Characterizing mild cognitive disorders in the young‐old over 8 years: Prevalence, estimated incidence, stability of diagnosis, and impact on IADLs

Estimating prevalence of early symptomatic Alzheimer's disease in the United States

INTRODUCTION

Understanding the prevalence of treatment-eligible Alzheimer's disease (AD) is crucial for policy planning.

METHODS

We used a comprehensive literature review and population cascade approach to estimate the number of amyloid-positive, clinically diagnosed patients with mild cognitive impairment (MCI) or mild dementia due to AD in the United States.

RESULTS

An estimated 666,646 individuals were identified as having MCI due to AD (range: 351,926-1,227,776) and 620,850 individuals as having mild dementia due to AD (range: 445,082-820,339). In a US population of 76 million individuals aged 60 or older in 2021, the estimates of MCI and mild dementia due to AD increased with age.

CONCLUSIONS

As earlier diagnosis of AD and new disease-modifying treatments become available, accurate population estimates are required to reduce uncertainty in the number of clinically diagnosed patients eligible for amyloid-targeting therapies.

Exploring the Impact of Age of Onset of Mild Cognitive Impairment on the Profile of Cognitive and Psychiatric Symptoms

The present study aims to explore the differences in the manifestation of cognitive decline and psychiatric symptoms across the different ages of MCI onset: early onset (EOMCI: <65 years old), middle onset (MOMCI: 65-75 years old), and late onset (LOMCI: >75 years old). It was hypothesized that individuals with EOMCI will preserve their cognitive functions to a greater extent as compared to individuals with LOMCI, even after adjusting the cognitive performance for age and education through the use of published Greek norms. The level of cognitive decline concerning MOMCI was evaluated for extracting more precise conclusions regarding the impact of the age of onset on the patterns of MCI symptomatology. The analyses of data were conducted in a Greek population of individuals with MCI, who were consecutive visitors of the Outpatient Memory Clinic of Nestor Alzheimer's Centre in Athens, Greece. The sample consisted of 297 participants who fulfilled the following inclusion criteria: MCI diagnosis based on Petersen's criteria, Greek mother language, and absence of a psychiatric history or chronic and incurable organic disease. The overall results support the presence of a cognitive advantage of the EOMCI group compared to the LOMCI group. In the MOMCI group, cognitive performance displayed a tendency to remain intermediate compared to the other two groups. Nonetheless, significant differences were observed when this group was compared with the LOMCI group. The current findings indicate that the age of onset should be taken under consideration in the neuropsychological assessment of individuals with MCI. The specific parameters could have implications in terms of prognosis as well as the design and implementation of tailored interventions.

Vitamin D status and cognitive performance in community-dwelling adults: A dose-response meta-analysis of observational studies

Low vitamin D status is linked with poorer cognition in adults while findings in relation to high levels are mixed.We performed a systematic review and meta-analyses to examine dose-response associations between 25-hydroxyvitamin D (25OHD) levelsand cognitive performance in community-dwelling adults. Thirty-eight observational studies were included in dose-response meta-analyses. Positive, nonlinear associations were identified between baseline25OHD levels and global cognition incross-sectional and longitudinal analyses, and for performance in memory and executive function in longitudinal analyses. When restricted to studies involving older adults, thepattern emerged forspecific domains in cross-sectional analyses. Poorer performance was associated with low 25OHD levels, while a sharp improvement was associated withlevels up to 60-70 nM/L. Further improvement was observed only for longitudinal global cognition. Our findings support the association between low vitamin D and poorer cognition and suggest levels of at least 60 nM/L are associated with better cognition during ageing.

Balance on the Brain: a randomised controlled trial evaluating the effect of a multimodal exercise programme on physical performance, falls, quality of life and cognition for people with mild cognitive impairment-study protocol

INTRODUCTION

Exercise and physical activity have been shown to improve cognition for people living with mild cognitive impairment (MCI). There is strong evidence for the benefits of aerobic exercise and medium evidence for participating in regular strength training for people with MCI. However, people living with MCI fall two times as often as those without cognitive impairment and the evidence is currently unknown as to whether balance training for people with MCI is beneficial, as has been demonstrated for older people without cognitive impairment. The aim of this study is to determine whether a balance-focused multimodal exercise intervention improves balance and reduces falls for people with MCI, compared with a control group receiving usual care.

METHODS AND ANALYSIS

This single blind randomised controlled trial (Balance on the Brain) will be offered to 396 people with MCI living in the community. The multimodal exercise intervention consists of two balance programmes and a walking programme to be delivered by physiotherapists over a 6-month intervention period. All participants will be followed up over 12 months (for the intervention group, this involves 6-month intervention and 6-month maintenance). The primary outcomes are (1) balance performance and (2) rate of falls. Physical performance, levels of physical activity and sedentary behaviour, quality of life and cognition are secondary outcomes. A health economic analysis will be undertaken to evaluate the cost-effectiveness of the intervention compared with usual care.

ETHICS AND DISSEMINATION

Ethics approval has been received from the South Metropolitan Health Service Human Research Ethics Committee (HREC), Curtin University HREC and the Western Australia Department of Health HREC; and approval has been received to obtain data for health costings from Services Australia. The results will be disseminated through peer-review publications, conference presentations and online platforms.

TRIAL REGISTRATION NUMBER

ACTRN12620001037998; Australian New Zealand Clinical Trials Registry (ANZCTR).

