Patterns of cognitive decline, conversion rates, and predictive validity for 3 models of MCI

Longitudinal Patterns and Predictors of Cognitive Impairment Classification Stability

OBJECTIVE

Classifications such as Cognitive Impairment, No Dementia (CIND) are thought to represent the transitory, pre-clinical phase of dementia. However, increasing research demonstrates that CIND represents a nonlinear, unstable entity that does not always lead to imminent dementia. The present study utilizes a longitudinal repeated measures design to gain a thorough understanding of CIND classification stability patterns and identify predictors of future stability. The objectives were to i) explore patterns of longitudinal stability in cognitive status across multiple assessments and ii) investigate whether select baseline variables could predict 6-year CIND stability patterns.

METHOD

Participants (N = 259) included older adults (aged 65-90 years) from Project MIND, a six-year longitudinal repeated measures design in which participants were classified as either normal cognition (NC) or CIND at each annual assessment. A latent transition analysis approach was adapted in order to identify and characterize transitions in CIND status across annual assessments. Participants were classified as either Stable NC, Stable CIND, Progressers, Reverters, or Fluctuaters. Multinomial logistic regression was employed to test whether baseline predictors were associated with cognitive status stability patterns.

RESULTS

The sample demonstrated high rates of reversion and fluctuation in CIND status across annual assessments. Additionally, premorbid IQ and CIND severity (i.e., single vs. multi-domain impairment) at baseline were significantly associated with select stability outcomes.

CONCLUSIONS

CIND status was unstable for several years following baseline assessment and cognitive reserve may delay or protect against demonstrable cognitive impairment. Further, consideration of cognitive impairment severity at the time of initial classification may improve CIND classifications.

Parameterizing Practice in a Longitudinal Measurement Burst Design to Dissociate Retest Effects From Developmental Change: Implications for Aging Neuroscience

Background: In longitudinal designs, the extraneous influence of retest effects can confound and obscure estimates of developmental change. The current study provides a novel approach to independently parameterize short-term retest effects and long-term developmental change estimates by leveraging a measurement burst design and three-level multilevel modeling. We further employ these short- and long-term slopes as predictors of cognitive status at long-term follow-up assessments.

Methods: Participants included 304 older adults from Project MIND: a longitudinal measurement burst study assessing cognitive performance across both biweekly sessions and annual retests. Participants were classified as either Healthy controls (HC) or Cognitively Impaired, not Demented (CIND) at baseline, the final burst assessment (Year 4), and at an additional four-year follow-up (Year 8). Response time inconsistencies (RTI) were computed at each burst occasion for a simple choice response time (CRT) task and a one-back response time (BRT) task. Three-level multilevel models were employed to simultaneously examine change in RTI for both CRT and BRT across weeks within years, as well as across years, in order to dissociate within-individual retest effects (short-term) from developmental (long-term) change slopes. Individual slopes were then extracted and utilized in a series of multinomial logistic regression equations to contrast short- vs. long-term RTI change as predictors of cognitive status.

Results: Separately parameterizing short- and long-term change estimates yielded distinct patterns of variation. CRT RTI remained stable across short-term weekly assessments, while significantly increasing across years. In contrast, BRT RTI decreased significantly across short-term assessments but showed no change across long-term assessments. After dissociating change estimates, short-term BRT as well as long-term CRT and BRT estimates predicted cognitive status at long-term follow-ups; increases in RTI, suggesting either an inability to benefit from retest or process-based developmental decline, were associated with an increased likelihood of being classified as CIND.

Conclusions: We showcase an innovative approach to dissociate retest effects from developmental change across and within individuals. Accurately parameterizing these distinct change estimates can both reduce systematic bias in longitudinal trend estimates as well as provide a clinically useful tool by utilizing retest effects to predict cognitive health and impairment.

Mild cognitive impairment in Aboriginal Australians

INTRODUCTION

Aboriginal Australians have among the highest rates of dementia worldwide, yet no study has investigated the subtypes, risk factors, or longer term outcomes of mild cognitive impairment (MCI) in this population.

METHODS

A total of 336 community-dwelling Aboriginal Australians aged ≥60 years participated in a longitudinal study, completing a structured interview at baseline. MCI (amnestic subtype, aMCI; non-amnestic subtype, naMCI) and dementia were diagnosed via cognitive screening, medical assessment, and clinical consensus. Associations between life-course factors and baseline MCI subtypes were examined using logistic regression. Conversion to dementia was assessed at 6-year follow-up.

