Identifying and characterizing trajectories of cognitive change in older persons with mild cognitive impairment

Trajectories and influencing factors of cognitive function and physical disability in Chinese older people

Introduction

Dementia and physical disability are serious problems faced by the aging population, and their occurrence and development interact.

Methods

Based on data from a national cohort of Chinese people aged 60 years and above from the China Health and Retirement Longitudinal Survey from 2011 to 2018, we applied the group-based trajectory model to identify the heterogeneous trajectories of cognitive function and physical disability in participants with different physical disability levels. Next, multinomial logistic regression models were used to explore the factors affecting these trajectories.

Results

The cognitive function trajectories of the Chinese older people could be divided into three characteristic groups: those who maintained the highest baseline level of cognitive function, those with a moderate baseline cognitive function and dramatic progression, and those with the worst baseline cognitive function and rapid-slow-rapid progression. The disability trajectories also fell into three characteristic groups: a consistently low baseline disability level, a low initial disability level with rapid development, and a high baseline disability level with rapid development. Compared with those free of physical disability at baseline, a greater proportion of participants who had physical disability at baseline experienced rapid cognitive deterioration. Education, income, type of medical insurance, gender, and marital status were instrumental in the progression of disability and cognitive decline in the participants.

Discussion

We suggest that the Chinese government, focusing on the central and western regions and rural areas, should develop education for the older people and increase their level of economic security to slow the rate of cognitive decline and disability among this age group. These could become important measures to cope with population aging.

The SNP rs6859 in NECTIN2 gene is associated with underlying heterogeneous trajectories of cognitive changes in older adults

BACKGROUND

Functional decline associated with dementia, including in Alzheimer's disease (AD), is not uniform across individuals, and respective heterogeneity is not yet fully explained. Such heterogeneity may in part be related to genetic variability among individuals. In this study, we investigated whether the SNP rs6859 in nectin cell adhesion molecule 2 (NECTIN2) gene (a major risk factor for AD) influences trajectories of cognitive decline in older participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI).

METHODS

We retrospectively analyzed records on 1310 participants from the ADNI database for the multivariate analysis. We used longitudinal measures of Mini-Mental State Examination (MMSE) scores in participants, who were cognitively normal, or having AD, or other cognitive deficits to investigate the trajectories of cognitive changes. Multiple linear regression, linear mixed models and latent class analyses were conducted to investigate the association of the SNP rs6859 with MMSE.

RESULTS

The regression coefficient per one allele dose of the SNP rs6859 was independently associated with MMSE in both cross-sectional (-2.23, p < 0.01) and linear mixed models (-2.26, p < 0.01) analyses. The latent class model with three distinct subgroups (class 1: stable and gradual decline, class 2: intermediate and late decline, and class 3: lowest and irregular) performed best in the posterior classification, 42.67% (n = 559), 21.45% (n = 281), 35.88% (n = 470) were classified as class 1, class 2, and class 3. In the heterogeneous linear mixed model, the regression coefficient per one allele dose of rs6859 - A risk allele was significantly associated with MMSE class 1 and class 2 memberships and related decline; Class 1 (-2.28, 95% CI: -4.05, -0.50, p < 0.05), Class 2 (-5.56, 95% CI: -9.61, -1.51, p < 0.01) and Class 3 (-0.37, 95% CI: -1.62, 0.87, p = 0.55).

CONCLUSIONS

This study found statistical evidence supporting the classification of three latent subclass groups representing complex MMSE trajectories in the ADNI cohort. The SNP rs6859 can be suggested as a candidate genetic predictor of variation in modeling MMSE trajectory, as well as for identifying latent classes with higher baseline MMSE. Functional studies may help further elucidate this relationship.

Understanding factors associated with the trajectory of subjective cognitive complaints in groups with similar objective cognitive trajectories

BACKGROUND

Cognitive complaints are often regarded as an early sign of Alzheimer's disease (AD) but may also occur in several other conditions and contexts. This study examines the correlates of cognitive complaint trajectories over a 5-year period in individuals who shared similar objective cognitive trajectories.

METHODS

We analyzed a subsample (n = 1748) of the MEMENTO cohort, consisting of individuals with subjective cognitive decline or mild cognitive impairment at baseline. Participants were stratified based on their latent MMSE trajectory over a 5-year period: "high and increasing," "subtle decline," and "steep decline." Within each of the three strata, we used a latent-class longitudinal approach to identify distinct trajectories of cognitive complaints. We then used multiple logistic regressions to examine the association between these complaint trajectories and several factors, including AD biomarkers (blood pTau/Aβ42 ratio, cortical thickness, APOE genotype), anxiety, depression, social relationships, a comorbidity-polypharmacy score, and demographic characteristics.