The complex burden of determining prevalence rates of mild cognitive impairment: A systematic review

Mild cognitive impairment (MCI) is a syndrome characterized by a decline in cognitive performance greater than expected for an individual's age and education level, but that does not interfere much with daily life activities. Establishing the prevalence of MCI is very important for both clinical and research fields. In fact, in a certain percentage of cases, MCI represents a prodromal condition for the development of dementia. Accordingly, it is important to identify the characteristics of MCI that allow us to predict the development of dementia. Also, initial detection of cognitive decline can allow the early implementation of prevention programs aimed at counteracting or slowing it down. To this end, it is important to have a clear picture of the prevalence of MCI and, consequently, of the diagnostic criteria used. According to these issues, this systematic review aims to analyze MCI prevalence, exploring the methods for diagnosing MCI that determine its prevalence. The review process was conducted according to the PRISMA statement. Three thousand one hundred twenty-one international articles were screened, and sixty-six were retained. In these studies, which involved 157,035 subjects, the prevalence of MCI ranged from 1.2 to 87%. The review results showed a large heterogeneity among studies due to differences in the subjects' recruitment, the diagnostic criteria, the assessed cognitive domains, and other methodological aspects that account for a higher range of MCI prevalence. This large heterogeneity prevents drawing any firm conclusion about the prevalence of MCI.

Predementia constructs: Mild cognitive impairment or mild neurocognitive disorder? A narrative review

BACKGROUND

Predementia is a heuristic umbrella concept to classify older adults with cognitive impairment who do not suffer dementia. Many diagnostic entities have been proposed to address this concept, but most of them have not had widespread acceptance.

AIMS

To review clinical definitions, epidemiologic data (prevalence, incidence) and rate of conversion to dementia of the main predementia constructs, with special interest in the two most frequently used: mild cognitive impairment (MCI) and minor neurocognitive disorder (miNCD).

METHODS

We have selected in three databases (MEDLINE, Web of Science and Google scholar) the references from inception to 31 December 2019 of relevant reviews, population and community-based surveys, and clinical series with >500 participants and >3 years follow-up as the best source of evidence.

MAIN RESULTS

The history of predementia constructs shows that MCI is the most referred entity. It is widely recognized as a clinical syndrome harbinger of dementia of several etiologies, mainly MCI due to Alzheimer's disease. The operational definition of MCI has shortcomings: vagueness of its requirement of "preserved independence in functional abilities" and others. The recent miNCD construct presents analogous difficulties. Current data indicate that it is a stricter predementia condition, with lower prevalence than MCI, less sensitivity to cognitive decline and, possibly, higher conversion rate to dementia.

CONCLUSIONS

MCI is a widely employed research and clinical entity. Preliminary data indicate that the clinical use of miNCD instead of MCI requires more scientific evidence. Both approaches have common limitations that need to be addressed.

Frailty and cognitive decline

Frailty and cognitive impairment are among the 2 most common geriatric syndromes. Their presence poses major risks to the elderly including greater disability, reduced quality of life, and higher morbi-mortality. Recent evidence suggest that frailty can be a risk factor for incident dementia. The opposite is also true since subjects with Alzheimer's disease and other dementia also present with more severe frailty measures. The mechanisms for the association between frailty and cognitive impairment is not clear, but possibly involves abnormalities in biological processes related to aging. Here, we will review the current evidence of the association between frailty and cognitive impairment. We will also review the possible biological mechanistic links between the 2 conditions. Finally, we will address potential therapeutic targets and interventions that can mitigate both conditions.

Diagnostic stability of schizophrenia: A systematic review

The objective is to systematically review previous literature on the diagnostic stability of schizophrenia, particularly to investigate prospective and retrospective consistency. We carried out a systematic literature search in PubMed and other minor sources from 1980 to July 2017. Specifically, prospective and retrospective consistency were examined. Thirty-nine studies were included, 5 focused on schizophrenia, 23 on psychotic episodes and 11 on psychiatric disorders in general. Samples sizes range from 60 to 10 058 subjects (total N = 39 965). The majority of studies (n = 26, 66.67%) were performed in Europe and North America and they had a prospective design (n = 27, 69.23%), with a median follow-up of 3 years. Prospective and retrospective consistency means were 84.29% and 67.15% respectively. Diagnostic change was also frequently measured (n = 12, mean 31.28%). The factors more commonly associated with diagnostic stability were: male sex, older age at the study inception, older age at onset, late stages of illness, family history of mental illness, poorer functioning and longer length of stay. Schizophrenia was found to have high diagnostic stability over time, although research on this topic is mainly focused in first psychotic episodes. More standardized methods are needed to further research diagnostic stability of schizophrenia over time and its determinants.

The relationship between basic, instrumental, and advanced activities of daily living and executive functioning in geriatric patients with neurocognitive disorders

OBJECTIVE

Although many studies explored the relationship between executive functions (EF) and activities of daily living (ADLs) in cognitive disorders, previous studies used measurements without well-defined levels of ADLs. This study explored the relationship between EF and the threefold classification of everyday functioning (basic or b-, instrumental or i-, and advanced or a-ADLs) and examined how EF account for the variance in this triad of everyday functioning.

METHODS

A sample of 44 cognitively healthy persons, 41 persons with mild cognitive impairment, and 35 persons with Alzheimer disease were assessed with comprehensive measures of EF and the b-, i-, and a-ADL tools.

