Registry for Alzheimer's Disease subscore.

CONCLUSION

The present results show a pattern of cytokines expression in the CSF of aMCI patients that might be relevant to the pathogeny of prodromal AD. Geriatr Gerontol Int 2017; 17: 239-245.

Hippocampal Subfield Atrophy in Multi-Domain but Not Amnestic Mild Cognitive Impairment

BACKGROUND/AIMS

To investigate differences in hippocampal (HP) subfields and the adjoining perirhinal and entorhinal cortices (PRC and ERC) between amnestic mild cognitive impairment (aMCI) and multi-domain amnestic MCI (mdMCI) patients, and controls.

METHODS

Nineteen patients characterized as aMCI were compared with 24 mdMCI patients and 31 controls by means of an automatic HP segmentation procedure.

RESULTS

We found significant atrophy of the PRC and ERC in aMCI relative to controls, whereas a more pronounced pattern of atrophy in most subfields, including total HP volume, was found in the mdMCI group. The mdMCI group also had a significant cornu ammonis sector 4 region with dentate gyrus, subiculum and total HP atrophy relative to aMCI.

CONCLUSION

The aMCI group showed atrophy in the PRC and ERC, whereas significantly more affection of the HP subfields was evident in mdMCI. The mdMCI group may thus represent clinical progression relative to aMCI coupled with HP subfield affection.

Neurophysiological correlates in Mild Cognitive Impairment detected using group Independent Component Analysis

Alzheimer's disease is the most prevalent cause of dementia. Mild Cognitive Impairment (MCI) is defined as a grey area between intact cognitive functioning and clinical dementia. Electroencephalography (EEG) has been used to identify biomarkers in dementia. Currently, there is a great interest in translating the study from raw signals to signal generators, trying to keep the relationship with neurophysiology. In the current study, EEG recordings during an encoding task were acquired in MCI subjects and healthy controls. Data was decomposed using group Independent Component Analysis (gICA) and the most neuronal components were analyzed using Phase Intertrial Coherence (PIC) and Phase shift Intertrial Coherence (PsIC). MCI subjects exhibited an increase of PIC in the theta band, while controls showed increase in PsIC in the alpha band. Correlation between PIC and PsIC and clinical scales were also found. Those findings indicate that the methodology proposed based in gICA can help to extract information from EEG recordings with neurophysiological meaning.

Interaction of erythrocyte eicosapentaenoic acid and physical activity predicts reduced risk of mild cognitive impairment

OBJECTIVES

To evaluate relationships between self-reported physical activity, proportions of long-chain omega-3 polyunsaturated fatty acids (LCn3) in erythrocyte content (percentage of total fatty acids) and risk of mild cognitive impairment (MCI) in older adults.

METHOD

A cross-sectional study was conducted. Community-dwelling male and female (n = 84) participants over the age of 65 years with and without MCI were tested for erythrocyte proportions of the LCn3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Physical activity was measured using a validated questionnaire.

RESULTS

The interaction between erythrocyte EPA, but not DHA, and increased physical activity was associated with increased odds of a non-MCI classification.

CONCLUSION

An interaction between physical activity and erythrocyte EPA content (percentage of fatty acids) significantly predicted MCI status in older adults. Randomised control trials are needed to examine the potential for supplementation with EPA in combination with increased physical activity to mitigate the risk of MCI in ageing adults.

Association of the C47T Polymorphism in SOD2 with Amnestic Mild Cognitive Impairment and Alzheimer's Disease in Carriers of the APOEε4 Allele

Oxidative stress plays an important part in amnestic mild cognitive impairment (aMCI), the prodromal phase of Alzheimer's disease (AD). Recent evidence shows that polymorphisms in the SOD2 gene affect the elimination of the reactive oxygen species (ROS) generated in mitochondria. The aim of this study was to determine whether the functional rs4880 SNP in the SOD2 gene is a risk factor associated with aMCI and sporadic AD. 216 subjects with aMCI, 355 with AD, and 245 controls have been studied. The SNP rs4880 of the SOD2 gene was genotyped by RT-PCR and the APOE genotype was determined by PCR and RFLPs. Different multinomial logistic regression models were used to determine the risk levels for aMCI and AD. Although the T allele of the SOD2 rs4880 SNP gene (rs4880-T) is not an independent risk for aMCI or AD, this allele increases the risk to aMCI patients carrying at least one APOEε4 allele. Moreover, rs4880-T allele and APOEε4 allele combination has been found to produce an increased risk for AD compared to aMCI reference patients. These results suggest that APOEε4 and rs4880-T genotype may be a risk for aMCI and a predictor of progression from aMCI to AD.

Impact of Nutrition on Cerebral Circulation and Cognition in the Metabolic Syndrome

The increasing prevalence of Metabolic Syndrome (MetS), defined as the clustering of abdominal obesity, dyslipidemia, hypertension, and hyperglycemia, appears to be driving the global epidemics cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). Nutrition has a major impact on MetS and plays an important role in the prevention, development, and treatment of its features. Structural and functional alterations in the vasculature, associated with MetS, might form the link between MetS and the increased risk of developing CVD and T2DM. Not only does the peripheral vasculature seem to be affected, but the syndrome has a profound impact on the cerebral circulation and thence brain structure as well. Furthermore, strong associations are shown with stroke, cognitive impairment, and dementia. In this review the impact of nutrition on the individual components of MetS, the effects of MetS on peripheral and cerebral vasculature, and its consequences for brain structure and function will be discussed.

The Prevalence of Mild Cognitive Impairment in Diverse Geographical and Ethnocultural Regions: The COSMIC Collaboration

Background

Changes in criteria and differences in populations studied and methodology have produced a wide range of prevalence estimates for mild cognitive impairment (MCI).

Methods

Uniform criteria were applied to harmonized data from 11 studies from USA, Europe, Asia and Australia, and MCI prevalence estimates determined using three separate definitions of cognitive impairment.