RESULTS

Among participants with high and increasing MMSE scores, greater baseline comorbidity-polypharmacy scores (odds ratio (OR) = 1.30, adjusted p = 0.03) were associated with higher odds of moderate and increasing cognitive complaints (as opposed to mild and decreasing complaints). Baseline depression and social relationships also showed significant associations with the complaint pattern but did not survive correction for multiple comparisons. Among participants with subtle decline in MMSE scores, greater baseline depression (OR = 1.76, adjusted p = 0.02) was associated with higher odds of moderate and increasing cognitive complaints (versus mild and decreasing). Similarly, baseline comorbidity-polypharmacy scores and pTau/Aβ42 ratio exhibited significant associations, but they did not survive correction. Among participants with a steep decline in MMSE scores, greater baseline comorbidity-polypharmacy scores increased the odds of moderate complaints (versus mild, OR = 1.38, unadjusted p = 0.03, adjusted p = 0.32), but this effect did not survive correction for multiple comparisons.

CONCLUSIONS

Despite similar objective cognitive trajectory, there is heterogeneity in the subjective perception of these cognitive changes. This perception was explained by both AD-related and, more robustly, non-AD-related factors. These findings deepen our understanding of the multifaceted nature of subjective cognitive complaints in individuals at risk for dementia and underscore the importance of considering a range of factors when interpreting cognitive complaints.

Uncovering heterogeneous cognitive trajectories in mild cognitive impairment: a data-driven approach

BACKGROUND

Given the complex and progressive nature of mild cognitive impairment (MCI), the ability to delineate and understand the heterogeneous cognitive trajectories is crucial for developing personalized medicine and informing trial design. The primary goals of this study were to examine whether different cognitive trajectories can be identified within subjects with MCI and, if present, to characterize each trajectory in relation to changes in all major Alzheimer's disease (AD) biomarkers over time.

METHODS

Individuals with a diagnosis of MCI at the first visit and ≥ 1 follow-up cognitive assessment were selected from the Alzheimer's Disease Neuroimaging Initiative database (n = 936; age 73 ± 8; 40% female; 16 ± 3 years of education; 50% APOE4 carriers). Based on the Alzheimer's Disease Assessment Scale-Cognitive Subscale-13 (ADAS-Cog-13) total scores from baseline up to 5 years follow-up, a non-parametric k-means longitudinal clustering method was performed to obtain clusters of individuals with similar patterns of cognitive decline. We further conducted a series of linear mixed-effects models to study the associations of cluster membership with longitudinal changes in other cognitive measures, neurodegeneration, and in vivo AD pathologies.

RESULTS

Four distinct cognitive trajectories emerged. Cluster 1 consisted of 255 individuals (27%) with a nearly non-existent rate of change in the ADAS-Cog-13 over 5 years of follow-up and a healthy-looking biomarker profile. Individuals in the cluster 2 (n = 336, 35%) and 3 (n = 240, 26%) groups showed relatively mild and moderate cognitive decline trajectories, respectively. Cluster 4, comprising about 11% of our study sample (n = 105), exhibited an aggressive cognitive decline trajectory and was characterized by a pronouncedly abnormal biomarker profile.

CONCLUSIONS

Individuals with MCI show substantial heterogeneity in cognitive decline. Our findings may potentially contribute to improved trial design and patient stratification.

Caregivers' depressive symptom trajectories and risk of cognitive impairment among older adults with functional limitations: A prospective cohort study

OBJECTIVES

Caregiver (CG)'s depression is common and its prevalence is rising. The relationship of CG depression with care recipients (CR)'s subsequent cognitive impairment remains unclear. This study examines the association of CG depressive symptoms trajectories with 6-year cognitive impairment risk among care recipients (CR) who are older adults with functional limitations.

METHODS

Retrospective analysis of prospectively collected data cohorts from 2010 to 2016. The sample included 810 community-dwelling older adults aged ≥75 years, dementia free at baseline, with their primary caregiver dyads. CG's depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale. The main outcomes were incident mild, moderate, and severe cognitive impairment of CRs measured using Short Portable Mental Status Questionnaire. Group-based trajectory modeling identified three CG depressive symptom trajectory groups. Competing risks regression analysis modeled the hazards as a function of CG depressive symptom trajectories.

RESULTS

Of 810 CRs, 3% developed severe cognitive impairment, 21% had moderate cognitive impairment, and 37% had mild cognitive impairment. Only CG's "Increasing" trajectory group predicted increased risk of CR's mild and moderate cognitive impairment relative to "persistently low" group (subhazard ratio [SHR] = 1.52, 95% confidence interval [CI], p < 0.05; SHR = 1.87, 95% CI, p < 0.05, respectively).

CONCLUSIONS AND IMPLICATIONS

Finding highlight the intricate and non-linear association between CG depressive trajectory and CR cognitive impairment. This evidence can be used to enlighten policymakers and health providers about the need for risk stratification screening for CG mental health and early treatment for CG depression to prevent or delay CR's cognitive impairment.