RESULTS

Correlations demonstrated that subjects with higher executive dysfunctions have more limitations in b-, i-, and a-ADLs. The highest significant correlations with measures of EF were seen in i- and a-ADLs (ranging from r = -0.193 to r = -0.559, P < 0.05). However, correlations with a-ADLs were not stronger than with i-ADLs. The multivariate analyses revealed Trail Making Test A (TMT-A) as a significant contributor of everyday functioning in b-ADLs, as well as i- and a-ADLs, and Clock Drawing Test (CDT) and Animal Fluency Test (AFT) seemed to contribute significantly to variance in i- and a-ADLs.

CONCLUSIONS

EF are less related to b-ADLs than i- and a-ADLs and contribute to the same amount of variance to limitations in both i- and a-ADLs. This study recommends using the TMT-A, CDT, and AFT as screening tools to indicate the need for profound evaluation of ADLs in older persons with neurocognitive disorders.

The incidence of mild cognitive impairment: A systematic review and data synthesis

Introduction

Incidence estimates of mild cognitive impairment (MCI) range widely. We obtained contemporary age-specific MCI incidence rates and examined sources of heterogeneity.

Methods

We conducted a systematic review of population-based studies from the Americas, Europe, and Australia using restrictive inclusion criteria to limit heterogeneity. Incidence was examined using 5-year age categories for MCI and amnestic/nonamnestic subtypes. Data were synthesized using quantitative and qualitative descriptive analyses and quantitative meta-analyses.

Results

Meta-analysis estimates (95% CI) of MCI incidence per 1000 person-years were 22.5 (5.1-51.4) for ages 75-79y, 40.9 (7.7-97.5) for ages 80-84y, and 60.1 (6.7-159.0) for ages 85+y. Despite restrictive inclusion criteria, considerable heterogeneity (measured by I²) remained. Meta-analysis findings and simple descriptive statistics were consistent and supported by qualitative review.

Discussion

Heterogeneity in MCI incidence estimates persisted across age-specific estimates from population samples, likely reflecting differences in populations and methods. Incidence rate ranges are important to consider with summary point estimates.

Convergent and concurrent validity of a report- versus performance-based evaluation of everyday functioning in the diagnosis of cognitive disorders in a geriatric population

ABSTRACTBackground:Several methods have been developed to evaluate activities of daily living (ADLs) in mild cognitive impairment (MCI) and mild dementia. This study evaluated the convergent and concurrent validity between (1) two report-based methods (the advanced (a)- and instrumental (i)-ADL tools) and (2) a performance-based method (the Naturalistic Action Test (NAT)) to check if their ability to differentiate between cognitively healthy comparisons (HCs), persons with MCI, and persons with mild Alzheimer's disease (AD) are comparable to each other.

METHOD

This was a cross-sectional study, undertaken in a geriatric day hospital. The participants comprised community-dwelling HCs (n = 21, median age 78.0 years, 61.9% female), MCI (n = 20, median age 79.5 years, 55.0% female), and AD (n = 20, median age 80.0 years, 85.0% female) adults. A diagnostic procedure for neurocognitive disorders was employed. In addition, the a- and i-ADL tools and the NAT were administered separately by blinded raters.

RESULTS

The NAT and both the a- and i-ADL tools showed significant differences between HCs, MCI, and AD participants. Convergent validity showed moderate to strong significant correlations between the NAT, and a- and i-ADL tools (range -0.583 to -0.663; p &lt; 0.01). Concurrent validity showed that the NAT (AUC 0.809-1.000) and the a- and i-ADL tools (AUC 0.739-0.964) presented comparable discriminatory accuracy (p = 0.0588).

CONCLUSIONS

In contrast to prior studies comparing report-based and performance-based methods of assessing ADL, this study indicates that the NAT and the a- and i-ADL tools have strong convergent and concurrent validity, and appear to have similar discriminatory power in differentiating between HCs, MCI, and AD.

Changes in the Hippocampal Volume and Shape in Early-Onset Mild Cognitive Impairment

OBJECTIVE

The aim of this study was to examine the change in the hippocampal volume and shape in early-onset mild cognitive impairment (EO-MCI) associated with the APOE ε4 carrier state.

METHODS

This study had 50 subjects aged 55-63 years, all of whom were diagnosed with MCI at baseline via the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet. The EO-MCI patients were divided into the MCI continued (MCIcont) and Alzheimer's disease (AD) converted (ADconv) groups 2 years later. The hippocampal volume and shape were measured for all the subjects. The local shape analysis (LSA) was used to conduct based on the 2-year-interval magnetic resonance imaging scans.

RESULTS

There was a significant correlation between APOE ε4 allele and hippocampal volume atrophy. Over two years, the volume reduction in the left hippocampus was found to be faster than that in the right hippocampus, especially in the APOE ε4 carriers. LSA showed that the 2 subfields were significantly affected in the left hippocampus.

CONCLUSION

These results suggest that the possession of APOE ε4 allele may lead to greater predilection for left hippocampal atrophy in EO-MCI, and some specific subfields of the hippocampus may be more prominently involved.

A Longitudinal Analysis of General Practitioner Service Use by Patients with Mild Cognitive Disorders in Australia

BACKGROUND

The aim of this study was to ascertain if participants diagnosed with any mild cognitive disorder (MCD) visited a general practitioner (GP) more than those without MCD and the effect of either depression or arthritis on GP use longitudinally.

