Outcomes of incident mild cognitive impairment in relation to case definition

The efficacy of cognitive interventions on the performance of instrumental activities of daily living in individuals with mild cognitive impairment or mild dementia: protocol for a systematic review and meta-analysis

BACKGROUND

Cognitive changes associated with mild cognitive impairment or mild dementia can lead to difficulties in completing instrumental activities of daily living. The ability to live independently at home and in the community is often compromised due to the inability to complete these activities. Cognitive interventions have been reported as beneficial in maintaining or improving cognitive functions among this group of adults. However, the effectiveness of different types of cognitive interventions on the performance of instrumental activities of daily living in older adults with mild cognitive impairment and mild dementia is not well established. The aim of this paper is to develop a protocol for a systematic review and meta-analysis to investigate the effectiveness of cognitive interventions in maintaining or improving the performance of instrumental activities of daily living in individuals with mild cognitive impairment or mild dementia.

METHODS

Randomised control studies which investigate the effectiveness of cognitive interventions on the performance in instrumental activities of daily living for older adults with mild cognitive impairment and mild dementia will be sought. A systematic search will be conducted in five databases: CINAHL, MEDLINE, EMBASE, PsycINFO and Cochrane Central Register of Controlled Trials. The search strategy was developed with assistance from a health science librarian. Two independent reviewers will perform the study selection and data extraction. Quality assessment will be implemented using the Physiotherapy Evidence Database (PEDro) scale. A narrative synthesis of the findings will be used to report outcomes of all included studies. If appropriate, a meta-analysis will combine the results of individual studies.

DISCUSSION

This systematic review and meta-analysis will determine the effectiveness of cognitive interventions in maintaining or improving the performance of IADL in individuals with MCI or mild dementia. It is anticipated that the results will inform rehabilitation professionals of the most effective cognitive interventions to be implemented into clinical practice. It will potentially provide substantial benefit to both the persons with MCI or dementia and the health care system by keeping more people out of full-time care and allowing those in full-time care to require less intensive support.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016042364.

Using virtual reality to distinguish subjects with multiple- but not single-domain amnestic mild cognitive impairment from normal elderly subjects

AIM

Spatial disorientation is a hallmark of amnestic mild cognitive impairment (aMCI) and Alzheimer's disease. Our aim was to use virtual reality to determine the allocentric and egocentric memory deficits of subjects with single-domain aMCI (aMCIsd) and multiple-domain aMCI (aMCImd). For this purpose, we introduced an advanced virtual reality navigation task (VRNT) to distinguish these deficits in mild Alzheimer's disease (miAD), aMCIsd, and aMCImd.

METHODS

The VRNT performance of 110 subjects, including 20 with miAD, 30 with pure aMCIsd, 30 with pure aMCImd, and 30 cognitively normal controls was compared. Our newly developed VRNT consists of a virtual neighbourhood (allocentric memory) and virtual maze (egocentric memory). Verbal and visuospatial memory impairments were also examined with Rey Auditory-Verbal Learning Test and Rey-Osterrieth Complex Figure Test, respectively.

RESULTS

We found that miAD and aMCImd subjects were impaired in both allocentric and egocentric memory, but aMCIsd subjects performed similarly to the normal controls on both tasks. The miAD, aMCImd, and aMCIsd subjects performed worse on finding the target or required more time in the virtual environment than the aMCImd, aMCIsd, and normal controls, respectively. Our findings indicated the aMCImd and miAD subjects, as well as the aMCIsd subjects, were more impaired in egocentric orientation than allocentric orientation.

CONCLUSION

We concluded that VRNT can distinguish aMCImd subjects, but not aMCIsd subjects, from normal elderly subjects. The VRNT, along with the Rey Auditory-Verbal Learning Test and Rey-Osterrieth Complex Figure Test, can be used as a valid diagnostic tool for properly distinguishing different forms of aMCI.

Increased Amplitude of the P3a ERP Component as a Neurocognitive Marker for Differentiating Amnestic Subtypes of Mild Cognitive Impairment

The event-related potential (ERP) technique has been shown to be useful for evaluating changes in brain electrical activity associated with different cognitive processes, particularly in Alzheimer's disease (AD). Longitudinal studies have shown that a high proportion of people with amnestic mild cognitive impairment (aMCI) go on to develop AD. aMCI is divided into two subtypes according to the presence of memory impairment only (single-domain aMCI: sdaMCI) or impairment of memory and other cognitive domains (multi-domain aMCI: mdaMCI). The main aim of this study was to examine the effects of sdaMCI and mdaMCI on the P3a ERP component associated with the involuntary orientation of attention toward unattended infrequent novel auditory stimuli. Participants performed an auditory-visual distraction-attention task, in which they were asked to ignore the auditory stimuli (standard, deviant, and novel) and to attend to the visual stimuli (responding to some of them: Go stimuli). P3a was identified in the Novel minus Standard difference waveforms, and reaction times (RTs) and hits (in response to Go stimuli) were also analyzed. Participants were classified into three groups: Control, 20 adults (mean age (M): 65.8 years); sdaMCI, 19 adults (M: 67 years); and mdaMCI, 11 adults (M: 71 years). In all groups, the RTs were significantly longer when Go stimuli were preceded by novel (relative to standard) auditory stimuli, suggesting a distraction effect triggered by novel stimuli; mdaMCI participants made significantly fewer hits than control and sdaMCI participants. P3a comprised two consecutive phases in all groups: early-P3a (e-P3a), which may reflect the orienting response toward the irrelevant stimuli, and late-P3a (l-P3a), which may be a correlate of subsequent evaluation of these stimuli. The e-P3a amplitude was significantly larger in mdaMCI than in sdaMCI participants, and the l-P3a amplitude was significantly larger in mdaMCI than in sdaMCI and Control participants, indicating greater involuntary capture of attention to unattended novel auditory stimuli and allocation of more attentional resources for the subsequent evaluation of these stimuli in mdaMCI participants. The e-P3a and l-P3a components showed moderate to high sensitivity and specificity for distinguishing between groups, suggesting that both may represent optimal neurocognitive markers for differentiating aMCI subtypes.

