Methodological considerations when establishing reliable and valid normative data: Canadian Longitudinal Study on Aging (CLSA) neuropsychological battery

Personality Traits and Health Behaviors as Predictors of Fall Among Community-Dwelling Older Adults: Findings From the Canadian Longitudinal Study on Aging

Objectives: To examine whether personality traits and health behaviors predict falls in community-dwelling older adults. Methods: Longitudinal data from the Canadian Longitudinal Study on Aging (CLSA) at baseline (2011-2015) and follow-up two (2018-2021) were analyzed using logistic regression for 5270 adults aged 65 and older, with an alpha level of 0.05. Results: At baseline, participants' mean age was 72 years, with 51.1% female. Most identified as White (96.7%) and had education beyond secondary (81.5%). Increased physical activity (OR: 1.012, 95% CI: 1.01-1.014), decreased alcohol consumption (OR: 1.634, 95% CI: 1.419-1.883), and smoking cessation (OR: 2.8, 95% CI: 2.198-3.568) increased fall risk, while conscientiousness (OR: 0.832, 95% CI: 0.792-0.874) and openness (OR: 0.959, 95% CI: 0.922-0.998) were protective at follow-up two. Personality changes significantly influence falls. Discussion: Findings highlight the complex interplay between personality traits, health behaviors, and falls, suggesting a one-size-fits-all approach to fall prevention may be insufficient.

The COVID-19 pandemic's effects on cognition and 24-hour movement behaviours: Findings from the CLSA

BACKGROUND

The COVID-19 pandemic may have negatively impacted cognition due to pandemic-associated changes in 24-h movement behaviours (i.e., physical activity, sedentary behaviour, and sleep). Whether the pandemic's effects vary by age and sex is unclear.

METHODS

We examined those participants (aged 45-85 years) of the Canadian Longitudinal Study on Aging (CLSA) with complete neuropsychological measures at baseline (2011-2015), no dementia/memory disorder, and partial or complete assessments at baseline, 3-year (FU1; 2015-2018), and 6-year follow-up (FU2; 2018-2021). Participants were categorized into pre-pandemic (N = 6174) or intra-pandemic (N = 5181) cohorts by FU2 assessment timing (before/after March 11th, 2020) and stratified by baseline age/sex. Cognition was measured with reliable change indices using: the Rey Auditory-Verbal Learning Test, Mental Alternation Test (MAT), and animal fluency. We indexed physical activity and sedentary behaviour using the Physical Activity Scale for the Elderly (PASE), and self-reported restless sleep.

FINDINGS

Compared with their pre-pandemic peers, intra-pandemic men aged 65-85 years had lower animal fluency (-0.40 points, 99 % CI: [-0.72, -0.07]), lower PASE (-16.48 points, 99 % CI: [-24.60, -8.36]) and 14 % higher probability of ≥4 h/day sedentary behaviour (99 % CI: [0.03, 0.26]) at FU2. Intra-pandemic women aged 65-85 years had lower MAT (-0.43 points, 99 % CI: [-0.86, -0.01]) and 12 % higher probability of ≥4 h/day sedentary behaviour (99 % CI: [0.01, 0.23]). There were no between-cohort differences for those aged 45-64 years. Pandemic-related changes in 24-h movement behaviours (FU1 to FU2) were not associated with cognitive changes, regardless of age or sex.

INTERPRETATION

The pandemic's effects on cognition and 24-h movement behaviours varied by age and sex; these effects are unrelated.

The association between memory, COVID-19 testing, and COVID-19 incidence in middle-aged and older adults: a prospective analysis of the CLSA

We investigated the association between pre-COVID-19 memory function and (a) receipt of a COVID-19 test and (b) incidence of COVID-19 using the COVID-19 Questionnaire Study (CQS) of the Canadian Longitudinal Study on Aging (CLSA). The CQS included 28,565 middle-aged and older adults. We regressed receipt of a COVID-19 test on participants' immediate and delayed recall memory scores and re-ran the regression models with COVID-19 incidence as the outcome. All regression models were adjusted for sociodemographic, lifestyle, and health covariates. In the analytical sample (n = 21,930), higher delayed recall memory (better memory) was significantly associated with lower COVID-19 incidence. However, this association was not significant for immediate recall memory. Immediate and delayed recall memory were not associated with receipt of a COVID-19 test. Health policymakers and practitioners may viewmemory status as a potential risk for COVID-19. Memory status may not be a barrier to COVID-19 testing.