Self-Administered Gerocognitive Examination: longitudinal cohort testing for the early detection of dementia conversion

Background

Significant cognitive changes as individuals’ age are not being identified in a timely manner, delaying diagnosis and treatments. Use of brief, multi-domain, self-administered, objective cognitive assessment tools may remove some barriers in assessing and identifying cognitive changes. We compared longitudinal Self-Administered Gerocognitive Examination (SAGE) test scores to non-self-administered Mini-Mental State Examination (MMSE) scores in 5 different diagnostic subgroups.

Methods

A cohort study evaluating annual rates of change was performed on 665 consecutive patients from Ohio State University Memory Disorders Clinic. Patients with at least two visits 6 months apart evaluated with SAGE and MMSE and classified according to standard clinical criteria as subjective cognitive decline (SCD), mild cognitive impairment (MCI), or Alzheimer’s disease (AD) dementia were included. The pattern of change in SAGE scores was compared to MMSE. One way and repeated measures ANOVA and linear regression models were used.

Results

Four hundred twenty-four individuals (40 SCD, 94 MCI non-converters to dementia, 70 MCI converters to dementia (49 to AD dementia and 21 to non-AD dementia), 220 AD dementia) met inclusion criteria. SAGE and MMSE scores declined respectively at annual rates of 1.91 points/year (p < 0.0001) and 1.68 points/year (p < 0.0001) for MCI converters to AD dementia, and 1.82 points/year (p < 0.0001) and 2.38 points/year (p < 0.0001) for AD dementia subjects. SAGE and MMSE scores remained stable for SCD and MCI non-converters. Statistically significant decline from baseline scores in SAGE occurred at least 6 months earlier than MMSE for MCI converters to AD dementia (14.4 vs. 20.4 months), MCI converters to non-AD dementia (14.4 vs. 32.9 months), and AD dementia individuals (8.3 vs. 14.4 months).

Conclusions

SAGE detects MCI conversion to dementia at least 6 months sooner than MMSE. Being self-administered, SAGE also addresses a critical need of removing some barriers in performing cognitive assessments. Limitations of our single-site cohort study include potential referral and sampling biases. Repetitively administering SAGE and identifying stability or decline may provide clinicians with an objective cognitive biomarker impacting evaluation and management choices.

Cognitive trajectories in multiple sclerosis: a long-term follow-up study

BACKGROUND

Cognitive impairment occurs in multiple sclerosis (MS) and undergoes a progressive worsening over disease course. However, clinicians still struggle to predict the course of cognitive function. To evaluate baseline clinical and imaging predictors of cognitive abilities worsening over time, we performed a latent trajectory analysis for cognitive performances in MS patients, up to 15 years from disease onset.

METHODS

We collected age, sex, education, dominant and non-dominant 9-hole peg test (9HP) and timed 25-foot walk (T25-FW) as well as MRI measures (grey matter volume and lesion load) within 6 months from disease diagnosis for relapsing-remitting MS (RR-MS) patients. At diagnosis and over the follow-up, we also assessed cognitive status through the symbol digit modalities test (SDMT). Cognitive impairment was defined by applying age-, gender- and education-adjusted normative values. Group-based trajectory analysis was performed to determine trajectories, and the predictive value of clinical and imaging variables at baseline was assessed through multinomial logistic regression.

RESULTS

We included 148 RR-MS (98 females and 50 males). Over 11 ± 4 year follow-up, 51.4% remained cognitively stable whereas 48.6% cognitively worsened. Cognitively worsening patients had a higher T25FW time (p = 0.004) and a reduced hippocampal volume at baseline (p = 0.04).

CONCLUSION

Physical disability as well as hippocampal atrophy might depict patients at risk of cognitive worsening over the disease course. Therefore, using such predictors, clinicians may select patients to carefully evaluate for cognitive impairment as to eventually introduce cognitive rehabilitation treatments.

Dual Trajectories of Social Isolation and Dementia in Older Adults: A Population-Based Longitudinal Study

Objectives: To identify the interrelations between the trajectories of social isolation and dementia in older adults. Methods: Data came from the National Health and Aging Trends Study 2011-2018 surveys. Group-based dual trajectory modeling was used to examine trajectories and their interrelations. Results: Four trajectories of social isolation-rarely isolated (62.2%), steady increase (13.5%), steady decrease (7.4%), and persistently isolated (16.9%) and dementia risk-persistently low risk (80.4%), increasing with early onset (3.9%), increasing with late onset (4.5%), and persistently high risk (11.2%) emerged. Two-thirds of the low-risk dementia group were in the rarely isolated group. The high-risk dementia group had the most overlap with the decreasing social isolation group (47%), followed by the persistently isolated group (28%). Conclusions: Social isolation and dementia mostly evolved in the same direction. However, the pattern of associations between these trajectories is intricate and may be reversed among long-term dementia survivors.