The mismatch negativity as an index of cognitive decline for the early detection of Alzheimer's disease

Evidence suggests that Alzheimer's disease (AD) is part of a continuum, characterized by long preclinical phases before the onset of clinical symptoms. In several cases, this continuum starts with a syndrome, defined as mild cognitive impairment (MCI), in which daily activities are preserved despite the presence of cognitive decline. The possibility of having a reliable and sensitive neurophysiological marker that can be used for early detection of AD is extremely valuable because of the incidence of this type of dementia. In this study, we aimed to investigate the reliability of auditory mismatch negativity (aMMN) as a marker of cognitive decline from normal ageing progressing from MCI to AD. We compared aMMN elicited in the frontal and temporal locations by duration deviant sounds in short (400 ms) and long (4000 ms) inter-trial intervals (ITI) in three groups. We found that at a short ITI, MCI showed only the temporal component of aMMN and AD the frontal component compared to healthy elderly who presented both. At a longer ITI, aMMN was elicited only in normal ageing subjects at the temporal locations. Our study provides empirical evidence for the possibility to adopt aMMN as an index for assessing cognitive decline in pathological ageing.

The New Criteria for Alzheimer's Disease - Implications for Geriatricians

Two new sets of criteria for Alzheimer’s disease (AD) are now in play, including one set released in 2014, and a proposal for a “new lexicon” for how to describe the disease spectrum. A 2012 Canadian consensus conference said that to then, none of the new criteria or terminology would change primary care practice; that is still likely to be so. For dementia consultants, however, the new criteria pose challenges and offer opportunities.

In general, the new criteria see an expanded role for bio-markers. Even so, the evidence base for this remains incomplete. Our understanding of the neuropathological criteria for dementia changed as the evidence base included more community cases. This is likely to inform the experience with biomarkers. At present, each of the criteria specifies an exclusive research role. Still, wider uptake is likely, especially in the United States.

Geriatricians should be aware of the fundamental change in the terminology now being employed: AD diagnosis no longer obliges a diagnosis of dementia. Until more data emerge—something to which geriatricians can contribute—there is reason to be cautious in the adoption of the new criteria, as they are likely to be least applicable to older adults.

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Deux nouvelles séries de critères pour le diagnostic de la maladie d’Alzheimer sont maintenant en vigueur, incluant une série publiée en 2014. Un « nouveau lexique » conceptualisant la maladie a également été proposé. En 2012, la Conférence consensuelle canadienne affirmait que, pour l’instant, ni les nouveaux critères ni la nouvelle terminologie ne modifiaient la pratique en première ligne. Néanmoins, pour les consultants spécialisés en démence, l’avènement de ces critères ouvre la porte à de nombreux défis et occasions.

En général, les nouveaux critères accordent une place grandissante aux biomarqueurs. Toutefois, les évidences qui sous-tendent leur utilisation demeurent incomplètes. L’étude de sujets provenant de la communauté ayant raffiné notre compréhension des critères neuropathologiques des démences, il est probable que notre expérience avec les biomarqueurs en bénéficierait également. Pour l’instant, ces critères sont réservés à la recherche. Cependant, leur adoption à plus large échelle est pressentie, particulièrement aux États-Unis.

Les gériatres canadiens doivent être conscients de la terminologie maintenant utilisée et du changement fondamental qui en découle : un diagnostic de maladie d’Alzheimer ne requiert plus un diagnostic de démence. Dans l’attente de nouvelles données – auxquelles les gériatres peuvent contribuer – il y a lieu de faire preuve de prudence dans l’adoption des nouveaux critères, car ils sont susceptibles de moins bien s’appliquer aux personnes âgées.