METHODS

2,551 participants aged 60-64 years at baseline completed the Personality and Total Health Through Life (PATH) study in Canberra. Follow-up data were collected after 4 and 8 years. A cognitive screening battery was used to screen participants into a substudy of MCD.

RESULTS

Participants with any MCD had greater GP use than cognitively healthy participants across all three waves (wave 1, M = 7.35 vs. 5.59; wave 2, M = 7.77 vs. 5.86; wave 3, M = 9.01 vs. 6.81). After adjusting for demographic and health factors, MCD was a significant predictor of GP use at all three waves (p < 0.05, CI 0.84-0.99).

CONCLUSION

This study has shown that MCD is associated with a higher use of GP visits, especially if the patient has a comorbid condition.

The epidemiology of driving in later life: Sociodemographic, health and functional characteristics, predictors of incident cessation, and driving expectations

AIM

To describe population-level characteristics of drivers and non-drivers in a cohort of older Australians and identify predictors of driving cessation and expectations.

METHODS

The sample comprised the oldest cohort of the PATH Through Life project who were assessed 4 times between 2001 and 2013. At waves 3 and 4 questions on driving were included in the study interview. Data were also collected on health, physical and cognitive function and psychosocial wellbeing. Descriptive analyses compared drivers and non-drivers on sociodemographic, health and functional variables and regression models identified predictors of cessation and driving expectations.

RESULTS

92.5% of the sample were current drivers. They reported better physical, mental and cognitive health than non-drivers. Drivers expected to drive for another 12.6 years, the majority drove 6+ days per week. Four percent of the sample ceased driving over the four year follow-up. Predictors of cessation were financial problems, driving expectations and driving fewer kilometres per week. Predictors of expectations were poorer self-rated health, mastery, difficulties reading maps, self-rated visual function, years of driving experience, and fewer kilometres driven per week.

CONCLUSION

Driving is normative for many older Australians in their 70s. Similar factors are associated with actual cessation and expectation of driving suggesting that older adults do have a sense of their expected driving life.

Effects of MCI subtype and reversion on progression to dementia in a community sample

OBJECTIVE

We sought to understand the trajectory of mild cognitive impairment (MCI) better by examining longitudinally different MCI subtypes and progression to dementia and reversion to normal cognition in a community sample.

METHODS

We evaluated the stability of MCI subtypes and risk of dementia over 4 biennial assessments as part of an ongoing prospective cohort study, the Sydney Memory and Ageing Study.

RESULTS

While prevalence of MCI and different MCI subtypes remains relatively stable across all assessments, reversion from MCI and transitions between different MCI subtypes were common. Up to 46.5% of participants classified with MCI at baseline reverted at some point during follow-up. The majority (83.8%) of participants with incident dementia were diagnosed with MCI 2 years prior to their dementia diagnosis. Both reverters and participants with stable MCI were at an increased risk of progression to dementia compared to those without MCI at baseline (HR 6.4, p = 0.02, and HR 24.7, p < 0.001, respectively); however, the risk of dementia in participants with MCI who did not revert was higher than in reverters (HR 2.5, p = 0.01). This effect was specific to amnestic subtypes (MCI reverters vs nonreverters: amnestic MCI HR 3.3, p = 0.006; nonamnestic MCI: HR 1.3, p = 0.67).

CONCLUSION

Our findings indicate that the relevance of reversion for progression risk depends on the MCI subtype. Subtype specificity and longitudinal characterization are required for the reliable identification of individuals at high risk of developing dementia.

Sex differences in the prevalence and incidence of mild cognitive impairment: A meta-analysis

OBJECTIVE

More women have Alzheimer's disease (AD) than men. Understanding sex differences in mild cognitive impairment (MCI) may further knowledge of AD etiology and prevention. We conducted a meta-analysis to examine sex differences in the prevalence and incidence of MCI, which included amnestic and non-amnestic subtypes.

METHOD

Systematic searches were performed in July 2015 using MEDLINE/PubMed, Scopus, and PsycINFO for population-or community-based studies with MCI data for men and women. Random-effects model were used.

RESULTS

Fifty-six studies were included. There were no statistically significant sex differences in prevalence or incidence of amnestic MCI. There was a significantly higher prevalence (p=0.038), but not incidence, of non-amnestic MCI among women. There were no sex differences in studies that combined both subtypes of MCI.

CONCLUSION

The only statistically significant finding emerging from this study was that women have a higher prevalence of non-amnestic MCI. To better understand sex differences in the preclinical stages of dementia, studies must better characterize the etiology of the cognitive impairment.

Validating the role of the Australian National University Alzheimer's Disease Risk Index (ANU-ADRI) and a genetic risk score in progression to cognitive impairment in a population-based cohort of older adults followed for 12 years

Background

The number of people living with dementia is expected to exceed 130 million by 2050, which will have serious personal, social and economic implications. Employing successful intervention and treatment strategies focused on disease prevention is currently the only available approach that can have an impact on the projected rates of dementia, with risk assessment being a key component of population-based risk reduction for identification of at-risk individuals. We evaluated a risk index comprising lifestyle, medical and demographic factors (the Australian National University Alzheimer’s Disease Risk Index [ANU-ADRI]), as well as a genetic risk score (GRS), for assessment of the risk of progression to mild cognitive impairment (MCI).