Evaluating trajectories of episodic memory in normal cognition and mild cognitive impairment: Results from ADNI

BACKGROUND

Memory assessment is a key factor for the diagnosis of cognitive impairment. However, memory performance over time may be quite heterogeneous within diagnostic groups.

METHOD

To identify latent trajectories in memory performance and their associated risk factors, we analyzed data from Alzheimer's Disease Neuroimaging Initiative (ADNI) participants who were classified either as cognitively normal or as Mild Cognitive Impairment (MCI) at baseline and were administered the Rey Auditory Verbal Learning test (RAVLT) for up to 9 years. Group-based trajectory modeling on the 30-minute RAVLT delayed recall score was applied separately to the two baseline diagnostic groups.

RESULTS

There were 219 normal subjects with mean age 75.9 (range from 59.9 to 89.6) and 52.5% male participants, and 372 MCI subjects with mean age 74.8 (range from 55.1 to 89.3) and 63.7% male participants included in the analysis. For normal subjects, six trajectories were identified. Trajectories were classified into three types, determined by the shape, each of which may comprise more than one trajectory: stable (~30% of subjects), curvilinear decline (~ 28%), and linear decline (~ 42%). Notably, none of the normal subjects assigned to the stable stratum progressed to dementia during the study period. In contrast, all trajectories identified for the MCI group tended to decline, although some participants were later re-diagnosed with normal cognition. Age, sex, and education were significantly associated with trajectory membership for both diagnostic groups, while APOE ɛ4 was only significantly associated with trajectories among MCI participants.

CONCLUSION

Memory trajectory is a strong indicator of dementia risk. If likely trajectory of memory performance can be identified early, such work may allow clinicians to monitor or predict progression of individual patient cognition. This work also shows the importance of longitudinal cognitive testing and monitoring.

Reliably Measuring Cognitive Change in the Era of Chronic HIV Infection and Chronic HIV-Associated Neurocognitive Disorders

HIV infection has become a chronic disease managed across the life span. In this context, the cognitive health of HIV infection needs to have methods for monitoring over time, in order to better anticipate HIV-associated neurocognitive disorder (HAND) trajectories in relation to biomarkers, and predict prognosis and especially the risk of dementia as People Living with HIV (PLHIV) age. In this chapter, we critically review several statistical frameworks to quantify cognitive change. We then provide a critical review of naturalistic longitudinal studies and selected randomized clinical trials assessing neurocognitive change as a primary outcome in PLHIV, conducted since the advent of the combined antiretroviral therapy era (censored January 2019). Doing so, we distinguish between PLHIV who were treated early and did not experience AIDS (CDC 1993), versus treated late, after experiencing AIDS and more severe immune compromise. Highlighting strengths and limitations of these studies, we emphasize that issues of reliability pertaining to the use of neuropsychological tests need careful consideration for the robust quantification of cognitive change, including measurement error, practice effect, inter-individual variability, baseline level of functioning, demographic effects, timeframe between testing intervals, normative longitudinal data, and operationalization of clinically meaningful neurocognitive change. In addition, issues pertaining to longitudinal analyses including type, amount and pattern of missing data and/or participant attrition, regression toward the mean, and survivor bias need to be properly addressed. We conclude by proposing future research directions with emphasis on research translation to clinical participants.

Cognition and drug adherence to oral hypoglycemic and antihypertensive agents in older adults

Background and objectives: Chronic disorders such as diabetes mellitus type II and hypertension have been associated with cognitive decline in older adults. It is unclear whether adherence to antihypertensive and oral hypoglycemic agents impact cognitive health. The objectives are to study the association between adherence to antihypertensive and oral hypoglycemic agents and cognitive status in community-living older adults. Methods: We used data from a large representative sample of older adults (N=2,286) covered under a public drug insurance plan in Quebec and participating in Quebec's health survey on older adults (ESA-study) with a Mini-Mental State Examination (MMSE) score ≥22 at baseline (T1) and examined one year later (T2). Participants with hypertension and diabetes mellitus type II were identified according to criteria used in the Canadian Chronic Disease Surveillance System. Antihypertensive and oral hypoglycemic prescriptions delivered were ascertained via Quebec's pharmaceutical database (RAMQ). Medication adherence was calculated using the medication possession ratio as a continuous variable in the year prior to and following baseline interview. Multivariate linear regressions were used to study the percentage change in MMSE scores between interviews (T1,T2) as a function of adherence to antihypertensive and oral hypoglycemic agents (before and after T1) controlling for potential confounders. Results: In participants with diabetes mellitus type II only, adherence to oral hypoglycemics was not associated with a change in MMSE scores. In participants with hypertension only, the change in MMSE scores was associated with adherence to antihypertensives (β 1.23; 95%CI: 0.29-2.17). In participants with comorbid hypertension and diabetes mellitus type II, the change in MMSE scores was associated with adherence to both antihypertensive and oral hypoglycemic agents (β 0.75; 95%CI: 0.01-1.48). Conclusions: Adherence to oral hypoglycemic agents and antihypertensive agents among older adults with hypertension and comorbid diabetes mellitus type II can have a preserving effect on cognitive health in older adults. Further research on the long-term impact on cognition is recommended.