Is Mild Cognitive Impairment a Valid Target of Therapy

The status of Mild Cognitive Impairment (MCI) as a valid construct is controversial. The term encompasses people with heterogeneous clinical profiles, and invites sub-classifications that still require validation. Still, much evidence suggests that, properly selected, many people with MCI - especially Amnestic MCI - are at a high risk of dementia. This paper considers the validity of the construct of MCI as a high-risk state for progression and a target for treatment. We conclude that the status of MCI as an entity remains controversial. On the one hand, it can be argued that the careful section of cases at high risk of developing dementia means that it is a valid target, with the goal being the prevention of dementia. Advocates of this view see a linear progression that they are trying to arrest, but studies have yet to show that this can be done. On the other hand, it can be argued that the patients who progressed did not develop dementia: they actually had a very early form of it. By this view, people without the progressive form will be needlessly exposed to antidementia drugs, and the others should be treated anyway. Why some people progress and others do not is not clear, but the variable rates of progression - between clinic-based and population-based samples and between very similar clinical trials with slightly different inclusion criteria - suggests that MCI is a heterogeneous entity. The phenomenon of slowing or non-progression itself should be investigated, and such investigations likely should extend to people now classified as having mild dementia.

Cognitive rehabilitation for mild cognitive impairment: developing and piloting an intervention

This was an exploratory study, with the purpose of developing and piloting an intervention for people with mild cognitive impairment (MCI) and their family members using cognitive rehabilitation. A case series design was used with pre- and post-intervention and 3-month follow-up outcome measures. Five participants (two males, three females; mean age 75 years) with a diagnosis of MCI attended the memory clinic with a family member. Intervention consisted of six to eight individual sessions of cognitive rehabilitation consisting of personalized interventions to address individually relevant goals delivered weekly. The main rehabilitation strategies utilized were external aids, personal diary, face-name association, relaxation, and encouraging participants to develop habits and routines. The primary outcome measure was goal attainment as assessed by Goal Attainment Scaling. Secondary outcome measures included measures of memory, anxiety, depression, and activities of daily living. Qualitative data were collected post-intervention by interview. Post-intervention 84% of the goals were attained, with 68% maintained at a 3-month follow-up. Mean anxiety and depression scores decreased during the intervention. No significant changes were recorded on a test of memory. The findings suggest that the strongest effect was in relation to compensatory strategies for prospective and episodic memory deficits. Feedback from participants during qualitative interviews indicated that they found strategies useful and implemented them in their daily routines. The findings support the use of a dyadic cognitive rehabilitation intervention for people with MCI and memory difficulties.

Mild cognitive impairment and mood: a systematic review

This systematic review, with meta-analyses conducted where data were available, aimed to investigate the prevalence of symptoms of depression and anxiety in mild cognitive impairment (MCI), and to establish how symptoms of depression and anxiety relate to the progression from no cognitive impairment to MCI, and from MCI to dementia. Sixty studies were included in the review. Meta-analyses indicated that symptoms of depression and anxiety were more prevalent in people with MCI than in people with normal cognitive function, and increased the risk of progression from no cognitive impairment to MCI. There were mixed results regarding the effect of such symptoms on progression from MCI to dementia. The findings highlight the need for more research in this area, which can inform attempts to slow or halt the progression of cognitive impairment in later life, with resulting benefits for quality of life.

Magnetic resonance spectroscopy in mild cognitive impairment: systematic review and meta-analysis

Research using proton magnetic resonance spectroscopy (MRS) can potentially elucidate metabolite changes representing early degeneration in Mild Cognitive Impairment (MCI), an early stage of dementia. We integrated the published literature using meta-analysis to identify patterns of metabolite changes in MCI. 29 MRS studies (with a total of 607 MCI patients and 862 healthy controls) were classified according to brain regions. Hedges' g was used as effect size in a random effects model. N-Acetyl Aspartate (NAA) measures were consistently reduced in posterior cingulate (PC), hippocampus, and the paratrigonal white matter (PWM). Creatine (Cr) concentration was reduced in the hippocampus and PWM. Choline (Cho) concentration was reduced in the hippocampus while Cho/Cr ratio was raised in the PC. Myo-inositol (mI) concentration was raised in the PC and mI/Cr ratio was raised in the hippocampus. NAA/mI ratio was reduced in the PC. NAA may be the most reliable marker of brain dysfunction in MCI though mI, Cho, and Cr may also contribute towards this.

Four-year outcome of mild cognitive impairment: the contribution of executive dysfunction

OBJECTIVE

The contribution of executive cognition (EC) to the prediction of incident dementia remains unclear. This prospective study examined the predictive value of EC for subsequent cognitive decline in persons with mild cognitive impairment (MCI) over a 4-year period.

METHOD

One hundred forty-one persons with MCI (amnestic and nonamnestic, single- and multiple-domain) received a baseline and two biennial follow-up assessments. Eighteen tests, assessing six different aspects of EC, were administered at baseline and at 2-year follow-up, together with screening cognitive and daily functioning measures. Longitudinal logistic regression models and generalized estimating equations (GEE) were used to examine whether EC could predict progression to a Clinical Dementia Rating Scale (CDR; C. P. Hughes, L. Berg, W. L. Danziger, L. A. Coben, & R. L. Martin, 1982, A new clinical scale for the staging of dementia, British Journal of Psychiatry, Vol. 140, pp. 566-572) score of 1 or more over the 4-year period, first at the univariate level and then in the context of demographic and clinical characteristics, daily functioning measures, and other neurocognitive factors.