Results

The published range of MCI prevalence estimates was 5.0%–36.7%. This was reduced with all cognitive impairment definitions: performance in the bottom 6.681% (3.2%–10.8%); Clinical Dementia Rating of 0.5 (1.8%–14.9%); Mini-Mental State Examination score of 24–27 (2.1%–20.7%). Prevalences using the first definition were 5.9% overall, and increased with age (P < .001) but were unaffected by sex or the main races/ethnicities investigated (Whites and Chinese). Not completing high school increased the likelihood of MCI (P ≤ .01).

Conclusion

Applying uniform criteria to harmonized data greatly reduced the variation in MCI prevalence internationally.

Predicting conversion to dementia in a memory clinic: A standard clinical approach compared with an empirically defined clustering method (latent profile analysis) for mild cognitive impairment subtyping

Introduction

Mild cognitive impairment (MCI) has clinical value in its ability to predict later dementia. A better understanding of cognitive profiles can further help delineate who is most at risk of conversion to dementia. We aimed to (1) examine to what extent the usual MCI subtyping using core criteria corresponds to empirically defined clusters of patients (latent profile analysis [LPA] of continuous neuropsychological data) and (2) compare the two methods of subtyping memory clinic participants in their prediction of conversion to dementia.

Methods

Memory clinic participants (MCI, n = 139) and age-matched controls (n = 98) were recruited. Participants had a full cognitive assessment, and results were grouped (1) according to traditional MCI subtypes and (2) using LPA. MCI participants were followed over approximately 2 years after their initial assessment to monitor for conversion to dementia.

Results

Groups were well matched for age and education. Controls performed significantly better than MCI participants on all cognitive measures. With the traditional analysis, most MCI participants were in the amnestic multidomain subgroup (46.8%) and this group was most at risk of conversion to dementia (63%). From the LPA, a three-profile solution fit the data best. Profile 3 was the largest group (40.3%), the most cognitively impaired, and most at risk of conversion to dementia (68% of the group).

Discussion

LPA provides a useful adjunct in delineating MCI participants most at risk of conversion to dementia and adds confidence to standard categories of clinical inference.

Mild cognitive decline. A position statement of the Cognitive Decline Group of the European Innovation Partnership for Active and Healthy Ageing (EIPAHA)

INTRODUCTION

Mild cognitive impairment (MCI) is a term used to describe a level of decline in cognition which is seen as an intermediate stage between normal ageing and dementia, and which many consider to be a prodromal stage of neurodegeneration that may become dementia. That is, it is perceived as a high risk level of cognitive change. The increasing burden of dementia in our society, but also our increasing understanding of its risk factors and potential interventions, require diligent management of MCI in order to find strategies that produce effective prevention of dementia.

AIM

To update knowledge regarding mild cognitive impairment, and to bring together and appraise evidence about the main features of clinical interest: definitions, prevalence and stability, risk factors, screening, and management and intervention.

METHODS

Literature review and consensus of expert opinion.

RESULTS AND CONCLUSION

MCI describes a level of impairment in which deteriorating cognitive functions still allow for reasonable independent living, including some compensatory strategies. While there is evidence for some early risk factors, there is still a need to more precisely delineate and distinguish early manifestations of frank dementia from cognitive impairment that is less likely to progress to dementia, and furthermore to develop improved prospective evidence for positive response to intervention. An important limitation derives from the scarcity of studies that take MCI as an endpoint. Strategies for effective management suffer from the same limitation, since most studies have focused on dementia. Behavioural changes may represent the most cost-effective approach.

Learning Classification Models of Cognitive Conditions from Subtle Behaviors in the Digital Clock Drawing Test

The Clock Drawing Test - a simple pencil and paper test - has been used for more than 50 years as a screening tool to differentiate normal individuals from those with cognitive impairment, and has proven useful in helping to diagnose cognitive dysfunction associated with neurological disorders such as Alzheimer's disease, Parkinson's disease, and other dementias and conditions. We have been administering the test using a digitizing ballpoint pen that reports its position with considerable spatial and temporal precision, making available far more detailed data about the subject's performance. Using pen stroke data from these drawings categorized by our software, we designed and computed a large collection of features, then explored the tradeoffs in performance and interpretability in classifiers built using a number of different subsets of these features and a variety of different machine learning techniques. We used traditional machine learning methods to build prediction models that achieve high accuracy. We operationalized widely used manual scoring systems so that we could use them as benchmarks for our models. We worked with clinicians to define guidelines for model interpretability, and constructed sparse linear models and rule lists designed to be as easy to use as scoring systems currently used by clinicians, but more accurate. While our models will require additional testing for validation, they offer the possibility of substantial improvement in detecting cognitive impairment earlier than currently possible, a development with considerable potential impact in practice.

Spectrum of cognition short of dementia: Framingham Heart Study and Mayo Clinic Study of Aging

OBJECTIVE

To understand the neuropsychological basis of dementia risk among persons in the spectrum including cognitive normality and mild cognitive impairment.

METHODS

We quantitated risk of progression to dementia in elderly persons without dementia from 2 population-based studies, the Framingham Heart Study (FHS) and Mayo Clinic Study of Aging (MCSA), aged 70 to 89 years at enrollment. Baseline cognitive status was defined by performance in 4 domains derived from batteries of neuropsychological tests (that were similar but not identical for FHS and MCSA) at cut scores corresponding to SDs of ≤-0.5, -1, -1.5, and -2 from normative means. Participants were characterized as having no cognitive impairment (reference group), or single or multiple amnestic or nonamnestic profiles at each cut score. Incident dementia over the following 6 years was determined by consensus committee at each study separately.

RESULTS

The pattern of hazard ratios for incident dementia, rates of incident dementia and positive predictive values across cognitive test cut scores, and number of affected domains was similar although not identical across the FHS and MCSA. Dementia risks were higher for amnestic profiles than for nonamnestic profiles, and for multidomain compared with single-domain profiles.