Methods

The ANU-ADRI was computed for the baseline assessment of 2078 participants in the Personality and Total Health (PATH) Through Life project. GRSs were constructed on the basis of 25 single-nucleotide polymorphisms previously associated with Alzheimer’s disease (AD). Participants were assessed for clinically diagnosed MCI and dementia as well as psychometric test-based MCI (MCI-TB) at 12 years of follow-up. Multi-state models were used to estimate the odds of transitioning from cognitively normal (CN) to MCI, dementia and MCI-TB over 12 years according to baseline ANU-ADRI and GRS.

Results

A higher ANU-ADRI score was associated with increased risk of progressing from CN to both MCI and MCI-TB (HR 1.07 [95% CI 1.04–1.11]; 1.07 [1.04–1.09]). The GRS was associated with transitions from CN to dementia (HR 4.19 [95% CI 1.72–10.20), but not to MCI or MCI-TB (HR 1.05 [95% CI 0.86–1.29]; 1.03 [0.87–1.21]). Limitations of our study include that the ethnicity of participants in the PATH project is predominately Caucasian, potentially limiting the generalisability of the results of this study to people of other ethnicities. Biomarkers of AD were not available to define MCI attributable to AD. Not all the predictive variables for the ANU-ADRI were available in the PATH project.

Conclusions

In the general population, the ANU-ADRI, comprising lifestyle, medical and demographic factors, is associated with the risk of progression from CN to MCI, whereas a GRS comprising the main AD risk genes was not associated with this risk. The ANU-ADRI may be used for population-level risk assessment and screening.

Electronic supplementary material

The online version of this article (doi:10.1186/s13195-017-0240-3) contains supplementary material, which is available to authorized users.

Assessment of Driving Safety in Older Adults with Mild Cognitive Impairment

BACKGROUND

With population aging, drivers with mild cognitive impairment (MCI) are increasing; however, there is little evidence available regarding their safety.

OBJECTIVE

We aimed to evaluate risk of unsafe on-road driving performance among older adults with MCI.

METHOD

The study was a cross-sectional observational study, set in Canberra, Australia. Participants were non-demented, current drivers (n = 302) aged 65 to 96 years (M = 75.7, SD = 6.18, 40% female) recruited through the community and primary and tertiary care clinics. Measures included a standardized on-road driving test (ORT), a battery of screening measures designed to evaluate older driver safety (UFOV®, DriveSafe, Multi-D), a neurocognitive test battery, and questionnaires on driving history and behavior.

RESULTS

Using Winblad criteria, 57 participants were classified as having MCI and 245 as cognitively normal (CN). While the MCI group had a significantly lower overall safety rating on the ORT (5.61 versus 6.05, p = 0.03), there was a wide range of driving safety scores in the CN and MCI groups. The MCI group performed worse than the CN group on the off-road screening tests. The best fitting model of predictors of ORT performance across the combined sample included age, the Multi-D, and DriveSafe, classifying 90.4% of the sample correctly.

CONCLUSION

Adults with MCI exhibit a similar range of driving ability to CN adults, although on average they scored lower on off-road and on-road assessments. Driving specific tests were more strongly associated with safety ratings than traditional neuropsychological tests.

Functional Disability in Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

Accumulating evidence suggests that the pre-dementia syndrome mild cognitive impairment (MCI) is characterized by decrements in instrumental activities of daily living (IADL). The current review was a quantitative synthesis of the available literature to objectively characterize IADL disability in MCI while clarifying inconsistencies in findings across studies. It was hypothesized that individuals with MCI would display significantly greater functional impairment relative to cognitively intact controls. Candidate moderators specified a priori included functional assessment approach, MCI subtype, depressive symptoms, and language conducted. Online databases (PubMed/MEDLINE and PsycINFO) and reference lists were searched to identify peer-reviewed publications assessing IADL in MCI compared to normal aging. A total of 151 effect sizes derived from 106 studies met inclusionary criteria (N = 62,260). Random effects models yielded a large overall summary effect size (Hedges' g = 0.76, 95 % confidence interval: 0.68 - 0.83, p < .001) confirmed in multi-level analyses adjusted for nesting of effect sizes within studies (g = 0.78, 95 % confidence interval: 0.69 - 0.87). Functional assessment strategy and MCI subtype were significant moderators of effect size, whereas depressive symptoms and language were not. Results convincingly demonstrate that MCI is associated with significant difficulties in the performance of complex everyday tasks. It appears that functional decline, like cognitive decline, exists on a continuum from healthy aging to dementia onset. Implications for clinical practice and research priorities are discussed.

Prognosis of Early-Onset vs. Late-Onset Mild Cognitive Impairment: Comparison of Conversion Rates and Its Predictors

BACKGROUND

Despite having the same histopathological characteristics, early-onset and late-onset Alzheimer's disease (AD) patients show some distinct clinical and neuropsychological profiles. Early Onset Mild Cognitive Impairment (EOMCI) is a less characterized group. The aim of this study is to characterize MCI probably due to AD in terms of the clinical, genetic, Cerebrospinal fluid (CSF) biomarkers profile and conversion rate of EOMCI, compared to the late-onset form (LOMCI).