RESULTS

Over the 4-year period, 56% of MCI patients remained stable, 35% progressed to CDR ≥ 1, and 8% reverted to normal (CDR = 0). Amnestic MCI subtypes were not associated with higher rates of progression to dementia, whereas subtypes with multiple impairments were so associated. Eight out of the 18 EC measures, including all three measures assessing inhibition of prepotent responses, predicted MCI outcome at the univariate level. However, the multivariate GEE model indicated that age, daily functioning, and overall cognitive functioning best predicted progression to dementia.

CONCLUSION

Measures of EC (i.e., inhibitory control) are associated with MCI outcome. However, age and global measures of cognitive and functional impairment are better predictors of incident dementia.

Mild cognitive impairment: statistical models of transition using longitudinal clinical data

Mild cognitive impairment (MCI) refers to the clinical state between normal cognition and probable Alzheimer's disease (AD), but persons diagnosed with MCI may progress to non-AD forms of dementia, remain MCI until death, or recover to normal cognition. Risk factors for these various clinical changes, which we term "transitions," may provide targets for therapeutic interventions. Therefore, it is useful to develop new approaches to assess risk factors for these transitions. Markov models have been used to investigate the transient nature of MCI represented by amnestic single-domain and mixed MCI states, where mixed MCI comprised all other MCI subtypes based on cognitive assessments. The purpose of this study is to expand this risk model by including a clinically determined MCI state as an outcome. Analyses show that several common risk factors play different roles in affecting transitions to MCI and dementia. Notably, APOE-4 increases the risk of transition to clinical MCI but does not affect the risk for a final transition to dementia, and baseline hypertension decreases the risk of transition to dementia from clinical MCI.

Prospective and Retrospective Memory Complaints in Mild Cognitive Impairment and Mild Alzheimer's Disease

Current management attempts for Alzheimer's disease (AD) focus on the identification of individuals in the preclinical stage. This has led to the development of the diagnostic concept of Mild Cognitive Impairment (MCI), which applies to individuals with declining cognitive abilities but largely preserved everyday functioning. Previous findings indicate that prospective memory deficits are a sensitive marker of preclinical AD and that awareness of prospective memory failures is particularly high, based on its dependence on executive functions. Thus, the goal of this study was to evaluate the usefulness of subjective prospective versus retrospective memory complaints for an initial screening for MCI and their respective associations with executive functions. 71 healthy older adults, 27 MCI patients, and 9 patients with mild AD completed the Prospective and Retrospective Memory Questionnaire (PRMQ) and three executive functions tests. The healthy and the MCI group could not be distinguished by their level of subjective prospective or retrospective memory complaints, but the mild AD patients differed from the other groups by complaining more about retrospective than prospective memory failures. For the healthy older adults, the prospective memory complaints were correlated to an inhibition test, whereas they did not correlate with any of the executive function tests in the MCI patients. In contrast, in both groups the retrospective memory complaints were related to a task switching test. The findings are discussed with respect to differences between the three groups in cognitive abilities, attention to failures of, use of mnemonic aids for, and everyday demands of prospective and retrospective memory.

The role of neuropsychology in prodromal dementia

SUMMARY Before dementia becomes manifest, it is preceded by a long period during which neuropathology exists without clinical symptoms, termed the prodromal stage of dementia (ProD). Owing to its relevance for clinical and research aspects, many efforts are being made to define, diagnose and investigate ProD in greater detail. The ProD state has often been studied in Alzheimer’s disease (AD), whereas less is known about the prodromes of the vascular, extrapyramidal and frontotemporal dementias. Since the operational criteria of ProD are unclear, many studies act on the assumption that ProD and mild cognitive impairment are equivalent concepts. However, owing to several methodological problems with the mild cognitive impairment construct, the viewpoint taken here is that ProD can be understood more profoundly in cohorts of normal elderly subjects. This article discusses the neuropsychological findings of longitudinal, population-based studies, which included elderly, normal subjects, who were followed for years, and made case–control comparisons. Neuropsychological findings clearly revealed deficits in cases (subjects who developed dementia later, mostly AD), which were present already at baseline. Cognitive abnormalities were apparent in the domains of episodic memory, but also in tasks tapping executive, psychomotor and visuospatial functions, attention and naming. Although subtle, these impairments were significant at the group level and often demonstrated deterioration to dementia. Early cognitive deficits of the ProD stage therefore represent markers for the identification of incident AD. It is concluded that neuropsychology is a useful method to screen subjects for ProD at an early time point, when individuals are still normally functioning.

The fate of the 0.5s: predictors of 2-year outcome in mild cognitive impairment

Impairments in executive cognition (EC) may be predictive of incident dementia in patients with mild cognitive impairment (MCI). The present study examined whether specific EC tests could predict which MCI individuals progress from a Clinical Dementia Rating (CDR) score of 0.5 to a score ≥1 over a 2-year period. Eighteen clinical and experimental EC measures were administered at baseline to 104 MCI patients (amnestic and non-amnestic, single- and multiple-domain) recruited from clinical and research settings. Demographic characteristics, screening cognitive measures and measures of everyday functioning at baseline were also considered as potential predictors. Over the 2-year period, 18% of the MCI individuals progressed to CDR ≥ 1, 73.1% remained stable (CDR = 0.5), and 4.5% reverted to normal (CDR = 0). Multiple-domain MCI participants had higher rates of progression to dementia than single-domain, but amnestic and non-amnestic MCIs had similar rates of conversion. Only three EC measures were predictive of subsequent cognitive and functional decline at the univariate level, but they failed to independently predict progression to dementia after adjusting for demographic, other cognitive characteristics, and measures of everyday functioning. Decline over 2 years was best predicted by informant ratings of subtle functional impairments and lower baseline scores on memory, category fluency, and constructional praxis.