CONCLUSIONS

Cognitive domain subtypes, defined by neuropsychologically derived cut scores and number of low-performing domains, differ substantially in prognosis in a conceptually logical manner that was consistent between FHS and MCSA. Neuropsychological characterization of elderly persons without dementia provides valuable information about prognosis. The heterogeneity of risk of dementia cannot be captured concisely with one test or a single definition or cutpoint.

Mild Neurocognitive Disorder: An Old Wine in a New Bottle

The American Psychiatric Association has recently published the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The DSM-IV category "Dementia, Delirium, Amnestic, and Other Cognitive Disorders" has undergone extensive revision. DSM-5 has renamed this category as "Neurocognitive Disorders" (NCD), which now covers three entities: delirium, major NCD, and mild NCD. The DSM-IV version of mild NCD resembles the DSM-5 version in name only. DSM-IV defined mild NCD based on a single criterion, whereas DSM-5 defines mild NCD by using several cognitive and related criteria. The main difference between mild NCD and the Key International Symposium criteria of mild cognitive impairment (MCI) is that the research work that led to the construct of MCI primarily involved elderly study participants (even though age was not part of the definition of MCI), whereas mild NCD includes acquired cognitive disorders of all age groups. DSM-5 essentially discusses the epidemiology and diagnostic markers of mild NCD by drawing congruence between MCI and mild NCD. The DSM-5 definition of mild NCD is anchored on four criteria and two specifiers. The four criteria refer to cognitive changes, functional activities, and exclusion of delirium and competing mental disorders. The two specifiers are the presumed etiologies of mild NCD and the presence or absence of behavioral problems. While the category "mild NCD" may improve reliability of diagnoses, it has yet to withstand scientific scrutiny to be considered a valid construct. This article reviews the DSM-5 criteria for mild NCD, compares them with the Key International Symposium MCI criteria, and discusses the pros and cons of the mild NCD construct.

Discriminative power of the advanced activities of daily living (a-ADL) tool in the diagnosis of mild cognitive impairment in an older population

BACKGROUND

Mild cognitive impairment (MCI) is characterized by subjective and objective memory impairments in the absence of manifest functional decline. Mild changes in activities of daily living (ADL) can be present and probably predict conversion to dementia. A new advanced (a)-ADL tool was developed, evaluating high-level activities and, taking each participant as their own reference, distinguishing a global Disability Index (a-ADL-DI), a Cognitive Disability Index (a-ADL-CDI), and a Physical Disability Index (a-ADL-PDI), based on the number of activities performed and the severity and causes of the functional problem. This study evaluates the discriminative validity of the a-ADL in MCI.

METHOD

Based upon clinical evaluation and a set of global, cognitive, mood, and functional assessments, 150 community-dwelling participants (average age 80.3 years (SD 5; 66-91)) were included and diagnosed as (1) cognitively healthy participants (n = 50); (2) patients with a-MCI (n = 48), or (3) mild to moderate AD (n = 52). The a-ADL tool was not a part of the clinical evaluation.

RESULTS

The a-ADL-DI and the a-ADL-CDI showed a sensitivity and specificity ranging from 70% to 94.2%, Positive Predictive Value ranging from 70% till 93.8%, and Negative Predictive Value from 64.4% and 93.8%, an area under the curve (AUC) ranging from 0.791 to 0.960. Functional decline related to physical deficits, as assessed by the a-ADL-PDI, did not discriminate between the different groups.

CONCLUSION

The a-ADL tool has a good ability to distinguish normal and pathological cognitive aging. Its discriminative power for underlying causes of limitations may be an advantage.

Dutch family physicians' awareness of cognitive impairment among the elderly

BACKGROUND

Dementia is often not formally diagnosed in primary care. To what extent this is due to family physicians' (FPs) watchful waiting, reluctance to diagnose or to their unawareness of the presence of cognitive impairment is unclear. The objective of this study was to assess FPs' awareness of cognitive impairment by comparing their evaluation of the absence or presence of cognitive impairment in older patients without an established diagnosis of dementia, with a reference test of cognitive functioning. In addition, we assessed which patient characteristics were associated with con- and discordance between FPs' evaluation of cognition and results of the reference test.

METHODS

The design was a nested diagnostic study. FPs (n = 29) of 15 primary care practices classified the cognitive status of all their patients ≥ 65 years of age (n = 7865) into four categories, based on recollection and medical records. All patients categorized as 'possible cognitive impairment or dementia' and a sample of patients categorized as 'no signs of cognitive impairment' randomly selected to match age and gender were offered to receive a reference test of cognitive function (the CAMCOG) to verify the FPs' label. This reference test could yield three outcomes: no cognitive impairment, amnestic mild cognitive impairment (aMCI) or dementia. Reference test results were weighted back to the original samples to provide estimates for the correct categorization of elderly as 'possible cognitive impairment or dementia' (positive predictive value [PPV]) and 'no signs of cognitive impairment' (negative predictive value [NPV]). Cognitive functioning was not assessed for patients evaluated by FPs as 'probable dementia' and 'unknown or no recent contact'. Characteristics associated with the con- or discordance of the FPs' classification and the reference test were assessed using logistic regression.

RESULTS

Complete reference test results were obtained from 318 elderly. FPs labeled 8.3 % of elderly 'possible cognitive impairment or dementia'. The PPV of this label for a CAMCOG score suggestive of dementia or aMCI was 47.1 % (95 %-confidence interval: 43.5 - 62.4 %). FPs labeled 83.7 % 'no signs of cognitive impairment'. The 1-NPV of this label for a CAMCOG score suggestive of dementia or aMCI was 12.5 % (95 %-CI 8.2 - 16.8 %). FPs labeled 3.6 % as 'probable dementia' and 4.5 % as 'unknown or no recent contact'. The odds that FPs' suspicion of cognitive impairment were confirmed by the CAMCOG were higher if persons were ADL dependent (OR 2.24 [95 %-CI 1.16 - 4.35]). The odds of FPs being unaware of the presence of cognitive impairment were higher in the older elderly (OR 1.15 [95 %-CI 1.09 - 1.23] per year).