RESULTS

Prevalent aMCI (n = 24) was associated with older age (odds ratio [OR] = 1.68, 95% confidence interval [CI]: 1.12 to 2.53), head injury (OR = 3.19, 95% CI: 1.35 to 7.56), symptoms of depression (OR = 1.52, 95% CI: 1.04 to 2.24), and lower blood pressure (OR = 0.53, 95% CI: 0.33 to 0.86). Prevalent naMCI (n = 29) was associated with low education (OR = 4.46, 95% CI: 1.53 to 13.05), unskilled work history (OR = 5.62, 95% CI: 2.07 to 13.90), higher body mass index (OR = 1.99, 95% CI: 1.30 to 3.04), and moderate to severe hearing loss (OR = 2.82, 95% CI: 1.06 to 7.55). A small proportion of MCI cases reverted to intact at follow-up (15%), but most remained stable (44%), developed dementia and/or died (41%).

DISCUSSION

Sociodemographic and clinical factors both contributed to baseline MCI and were distinct for MCI subtypes, with similar patterns of conversion to dementia for amnestic and non-amnestic MCI.

Is Benzodiazepine Use Associated With the Risk of Dementia and Cognitive Impairment–Not Dementia in Older Persons? The Canadian Study of Health and Aging

Background: The use of benzodiazepines in relation to cognitive decline remains an area of controversy in aging populations. Objective: This study aims to evaluate the risk of cognitive impairment–not dementia (CIND), Alzheimer disease (AD), and all-cause dementia with benzodiazepine use. The effect modification by sex was also investigated. Methods: Data come from the Canadian Study of Health and Aging, a 10-year multicentric study involving 10 263 participants randomly selected, 65 years and older, living in the community and in institutions. Current exposure to benzodiazepines was assessed in a face-to-face interview or self-reported in a questionnaire. Cox proportional hazard regression models, using age as time scale, were conducted to estimate hazard ratios, with adjustment for sex, education, smoking, alcohol intake, depression, physical activity, nonsteroidal anti-inflammatory drug use, and vascular comorbidities. Results: Data sets included 5281 participants for dementia as the outcome, 5015 for AD, and 4187 for CIND. Compared with nonusers, current use of benzodiazepines was associated with an increased risk of CIND (hazard ratio = 1.36; 95% CI = 1.08-1.72) in the simplest model. Results remained similar in the fully adjusted model (hazard ratio = 1.32; 95% CI = 1.04-1.68). There was no association between benzodiazepine use and the risk of dementia or AD. All these effects were similar between men and women. Conclusion and Relevance: Benzodiazepine use in older people from the general population is related to subsequent occurrence of cognitive dysfunction but not implicated in the pathogenesis of dementia or AD. Caution should be exercised when prescribing benzodiazepines to preserve global cognitive function.

Exposure to polychlorinated biphenyls and organochlorine pesticides and risk of dementia, Alzheimer's disease and cognitive decline in an older population: a prospective analysis from the Canadian Study of Health and Aging

BACKGROUND

Little attention has been paid to neurotoxicants on the risk of dementia. Exposure to known neurotoxicants such as polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides is suspected to have adverse cognitive effects in older populations.

OBJECTIVE

To assess whether plasma concentrations of PCBs and OC pesticides are associated with the risk of cognitive decline, Alzheimer's disease (AD) and of all-cause dementia in the Canadian older population.

METHODS

Analyses were based on data from the Canadian Study of Health and Aging, a 3-phase, 10-year population-based study of individuals aged 65+ years. Analyses included 669 clinically assessed subjects, of which 156 developed dementia including 108 incident cases of AD. Subjects were screened at each phase with the 100-point Modified Mini-Mental State Examination (3MS), a measurement of global cognitive function. Statistical analyses included Cox proportional hazards model when the outcome was dementia or AD, and a repeated-measure mixed model when the outcome was the 3MS score.

RESULTS

No association of PCB and OC pesticides with the risk of dementia and AD was observed. Elevated concentrations of PCB congeners nos 118, 153, 156, 163, and OC pesticides 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p'-DDT) and its metabolite 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) were significantly associated with cognitive decline as assessed with the 3MS. A posteriori analyses suggested that only p,p'-DDE was significantly related to a higher cognitive decline in time based on the 3MS among incident cases of dementia compared to subjects remaining nondemented.