Exercising the brain to avoid cognitive decline: examining the evidence

Dementias and related cognitive disorders of the brain are strongly age-associated and prevalence is expected to rise dramatically with a rapidly aging population. As a result, there has been increasing attention on the prevention and treatment of cognitive decline associated with these conditions. A number of approaches have been designed to maintain and strengthen the cognitive capacity of the healthy, as well as the pathologically damaged brain. Evidence suggests that despite advancing age, our brains, and thus our cognitive functions, retain the ability to be maintained and strengthened through the biological process of neuroplasticity. With this opportunity, a new commercial field of ‘brain fitness’ has been launched to bring to the market training exercises and games that maintain and strengthen cognitive abilities in adulthood. However, the majority of brain fitness methods and products now marketed and sold to consumers have scant scientific evidence to support their effectiveness.

Effect of different impairment criteria on prevalence of “objective” mild cognitive impairment in a community sample

OBJECTIVES

Objective cognitive impairment determined by neuropsychological test performance is a core criterion for the diagnosis of mild cognitive impairment (MCI), yet no consensus has been reached on how this criterion should be operationalized. The aims of this study were to investigate the effect of varying the criteria used to determine cognitive impairment (CI) on prevalence and case definition and to examine comparability of different criteria.

DESIGN

Cross-sectional study.

SETTING

Sydney Memory and Ageing Study, Australia.

PARTICIPANTS

Nine hundred eighty-seven nondemented community-dwelling adults aged 70-90 years were enrolled in this study.

MEASUREMENTS

Participants received a comprehensive neuropsychological test battery measuring four cognitive domains. They were classified as normal or cognitively impaired by applying two types of “impairment” rule that varied the statistical threshold for impairment and the criteria used to determine impairment for each cognitive domain. Prevalence of four MCI cognitive subtypes was determined according to nine different criteria and two types of normative data. Rates of CI were compared in persons of English-speaking and non-English-speaking backgrounds (NESB).

RESULTS

Prevalence of CI ranged from 4 to 70% depending on the impairment criteria used. Agreement between different criteria was poor to moderate. This lack of consistency had greatest impact on MCI subtype classifications with many being reclassified as “normal” or into a different subtype when stringency of the criteria was increased or decreased. Higher rates of impairment were found in persons of NESB across all cognitive domains.

CONCLUSIONS

The prevalence of CI was strongly affected by the choice of neuropsychological assessment parameters. Guidelines for operationalizing CI are required.

Prevalence of dementia and cognitive impairment in Southeastern Spain: the Ariadna study

OBJECTIVES

To estimate the prevalence of amnestic mild cognitive impairment (aMCI), cognitive impairment, no dementia (CIND) and dementia in a general elderly population and to examine the associated socio-demographic factors.

METHODS

The Ariadna study is a population-based cross-sectional study of cognitive function involving 1074 individuals aged 65-96 years from the Murcia Region of southeastern Spain. Prevalence, adjusted odds ratio (OR) and 95% confidence intervals (CI) were calculated.

RESULTS

The overall prevalence was 8.7% (95% CI 7.1-10.5) for aMCI, 14.5% (95% CI 12.4-16.8) for CIND and 5.5% (95% CI 4.3-7.1) for dementia. Dementia was associated with age (OR 1.13 95% CI 1.09-1.18 for a 1-year increase in age). Illiterate subjects were more likely to present aMCI (OR 2.59; 95% CI 1.09-6.14) and dementia (OR 4.09; 95% CI 1.28-13.08) than subjects with secondary or higher education. Rural area residents (OR 2.13, 95% CI 1.07-4.24) and women (OR 1.53, 95% CI 1.06-2.22) were more likely to have CIND.

CONCLUSION

The prevalence of dementia was low, despite a high prevalence of aMCI and CIND. Dementia was strongly associated with age and education. CIND was associated with living in a rural area and with female sex, while aMCI was associated with illiteracy.

Biracial population study of mortality in mild cognitive impairment and Alzheimer disease

OBJECTIVE

To assess mortality associated with mild cognitive impairment (MCI) and Alzheimer disease (AD) among older African Americans and whites from an urban community.

DESIGN

Longitudinal population-based observational study.

SETTING

Four adjacent neighborhoods in Chicago, Illinois.

PARTICIPANTS

Persons deemed free of dementia in a previous wave of data collection (n = 1715) underwent detailed clinical evaluation: 802 had no cognitive impairment (46.8%), 597 had MCI (34.8%), 296 had AD (17.3%), and 20 had other forms of dementia (1.2%).