CONCLUSION

Evaluation of FPs' classification of the global cognitive function of elderly without a firm diagnosis of dementia showed both over- and unawareness of the presence of cognitive impairment. FPs were more often unaware of cognitive impairment in the older elderly.

Altered Functional Connectivity of Fusiform Gyrus in Subjects with Amnestic Mild Cognitive Impairment: A Resting-State fMRI Study

Visual cognition such as face recognition requests a high degree of functional integration between distributed brain areas of a network. It has been reported that the fusiform gyrus (FG) is an important brain area involved in facial cognition; altered connectivity of FG to some other regions may lead to a deficit in visual cognition especially face recognition. However, whether functional connectivity between the FG and other brain areas changes remains unclear in the resting state in amnestic mild cognitive impairment (aMCI) subjects. Here, we employed a resting-state functional MRI (fMRI) to examine alterations in functional connectivity of left/right FG comparing aMCI patients with age-matched control subjects. Forty-eight aMCI and 38 control subjects from the Alzheimer’s disease Neuroimaging Initiative were analyzed. We concentrated on the correlation between low frequency fMRI time courses in the FG and those in all other brain regions. Relative to the control group, we found some discrepant regions in the aMCI group which presented increased or decreased connectivity with the left/right FG including the left precuneus, left lingual gyrus, right thalamus, supramarginal gyrus, left supplementary motor area, left inferior temporal gyrus, and left parahippocampus. More importantly, we also obtained that both left and right FG have increased functional connections with the left middle occipital gyrus (MOG) and right anterior cingulate gyrus (ACC) in aMCI patients. That was not a coincidence and might imply that the MOG and ACC also play a critical role in visual cognition, especially face recognition. These findings in a large part supported our hypothesis and provided a new insight in understanding the important subtype of MCI.

Treatment of Mild Cognitive Impairment

OPINION STATEMENT

It is increasingly evident that early identification of cognitive impairment in older adults presents opportunities for interventions that aim to mitigate the impact of cognitive symptoms on daily function and that attempt to delay (or ultimately prevent) progression from mild cognitive impairment (MCI) to dementia. To date, no intervention has proven protective in ultimately preventing conversion to dementia. However, several lifestyle, dietary, and pharmacologic interventions have suggested symptomatic benefit for those having MCI. A number of diet and lifestyle recommendations have been associated with decreased risk of dementia both in cognitively intact older adults and in those having mild cognitive impairment. Thus, these recommendations may be appropriate for both people presenting with subjective cognitive concerns and for those having objective evidence of memory problems. It remains less certain whether adopting these lifestyle habits in later life confers the benefits seen in epidemiological cohorts (where people have likely practiced them for many years). Discussion of starting on a cholinesterase inhibitor is appropriate for those having MCI, particularly those in whom the MCI is thought to have a vascular etiology or to represent the prodromal stage of a neurodegenerative disease. Recent meta-analyses exploring the use of cholinesterase inhibitors in patients having MCI have concluded that there is no evidence to support this practice. Although meta-analytic techniques seemingly strengthen the confidence in a recommendation via the incorporation of a large number of subjects analyzed, the technique is not capable of overcoming any inherent weaknesses of the individual studies included in the analysis. It is arguable whether studies in MCI may have employed endpoints poorly adapted to investigating effect of cholinesterase inhibitors. Most studies have used cognitive screening examinations, all of which stretch their detection ability to identify subjects with MCI, let alone discriminate subtle differences between them. Some have used conversion from MCI to dementia as an endpoint, which may not be the best measure for a symptomatic treatment. Further, once conversion to dementia has occurred, a cholinesterase inhibitor would be started in most (if not all) clinical settings, a reality not well reflected in most study designs. Additionally, several large studies have not permitted subject stratification by APOE carrier status, another important defect in assessing outcome. In clinical practice, our center typically does recommend cholinesterase inhibitors for patients having MCI. Despite the modest effect size, many patients do wish to start on treatment. It appears that this is a generally accepted practice and experience, as most clinical trials for prodromal Alzheimer's disease specify that participants should be taking a cholinesterase inhibitor.

Serum 25-hydroxyvitamin D level and the risk of mild cognitive impairment and dementia: the Korean Longitudinal Study on Health and Aging (KLoSHA)

OBJECTIVE

The association of low vitamin D status with mild cognitive impairment (MCI), a preclinical condition that can lead to dementia, has not yet been fully explored. Our aim was to investigate the association between vitamin D status and the future risk of MCI and dementia in older adults.

DESIGN, SETTING AND PARTICIPANTS

We conducted a population-based prospective study as a part of the Korean Longitudinal Study on Health and Aging. Four hundred and twelve elderly participants who completed evaluations of cognitive function and metabolic parameters in 2005-2006 and 2010-2011 were analysed.

MAJOR OUTCOME MEASURE

The rate of development of MCI or dementia during the study period was compared according to baseline vitamin D status. Binary logistic regression analysis was performed to investigate any independent association between vitamin D status and the risks of MCI or dementia.

RESULTS

Among 405 subjects that remained after excluding seven demented subjects at baseline, 338 subjects remained unchanged or improved in their diagnosis for cognitive function during the study period, whereas 67 subjects showed progression to MCI or dementia. When analyzing 236 subjects whose baseline mini-mental state examination (MMSE) scores were <27, severe vitamin D deficiency at baseline, defined as <25 nmol/l, was independently associated with the progression of cognitive impairment. Among 297 subjects who were normal at baseline, 50 acquired MCI and 247 remained normal. Severe vitamin D deficiency was also independently associated with the development of MCI when analyzing 145 subjects whose baseline MMSE scores were <27.