CONCLUSION

PCB and OC pesticide plasma concentrations were not related to the incident diagnosis of neither dementia, nor AD. Using the 3MS scores as the outcome, higher concentrations of four PCB congeners and two OC pesticides were associated with lower cognitive performances in subjects. The association of p,p'-DDE with cognitive decline in time in incident cases of dementia merits further investigation.

Design, synthesis and evaluation of vilazodone-tacrine hybrids as multitarget-directed ligands against depression with cognitive impairment

Depression, a severe mental disease, is greatly difficult to treat and easy to induce other neuropsychiatric symptoms, the most frequent one is cognitive impairment. In this study, a series of novel vilazodone-tacrine hybrids were designed, synthesized and evaluated as multitarget agents against depression with cognitive impairment. Most compounds exhibited good multitarget activities and appropriate blood-brain barrier permeability. Specifically, compounds 1d and 2a exhibited excellent 5-HT_1A agonist activities (1d, EC₅₀ = 0.36 ± 0.08 nM; 2a, EC₅₀ = 0.58 ± 0.14 nM) and 5-HT reuptake inhibitory activities (1d, IC₅₀ = 20.42 ± 6.60 nM; 2a, IC₅₀ = 22.10 ± 5.80 nM). In addition, they showed moderate ChE inhibitory activities (1d, AChE IC₅₀ = 1.72 ± 0.217 μM, BuChE IC₅₀ = 0.34 ± 0.03 μM; 2a, AChE IC₅₀ = 2.36 ± 0.34 μM, BuChE IC₅₀ = 0.10 ± 0.01 μM). Good multitarget activities with goodt blood-brain barrier permeability of 1d and 2a make them good lead compounds for the further study of depression with cognitive impairment.

Temporal unfolding of declining episodic memory on the Free and Cued Selective Reminding Test in the predementia phase of Alzheimer's disease: Implications for clinical trials

Introduction

Free and Cued Selective Reminding Test (FCSRT) performance identifies patients with preclinical disease at elevated risk for developing Alzheimer's dementia, predicting diagnosis better than other memory tests.

Methods

Based on literature mapping FCSRT performance to clinical outcomes and biological markers, and on longitudinal preclinical data from the Baltimore Longitudinal Study of Aging, we developed the Stages of Objective Memory Impairment (SOMI) model. Five sequential stages of episodic memory decline are defined by Free Recall (FR) and Total Recall (TR) score ranges and years prior to dementia diagnosis. We sought to replicate the SOMI model using longitudinal assessments of 142 Einstein Aging Study participants who developed AD over 10 years.

Results

Time to diagnosis was at least seven years if FR was intact, at least four years if TR was intact, and two years if TR was impaired, consistent with SOMI model predictions. The SOMI identified incipient dementia with excellent sensitivity and specificity.

Discussion

The SOMI model provides an efficient approach for clinical trial cognitive screening in advance of more costly biomarker studies and ultimately in clinical practice, and provides a vocabulary for understanding AD biomarker patterns and for re-analysis of existing clinical trial data.

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.

Prognostic Significance of Mild Cognitive Impairment Subtypes for Dementia and Mortality: Data from the NEDICES Cohort

BACKGROUND

The predictive value of diverse subtypes of mild cognitive impairment (MCI) for dementia and death is highly variable.

OBJECTIVE

To compare the predictive value of several MCI subtypes in progression to dementia and/or mortality in the NEDICES (Neurological Disorders in Central Spain) elderly cohort.

METHODS

Retrospect algorithmic MCI subgroups were established in a non-dementia baseline NEDICES cohort using Spanish adaptations of the original Mini-Mental State Examination (MMSE-37) and Pfeffer's Functional Activities Questionnaire (Pfeffer-11). The presence of MCI was defined according two cognitive criteria: using two cut-offs points on the total MMSE-37 score. Five cognitive domains were used to establish the MCI subtypes. Functional capacity (Pfeffer-11) was preserved or minimally impaired in all MCI participants. The incident dementia diagnoses were established by specialists and the mortality data obtained from Spanish official registries.

RESULTS

3,411 participants without dementia were assessed in 1994-5. The baseline prevalence of MCI varied according to the MCI definition (4.3%-31.8%). The follow-up was a mean of 3.2 years (1997-8). The dementia incidence varied between 14.9 and 71.8 per 1,000/person-years. The dementia conversion rate was increased in almost all MCI subgroups (p >  0.01), and mortality rate was raised only in four MCI subtypes. The amnestic-multi-domain MCI (aMd-MCI) had the best dementia predictive accuracy (highest positive likelihood ratio and highest clinical utility when negative).

