Practice effects due to serial cognitive assessment: Implications for preclinical Alzheimer's disease randomized controlled trials

Cognitive changes in schizophrenia before and after illness onset: A meta-analysis examining consistency in measurement tools as a moderator

Background

Cognitive impairment, a core feature of schizophrenia, is often evident before the onset of illness. The current study aimed to quantify IQ decline following the onset of illness by conducting a meta-analysis of longitudinal studies that evaluated cognitive functioning both before and after the first psychotic episode. Consistency in measurement tools - i.e. whether the same measurement tool was used at both assessments - was considered a potential moderating variable.

Method

Eleven studies were included in the meta-analysis - seven using the same measurement tool at both time-points and four using different tools. In addition, meta-regression explored whether the magnitude of IQ decline was associated with age at baseline.

Results

The meta-analysis effect size was -0.343 (95 % CI: -0.503 to -0.184), equivalent to a decrease of 5 IQ points. Use of the same (SMD -0.321, 95 % CI: -0.501 to -0.142) vs different (SMD -0.427, 95 % CI: -0.777 to -0.077) measurement tools was not a moderator of IQ change (p = 0.279). The meta-regression results were not significant (p = 0.544).

Conclusion

The current meta-analysis indicates a slight cognitive decline from the premorbid stage to post-onset. The use of different measurement tools yielded a slightly larger effect size and greater heterogeneity, suggesting that employing the same assessment tool could lead to more accurate results. Future longitudinal studies should focus on determining the timeline of cognitive decline.

Frequency and Early Predictors of Cognitive Deterioration in Amyotrophic Lateral Sclerosis: A Longitudinal Population-Based Study

OBJECTIVE

The objective is to evaluate cognitive and behavioral progression and identify early predictors of these changes in a cohort of amyotrophic lateral sclerosis (ALS) patients.

METHODS

A total of 161 ALS patients were tested at diagnosis (T0), and 107 were re-tested after 1 year (T1) using cognitive/behavioral tests. All patients underwent whole-genome sequencing, and 46 patients (ALS-normal cognition [CN]) underwent [18F]Fluorodeoxyglucose positron emission tomography.

RESULTS

Of the 161 patients, 107 were re-rested at T1; non-retested patients included 10 with frontotemporal dementia and 44 who were either non-testable or deceased. At T0, 67 patients (62.6%) were classified as ALS-CN, whereas 40 (38.4%) showed some degree of cognitive/behavioral impairment. Eighteen ALS-CN patients (26.9%) experienced cognitive decline at T1. Phenoconverters had lower baseline scores in letter fluency (Letter Fluency Test [FAS]) (p < 0.001), Edinburgh Cognitive and Behavioral ALS Screen (ECAS) verbal fluency score (p = 0.017). Both tests were independently predictive of phenoconversion in binary logistic regression models, with optimal cut-off scores of 28.75 and 14.2, with good sensitivity and specificity. Other predictors included older age, lower education, and ALS-related genetic variants. Phenoconverters were hypometabolic in the left temporal lobe. Thirteen (32.5%) of the 40 patients with cognitive impairment at T0 worsened by T1, with FAS (p = 0.02) and the ECAS verbal fluency score (p = 0.023) predicting further decline.

INTERPRETATION

Approximately 30% of ALS patients experienced cognitive/behavioral decline within the first year after diagnosis. FAS and ECAS verbal fluency were predictive of cognitive phenoconversion. Our findings highlight the importance of early detection of at-risk individuals and the need for longitudinal cognitive assessments to monitor disease progression. ANN NEUROL 2025;97:1122-1133.

Modeling Disease Progression and Placebo Response in Huntington Disease: Insights From Enroll-HD and GENERATION HD1 Cohorts

BACKGROUND AND OBJECTIVES

Huntington disease is a rare neurodegenerative disorder with no disease-modifying therapies. This study aimed to quantify longitudinal changes in Unified Huntington's Disease Rating Scale (UHDRS) scores and evaluate their susceptibility to placebo response, enhancing our understanding of disease progression and ability to optimize future trials.

METHODS

We used data from the Enroll-HD natural history study (NCT01574053) and the GENERATION HD1 phase 3 clinical trial (NCT03761849) to model disease progression and placebo response for UHDRS scores, which are commonly used to evaluate disease progression in clinical trials.