METHODS

159 MCI patients were divided in two groups: 52 EOMCI (onset < 65 years) and 107 LOMCI (onset ≥ 65 years). We investigated differences in neuropsychological scores, clinical variables, ApoE genotype, CSF biomarkers (Aβ42, t-Tau and p-Tau) in both groups. Conversion was ascertained during follow-up.

RESULTS

EOMCI showed a longer duration of symptoms prior to the first evaluation (EOMCI = 4.57 vs. LOMCI = 3.31, p = 0.008) and scored higher on the subjective memory complaints scale (9.91 vs. 7.85, p = 0.008), but performed better in brief cognitive tests (27.81 vs. 26.51, p < 0.001 in Mini-Mental State Examination; 19.84 vs. 18.67, p = 0.005 in Montreal Cognitive Assessment) than LOMCI. ApoE genotype distribution and CSF biomarker profile were similar in both groups, as was the conversion risk. Lower Aβ42 (Hazard ratio (HR): 0.998, 95% Confidence Interval (CI) = [0.996⁻1.000], p = 0.042), higher t-Tau levels (HR: 1.003, 95%CI = [1.000⁻1.005], p = 0.039) and higher scores in the Alzheimer Disease Assessment Scale-Cognitive (HR: 1.186, 95%CI = [1.083⁻1.299], p = 0.002) increased the risk of conversion.

DISCUSSION

Despite differences in memory performance and memory complaints, EOMCI and LOMCI seem to represent indistinct biological groups that do not have a higher risk of conversion to AD or differ in risk factors for conversion.

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.

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.

Associations between a patient-reported outcome (PRO) measure of sarcopenia and falls, functional status, and physical performance in older patients with cancer

OBJECTIVE

In older patients with cancer, we aimed to investigate associations between a patient-reported outcome measure for sarcopenia (SarcoPRO) and the Short Physical Performance Battery (SPPB), self-reported falls, and limitations in instrumental activities of daily living (IADLs).

MATERIALS AND METHODS

Assessments were conducted as part of the initial evaluation of older, often frail, patients with cancer seen in the Specialized Oncology Care and Research in the Elderly (SOCARE) clinic. Univariate associations were evaluated using Spearman's correlation and Wilcoxon sign ranked tests. Logistic regressions were used to identify associations of clinical factors and SarcoPRO scores or SPPB scores with falls and IADL limitations.

RESULTS

In total, 174 older patients with cancer were evaluated. A moderate correlation was found between the SarcoPRO and the SPPB (ρ=0.62). After adjusting for multiple clinical factors, neither the SarcoPRO nor the SPPB were associated with falls. In contrast, both higher SarcoPRO (i.e., worse) and lower SPPB (i.e., worse) scores were associated with limitations in IADLs (odds ratio for one unit change in predictor: SarcoPRO: 1.06, p<0.0001; SPPB: 0.71, p=0.003, respectively). Models using the SarcoPRO and SPPB explained similar amounts of variability in association with IADL limitations (AUC: 0.88 vs. 0.87, respectively).

CONCLUSIONS

The SarcoPRO was moderately associated with the SPPB, an objective measure of physical performance, and was associated with limitations in IADLs. Thus, older patients with cancer who present with IADL limitations should be screened for sarcopenia. The SarcoPRO shows promise as a measure for screening as well as outcome assessment for research on sarcopenia.

Elevated rates of mild cognitive impairment in HIV disease

With the rising number of individuals in their 50s and 60s who are infected with HIV, concerns have emerged about possible increases in the rates of non-HIV-associated dementias. The current study examined the prevalence of mild cognitive impairment (MCI) in older HIV-infected adults, since MCI is an intermediate state between typical cognitive aging and dementia that emerges in this age range. Participants included 75 adults with HIV disease aged 50 years and older who were on combination antiretroviral therapy (cART) and had undetectable plasma viral loads and 80 demographically similar HIV-seronegative comparison subjects. Participants completed a research neuropsychological evaluation that was used to classify MCI according to the comprehensive diagnostic scheme described by Bondi et al. (J Alzheimers Dis 42:275-289, 2014). HIV-infected persons were over seven times more likely to have an MCI designation (16 %) than their seronegative counterparts (2.5 %). Within the HIV+ cohort, MCI had minimal overlap with diagnoses of asymptomatic neurocognitive impairment and was significantly associated with older age, lower Karnofsky Scale of Performance Scores, and mild difficulties performing instrumental activities of daily living (iADLs). HIV infection in older adults is associated with a notably elevated concurrent risk of MCI, which may increase the likelihood of developing non-HIV-associated dementias as this population ages further.

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.

Hippocampal atrophy is associated with subjective memory decline: The PATH Through Life study

OBJECTIVE

To investigate whether subjective memory decline (SMD) in cognitively healthy individuals is associated with hippocampal atrophy.

METHODS

Multiple regression analyses assessing the relationship between hippocampal atrophy over 4 years and SMD at baseline and follow-up in 305 cognitively healthy individuals aged 60-64 years free from dementia, mild cognitive impairment, and other neurological disorders.

RESULTS

SMD at baseline was not a significant predictor of hippocampal atrophy. However, SMD at follow-up was associated with greater hippocampal atrophy. Associations were reduced but remained significant after controlling for anxiety and depression symptomatology.

CONCLUSION

Hippocampal atrophy was associated with incident/persisting SMD and this association was not, or only partly, explained by anxiety and depression symptomatology. These results are consistent with a biological origin to subjective memory decline. SMD should be included in screening and neuropsychological batteries.