CONCLUSIONS

Those with aMd-MCI were at greatest risk of progression to dementia, as in other surveys and might be explored with increased attention in MCI research and in dementia preventive trials.

Cognition, even in the normal range, predicts disability: cross-sectional and prospective analyses of a population-based sample

OBJECTIVE

To determine if the modified mini-mental state examination (3MS) predicts functional status and if any effect on function is observed within the normal range of cognition.

DESIGN

Cohort study.

SETTING

Community-dwelling older adults in the Canadian province of Manitoba sampled in 1991 and followed in 1996.

PARTICIPANTS

Baseline sample of 1751 adults aged 65+ from a representative registry. Five years later, 1028 participants remained in the community and had no missing data.

MEASUREMENTS

The 3MS, age, gender, education, living arrangements, self-rated health, and depressive symptoms were self-reported. Functional status was assessed using the Older Americans Resource Survey, which was dichotomized into no/mild disability versus moderate/severe disability.

RESULTS

Baseline 3MS score predicted baseline functional status. This effect was a gradient across the entire 3MS score, extending into the normal range with no apparent threshold. In logistic regression models, the unadjusted odds ratio (OR, 95% confidence interval) for the association of 3MS score with disability was 0.94 (0.93, 0.95); the adjusted OR was 0.96 (0.95, 0.98) in models including age, gender, education, and other covariates. Baseline 3MS score also predicted functional status 5 years later: The unadjusted OR for disability was 0.94 (0.92, 0.95); the adjusted OR was 0.97 (0.95, 0.99). Again, the risk of functional impairment at time 2 was a gradient effect, extending into the normal range of baseline 3MS score.

CONCLUSIONS

The 3MS predicts functional decline, and this effect is a gradient effect. These results support the hypothesis that cognition is a continuum in risk.

Domain Transfer Learning for MCI Conversion Prediction

Machine learning methods have successfully been used to predict the conversion of mild cognitive impairment (MCI) to Alzheimer's disease (AD), by classifying MCI converters (MCI-C) from MCI nonconverters (MCI-NC). However, most existing methods construct classifiers using data from one particular target domain (e.g., MCI), and ignore data in other related domains (e.g., AD and normal control (NC)) that may provide valuable information to improve MCI conversion prediction performance. To address is limitation, we develop a novel domain transfer learning method for MCI conversion prediction, which can use data from both the target domain (i.e., MCI) and auxiliary domains (i.e., AD and NC). Specifically, the proposed method consists of three key components: 1) a domain transfer feature selection component that selects the most informative feature-subset from both target domain and auxiliary domains from different imaging modalities; 2) a domain transfer sample selection component that selects the most informative sample-subset from the same target and auxiliary domains from different data modalities; and 3) a domain transfer support vector machine classification component that fuses the selected features and samples to separate MCI-C and MCI-NC patients. We evaluate our method on 202 subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI) that have MRI, FDG-PET, and CSF data. The experimental results show the proposed method can classify MCI-C patients from MCI-NC patients with an accuracy of 79.4%, with the aid of additional domain knowledge learned from AD and NC.

Reducing false positive diagnoses in mild cognitive impairment: the importance of comprehensive neuropsychological assessment

BACKGROUND AND PURPOSE

Longitudinal studies of mild cognitive impairment (MCI) report that a sizeable proportion of MCI cases revert to normal levels of functioning over time. The rate of recovery from MCI indicates that existing MCI diagnostic criteria result in an unacceptably high rate of false positive diagnoses and lack adequate sensitivity and specificity.

METHODS

The aim of the present study was to identify a set of neuropsychological measures able to differentiate between true positive cases of MCI from those who were unimpaired at 11 months' follow-up.

RESULTS

A discriminant function analysis identified that a combination of measures of complex sustained attention, semantic memory, working memory, episodic memory and selective attention correctly classified outcome in more than 80% of cases. The rate of false positive diagnoses (5.93%) was considerably lower than is evident in previously published MCI studies.

CONCLUSIONS

The results of the present study indicate that the rate of false positive MCI diagnoses can be significantly reduced through the use of sensitive and specific neuropsychological measures of memory and non-memory functions.