Episodic memory performance in a multi-ethnic longitudinal study of 13,037 elderly

Age-related changes in memory are not uniform, even in the absence of dementia. Characterization of non-disease associated cognitive changes is crucial to gain a more complete understanding of brain aging. Episodic memory was investigated in 13,037 ethnically diverse elderly (ages 72 to 85 years) with two to 15 years of follow-up, and with known dementia status, age, sex, education, and APOE genotypes. Adjusted trajectories of episodic memory performance over time were estimated using Latent Class Mixed Models. Analysis was conducted using two samples at baseline evaluation: i) non-cognitively impaired individuals, and ii) all individuals regardless of dementia status. We calculated the age-specific annual incidence rates of dementia in the non-demented elderly (n = 10,220). Two major episodic memory trajectories were estimated: 1) Stable-consisting of individuals exhibiting a constant or improved memory function, and 2) Decliner-consisting of individuals whose memory function declined. The majority of the study participants maintain their memory performance over time. Compared to those with Stable trajectory, individuals characterized as Decliners were more likely to have non-white ethnic background, fewer years of education, a higher frequency of ε4 allele at APOE gene and five times more likely to develop dementia. The steepest decline in episodic memory was observed in Caribbean-Hispanics compared to non-Hispanic whites (p = 4.3 x 10(-15)). The highest incident rates of dementia were observed in the oldest age group, among those of Caribbean-Hispanics ancestry and among Decliners who exhibited rates five times higher than those with Stable trajectories (11 per 100 person-years versus 3 per 100 person-years. Age, education, ethnic background and APOE genotype influence the maintenance of episodic memory. Declining memory is one of the strongest predictors of incident dementia.

An examination of the heterogeneity in the pattern and association between rates of change in grip strength and global cognition in late life. A multivariate growth mixture modelling approach

Background

previous research has demonstrated how older adults exhibit different patterns of change in cognitive and physical functioning, suggesting differences in the underlying causal processes.

Objective

to (i) identify subgroups of older adults that best account for different patterns of longitudinal change in performance on global cognition and grip strength, (ii) examine the interrelationship between global cognition and grip strength trajectories within these subgroups and (iii) identify demographic and health-related markers of class membership.

Methods

multivariate growth mixture models (GMM) were used to identify groups of individuals with similar developmental trajectories of muscle strength measured by grip strength, and global cognition measured by Mini Mental State Examination (MMSE).

Results

GMM analyses indicated high, moderate and low functioning groups. Individuals in the high and moderate classes demonstrated better cognitive and physical functioning at the start of the study and less decline than those in the low functioning group. Notably, cognitive performance was related to physical functioning at study entry only among individuals in the low functioning group.

Conclusion

the study demonstrates the applicability of the multivariate GMM to achieve a better understanding of the heterogeneity of various aging related processes.

Prediction Models of Cognitive Trajectories in Patients with Nonamnestic Mild Cognitive Impairment

To evaluate prediction models of cognitive trajectories in patients with nonamnestic mild cognitive impairment (naMCI) using group-based trajectory analysis, we evaluated 121 patients with naMCI who underwent at least their first three yearly assessments. Group-based trajectory models were used to classify cognitive trajectories based on Clinical Dementia Rating Sum of Boxes scores over four years in patients with naMCI. A total of 22 patients (18.2%) were classified into the “fast-decliners” group, while 99 patients (81.8%) were classified into the “slow-decliners” group. The mean age was higher in the fast-decliners than in the slow-decliners (p = 0.037). Compared to the slow-decliners, the fast-decliners were more frequently impaired in the domains of language (p = 0.038) and frontal/executive functions (p = 0.042), and had more frequent multiple-domain cognitive impairment (p = 0.006) on baseline neuropsychological tests. The rate of conversion to dementia was significantly higher in the fast-decliners than in the slow-decliners (86.4% vs. 10.1%, p < 0.001). Our findings showed that there are indeed distinct patterns of cognitive trajectories in patients with naMCI. Close observation of naMCI patients’ baseline demographic and clinical profiles in clinical settings may help identify individuals at greatest risk for dementia.

Using Base Rate of Low Scores to Identify Progression from Amnestic Mild Cognitive Impairment to Alzheimer's Disease

OBJECTIVES

To investigate the implications of obtaining one or more low scores on a battery of cognitive tests on diagnosing mild cognitive impairment (MCI).

DESIGN

Observational longitudinal study.

SETTING

Alzheimer's Disease Neuroimaging Initiative.

PARTICIPANTS

Normal controls (NC, n = 280) and participants with MCI (n = 415) according to Petersen criteria were reclassified using the Jak/Bondi criteria and number of impaired tests (NIT) criteria.