CONCLUSION

Severe vitamin D deficiency was independently associated with the future risk of MCI as well as dementia, especially in older adults whose baseline MMSE scores had decreased only modestly.

Cognitive impairment and its consequences in everyday life: experiences of people with mild cognitive impairment or mild dementia and their relatives

BACKGROUND

The aim of this study was to explore experiences of cognitive impairment, its consequences in everyday life and need for support in people with mild cognitive impairment (MCI) or mild dementia and their relatives.

METHODS

A qualitative approach with an explorative design with interviews was chosen. The participants included five people with MCI and eight people with mild dementia and their relatives. All participants were recruited at a geriatric memory clinic in Sweden. The Grounded Theory method was used.

RESULTS

The following categories emerged: noticing cognitive changes; changed activity patterns; coping strategies; uncertainty about own ability and environmental reactions; support in everyday life; support from the healthcare system; consequences in everyday life for relatives; and support for relatives. The main findings were that people with MCI and dementia experienced cognitive changes that could be burdensome and changed activity patterns. Most of them, however, considered themselves capable of coping on their own. The relatives noticed cognitive changes and activity disruptions to a greater extent and tried to be supportive in everyday life. Degree of awareness varied and lack of awareness could lead to many problems in everyday life.

CONCLUSIONS

Perceived cognitive impairment and its consequences in everyday life were individual and differed among people with MCI or dementia and their relatives. Thus, healthcare professionals must listen to both people with cognitive impairment and their relatives for optimal individual care planning. Support such as education groups and day care could be more tailored towards the early stages of dementia.

[Quality of registration of dementia diagnosis in primary care: The situation in Spain in 2002-2011]

Objetivo

Comprobar el diagnóstico asociado al tratamiento específico para demencia en la historia clínica electrónica de atención primaria (HCE-AP) y analizar los factores asociados a la calidad del registro

Método

Estudio descriptivo de los pacientes con anticolinesterásicos o memantina registrados en la Base para Investigación Farmacoepidemiológica en atención primaria (BIFAP) 2011: 24.575 pacientes entre 2002 y 2011. Los diagnósticos asociados a la primera prescripción de estos fármacos se agruparon en 5 categorías: «demencia», «alteraciones de memoria», «enfermedades relacionadas con demencia», «procesos intercurrentes» y «códigos de conveniencia». Se calculó la prevalencia de cada categoría por edad y sexo en cada año de estudio (IC 95%) y se analizaron asociaciones y tendencia 2002-2011, utilizando diferencias de proporciones para muestras independientes y regresión logística binaria.

Resultados

El 56,5% (IC 95%: 55,8-57,1) de los pacientes tenían asociado código «demencia» a la primera prescripción. Se registró mejor en mujeres (OR: 1,09 [IC 95%: 1,03-1,15]) y al aumentar el tiempo transcurrido (OR: 1,07 [IC 95%: 1,06-1,08] por cada año de seguimiento). Los «códigos de conveniencia» (16,3% [IC 95%: 15,8-16,7]) se utilizaron más en mujeres y ≥ 80 años; las «alteraciones de memoria» (12,4% [IC 95%: 12,0-12,8]), «enfermedades relacionadas» (4,6% [IC 95%: 4,4-4,8]) y «procesos intercurrentes» (10,3% [IC 95%: 9,9-10,6]) más en hombres y < 80 años. De 2002 a 2011 mejoró el uso de «códigos de conveniencia».

Conclusiones

Casi la mitad de los pacientes con anticolinesterásicos o memantina no tienen registrado diagnóstico de demencia en su HCE-AP. El registro mejora al aumentar el tiempo de seguimiento. Se requieren mejoras de la HCE-AP, coordinación asistencial adecuada y actitud activa para aumentar la calidad del registro de demencia.

Identification and assessment of functional performance in mild cognitive impairment: a survey of occupational therapy practices

BACKGROUND/AIM

Despite the amount of research evidence pointing to functional changes experienced by individuals with mild cognitive impairment (MCI), we still do not understand how occupational therapists are currently addressing these concerns. Thus, we designed a national study to investigate Canadian occupational therapists practices with this clientele.

METHODS

We conducted a Canada-wide online survey to investigate occupational therapists' practices with clients with potential MCI. Clinicians were prompted by a case vignette that described two clients: one vignette included cues associated with amnestic MCI (aMCI), the other non-amnestic MCI (naMCI). Specifically, clinicians were asked to identify potential concerns and to indicate the screening and assessment tools they would use in clinical practice.

RESULTS

Two hundred and eighty-five participants met the inclusion criteria and were included in the final analysis. The average clinician age was 38.6 (SD = 10.3), 92% were female and 71.2% worked full-time. Almost all clinicians identified a concern in both vignettes, with cognitive concerns being identified more frequently than functional concerns [i.e. Instrumental Activities of Daily Living (IADL) concerns]. In terms of assessment practices, 18 standardised IADL assessments and 10 standardised cognitive assessments have been reported.

CONCLUSION

Encouragingly, almost all clinicians identified a concern. However, some are still missing the IADL cues. Moreover, the lack of consensus in terms of which assessment practices to employ indicates that clinicians might benefit from guidelines in this area of practice.

Hippocampal atrophy varies by neuropsychologically defined MCI among men in their 50s

OBJECTIVE

In an effort to address earliest detection of mild cognitive impairment (MCI), we examined hippocampal volumes and atrophy in middle-aged men to explore neuroanatomical support for different neuropsychological definitions of MCI.

METHODS

460 men aged 51-60 years underwent neuropsychological testing and MRI. MCI was defined according to five criteria sets. MRI-derived hippocampal volume and hippocampal occupancy (HOC) were obtained via FreeSurfer. Statistical analyses were performed using linear mixed models.