Single-domain amnestic mild cognitive impairment identified by cluster analysis predicts Alzheimer's disease in the european prospective DESCRIPA study

BACKGROUND/AIMS

To identify prodromal Alzheimer's disease (AD) subjects using a data-driven approach to determine cognitive profiles in mild cognitive impairment (MCI).

METHODS

A total of 881 MCI subjects were recruited from 20 memory clinics and followed for up to 5 years. Outcome measures included cognitive variables, conversion to AD, and biomarkers (e.g. CSF, and MRI markers). Two hierarchical cluster analyses (HCA) were performed to identify clusters of subjects with distinct cognitive profiles. The first HCA included all subjects with complete cognitive data, whereas the second one selected subjects with very mild MCI (MMSE ≥28). ANOVAs and ANCOVAs were computed to examine whether the clusters differed with regard to conversion to AD, and to AD-specific biomarkers.

RESULTS

The HCAs identified 4-cluster solutions that best reflected the sample structure. One cluster (aMCIsingle) had a significantly higher conversion rate (19%), compared to subjective cognitive impairment (SCI, p < 0.0001), and non-amnestic MCI (naMCI, p = 0.012). This cluster was the only one showing a significantly different biomarker profile (Aβ42, t-tau, APOE ε4, and medial temporal atrophy), compared to SCI or naMCI.

CONCLUSION

In subjects with mild MCI, the single-domain amnestic MCI profile was associated with the highest risk of conversion, even if memory impairment did not necessarily cross specific cut-off points. A cognitive profile characterized by isolated memory deficits may be sufficient to warrant applying prevention strategies in MCI, whether or not memory performance lies below specific z-scores. This is supported by our preliminary biomarker analyses. However, further analyses with bigger samples are needed to corroborate these findings.

Prognosis of mild cognitive impairment in general practice: results of the German AgeCoDe study

PURPOSE

The concept of mild cognitive impairment (MCI) has recently been introduced into the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) as mild neurocognitive disorder, making it a formal diagnosis. We investigated the prognostic value of such a diagnosis and analyzed the determinants of the future course of MCI in the AgeCoDe study (German Study on Ageing, Cognition, and Dementia in Primary Care Patients).

METHODS

We recruited 357 patients with MCI aged 75 years or older from primary care practices and conducted follow-up with interviews for 3 years. Depending on the course of impairment over time, the patients were retrospectively split into 4 groups representing remittent, fluctuating, stable, and progressive courses of MCI. We performed ordinal logistic regression analysis and classification and regression tree (CART) analysis.

RESULTS

Overall, 41.5% of the patients had remission of symptoms with normal cognitive function 1.5 and 3 years later, 21.3% showed a fluctuating course, 14.8% had stable symptoms, and 22.4% had progression to dementia. Patients were at higher risk for advancing from one course to the next along this spectrum if they had symptoms of depression, impairment in more than 1 cognitive domain, or more severe cognitive impairment, or were older. The result on a test of the ability to learn and reproduce new material 10 minutes later was the best indicator at baseline for differentiating between remittent and progressive MCI. Symptoms of depression modified the prognosis.

CONCLUSIONS

In primary care, about one-quarter of patients with MCI have progression to dementia within the next 3 years. Assessments of memory function and depressive symptoms are helpful in predicting a progressive vs a remittent course. When transferring the concept of MCI into clinical diagnostic algorithms (eg, DSM-5), however, we should not forget that three-quarters of patients with MCI stayed cognitively stable or even improved within 3 years. They should not be alarmed unnecessarily by receiving such a diagnosis.

Lowered performance in working memory and attentional sub-processes are most prominent in multi-domain amnestic mild cognitive impairment subtypes

BACKGROUND

Research suggests that working memory and attention deficits may be present in mild cognitive impairment (MCI). However, the functional status of these domains within revised MCI subtypes remains unclear, particularly because previous studies have examined these cognitive domains with the same tests that were used to classify MCI subtypes. The aim of this study was to examine working memory and attention function in MCI subtypes on a battery of neuropsychological tests that were distinct from those used to classify MCI subtypes

METHODS

A total of 122 adults aged 60-90 years were classified at baseline as amnestic MCI, non-amnestic MCI, and multi-domain amnestic (a-MCI+). The attentional and working memory capacity of participants was examined using a battery of tests distinct from those used to classify MCI at screening.

RESULTS

The a-MCI+ group demonstrated the poorest performance on all working memory tasks and specific sub-processes of attention. The non-amnestic MCI group had lowered performance on visual span and complex sustained attention only. There was no evidence of either attentional or working memory impairment in the amnestic MCI participants.