Baseline nutrition risk as measured by SCREEN-8 predicts self-reported 12-month healthcare service use of older adults 3 years later

This study investigated whether nutrition risk, as measured by SCREEN-8 at baseline, was associated with self-reported healthcare service use in the past 12 months among community-dwelling older adults who were interviewed 3 years later. Data from the Canadian Longitudinal Study on Aging were used. SCREEN-8 assessed nutrition risk among community-dwelling persons ages 55+. Multivariable logistic regression determined if baseline SCREEN-8 score was associated with the following healthcare services reported to occur in the 12 months preceding the 3-year follow-up period: (i) overnight hospital admission (n = 13 623), (ii) emergency room visit (n = 13 614), (iii) contacting a family doctor (n = 13 616), (iv) visiting dental professional (n = 13 288), and (v) visiting a doctor due to an infection (n = 13 171) after adjusting for demographic and health variables. Those with higher SCREEN-8 scores (lower nutrition risk) had significantly lower odds of reporting: (i) an overnight hospital admission (χ2 (27, 13 587) = 10.59,  p < 0.001); (ii) visiting a hospital emergency room (χ2 (27, 13 578) = 9.64, p < 0.001); and (iii) visiting a doctor due to an infection (χ2 (27, 13 135) = 10.32, p < 0.001) at 3-year follow-up. Less nutrition risk was significantly associated with higher odds of reporting visiting a dental professional (χ2 (27, 13 252) = 17.88, p < 0.001). Baseline nutrition risk was not significantly associated with visiting a family doctor at the 3-year follow-up. SCREEN-8 predicted future self-reported 12-month healthcare service use among older adults in expected directions.

Case Reports in the Integration of Technology with Cognitive Rehabilitation for Individuals with Memory Concerns and Their Care Partners

OBJECTIVE

Technology can be combined with psychological interventions to support older adults with memory concerns. Using a bi-phasic design, cognitive rehabilitation (CR) was integrated with off-the-shelf technology and delivered to two people with cognitive impairment, and one care partner.

METHOD

Pre- and post-intervention assessments were completed for all participants. Individuals with memory problems received pre- and post-intervention remote neuropsychological assessment (i.e., Rey auditory verbal learning test; mental alternations test; animal fluency), and the hospital anxiety and depression scale (HADS). The care partner completed the HADS, Zarit burden interview, and neuropsychiatric inventory questionnaire. Change metrics incorporated reliable change indices where possible. Goals were tracked using the Canadian occupation performance measure; these data were analyzed through visual inspection. A research journal (used to document intervention process) was analyzed thematically.

RESULTS

Results cautiously suggested our integration was feasible and acceptable across several technologies and varying goals. Across participants, significant changes in goal progress suggested the integration of technology with CR successfully facilitated goal performance and satisfaction. The research journal underscored the importance of a visual component, intervention flexibility, and a strong therapeutic alliance in integrating technology and CR.

CONCLUSIONS

CR and technology present a promising avenue for supporting people living with cognitive impairment. Further exploration of technology and CR with a range of etiologies and target goals is warranted.

Modifiable Risk Factors Associated With Cognitive Decline in Late Life Depression: Findings From the Canadian Longitudinal Study on Aging: Facteurs de risque modifiables associés au déclin cognitif dans la dépression en fin de vie : constatations de l'Étude longitudinale canadienne sur le vieillissement

OBJECTIVE

Depression in later life is associated with a two-fold increased risk of dementia. It is not clear to what extent potentially modifiable risk factors account for this association.

METHOD

Older adults (age 50 + ) with objective health measures (n = 14,014) from the Canadian Longitudinal Study on Aging were followed for a mean duration of 35 months. Linear regression analyses were used to determine if clinically significant depression (Centre for Epidemiologic Studies Depression scale score (CESD) ≥ 10) was associated with global cognitive decline, assessed with a neuropsychological battery during follow-up, and if modifiable risk factors mediated this association.