MEASUREMENTS

Diagnostic statistics and hazard ratios of progression to Alzheimer's disease (AD) were compared according to diagnostic criteria.

RESULTS

The NIT criteria were a better predictor of progression to AD than the Petersen or Jak/Bondi criteria, with optimal sensitivity, specificity, and positive and negative predictive value.

CONCLUSION

Considering normal variability in cognitive test performance when diagnosing MCI may help identify individuals at greatest risk of progression to AD with greater certainty.

Association of Low-Level Ozone with Cognitive Decline in Older Adults

Increasing evidence points to an association of airborne pollutant exposure with respiratory, cardiovascular, and neurological pathology. We examined whether or not ground-level ozone or fine particulate matter ≤ 2.5 μm in diameter (PM2.5) was associated with accelerated cognitive decline. Using repeated measures mixed regression modeling, we analyzed cognitive performance of a geographically diverse sampling of individuals from the National Alzheimer's Coordinating Center between 2004-2008. Ambient air concentrations of ozone and PM2.5 were established using a space-time Hierarchical Bayesian Model that statistically merged air monitor data and modeled air quality estimates. We then compared the ambient regional concentrations of ozone and PM2.5 with the rate of cognitive decline in residents within those regions. Increased levels of ozone correlated with an increased rate of cognitive decline, following adjustment for key individual and community-level risk factors. Furthermore, individuals harboring one or more APOE4 alleles exhibited a faster rate of cognitive decline. The deleterious association of ozone was confined to individuals with normal cognition who eventually became cognitively impaired as opposed to those who entered the study with baseline impairment. In contrast to ozone, we did not observe any correlation between ambient PM2.5 and cognitive decline at regulatory limits set by the Environmental Protection Agency. Our findings suggest that prolonged exposure to ground-level ozone may accelerate cognitive decline during the initial stages of dementia development.

Trajectories of Verbal Episodic Memory in Middle-Aged and Older Adults: Evidence from the English Longitudinal Study of Ageing

OBJECTIVES

To identify distinct latent groups of baseline levels and age-related decline in verbal episodic memory in middle-aged and older adults, and to identify factors associated with these trajectories.

DESIGN

Longitudinal study of six data collections over a period of 10 years.

SETTING

Population-based cohort in England.

PARTICIPANTS

9,515 community-dwelling adults aged 50-79 years.

MEASUREMENTS

Six repeated measurements of immediate and delayed recall of 10 words over 10-year follow-up. Group-based trajectory modeling was used to identify patterns of baseline levels and subsequent decline in memory in two age categories (50-64 and 65-79 years), and to investigate associations between trajectories and baseline predictors of group membership (gender, education, household wealth, marital status, smoking and physical activity) and time-varying covariates (depressive symptoms and number of chronic conditions).

RESULTS

Four trajectories were identified and labelled according to baseline status and decline in memory: very low/decline (9.8%), low/stable (40.2%), average/stable (39.5%) and good/stable (10.5%) in the younger group, and very low/rapid decline (15.7%), low/decline (32.0%), average/stable (38.8%), and good/stable (13.5%) in older participants. In people with stable or declining trajectories, a higher number of depressive symptoms and the presence of cardiovascular diseases were associated with worse memory. Female sex, younger age, and higher education, wealth and physical activity were consistently associated with more favourable trajectories.

CONCLUSIONS

We identified four memory trajectories. Factors known to be associated with cognitive reserve (such as education, wealth and physical activity) were associated with better memory function while depressive symptoms and cardiovascular disease were associated with poorer memory. This suggests that interventions to reduce depressive symptoms and better manage cardiovascular risk factors and disease in midlife may help prevent or delay future memory decline.

Distinct Cognitive Trajectories in the First Year After Hip Fracture

OBJECTIVES

Change in cognitive functioning is often observed after hip fracture. Different patterns, with both improvement and decline, are expected, depending on premorbid cognitive functioning and events that occur during hospitalization. These patterns are unknown and important for older hip fracture patients with different levels of premorbid cognitive functioning.

DESIGN, SETTING, PARTICIPANTS, MEASUREMENTS

We conducted a secondary analysis of a multi-center randomized controlled trial. 302 consecutive patients aged 65-102 years old, admitted for hip fracture surgery, were enrolled. The Mini Mental State Examination (MMSE) was obtained at hospital admission, at discharge, and at 3 and 12 months after discharge. Cognitive trajectories were identified with Group Based Trajectory Modelling, using the repeated MMSE measurements as outcome variable. To illustrate the specific characteristics of this relative novel methodological approach, it was contrasted with results obtained from linear mixed effects modeling.