CONCLUSION

When MCI cohorts are assessed on measures distinct from those used at classification, a-MCI+ subjects had the most compromised working memory and attention function. These results support previous findings that suggest a-MCI+ more closely resembles early stage Alzheimer's disease and those with a-MCI+ may be at increased rate of future cognitive decline compared to those with other MCI subtypes.

Impact of different operational definitions on mild cognitive impairment rate and MMSE and MoCA performance in transient ischaemic attack and stroke

BACKGROUND

Mild cognitive impairment (MCI) is at least as prevalent as dementia after transient ischaemic attack (TIA)/stroke and is increasingly recognised as an important outcome in observational studies and randomised trials. However, there is no consensus on how impairment should be defined, and numerous different criteria exist. Previous studies have shown that different criteria for cognitive impairment impact on prevalence rates in epidemiological studies. However, there are few data on how operational differences within established criteria (e.g. Petersen-MCI) affect measured impairment rates and the performance of short cognitive tests such as the Mini Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), particularly in cerebrovascular disease. We therefore evaluated the effect of different operational definitions on measured rates of Petersen-MCI and on reliability of short cognitive tests in patients with TIA and stroke.

METHODS

Consecutive patients underwent the MMSE, MoCA and neuropsychological battery ≥1 year after TIA or stroke in a population-based study. MCI was defined using the Petersen method and subclassified as single or multiple domain, both with (original) and without (modified) subjective memory impairment. Different cut-offs (>1, >1.5 and >2 standard deviations, SD) on a given test relative to published norms were compared together with use of single versus multiple tests to define domain impairment.

RESULTS

91 non-demented subjects completed neuropsychological testing (mean age ± SD 69.7 ± 11.6 years, 54 male, 49 stroke) at a mean of 3.1 ± 1.9 years after the index event. Rates of cognitive impairment ranged from 14/91 (15%) for MCI-original at >2 SD cut-off to 61/91 (67%) MCI-modified at >1 SD cut-off, and the proportion of MCI that was multiple domain varied, e.g. 24/46 (52%) versus only 5/27 (20%) at 1 versus 2 SD cut-off for MCI-modified. Requirement for subjective memory complaint approximately halved estimates [e.g. 17 (19%) vs. 39 (43%) for MCI at 1.5 SD cut-off, single test definition], whereas use of multiple tests versus a single test to define a cognitive domain had less impact. In general, diagnostic accuracy was higher, and optimal cut-offs lower, on MMSE and MoCA for multiple-domain versus single-domain MCI, but the MoCA appeared superior for detecting MCI-modified, whereas the MMSE performed well in detecting MCI-original.

CONCLUSION

Even within established criteria for MCI, differences in operational methodology result in 4-fold variation in MCI estimates. Optimal MMSE and MoCA cut-offs are lower, and reliability more similar, when criteria for MCI are more stringent. Our findings have implications for sample size and adjusted relative risk calculations in randomised trials and for comparisons between studies.

Factors predicting reversion from mild cognitive impairment to normal cognitive functioning: a population-based study

INTRODUCTION

Mild cognitive impairment (MCI) is associated with an increased risk of developing dementia. However, many individuals diagnosed with MCI are found to have reverted to normal cognition on follow-up. This study investigated factors predicting or associated with reversion from MCI to normal cognition.

METHODS

Our analyses considered 223 participants (48.9% male) aged 71-89 years, drawn from the prospective, population-based Sydney Memory and Ageing Study. All were diagnosed with MCI at baseline and subsequently classified with either normal cognition or repeat diagnosis of MCI after two years (a further 11 participants who progressed from MCI to dementia were excluded). Associations with reversion were investigated for (1) baseline factors that included diagnostic features, personality, neuroimaging, sociodemographics, lifestyle, and physical and mental health; (2) longitudinal change in potentially modifiable factors.

RESULTS

There were 66 reverters to normal cognition and 157 non-reverters (stable MCI). Regression analyses identified diagnostic features as most predictive of prognosis, with reversion less likely in participants with multiple-domain MCI (p = 0.011), a moderately or severely impaired cognitive domain (p = 0.002 and p = 0.006), or an informant-based memory complaint (p = 0.031). Reversion was also less likely for participants with arthritis (p = 0.037), but more likely for participants with higher complex mental activity (p = 0.003), greater openness to experience (p = 0.041), better vision (p = 0.014), better smelling ability (p = 0.040), or larger combined volume of the left hippocampus and left amygdala (p<0.040). Reversion was also associated with a larger drop in diastolic blood pressure between baseline and follow-up (p = 0.026).