MAIN OUTCOME MEASURE

All-cause mortality.

RESULTS

During as many as 10 years of observation (mean [SD], 4.7 [3.0] years), 634 individuals died (37.0%). Compared with people without cognitive impairment, risk of death was increased by about 50% among those with MCI (hazard ratio [95% confidence interval], 1.48 [1.22-1.80]) and was nearly 3-fold greater among those with AD (2.84 [2.29-3.52]). These effects were seen among African Americans and whites and did not differ by race. Among participants with MCI, risk of death increased with more severe cognitive impairment, and this effect did not vary by race. A similar effect was seen among participants with AD, but it was slightly stronger for African Americans vs whites. In the MCI and AD groups, the association of cognitive impairment with survival was stronger for perceptual speed than for other cognitive functions.

CONCLUSION

The presence and severity of MCI and AD are associated with reduced survival among African Americans, and these effects are comparable to those seen among whites.

Rate of progression of mild cognitive impairment to dementia--meta-analysis of 41 robust inception cohort studies

OBJECTIVE

To quantify the risk of developing dementia in those with mild cognitive impairment (MCI).

METHOD

Meta-analysis of inception cohort studies.

RESULTS

Forty-one robust cohort studies were identified. To avoid heterogeneity clinical studies, population studies and clinical trials were analysed separately. Using Mayo defined MCI at baseline and adjusting for sample size, the cumulative proportion who progressed to dementia, to Alzheimer's disease (AD) and to vascular dementia (VaD) was 39.2%, 33.6% and 6.2%, respectively in specialist settings and 21.9%, 28.9% and 5.2%, respectively in population studies. The adjusted annual conversion rate (ACR) from Mayo defined MCI to dementia, AD and VaD was 9.6%, 8.1% and 1.9%, respectively in specialist clinical settings and 4.9%, 6.8% and 1.6% in community studies. Figures from non-Mayo defined MCI and clinical trials are also reported.

CONCLUSION

The ACR is approximately 5-10% and most people with MCI will not progress to dementia even after 10 years of follow-up.

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

OBJECTIVES

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

METHOD

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

RESULTS

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

CONCLUSION

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

Neuropsychological contributions to the early identification of Alzheimer's disease

A wealth of evidence demonstrates that a prodromal period of Alzheimer's disease (AD) exists for some years prior to the appearance of significant cognitive and functional declines required for the clinical diagnosis. This prodromal period of decline is characterized by a number of different neuropsychological and brain changes, and reliable identification of individuals prior to the development of significant clinical symptoms remains a top priority of research. In this review we provide an overview of those neuropsychological changes. In particular, we examine specific domains of cognition that appear to be negatively affected during the prodromal period of AD, and we review newer analytic strategies designed to examine cognitive asymmetries or discrepancies between higher-order cognitive functions versus fundamental skills. Finally, we provide a critical examination of the clinical concept of Mild Cognitive Impairment and offer suggestions for an increased focus on the impact of cerebrovascular disease (CVD) and CVD risk during the prodromal period of AD.

Neuropsychological contributions to the early identification of Alzheimer's disease

A wealth of evidence demonstrates that a prodromal period of Alzheimer's disease (AD) exists for some years prior to the appearance of significant cognitive and functional declines required for the clinical diagnosis. This prodromal period of decline is characterized by a number of different neuropsychological and brain changes, and reliable identification of individuals prior to the development of significant clinical symptoms remains a top priority of research. In this review we provide an overview of those neuropsychological changes. In particular, we examine specific domains of cognition that appear to be negatively affected during the prodromal period of AD, and we review newer analytic strategies designed to examine cognitive asymmetries or discrepancies between higher-order cognitive functions versus fundamental skills. Finally, we provide a critical examination of the clinical concept of Mild Cognitive Impairment and offer suggestions for an increased focus on the impact of cerebrovascular disease (CVD) and CVD risk during the prodromal period of AD.

Prevention of CIND by physical activity: different impact on VCI-ND compared with MCI

BACKGROUND

Cognitive impairment that does not meet the criteria for dementia ("Cognitive Impairment, No Dementia" -- CIND) is a heterogeneous category with an increased risk of dementia. While greater physical activity is generally associated with a lower odds of both dementia and CIND, whether this effect applies across subgroups is not known.

OBJECTIVES

To investigate the association between physical activity and the risk of vascular CIND (VCI-ND) or mild cognitive impairment (MCI).

METHODS

In the Canadian Study of Health and Aging community-dwelling cohort, of 4683 people who were not impaired at baseline, 3945 remained without cognitive impairment at 5 years, 454 were diagnosed with CIND, and 284 with dementia. Incident CIND and VCI-ND (n=163) and MCI (n=100) subtypes were investigated in relation to baseline physical activity, stratified by sex.

RESULTS

In women, moderate-high exercise was associated with a lower odds of CIND (OR=0.62, 95% CI=0.46-0.84) and VCI-ND (0.34, 0.18-0.63) relative to low exercise. There was no association for men or for MCI.

CONCLUSION

Exercise appears to reduce the risk of VCI-ND in women. Whether the lack of an effect of exercise on the odds of MCI reflects that 'prevented AD' is indistinguishable from MCI is an intriguing possibility that merits further study.