RESULTS

Differences in HOC between normal cognitive functioning, amnestic, and non-amnestic MCI were observed using MCI criteria that required one impaired (>1.5 SD) cognitive measure in a given cognitive domain or a cognitive composite score method with a cut-point 2 SD below the mean. Differences in standard hippocampal volume were only found between normal and amnestic presentations and only when using the composite score method.

CONCLUSION

Results provide empirical support for detection of pre-MCI in younger cohorts. Convergence of neuropsychological and neuroanatomical data, particularly HOC (as opposed to standard cross-sectional volume), supports early identification of MCI as defined by some neuropsychological criteria.

The most frequently used tests for assessing executive functions in aging

There are numerous neuropsychological tests for assessing executive functions in aging, which vary according to the different domains assessed.

OBJECTIVE

To present a systematic review of the most frequently used instruments for assessing executive functions in older adults with different educational levels in clinical and experimental research.

METHODS

We searched for articles published in the last five years, using the PubMed database with the following terms: "neuropsychological tests", "executive functions", and "mild cognitive impairment". There was no language restriction.

RESULTS

25 articles fulfilled all the inclusion criteria. The seven neuropsychological tests most frequently used to evaluate executive functions in aging were:[1] Trail Making Test (TMT) Form B;[2] Verbal Fluency Test (VFT) - F, A and S;[3] VFT Animals category;[4] Clock Drawing Test (CDT);[5] Digits Forward and Backward subtests (WAIS-R or WAIS-III);[6] Stroop Test; and[7] Wisconsin Card Sorting Test (WCST) and its variants. The domains of executive functions most frequently assessed were: mental flexibility, verbal fluency, planning, working memory, and inhibitory control.

CONCLUSION

The study identified the tests and domains of executive functions most frequently used in the last five years by research groups worldwide to evaluate older adults. These results can direct future research and help build evaluation protocols for assessing executive functions, taking into account the different educational levels and socio-demographic profiles of older adults in Brazil.

Carotid intima-media thickness is associated with the progression of cognitive impairment in older adults

BACKGROUND AND PURPOSE

We investigated the association between cardiovascular risk factors, including carotid intima-media thickness (CIMT), and future risk of mild cognitive impairment (MCI) and dementia in elderly subjects.

METHODS

We conducted a population-based prospective study as a part of the Korean Longitudinal Study on Health and Aging. Our study included 348 participants who were nondemented at the baseline (mean age, 71.7±6.3 years) and underwent cognitive evaluation at the 5-year follow-up. Baseline cardiovascular risk factors were compared according to the development of MCI or dementia during the study period.

RESULTS

At the baseline evaluation, 278 subjects were cognitively normal and 70 subjects had MCI. Diagnoses of cognitive function either remained unchanged or improved during the study period in 292 subjects (nonprogression group), whereas 56 subjects showed progression of cognitive impairment to MCI or dementia (progression group). The progression group exhibited a higher prevalence of hypertension and greater CIMT compared with the nonprogression group. Other baseline cardiovascular risk factors, including sex, body mass index, diabetes mellitus, insulin resistance, total cholesterol, waist-to-hip ratio, visceral fat, pulse wave velocity, and ankle-brachial index, were not significantly different between 2 groups. The association between greater baseline CIMT and the progression of cognitive impairment was maintained after adjustment for conventional baseline risk factors of cognitive impairment. Greater baseline CIMT was also independently associated with the development of MCI in the subjects whose baseline cognitive function was normal.

CONCLUSIONS

Greater baseline CIMT was independently associated with the risk of cognitive impairment, such as MCI and dementia in elderly subjects.

Risk Stratification Using Cerebrospinal Fluid Biomarkers in Patients with Mild Cognitive Impairment: An Exploratory Analysis

BACKGROUND

Cerebrospinal fluid (CSF) biomarkers can distinguish Alzheimer's disease (AD) patients from normal controls; however, their interpretation and potential for use in patients with mild cognitive impairment (MCI) remains unclear.

OBJECTIVE

To examine whether biomarker levels allow for risk stratification among MCI patients who are at increased risk to develop AD, thus allowing for improved targeting of early interventions for those whose risk are higher.

METHODS

We analyzed data from the Alzheimer's Disease Neuroimaging Initiative on MCI patients (n = 195) to estimate their risk of developing AD for up to 6 years on the basis of baseline CSF biomarkers. We used time-dependent receiver operating characteristic analysis to identify the best combination of biomarkers to discriminate those who converted to AD from those who remained stable. We used these data to construct a multi-biomarker score and estimated the risk of progression to AD for each quintile of the multi-biomarker score.

RESULTS

We found that Aβ(1-42) and P-tau(181p) were the best combination among CSF biomarkers to predict the overall risk of developing AD among MCI patients (area under the curve = 0.77). The hazard ratio of developing AD among MCI patients with high-risk (3rd-5th quintiles) biomarker levels was about 4 times greater than MCI patients with low-risk (1st quintile) levels (95% confidence interval, 1.93-7.26).

CONCLUSION

Our study identifies MCI patients at increased risk of developing AD by applying a multi-biomarker score using CSF biomarker results. Our findings may be of value to MCI patients and their clinicians for planning purposes and early intervention as well as for future clinical trials.

Assessing the discriminant ability, reliability, and comparability of multiple short forms of the Boston Naming Test in an Alzheimer's disease center cohort

BACKGROUND

The Boston Naming Test (BNT) is a commonly used neuropsychological test of confrontation naming that aids in determining the presence and severity of dysnomia. Many short versions of the original 60-item test have been developed and are routinely administered in clinical/research settings. Because of the common need to translate similar measures within and across studies, it is important to evaluate the operating characteristics and agreement of different BNT versions.

METHODS

We analyzed longitudinal data of research volunteers (n = 681) from the University of Kentucky Alzheimer's Disease Center longitudinal cohort.