Blood pressure, brain structure, and cognition: opposite associations in men and women

BACKGROUND

Research on associations between blood pressure, brain structure, and cognitive function has produced somewhat inconsistent results. In part, this may be due to differences in age ranges studied and because of sex differences in physiology and/or exposure to risk factors, which may lead to different time course or patterns in cardiovascular disease progression. The aim of this study was to investigate the impact of sex on associations between blood pressure, regional cerebral volumes, and cognitive function in older individuals.

METHODS

In this cohort study, brachial blood pressure was measured twice at rest in 266 community-based individuals free of dementia aged 68-73 years who had also undergone a brain scan and a neuropsychological assessment. Associations between mean blood pressure (MAP), regional brain volumes, and cognition were investigated with voxel-wise regression analyses.

RESULTS

Positive associations between MAP and regional volumes were detected in men, whereas negative associations were found in women. Similarly, there were sex differences in the brain-volume cognition relationship, with a positive relationship between regional brain volumes associated with MAP in men and a negative relationship in women.

CONCLUSIONS

In this cohort of older individuals, higher MAP was associated with larger regional volume and better cognition in men, whereas opposite findings were demonstrated in women. These effects may be due to different lifetime risk exposure or because of physiological differences between men and women. Future studies investigating the relationship between blood pressure and brain structure or cognitive function should evaluate the potential for differential sex effects.

Normative data for 8 neuropsychological tests in older blacks and whites from the atherosclerosis risk in communities (ARIC) study

Accurate assessment of cognitive impairment requires comparison of cognitive performance in individuals to performance in a comparable healthy normative population. Few prior studies have included a large number of black participants and few have excluded participants from the normative sample with subclinical/latent neurological disease or dementia. This study provides age, race, and education-specific normative data for 8 cognitive tests derived from 320 black and 392 white participants aged 61 to 82 years (mean 71 y) in the Atherosclerosis Risk in Communities (ARIC) study without clinical or subclinical/latent neurological disease. Normative data are provided for the Delayed Word Recall Test, Logical Memory Parts I and II, the Word Fluency Test, Animal Naming, the Trail Making Test Parts A and B and the Digit Symbol Substitution Test. Age, race, and education-specific mean and -1.5 SD scores are given in tabular form and graphically, as well as regression-based equations to derive adjusted score cut-points. These robust normative data should enhance comparison across studies of cognitive aging, where these measures are widely used, and improve interpretation of performance on these tests for the diagnosis of cognitive impairment not only within the ARIC cohort, but also among older blacks and whites with similar demographics.

Brain pathology contributes to simultaneous change in physical frailty and cognition in old age

OBJECTIVE

First, we tested the hypothesis that the rate of change of physical frailty and cognitive function in older adults are correlated. Next, we examined if their rates of change are associated with the same brain pathologies.

METHODS

About 2,167 older adults participating in the Religious Orders Study and the Rush Memory and Aging Project had annual clinical evaluations. Bivariate random coefficient models were used to estimate simultaneously the rates of change in both frailty and cognition, and the correlation of change was characterized by a joint distribution of the random effects. Then, we examined whether postmortem indices from deceased were associated with the rate of change of frailty and cognition.

RESULTS

During an average follow-up of 6 years, frailty worsened by 0.09 unit/y and cognition declined by 0.08 unit/y. Most individuals showed worsening frailty and cognition (82.8%); 17% showed progressive frailty alone and <1% showed only cognitive decline. The rates of change of frailty and cognition were strongly correlated (ρ = -0.73, p < .001). Among deceased (N = 828), Alzheimer's disease pathology, macroinfarcts, and nigral neuronal loss showed independent associations with the rate of change in both frailty and cognition (all ps < .001). In these models, demographics explained about 9% of the variation in individual rate of change in frailty, and neuropathologies explained about 8%. In contrast, demographics and neuropathologies accounted for 2% and 30%, respectively, of the variance in the cognitive decline.

CONCLUSION

The rates of change in frailty and cognition are strongly correlated and this may be due in part because they share a common pathologic basis.

APOE and COMT polymorphisms are complementary biomarkers of status, stability, and transitions in normal aging and early mild cognitive impairment

Objective: Research has reported associations among selected genetic susceptibility biomarkers and risk of (a) normal cognitive aging decrements, (b) established mild cognitive impairment (MCI), and (c) sporadic Alzheimer's disease (AD). In focusing on the transitional normal-to-early MCI phase, we examine associations among three theoretically relevant polymorphisms (APOE [rs429358, rs7412], BDNF [rs6265], COMT [rs4680]) and both baseline cognitive status (MCI vs. normal aging) and two-wave (four-year) longitudinal stability or change profiles. The latter included three profiles: (a) stable as normal aging, (b) stable or chronic impairment (MCI-to-MCI), and (c) emergence of impairment (normal-to-MCI).

Method: Genotyped older adults (n = 237 at baseline; age range = 64–91; 62% women) from the Victoria Longitudinal Study were examined for (a) independent and interactive associations of three genetic polymorphisms with (b) two objectively classified cognitive status groups (not-impaired controls (NIC) and MCI) at (c) both baseline and across a two-wave (four-year) longitudinal interval.