Mild cognitive impairment as predictor for Alzheimer's disease in clinical practice: effect of age and diagnostic criteria

BACKGROUND

We investigated whether the predictive accuracy of mild cognitive impairment (MCI) for Alzheimer-type dementia (AD) in a clinical setting is dependent on age and the definition of MCI used.

METHOD

Non-demented subjects older than 40 (n=320) who attended a memory clinic of a university hospital were reassessed 5 years later for the presence of AD. MCI was diagnosed according to the criteria of amnestic MCI, mild functional impairment (MFI), ageing-associated cognitive decline (AACD), and age-associated memory impairment (AAMI). The main outcome measure was the area under the curve (AUC) of a receiver operating characteristic (ROC) curve. Analyses were conducted on the entire sample and on subgroups of subjects aged 40-54, 55-69 and 70-85 years.

RESULTS

A diagnosis of AD at follow-up was made in 58 subjects. Four of them were in the 40-54 age group, 29 in the 55-69 age group and 25 in the 70-85 age group. The diagnostic accuracy in the entire sample was low to moderately high with AUCs ranging from 0.56 (AACD) to 0.75 (amnestic MCI). A good predictive accuracy with an AUC >0.80 was only observed in subjects aged 70-85 using the criteria of amnestic MCI (AUC=0.84).

CONCLUSIONS

The predictive accuracy of MCI for AD is dependent on age and the definition of MCI used. The predictive accuracy is good only for amnestic MCI in subjects 70-85 years. As subjects with prodromal AD are often younger than 70, the usefulness of MCI as predictor of AD in clinical practice is limited.

Lipid-lowering agents and the risk of cognitive impairment that does not meet criteria for dementia, in relation to apolipoprotein E status

Lipid-lowering agents (LLAs) might lower the risk of dementia, but any impact on other forms of cognitive impairment is not clear. We examined LLAs in relation to cognitive impairment, no dementia (CIND) and apolipoprotein E4 status. In a case control study from the Canadian Study of Health and Aging, cases (n = 347) had developed CIND between the first and second study waves and controls (n = 693) had no cognitive impairment at either time. LLA use was associated with a lower odds of incident CIND in those <80 years of age (OR 0.37; 95% CI 0.15-0.93) but not for those aged >or=80 years (OR 0.56; 95% CI 0.15-2.10). The reduced risk was significant for statins but not for other LLAs. Adjusting for apolipoprotein E4 status did not change the point estimates of the ORs. The greatest impact of LLAs was seen in the CIND subtype circumscribed memory impairment.

Mild cognitive impairment and the 7 uses of epidemiology

In 1907, Alzheimer's single case report of presenile dementia led to the condition being recognized as a rare disease of middle-aged people. In 1964, Roth and colleagues reported an epidemiologic survey showing that the same condition was in fact a relatively common disease of the elderly. In 1987, Katzman introduced the concept of brain reserve, suggesting how individuals could have Alzheimer disease pathology in their brains without clinically manifesting the disease. In 1999, Petersen described mild cognitive impairment (MCI) as an amnestic state, since broadened to include other cognitive deficits, which, in the majority of patients, was a prelude to the development of full-blown Alzheimer disease or other dementia. MCI today is in some ways analogous to Alzheimer disease a century ago. We recognize and describe MCI clinically, among patients with memory complaints, but we do not know its distribution, outcomes, and risk factors in the elderly population at large. All population-based studies to date have found MCI to be an unstable and heterogeneous entity with a far wider range of outcomes than in the clinical setting, including reversion to normal in a substantial proportion. However, these studies thus far have been purely descriptive, and retro-fitted on to existing studies of dementia, using measurements not necessarily appropriate for the assessment of MCI. This review will address what is known and what has yet to be determined about MCI from the perspectives of the classic 7 uses of epidemiology.

Is mild cognitive impairment a distinct clinical entity?

Mild cognitive impairment is a syndrome characterized by significant cognitive deficits in the absence of dementia. Persons with mild cognitive impairment have a high risk of developing Alzheimer’s disease and other dementias. However, opinion on whether mild cognitive impairment is a prodromal phase of Alzheimer’s disease and should be treated is divided. The first part of this article will address some of the controversies in mild cognitive impairment on which most researchers have now reached an agreement. Second, we will discuss some of the remaining major controversies in the field, and suggest some avenues for future research. The article will focus around two questions: Is mild cognitive impairment a distinct clinical entity and should it be treated as Alzheimer’s disease?

Cognitive impairment of acute onset in the Consortium to Investigate Vascular Impairment of Cognition (CIVIC) study: occurrence, correlates, and outcomes

OBJECTIVE

Having demonstrated that dementia of acute onset represents a distinct syndrome with distinct outcomes, the authors investigated whether similar attributes describe cognitive impairment of acute onset (CIAO).

METHODS

The authors conducted a secondary analysis of the Consortium to Investigate Vascular Impairment of Cognition study.