RESULTS

Depression was associated with an excess of risk factors for cognitive decline including: vascular disease, hypertension, diabetes, apnoea during sleep, higher body mass index, smoking, physical inactivity and lack of social participation. In regression analyses depression remained independently associated with cognitive decline over time (beta -0.060, P = 0.038) as did cerebrovascular disease (beta -0.197, P < 0.001), HbA1C (beta -0.059, P < 0.001), visual impairment (beta -0.070, P = 0.007), hearing impairment (beta -0.098, P < 0.001) and physical inactivity (beta -0.075, P = 0.014). In mediation analyses, we found that cerebrovascular disease (z = -3.525, P < 0.001), HbA1C (z = -4.976, P < 0.001) and physical inactivity (z = -3.998, P < 0.001) partially mediated the association between depression and cognitive decline.

CONCLUSIONS

In this large sample of Canadian older adults incorporating several objective health measures, older adults with depression were at increased risk of cognitive decline and had an excess of potentially modifiable risk factors. Clinicians should pay particular attention to control of diabetes, physical inactivity and risk factors for cerebrovascular disease in older adults presenting with depression as they can contribute to accelerated cognitive decline and may be addressed during routine clinical care.

Mediation of Post-Stroke Function by Cognition in the Canadian Longitudinal Study on Aging

INTRODUCTION

Cognitive and functional impairment after stroke are common, but the relation between cognitive and functional decline after stroke is not well studied.

METHODS

We used the comprehensive cohort in the Canadian Longitudinal Study on Aging to identify those with prior stroke, and we calculated reliable cognitive change scores from baseline to follow-up for the memory and executive domains. Functional decline was defined as an increase in the number of dependent daily activities. Using formal mediation analysis, we tested the presence and degree of mediation of the association between stroke and functional decline by cognitive decline.

RESULTS

There were 22,648 individuals with memory change scores (325 with stroke) and 17,613 individuals with executive change scores (241 with stroke). History of stroke was significantly associated with memory decline (-0.26 standard deviations, 95% CI -0.33 to -0.19), executive decline (-0.22, 95% CI -0.36 to -0.09), and new functional impairment (adjusted odds ratio 2.31, 95% CI 1.80-2.97) over a median of 3-year follow-up. Cognitive decline was a significant mediator of functional decline. Memory decline mediated only 5% of the relationship, whereas executive and overall cognitive decline mediated 13% and 22%, respectively.

CONCLUSION

Cognitive decline is a mediator of the association between prior stroke and functional decline; consequently, strategies to delay, attenuate, or prevent cognitive decline after stroke may be important to preserving long-term functional status.

Prioritizing determinants of cognitive function in healthy middle-aged and older adults: insights from a machine learning regression approach in the Canadian longitudinal study on aging

Introduction

The preservation of healthy cognitive function is a crucial step toward reducing the growing burden of cognitive decline and impairment. Our study aims to identify the characteristics of an individual that play the greatest roles in determining healthy cognitive function in mid to late life.

Methods

Data on the characteristics of an individual that influence their health, also known as determinants of health, were extracted from the baseline cohort of the Canadian Longitudinal Study of Aging (2015). Cognitive function was a normalized latent construct score summarizing eight cognitive tests administered as a neuropsychological battery by CLSA staff. A higher cognitive function score indicated better functioning. A penalized regression model was used to select and order determinants based on their strength of association with cognitive function. Forty determinants (40) were entered into the model including demographic and socioeconomic factors, lifestyle and health behaviors, clinical measures, chronic diseases, mental health status, social support and the living environment.

Results

The study sample consisted mainly of White, married, men and women aged 45-64 years residing in urban Canada. Mean overall cognitive function score for the study sample was 99.5, with scores ranging from 36.6 to 169.2 (lowest to highest cognitive function). Thirty-five (35) determinants were retained in the final model as significantly associated with healthy cognitive functioning. The determinants demonstrating the strongest associations with healthy cognitive function, were race, immigrant status, nutritional risk, community belongingness, and satisfaction with life. The determinants demonstrating the weakest associations with healthy cognitive function, were physical activity, greenness and neighborhood deprivation.

Conclusion

Greater prioritization and integration of demographic and socioeconomic factors and lifestyle and health behaviors, such greater access to healthy foods and enhancing aid programs for low-income and immigrant families, into future health interventions and policies can produce the greatest gains in preserving healthy cognitive function in mid to late life.