Results: First, logistic regression revealed that the presence of at least one APOE ε4 allele (the risk factor for AD) was linked to greater baseline risk of objective MCI. Second, multinomial logistic regression revealed that (a) the presence of an APOE ε4 allele was associated with an increased risk of 4-year MCI status stability (chronicity), and (b) the COMT homozygous risk genotype (G/G or Val/Val) was associated with an increased risk of both MCI-to-MCI stability (chronicity) and emerging NIC-to-MCI conversion.

Discussion: Both chronicity and emergence of objectively classified early cognitive impairment may be genetically heterogeneous phenomena, with influences from a panel of both normal cognitive aging (COMT) and AD-related (APOE) polymorphisms.

Relating education, brain structure, and cognition: the role of cardiovascular disease risk factors

The protective effect of education on cognitive and brain health is well established. While the direct effects of individual cardiovascular disease (CVD) risk factors (i.e., hypertension, smoking, diabetes, and obesity) on cerebral structure have been investigated, little is understood about the possible interaction between the protective effect of education and the deleterious effects of CVD risk factors in predicting brain ageing and cognition. Using data from the PATH Through Life study (N = 266), we investigated the protective effect of education on cerebral structure and function and tested a possible mediating role of CVD risk factors. Higher education was associated with larger regional grey/white matter volumes in the prefrontal cortex in men only. The association between education and cognition was mediated by brain volumes but only for grey matter and only in relation to information processing speed. CVD risk factors did not mediate the association between regional volumes and cognition. This study provides additional evidence in support for a protective effect of education on cerebral structures and cognition. However, it does not provide support for a mediating role of CVD risk factors in these associations.

Cognitive correlates of functional abilities in individuals with mild cognitive impairment: comparison of questionnaire, direct observation, and performance-based measures

The relationship between, and the cognitive correlates of, several proxy measures of functional status were studied in a population with mild cognitive impairment (MCI). Participants were 51 individuals diagnosed with MCI and 51 cognitively healthy older adults (OA). Participants completed performance-based functional status tests and standardized neuropsychological tests, and performed eight activities of daily living (e.g., watered plants, filled medication dispenser) while under direct observation in a campus apartment. An informant interview about everyday functioning was also conducted. Compared to the OA control group, the MCI group performed more poorly on all proxy measures of everyday functioning. The informant report of instrumental activities of daily living (IADL) did not correlate with the two performance-based measures; however, both the informant-report IADL and the performance-based everyday problem-solving test correlated with the direct observation measure. After controlling for age and education, cognitive predictors did not explain a significant amount of variance in the performance-based measures; however, performance on a delayed memory task was a unique predictor for the informant-report IADL, and processing speed predicted unique variance for the direct observation score. These findings indicate that differing methods for evaluating functional status are not assessing completely overlapping aspects of everyday functioning in the MCI population.

Emergence of mild cognitive impairment in late middle-aged adults in the wisconsin registry for Alzheimer's prevention

AIM

It is difficult to reliably detect the earliest signs of Alzheimer's disease (AD)-associated cognitive impairment. Our aim was to compare 3 psychometric methods of identifying amnestic mild cognitive impairment (aMCI) in a middle-aged longitudinal cohort enriched for AD risk.

METHODS

Wisconsin Registry for Alzheimer's Prevention (WRAP) participants with 3 waves of cognitive assessment over approximately 6 years were coded as meeting each of 3 psychometric aMCI definitions: (a) 'aMCI standard-baseline' used published norms to establish cutoffs for baseline performance; (b) 'aMCI robust-baseline' applied WRAP-specific robust norms to baseline, and (c) 'aMCI robust-multiwave' applied these robust norms across 3 waves of assessment. Each group was compared to a cognitively healthy subset.

RESULTS

Half the aMCI standard-baseline and one third of the aMCI robust-baseline group reverted to normal ranges at follow-up. Only the aMCI robust-multiwave method had an aMCI × age interaction showing significantly worse age-related memory declines in the aMCI group compared to the cognitively healthy group over 6 years of follow-up.

CONCLUSION

Both cross-sectional methods showed instability over time, with many reverting to normal performance after baseline. The multiwave approach identified a group who showed progressive memory declines over 3 visits. Being able to detect progressive decline in late middle age is a critical step in improving prevention efforts.

Prevalence and correlates of mild cognitive impairment in adults aged over 50 years with subjective cognitive complaints in primary care centers

AIM

To examine the prevalence and correlates of mild cognitive impairment in adults aged over 50 years attending primary care centers with complaints of cognitive failure.

METHODS

A sample of 689 individuals aged ≥ 50 years with no previous diagnosis of dementia was assessed by use of the Mini-Mental State Examination, the Cambridge Cognitive Examination-Revised and the California Verbal Learning Test--to evaluate the mild cognitive impairment as dependent variables--and administration of a questionnaire on cognitive complaints and other instruments--to measure correlates.

RESULTS

The prevalence of mild cognitive impairment was 31.40%, and positive associations were found for age, occupation, subjective memory complaints, reading habits and level of vocabulary. In the logistic regression, modeled mild cognitive impairment was associated with age (70 years or older), subjective cognitive complaints and level of vocabulary.

CONCLUSION

Almost one-third of the adults aged ≥ 50 years attending primary care centers with subjective cognitive complaints were affected by mild cognitive impairment. Early evaluation of cognitive functioning is essential to establish adequate preventive and intervention strategies.