RESULTS

Ninety patients met our criteria for CIAO. Compared with cognitive impairment of gradual onset, CIAO was associated with vascular features (odds ratio [OR]: 12.3, 95% confidence interval [CI]: 3.2-47.9), dementias other than Alzheimer disease (OR: 6.5, 95% CI: 2.1-20.8), and decreased survival (hazard ratio: 2.8, 95% CI: 1.6-4.6).

CONCLUSIONS

Patients with CIAO are clinically identifiable and have distinct outcomes.

Older adults with cognitive complaints show brain atrophy similar to that of amnestic MCI

OBJECTIVE

To examine the neural basis of cognitive complaints in healthy older adults in the absence of memory impairment and to determine whether there are medial temporal lobe (MTL) gray matter (GM) changes as reported in Alzheimer disease (AD) and amnestic mild cognitive impairment (MCI).

METHODS

Participants were 40 euthymic individuals with cognitive complaints (CCs) who had normal neuropsychological test performance. The authors compared their structural brain MRI scans to those of 40 patients with amnestic MCI and 40 healthy controls (HCs) using voxel-based morphometry and hippocampal volume analysis.

RESULTS

The CC and MCI groups showed similar patterns of decreased GM relative to the HC group on whole brain analysis, with differences evident in the MTL, frontotemporal, and other neocortical regions. The degree of GM loss was associated with extent of both memory complaints and performance deficits. Manually segmented hippocampal volumes, adjusted for age and intracranial volume, were significantly reduced only in the MCI group, with the CC group showing an intermediate level.

CONCLUSIONS

Cognitive complaints in older adults may indicate underlying neurodegenerative changes even when unaccompanied by deficits on formal testing. The cognitive complaint group may represent a pre-mild cognitive impairment stage and may provide an earlier therapeutic opportunity than mild cognitive impairment. MRI analysis approaches incorporating signal intensity may have greater sensitivity in early preclinical stages than volumetric methods.

Memory Complaint Is Not Necessary for Diagnosis of Mild Cognitive Impairment and Does Not Predict 10-Year Trajectories of Functional Disability, Word Recall, or Short Portable Mental Status Questionnaire Limitations

OBJECTIVES

To evaluate the prevalence and utility of memory complaint in a geographically representative cohort and, in cases with mild cognitive impairment (MCI), to determine whether memory complaint alters 10-year trajectories of disability in activities of daily living (ADLs), Short Portable Mental Status Questionnaire (SPMSQ) score, and 20-item word recall.

DESIGN

Prospective cohort study.

SETTING

Washington and Iowa counties, Iowa.

PARTICIPANTS

Iowa Established Populations for Epidemiologic Studies of the Elderly (N = 3,673; aged > or =65; 61.3% female; 99.9% white).

MEASUREMENTS

Age, sex, education, SPMSQ score, 20-item word recall, ADL or instrumental ADL disability, and chronic medical conditions.

RESULTS

The prevalence of memory complaint was 34%. Although proportionally more cognitively impaired individuals were in the memory complaint group (34% vs 27%), the pattern of subclassification into cognitively intact and MCI Stage 1 and 2 subgroups was similar for people with and without memory complaint. Median SPMSQ score and number of words recalled at baseline were comparable across memory complaint categories in each subgroup. MCI participants without subjective memory complaint constituted a larger proportion of the overall sample than individuals with subjective memory complaint (460 (14%) vs 295 (8.9%)) and of persons objectively classified as having MCI (61% vs 39%). The distribution of individual 10-year change in ADL disability, SPMSQ score, and word recall were similar for those with and without memory complaint across all subgroups of cognitive impairment.

CONCLUSION

Memory complaint is not necessary for MCI diagnosis and does not distinguish cases with different progression rates in disability or cognitive impairment. 2006.

APOE genotype, vascular risk factors, memory test performance and the five-year risk of vascular cognitive impairment or Alzheimer's disease

The APOE epsilon4 gene and poor memory test performance have each been associated with an increased risk of developing dementia, but the relationship between these risk factors in predicting dementia is unclear. We examined the multivariate effects of APOE genotype, memory test performance and vascular risk factors in predicting incident Alzheimer's disease (AD) and vascular cognitive impairment (VCI) in the Canadian Study of Health and Aging. Delayed free recall was measured by the Buschke Cued Recall Test (BCRT). The study sample included 223 people who were identified as having no cognitive impairment (NCI) and either APOE epsilon3/epsilon3 or epsilon3/epsilon4 genotypes at the baseline clinical assessment. After 5 years, 182 (82%) still had NCI, 21 developed VCI (9%) and 20 AD (9%). Multivariate analyses demonstrated that APOE epsilon4 increased the risk of AD (OR, 3.48; CI, 1.15-10.48) but not VCI (OR, 0.89; CI, 0.24-3.27). Vascular risk factors increased the risk of VCI (OR, 2.18; CI, 1.36-3.51) but not AD (OR, 0.68; CI, 0.38-1.20). Lower BCRT scores conferred an increased risk of both VCI (OR, 1.75; CI, 1.27-2.42) and AD (OR, 1.86; CI, 1.29-2.67) but attenuated the APOE epsilon4 effect in AD. VCI and AD have different risk profiles and outcomes, but subtle memory difficulties may be an early feature of both.