Automated procedure for demographic adjustments on cognitive test scores

Performances of normal people on cognitive tests are known to vary by demographic characteristics, such as age, education, and sex. Thus, cognitive test scores should be corrected for demographic influences when they are used to detect below-expected results due to disease or injury involving the central nervous system (CNS). Normative corrections, if estimated from a large, diverse, and well-characterized cohort of controls, help to remove expected differences in cognitive performance associated with normal demographic characteristics and associated socio-economic disadvantages. In this paper, we (1) describe in detail the process of generating regression-based normative standards, and its advantages and limitations, (2) provide recommendations for applying these normative standards to data from individuals and populations at risk for CNS dysfunction, and (3) introduce an R package, test2norm, that contains functions for producing and applying normative formulas to generate demographically corrected scores for measuring deviations from expected, normal cognitive performances.

Cognitive impairment indicator for the neuropsychological test batteries in the Canadian Longitudinal Study on Aging: definition and evidence for validity

BACKGROUND

Prevalence of overall cognitive impairment based on each participant's performance across a neuropsychological battery is challenging; consequently, we define and validate a dichotomous cognitive impairment/no cognitive indicator (CII) using a neuropsychological battery administered in a population-based study. This CII approximates the clinical practice of interpretation across a neuropsychological battery and can be applied to any neuropsychological dataset.

METHODS

Using data from participants aged 45-85 in the Canadian Longitudinal Study on Aging receiving a telephone-administered neuropsychological battery (Tracking, N = 21,241) or a longer in-person battery (Comprehensive, N = 30,097), impairment was determined for each neuropsychological test based on comparison with normative data. We adjusted for the joint probability of abnormally low scores on multiple neuropsychological tests using baserates of low scores demonstrated in the normative samples and created a dichotomous CII (i.e., cognitive impairment vs no cognitive impairment). Convergent and discriminant validity of the CII were assessed with logistic regression analyses.

RESULTS

Using the CII, the prevalence of cognitive impairment was 4.3% in the Tracking and 5.0% in the Comprehensive cohorts. The CII demonstrated strong convergent and discriminant validity.

CONCLUSIONS

The approach for the CII is a feasible method to identify participants who demonstrate cognitive impairment on a battery of tests. These methods can be applied in other epidemiological studies that use neuropsychological batteries.

The association between shift work exposure and cognitive impairment among middle-aged and older adults: Results from the Canadian Longitudinal Study on Aging (CLSA)

BACKGROUND

Shift work, especially rotating and night shift work, has been linked to a wide range of detrimental health outcomes. Occupational factors like shift work and their potential impact on cognitive functions have received little attention, and the evidence is inconclusive. The objective of our study is to explore associations between shift work exposure and cognitive impairment indicators based on comparisons with the normative standards from the Canadian population.

METHODS

Cross-sectional analyses were performed using baseline Canadian Longitudinal Study on Aging database, including 47,811 middle-aged and older adults (45-85 years). Three derived shift work variables were utilized: ever exposed to shift work, shift work exposure in longest job, and shift work exposure in current job. Four cognitive function tests were utilized, Rey Auditory Verbal Learning Tests (immediate and delayed) representing memory domain, and Animal Fluency, and Mental Alteration, representing the executive function domain. All cognitive test scores included in study were normalized and adjusted for the participant's age, sex, education and language of test administration (English and French), which were then compared to normative data to create "cognitive impairment' variables. Unadjusted and adjusted multivariable logistic regression models were used to determine associations between shift work variables and cognitive impairment individually (memory and executive function domains), and also for overall cognitive impairment.

RESULT

Overall, one in every five individuals (21%) reported having been exposed to some kind of shift work during their jobs. Exposure to night shift work (both current and longest job) was associated with overall cognitive impairment. In terms of domain-based measures, night shift work (longest job) was associated with memory function impairment, and those exposed to rotating shift work (both current and longest job) showed impairment on executive function measures, when compared to daytime workers.

CONCLUSION

This study suggests disruption to the circadian rhythm, due to shift work has negative impact on cognitive function in middle-aged and older adults and this warrants further investigation.