CONCLUSIONS

With the notable exception of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) 15-item BNT, short forms were internally consistent and highly correlated with the full version; these measures varied by diagnosis and generally improved from normal to mild cognitive impairment (MCI) to dementia. All short forms retained the ability to discriminate between normal subjects and those with dementia. The ability to discriminate between normal and MCI subjects was less strong for the short forms than the full BNT, but they exhibited similar patterns. These results have important implications for researchers designing longitudinal studies, who must consider that the statistical properties of even closely related test forms may be quite different.

Buying time: a rationale for examining the use of circadian rhythm and sleep interventions to delay progression of mild cognitive impairment to Alzheimer's disease

As of 2010, the worldwide economic impact of dementia was estimated at $604 billion USD; and without discovery of a cure or effective interventions to delay disease progression, dementia's annual global economic impact is expected to surpass $1 trillion USD as early as 2030. Alzheimer's disease (AD) is the leading cause of dementia accounting for over 75% of all cases. Toxic accumulation of amyloid beta (Aβ), either by overproduction or some clearance failure, is thought to be an underlying mechanism of the neuronal cell death characteristic of AD-though this amyloid hypothesis has been increasingly challenged in recent years. A compelling alternative hypothesis points to chronic neuroinflammation as a common root in late-life degenerative diseases including AD. Apolipoprotein-E (APOE) genotype is the strongest genetic risk factor for AD: APOE-ε4 is proinflammatory and individuals with this genotype accumulate more Aβ, are at high risk of developing AD, and almost half of all AD patients have at least one ε4 allele. Recent studies suggest a bidirectional relationship exists between sleep and AD pathology. Sleep may play an important role in Aβ clearance, and getting good quality sleep vs. poor quality sleep might reduce the AD risk associated with neuroinflammation and the ε4 allele. Taken together, these findings are particularly important given the sleep disruptions commonly associated with AD and the increased burden disrupted sleep poses for AD caregivers. The current review aims to: (1) identify individuals at high risk for dementia who may benefit most from sleep interventions; (2) explore the role poor sleep quality plays in exacerbating AD type dementia; (3) examine the science of sleep interventions to date; and (4) provide a road map in pursuit of comprehensive sleep interventions, specifically targeted to promote cognitive function and delay progression of dementia.

Cognitive reserve and the risk for Alzheimer's disease: a longitudinal study

This study investigates how cognitive reserve (CR) interacts with neurodegeneration (quantified by medial temporal atrophy, MTA) and macroscopic white matter lesions (WMLs) in delaying the conversion from amnestic mild cognitive impairment to Alzheimer's disease (AD). Forty-two amnestic mild cognitive impairment patients were consecutively recruited. They underwent magnetic resonance imaging and a comprehensive questionnaire to classify them as individuals with low or high CR. Patients were then clinically followed-up for 2 years. The patients' risk for conversion to AD because of CR was estimated by controlling for cognitive efficiency, MTA, and WMLs at baseline. Global cognition was the best predictor of conversion to AD in low CR patients. Conversely, in high CR patients only, WMLs (but not MTA) highly contributed in increasing the risk for conversion to AD. In conclusion, CR interacts with both patients' cognitive features and WMLs in modulating the impact of AD pathology. This seems relevant for clinical prognosis and therapeutic strategies.

Mild cognitive impairment and mild dementia: a clinical perspective

Mild cognitive impairment and mild dementia are common problems in the elderly. Primary care physicians are the first point of contact for most patients with these disorders and should be familiar with their diagnosis, prognosis, and management. Both mild cognitive impairment and mild dementia are characterized by objective evidence of cognitive impairment. The main distinctions between mild cognitive impairment and mild dementia are that in the latter, more than one cognitive domain is invariably involved and substantial interference with daily life is evident. The diagnosis of mild cognitive impairment and mild dementia is based mainly on the history and cognitive examination. The prognosis for mild cognitive impairment and mild dementia is an important motivation for diagnosis because in both, there is a heightened risk for further cognitive decline. The etiology of mild cognitive impairment and mild dementia can often be established through the clinical examination, although imaging and other laboratory tests may also contribute. Although Alzheimer disease is the most common cause of both, cerebrovascular disease and Lewy body disease make important contributions. Pharmacological treatments are of modest value in mild dementia due to Alzheimer disease, and there are no approved pharmacological treatments for mild cognitive impairment of any etiology. Nonetheless, new-onset cognitive impairment is a worrisome symptom to patients and families that demands answers and advice. If a patient is having difficulties managing medications, finances, or transportation independently, diagnosis and intervention are necessary to ensure the health and safety of the patient.

Mild cognitive impairment: diagnosis, longitudinal course, and emerging treatments

Mild cognitive impairment (MCI) is widely regarded as the intermediate stage of cognitive impairment between the changes seen in normal cognitive aging and those associated with dementia. Elderly patients with MCI constitute a high-risk population for developing dementia, in particular Alzheimer's disease (AD). Although the core clinical criteria for MCI have remained largely unchanged, the operational definition of MCI has undergone several revisions over the course of the last decade and remains an evolving diagnosis. Prognostic implications of this diagnosis are becoming clearer with regard to the risk of progressive cognitive deterioration. Although patients with MCI may represent an optimal target population for pharmacological and non-pharmacological interventions, results from clinical trials have been mixed and an effective treatment remains elusive. This article provides a brief overview of the evolution of the concept of MCI and reviews current diagnostic criteria, the longitudinal course of the disorder, and current and emerging treatments for MCI.