RESULTS

146 (48.3%) patients had premorbid cognitive impairment and 85 patients (28.1%) experienced delirium during admission. Three distinct cognitive trajectories were identified and labeled based on different MMSE course over time: improvement (57.9%), stable (28.1%), and rapid decline (13.9%), with an annual MMSE change of 1.7, 0.8, and -3.5 points respectively. With mixed effects modeling an overall annual increase of 0.7 MMSE points was estimated for the group as a whole.

CONCLUSION

Three distinct cognitive trajectories were identified in a population of older hip fracture patients. These trajectory groups can be used as a starting point to inform patients and caregivers on the possible prognosis after hip fracture. Group based trajectory modelling is a useful technique when the purpose is to describe patterns of change within a population and a variety of trajectories are expected to exist.

Empirically Defining Trajectories of Late-Life Cognitive and Functional Decline

BACKGROUND

Alzheimer's disease (AD) is associated with variable cognitive and functional decline, and it is difficult to predict who will develop the disease and how they will progress.

OBJECTIVE

This exploratory study aimed to define latent classes from participants in the Alzheimer's Disease Neuroimaging Initiative (ADNI) database who had similar growth patterns of both cognitive and functional change using Growth Mixture Modeling (GMM), identify characteristics associated with those trajectories, and develop a decision tree using clinical predictors to determine which trajectory, as determined by GMM, individuals will most likely follow.

METHODS

We used ADNI early mild cognitive impairment (EMCI), late MCI (LMCI), AD dementia, and healthy control (HC) participants with known amyloid-β status and follow-up assessments on the Alzheimer's Disease Assessment Scale - Cognitive Subscale or the Functional Activities Questionnaire (FAQ) up to 24 months postbaseline. GMM defined trajectories. Classification and Regression Tree (CART) used certain baseline variables to predict likely trajectory path.

RESULTS

GMM identified three trajectory classes (C): C1 (n = 162, 13.6%) highest baseline impairment and steepest pattern of cognitive/functional decline; C3 (n = 819, 68.7%) lowest baseline impairment and minimal change on both; C2 (n = 211, 17.7%) intermediate pattern, worsening on both, but less steep than C1. C3 had fewer amyloid- or apolipoprotein-E ɛ4 (APOE4) positive and more healthy controls (HC) or EMCI cases. CART analysis identified two decision nodes using the FAQ to predict likely class with 82.3% estimated accuracy.

CONCLUSIONS

Cognitive/functional change followed three trajectories with greater baseline impairment and amyloid and APOE4 positivity associated with greater progression. FAQ may predict trajectory class.

Identifying Neurocognitive Decline at 36 Months among HIV-Positive Participants in the CHARTER Cohort Using Group-Based Trajectory Analysis

Introduction

While HIV-associated neurocognitive impairment remains common despite the widespread use of combined antiretroviral therapy (cART), there have been relatively few studies investigating the trajectories of neurocognitive change in longitudinal NeuroAIDS studies.

Objective

To estimate the magnitude and pattern of neurocognitive change over the first 3 years of follow-up using Group-Based Trajectory Analysis (GBTA) applied to participants in the longitudinal arm of the CHARTER cohort.

Method

The study population consisted of 701 CHARTER participants who underwent neuropsychological (NP) testing on at least 2 occasions. Raw test scores on 15 NP measures were modeled using GBTA. Each trajectory was categorized as stable, improved or declined, according to two different criteria for change (whether the magnitude of the estimated change at 36 months differed ≥ 0.5 standard deviations from baseline value or changed by > the standard error of measurement estimated at times 1 and 2). Individuals who declined on one or more NP measures were categorized as decliners.

Results

Overall, 111 individuals (15.8%) declined on at least one NP test over 36 months, with the vast majority showing decline on a single NP test (93/111-83.8%). The posterior probability of group assignment was high in most participants (71%) after only 2 sessions, and in the overwhelming majority of those with 3+ sessions. Heterogeneity of trajectories was the norm rather than the exception. Individuals who declined had, on average, worse baseline NP performance on every test, were older, had a longer duration of HIV infection and more follow-up sessions.

Conclusion

The present study identified heterogeneous trajectories over 3 years across 15 NP raw test scores using GBTA. Cognitive decline was observed in only a small subset of this study cohort. Decliners had demographics and HIV characteristics that have been previously associated with cognitive decline, suggesting clinical validity for the method.

Understanding and optimizing brain health in HIV now: protocol for a longitudinal cohort study with multiple randomized controlled trials

Background

Chronic HIV infection commonly affects both cognition and mental health, even with excellent systemic viral control. The causes of compromised brain health are likely to be a multi-factorial combination of HIV-related biological factors, co-morbidities such as aging and cerebrovascular disease, and the erosion of coping skills, physical health, and social supports resulting from the strains of living with a chronic illness.