The Rey Auditory Verbal Learning Test: Cross-validation of Mayo Normative Studies (MNS) demographically corrected norms with confidence interval estimates

OBJECTIVE

The Mayo Normative Studies (MNS) represents a robust dataset that provides demographically corrected norms for the Rey Auditory Verbal Learning Test. We report MNS application to an independent cohort to evaluate whether MNS norms accurately adjust for age, sex, and education differences in subjects from a different geographic region of the country. As secondary goals, we examined item-level patterns, recognition benefit compared to delayed free recall, and derived Auditory Verbal Learning Test (AVLT) confidence intervals (CIs) to facilitate clinical performance characterization.

METHOD

Participants from the Emory Healthy Brain Study (463 women, 200 men) who were administered the AVLT were analyzed to demonstrate expected demographic group differences. AVLT scores were transformed using MNS normative correction to characterize the success of MNS demographic adjustment.

RESULTS

Expected demographic effects were observed across all primary raw AVLT scores. Depending on sample size, MNS normative adjustment either eliminated or minimized all observed statistically significant AVLT differences. Estimated CIs yielded broad CI ranges exceeding the standard deviation of each measure. The recognition performance benefit across age ranged from 2.7 words (SD = 2.3) in the 50-54-year-old group to 4.7 words (SD = 2.7) in the 70-75-year-old group.

CONCLUSIONS

These findings demonstrate generalizability of MNS normative correction to an independent sample from a different geographic region, with demographic adjusted performance differences close to overall performance levels near the expected value of T = 50. A large recognition performance benefit is commonly observed in the normal aging process and by itself does not necessarily suggest a pathological retrieval deficit.

Testing a polygenic risk score for morphological microglial activation in Alzheimer's disease and aging

Neuroinflammation and the activation of microglial cells are among the earliest events in Alzheimer's disease (AD). However, direct observation of microglia in living people is not currently possible. Here, we indexed the heritable propensity for neuroinflammation with polygenic risk scores (PRS), using results from a recent genome-wide analysis of a validated post-mortem measure of morphological microglial activation. We sought to determine whether a PRS for microglial activation (PRS mic ) could augment the predictive performance of existing AD PRSs for late-life cognitive impairment. First, PRS mic were calculated and optimized in a calibration cohort (Alzheimer's Disease Neuroimaging Initiative (ADNI), n=450), with resampling. Second, predictive performance of optimal PRS mic was assessed in two independent, population-based cohorts (total n=212,237). Our PRS mic showed no significant improvement in predictive power for either AD diagnosis or cognitive performance. Finally, we explored associations of PRS mic with a comprehensive set of imaging and fluid AD biomarkers in ADNI. This revealed some nominal associations, but with inconsistent effect directions. While genetic scores capable of indexing risk for neuroinflammatory processes in aging are highly desirable, more well-powered genome-wide studies of microglial activation are required. Further, biobank-scale studies would benefit from phenotyping of proximal neuroinflammatory processes to improve the PRS development phase.

Testing a Polygenic Risk Score for Morphological Microglial Activation in Alzheimer's Disease and Aging

BACKGROUND

Neuroinflammation and the activation of microglial cells are among the earliest events in Alzheimer's disease (AD). However, direct observation of microglia in living people is not currently possible. Here, we indexed the heritable propensity for neuroinflammation with polygenic risk scores (PRS), using results from a recent genome-wide analysis of a validated post-mortem measure of morphological microglial activation.

OBJECTIVE

We sought to determine whether a PRS for microglial activation (PRSmic) could augment the predictive performance of existing AD PRSs for late-life cognitive impairment.

METHODS

First, PRSmic were calculated and optimized in a calibration cohort (Alzheimer's Disease Neuroimaging Initiative (ADNI), n = 450), with resampling. Second, predictive performance of optimal PRSmic was assessed in two independent, population-based cohorts (total n = 212,237). Finally, we explored associations of PRSmic with a comprehensive set of imaging and fluid AD biomarkers in ADNI.

RESULTS

Our PRSmic showed no significant improvement in predictive power for either AD diagnosis or cognitive performance in either external cohort. Some nominal associations were found in ADNI, but with inconsistent effect directions.

CONCLUSION

While genetic scores capable of indexing risk for neuroinflammatory processes in aging are highly desirable, more well-powered genome-wide studies of microglial activation are required. Further, biobank-scale studies would benefit from phenotyping of proximal neuroinflammatory processes to improve the PRS development phase.