DISCUSSION

Numerous factors are associated with reversion from MCI to normal cognition. Assessing these factors could facilitate more accurate prognosis of individuals with MCI. Participation in cognitively enriching activities and efforts to lower blood pressure might promote reversion.

The STROBE statement and neuropsychology: lighting the way toward evidence-based practice

Reporting appropriate research detail across clinical disciplines is often inconsistent or incomplete. Insufficient report detail reduces confidence in findings, makes study replication more difficult, and decreases the precision of data available for critical review including meta-analysis. In response to these concerns, cooperative attempts across multiple specialties have developed explicit research reporting standards to guide publication detail. These recommendations have been widely adopted by high impact medical journals, but have not yet been widely embraced by neuropsychology. The STROBE Statement (STrengthening the Reporting of Observational studies in Epidemiology) is particularly relevant to neuropsychology since clinical research is often based on non-funded studies of patient samples. In this paper we describe the STROBE Statement and demonstrate how STROBE criteria, applied to reporting of neuropsychological findings, will maintain neuropsychology's position as a leader in quantifying brain-behavior relationships. We also provide specific recommendations for data reporting and disclosure of perceived conflicts of interest that will further enhance reporting transparency for possible perceived sources of bias. In an era in which evidence-based practice assumes an increasingly prominent role, improved reporting standards will promote better patient care, assist in developing quality practice guidelines, and ensure that neuropsychology remains a vigorous discipline in the clinical neurosciences that consciously aspires to high methodological rigor.

The influence of cognitive impairment with no dementia on driving restriction and cessation in older adults

Cognitively impaired older adults may be at increased risk of unsafe driving. Individuals with insight into their own impairments may minimize their risk by restricting or stopping driving. The purpose of this study was to examine the influence of cognitive impairment on driving status and driving habits and intentions. Participants were classified as cognitively impaired, no dementia single (CIND-single), CIND-multiple, or not cognitively impaired (NCI) and compared on their self-reported driving status, habits, and intentions to restrict or quit driving in the future. The groups differed significantly in driving status, but not in whether they restricted their driving or reduced their driving frequency. CIND-multiple group also had significantly higher intention to restrict/stop driving than the NCI group. Reasons for restricting and quitting driving were varied and many individuals reported multiple reasons, both external and internal, for their driving habits and intentions. Regardless of cognitive status, none of the current drivers were seriously thinking of restricting or quitting driving in the next 6 months. It will be important to determine, in future research, how driving practices change over time and what factors influence decisions to restrict or stop driving for people with cognitive impairment.

Memory and Executive Screening (MES): a brief cognitive test for detecting mild cognitive impairment

Background

Mild cognitive impairment (MCI), defined as a transitional zone between normal cognition and dementia, requires a battery of formal neuropsychological tests administered by a trained rater for its diagnosis. The objective of this study was to develop a screening tool for MCI.

Methods

One hundred ninety seven cognitively normal controls (NC), one hundred sixteen patients with amnestic MCI –single domain (aMCI-sd), one hundred ninety five patients with amnestic MCI-multiple domain (aMCI-md), and two hundred twenty eight patients with mild Alzheimer’s disease (AD) were evaluated by comprehensive neuropsychological tests and by the Memory and Executive Screening (MES).

Results

Correlation analysis showed that the three indicators of the MES were significantly negatively related with age (P<0.05), yet not related with education (P>0.05). There was no ceiling or floor effect. Test completion averaged seven minutes (421.14±168.31 seconds). The receiver operating characteristics (ROC) analyses performed on the aMCI-sd group yielded 0.89 for the area under the curve (AUC) (95% CI, 0.85–0.92) for the MES-total score, with sensitivity of 0.795 and specificity of 0.828. There was 81% correct classification rate when the cut-off was set at less than 75. Meanwhile, the aMCI-md group yielded 0.95 for the AUC (95% CI, 0.93–0.97) for the MES-total score, with sensitivity of 0.87 and specificity of 0.91, and 90% correct classification rate when the cut-off was set at less than 72.

Conclusion

The MES, minimally time-consuming, may be a valid and easily administered cognitive screening tool with high sensitivity and specificity for aMCI, with single or multiple domain impairment.