Methods/design

This study aims to provide a better understanding of the relationship between cognitive complaints, depression, and objectively measured cognitive impairment in HIV, and of the key factors, whether biological or personal, which relate to these presentations and to their evolution over time. Characterization of this heterogeneity will permit more focused pathophysiological studies, and allow more targeted interventions. The project makes extensive use of Web-based research and health care delivery tools, aiming to provide cost-effective, “clinic ready” tools to improve brain health in HIV. This project has two overarching aims, reflecting our dual goals of understanding and improving brain health in HIV, focusing on cognitive impairment, its contributors and consequences.

The objectives are to contribute evidence for the validity of a brief brain health assessment, to estimate the extent to which HIV-related cognition-relevant clinical factors and patient-centered outcomes inter-relate and evolve over time, allowing identification of the mechanisms underpinning longitudinal change in brain health and to contribute evidence for the feasibility, effectiveness potential, acceptability, and underlying mechanisms of promising interventions for optimizing brain health. We adopt a cohort multiple randomized control trials design. A total of 900 participants will be characterized prospectively over a 27-month period to answer questions about the evolution of outcomes of interest. All participants will be offered basic brain health self-management information. Sub-groups will participate in pilot studies of specific, more intensive interventions to provide pragmatic evidence for feasibility, effectiveness, and comparative effectiveness.

Discussion

This work will provide needed estimates of the burden, heterogeneity, evolution, and mechanisms underlying compromised brain health in HIV, and test a range of promising non-pharmacological interventions. This is an on-going study; the trials nested within this cohort that are currently recruiting participants were registered on 7 October 2015 (Clinicaltrials.gov NCT02571504 and NCT02571595).

Predicting the post-treatment recovery of patients suffering from traumatic brain injury (TBI)

Predicting the evolution of individuals is a rather new mining task with applications in medicine. Medical researchers are interested in the progression of a disease and/or how do patients evolve or recover when they are subjected to some treatment. In this study, we investigate the problem of patients' evolution on the basis of medical tests before and after treatment after brain trauma: we want to understand to what extend a patient can become similar to a healthy participant. We face two challenges. First, we have less information on healthy participants than on the patients. Second, the values of the medical tests for patients, even after treatment started, remain well-separated from those of healthy people; this is typical for neurodegenerative diseases, but also for further brain impairments. Our approach encompasses methods for modelling patient evolution and for predicting the health improvement of different patients' subpopulations, i.e. prediction of label if they recovered or not. We test our approach on a cohort of patients treated after brain trauma and a corresponding cohort of controls.

Progression from mild cognitive impairment to dementia: a 3-year longitudinal study

OBJECTIVE

To examine characteristics that predict the progression from mild cognitive impairment to dementia.

METHODS

Of 970 patients recruited from nine memory clinics around Australia, 185 had mild cognitive impairment diagnosed. Measures of cognitive ability, functional ability, and neuropsychiatric symptoms were completed at baseline and over 3 years of follow up.

RESULTS

Over 3 years, 52 (28%) patients with mild cognitive impairment developed dementia. Older age, lower cognitive ability at baseline, and faster decline in cognitive ability over the first 6 months of follow up, but not depression, predicted progression to dementia.

CONCLUSIONS

The findings confirm that simple clinical data such as age, cognitive ability at baseline, and rate of cognitive decline are important predictors of progression from mild cognitive impairment to dementia over 3 years.

Perceived eye region and the processing of fearful expressions in mild cognitive impairment patients

BACKGROUND

The aim of the present study was to assess the possibility of compensating early facial expression recognition impairments in amnestic Mild Cognitive Impairment (a-MCI) patients.

METHODS

Twelve patients with a-MCI and 17 healthy participants matched according to age and education participated in the study. The originality of the present study was to cue the recognition of facial expressions (happiness, anger, fear, and neutral) by comparing eye region expressions and entire facial expressions.

RESULTS

A deficit in the recognition of fearful expressions was observed in a-MCI patients relative to the control group, whereas recognition of all the other emotional expressions was spared. Nevertheless, when eye expressions cued the recognition of fearful facial expressions, the performance of normal controls and a-MCI patients was comparable.

CONCLUSION

The present paper indicates a selective impairment in fear recognition in the prodromal state of Alzheimer's disease, and the possibility of compensating this deficit by orienting selective attention on specific facial features.

Predictors of future cognitive decline in persons with mild cognitive impairment

This study sought first to identify individual items of the Mini-Mental State Examination (MMSE) and demographic variables at baseline that predicted the trajectories of cognitive change among patients with mild cognitive impairment (MCI), and second to quantify the risk of cognitive decline in such patients based on their pattern of failure of MMSE items. 187 MCI patients were evaluated serially with the MMSE for up to 3.5 years. Patients who followed a declining cognitive trajectory differed from the stable reference group in their baseline profile of MMSE test performance. Patient age and performance on delayed recall, constructional praxis, attention, and orientation to time and floor predicted future cognitive decline with good accuracy (79.9%) and specificity (86.4%), and moderate sensitivity (67.2%). These results are presented in the form of a simple clinical tool for quantifying risk of future cognitive decline in MCI.