Homotaurine induces measurable changes of short latency afferent inhibition in a group of mild cognitive impairment individuals

Current treatment options for patients with Alzheimer's disease (AD) are limited at providing symptomatic relief, with no effects on the underlying pathophysiology. Recently, advances in the understanding of the AD pathogenesis highlighted the role of ABeta (Aβ) oligomers particularly interfering with mechanisms of cortical plasticity such as long-term potentiation (LTP) and long-term depression (LTD). These findings led to the development of potential anti-amyloid therapies, and among them homotaurine, a glycosaminoglycan mimetic designed to interfere with the actions of Aβ early in the cascade of amyloidogenic events, and by its γ-aminobutyric acid type (GABA) A receptor affinity. Recently, we showed that AD patients have impaired LTP-like cortical plasticity, as measured by standard theta burst stimulation protocols applied over the primary motor cortex (M1). Furthermore, AD patients have a weakened short latency afferent inhibition (SLAI), a neurophysiological measure of central cholinergic transmission, which changes reflect the cholinergic dysfunction occurring in the pathology. Here, we aimed at investigating whether homotaurine administration could modulate in vivo measured mechanisms of synaptic plasticity, namely LTP and LTD, and also SLAI in a group of mild cognitive impaired patients. We observed that homotaurine administration did not induce relevant changes of both LTP and LTD recordings, while induced changes of SLAI in our group of patients. We suggest that homotaurine effects are dependent on changes of cortical GABA transmission suggesting a potential role for this compound in ameliorating the cholinergic transmission by modulating the inhibitory cortical activity.

The 2013 SFRBM discovery award: selected discoveries from the butterfield laboratory of oxidative stress and its sequela in brain in cognitive disorders exemplified by Alzheimer disease and chemotherapy induced cognitive impairment

This retrospective review on discoveries of the roles of oxidative stress in brain of subjects with Alzheimer disease (AD) and animal models thereof as well as brain from animal models of chemotherapy-induced cognitive impairment (CICI) results from the author receiving the 2013 Discovery Award from the Society for Free Radical Biology and Medicine. The paper reviews our laboratory's discovery of protein oxidation and lipid peroxidation in AD brain regions rich in amyloid β-peptide (Aβ) but not in Aβ-poor cerebellum; redox proteomics as a means to identify oxidatively modified brain proteins in AD and its earlier forms that are consistent with the pathology, biochemistry, and clinical presentation of these disorders; how Aβ in in vivo, ex vivo, and in vitro studies can lead to oxidative modification of key proteins that also are oxidatively modified in AD brain; the role of the single methionine residue of Aβ(1-42) in these processes; and some of the potential mechanisms in the pathogenesis and progression of AD. CICI affects a significant fraction of the 14 million American cancer survivors, and due to diminished cognitive function, reduced quality of life of the persons with CICI (called "chemobrain" by patients) often results. A proposed mechanism for CICI employed the prototypical ROS-generating and non-blood brain barrier (BBB)-penetrating chemotherapeutic agent doxorubicin (Dox, also called adriamycin, ADR). Because of the quinone moiety within the structure of Dox, this agent undergoes redox cycling to produce superoxide free radical peripherally. This, in turn, leads to oxidative modification of the key plasma protein, apolipoprotein A1 (ApoA1). Oxidized ApoA1 leads to elevated peripheral TNFα, a proinflammatory cytokine that crosses the BBB to induce oxidative stress in brain parenchyma that affects negatively brain mitochondria. This subsequently leads to apoptotic cell death resulting in CICI. This review outlines aspects of CICI consistent with the clinical presentation, biochemistry, and pathology of this disorder. To the author's knowledge this is the only plausible and self-consistent mechanism to explain CICI. These two different disorders of the CNS affect millions of persons worldwide. Both AD and CICI share free radical-mediated oxidative stress in brain, but the source of oxidative stress is not the same. Continued research is necessary to better understand both AD and CICI. The discoveries about these disorders from the Butterfield Laboratory that led to the 2013 Discovery Award from the Society of Free Radical and Medicine provide a significant foundation from which this future research can be launched.

Age-correction of test scores reduces the validity of mild cognitive impairment in predicting progression to dementia

Objectives

A phase of mild cognitive impairment (MCI) precedes most forms of neurodegenerative dementia. Many definitions of MCI recommend the use of test norms to diagnose cognitive impairment. It is, however, unclear whether the use of norms actually improves the detection of individuals at risk of dementia. Therefore, the effects of age- and education-norms on the validity of test scores in predicting progression to dementia were investigated.

Methods

Baseline cognitive test scores (Syndrome Short Test) of dementia-free participants aged ≥65 were used to predict progression to dementia within three years. Participants were comprehensively examined one, two, and three years after baseline. Test scores were calculated with correction for (1) age and education, (2) education only, (3) age only and (4) without correction. Predictive validity was estimated with Cox proportional hazard regressions. Areas under the curve (AUCs) were calculated for the one-, two-, and three-year intervals.

Results

82 (15.3%) of initially 537 participants, developed dementia. Model coefficients, hazard ratios, and AUCs of all scores were significant (p<0.001). Predictive validity was the lowest with age-corrected scores (−2 log likelihood  = 840.90, model fit χ² (1)  = 144.27, HR  = 1.33, AUCs between 0.73 and 0.87) and the highest with education-corrected scores (−2 log likelihood  = 815.80, model fit χ² (1)  = 171.16, HR  = 1.34, AUCs between 0.85 and 0.88).

Conclusion

The predictive validity of test scores is markedly reduced by age-correction. Therefore, definitions of MCI should not recommend the use of age-norms in order to improve the detection of individuals at risk of dementia.

The role of egocentric and allocentric abilities in Alzheimer's disease: a systematic review

A great effort has been made to identify crucial cognitive markers that can be used to characterize the cognitive profile of Alzheimer's disease (AD). Because topographical disorientation is one of the earliest clinical manifestation of AD, an increasing number of studies have investigated the spatial deficits in this clinical population. In this systematic review, we specifically focused on experimental studies investigating allocentric and egocentric deficits to understand which spatial cognitive processes are differentially impaired in the different stages of the disease. First, our results highlighted that spatial deficits appear in the earliest stages of the disease. Second, a need for a more ecological assessment of spatial functions will be presented. Third, our analysis suggested that a prevalence of allocentric impairment exists. Specifically, two selected studies underlined that a more specific impairment is found in the translation between the egocentric and allocentric representations. In this perspective, the implications for future research and neurorehabilitative interventions will be discussed.