Nonsteroidal anti-inflammatory drug use and the risk of cognitive impairment and Alzheimer's disease

BACKGROUND

Some observational studies have established an association between exposure to nonsteroidal anti-inflammatory drugs (NSAIDs) and a decreased risk of subsequently developing Alzheimer's disease (AD). Mild cognitive impairment or cognitive impairment, not dementia (CIND) is more likely to convert to AD, and no specific preventive method is currently available. The objective of this study was to determine the association of NSAID use in 5276 cognitively normal subjects of the Canadian Study of Health and Aging, a 10-year population-based cohort study, with the incidence of CIND, AD, and all-cause dementia.

METHODS

Hazard ratios were calculated from Cox proportional hazards models with age as the time scale according to three study samples including 824 cases of dementia (563 cases of AD), 630 cases of dementia (435 cases of AD), and 883 cases of CIND, respectively. Adjustments were made for gender, education, lifestyle factors, comorbid diseases, and vascular risk factors.

RESULTS

Lower risks for AD and all-cause dementia were significantly associated with the use of any NSAIDs and the salicylates without barbiturates subgroup in the study sample including subjects with CIND at baseline. There was a weak association between any NSAIDs and the risk of CIND (hazard ratio, 0.87; 95% confidence interval, 0.76-1.00).

CONCLUSION

These results suggest that there is an association between NSAID use and a lower incidence of AD and, to a lesser extent, of CIND.

Risk profiles of subtypes of mild cognitive impairment: the sydney memory and ageing study

OBJECTIVES

To compare the risk profiles of mild cognitive impairment (MCI) subtypes in a population-based elderly sample.

DESIGN

Cross-sectional study.

SETTING

The population-based Sydney Memory and Ageing Study.

PARTICIPANTS

Seven hundred fifty-seven English-speaking, community-dwelling individuals without dementia aged 70 to 90.

MEASUREMENTS

Comprehensive neuropsychological assessments were used to diagnose MCI and its subtypes, categorized as amnestic (aMCI) or nonamnestic (naMCI) and as single- (sdMCI) or multiple- (mdMCI) domain. Risk profiles were derived from sociodemographic; lifestyle; and cardiac, physical, mental, and general health data. Whole-sample and sex-specific comparisons between aMCI and naMCI and between mdMCI and sdMCI were made using age- (and sex-) adjusted multiple regressions comprising initially significant univariate factors.

RESULTS

Risk factors for MCI were presence of the apolipoprotein E (APOE) ε4 allele, heart disease, high homocysteine, poor odor identification ability, low visual acuity, and lower mental activity. The odds of having naMCI rather than aMCI were lower with greater levels of social activity and greater if taking antihypertensives, the latter particularly in men. The odds of naMCI were greater in men taking antidepressants or with a longer 6-meter walk time and in women with hypertension. The odds of having mdMCI rather than sdMCI were greater in participants with a history of depression or having the APOE ε4 allele. Greater odds of mdMCI were also associated with lower mental activity, particularly for women. For men, the odds of mdMCI were greater with the APOE ε4 allele and lower if diagnosed with high cholesterol.

CONCLUSION

MCI subtypes exhibit distinctive, sex-dependent risk profiles. This is consistent with MCI subtypes having different etiologies and outcomes and supports the idea that subtyping MCI may offer predictive validity and clinical application.

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.

Should mild cognitive impairment be subtyped?

PURPOSE OF REVIEW

To review evidence on the validity and utility of recent approaches to subtyping late-life mild cognitive impairment.

RECENT FINDINGS

There is growing evidence that amnestic mild cognitive impairment is associated with biomarkers for Alzheimer's disease, while nonamnestic mild cognitive impairment maps more closely to cerebrovascular disease. The former is more likely to progress to dementia than the latter. Mild impairment in multiple cognitive domains appears to represent a more advanced disease state than single-domain impairment, and is more likely to progress to dementia. The cognitive subtypes have imprecise boundaries and have limited ecological validity. Approaches to subtyping that also incorporate biomarkers increase diagnostic specificity and have greater predictive value. However, these approaches have yet to be validated outside specialized memory clinic populations.

SUMMARY

Mild cognitive impairment as currently defined is still etiologically and prognostically heterogeneous, particularly outside specialty clinical settings. The objective of further subtyping is to delineate subgroups that are more clinically homogeneous. The current cognitive subtypes have some validity and utility but additional approaches should be explored so as to enhance these properties.