RESULTS

We included 8,071 Enroll-HD participants (mean baseline age: 51.4 years, 51.5% female) to develop a natural history progression model using baseline characteristics as predictive covariates. This model was then used to predict natural history progression of 260 participants from the GENERATION HD1 placebo arm (mean baseline age: 48.7 years, 43.5% female).The progression measured by Total Functional Capacity (TFC) in the GENERATION HD1 placebo arm aligned with predicted natural history (within 95% CI), indicating no significant placebo response. However, significant improvements (outside the 95% CI of the model) were observed after baseline for Total Motor Score (TMS), Symbol Digit Modalities Test (SDMT) score, and Stroop Word Reading (SWR) score. The improvement in TMS persisted until the end of the dosing period (week 69), converging to natural history predictions at subsequent follow-up visits (weeks 85 and 101), suggesting a placebo effect. By contrast, cognitive scores (SDMT and SWR) showed sustained significant improvement (outside the 95% CI) up to the final follow-up visit at week 101, likely due to practice effects from the more frequent testing schedule in GENERATION HD1 compared with the annual assessments in Enroll-HD. Consequently, the composite UHDRS (cUHDRS) score, a linear combination of TFC, TMS, SDMT, and SWR, is influenced by both placebo and practice effects.

DISCUSSION

Our results suggest that clinical scores in Huntington disease trials are susceptible to long-term placebo responses. These effects should be considered in future trial designs, especially when comparing trial data with natural history studies. Although based on the largest Huntington's trial, our results rely on limited placebo data and may not generalize to other trials with different populations, treatments, and designs.

Sex differences in cognitive trajectories and practice effects in a cohort of older Londoners: The role of risk factors

BackgroundSex differences in cognitive abilities have been reported; however, the underlying reasons remain unclear.ObjectiveTo (i) investigate sex differences in cognitive performance, (ii) evaluate the contributions of established dementia risk factors to these differences, and (iii) examine the role of non-modifiable risk factors on sex differences in cognitive performance.MethodsAmong 964 cognitively unimpaired participants (aged 60-85) of the UK CHARIOT-PRO Main Study, we assessed cross-sectional and longitudinal associations, over up to 3 years of follow-up, between sex and cognitive performance, using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS).ResultsSex differences, mostly favoring women were observed at baseline across almost all RBANS indices including the total scale (Cohen's d = 0.3, adjusted mean difference in score = -5.4, p < 0.001). Sex differences were observed in Practice effects (PEs), with men showing less PE in almost all cognitive domains including the total scale (adjusted 1.3, p = 0.002). Greater sex differences in PEs, were documented among the 'older' participants in two out of five cognitive domains including the immediate memory index (mean difference: older (69-85 years) group = -3.2, p = 0.002); younger (60-68 years) group = -0.8, p = 0.4). Sex differences were more pronounced among 'Apolipoprotein-Ꜫ4 -carriers' in three out of five domains including the total scale (mean difference in carriers = -2.6, p = 0.002); non-carriers = -0.7, p = 0.3).ConclusionsSex differences in cognition and PE were observed after adjusting for risk factors associated with Alzheimer's disease. Future studies should also consider the effects of sex on non-modifiable risk factors and PEs to identify potential 'masked' neuropathology.

Novel Neurocognitive Testing Tool for Early Neurotoxicity Detection Following Anti-CD19 and Anti-BCMA Chimeric Antigen Receptor (CAR) T-cell Therapy: A Pilot Study

BACKGROUND

Immune effector cell-associated neurotoxicity syndrome (ICANS) can be a severe, life-threatening toxicity following CAR T-cell therapy. While currently evaluated by the immune effector cell-associated encephalopathy (ICE) score, not all patients have changes in their ICE score and not all signs and symptoms of neurotoxicity are captured.

METHODS

We conducted a prospective, single center cohort pilot study to evaluate a novel, rapid neurocognitive assessment tool (CART-NS) in detecting early, subtle neurotoxicity prior to the onset of ICANS and any deterioration in the ICE score. CART-NS includes 8 abbreviated forms of neurocognitive tests and 2 symptom questionnaires. Following baseline measurements, CART-NS was administered at 8-hour intervals during the first 30 days after CAR T-cell infusion.

RESULTS

Performance on all measures was significantly lower when patients developed Grade 1 or 2 ICANS (P < .05). Performance on Oral Symbol Digit, Stroop, and the Paced Visual Serial Addition Test was lower between Day 0 and +3 in patients who developed ICANS and persisted even after clinical resolution. Early changes in the Stroop test (AUC = 0.857, 95% CI 0.628-1.000) were most predictive of ICANS onset when measured during the first 36 hour following CAR T-cell infusion. Significant elevations in CRP, G-CSF, GM-CSF, IFNγ, IL-10, IL-15, IL-27, and MIG/CXCL-9 were associated with ICANS development.

CONCLUSION

Brief neurocognitive testing can be feasibly applied for the early detection of ICANS after CAR T-cell therapy, predict which patients may go on to develop ICANS in the first 30 days, and overcome limitations of the ICE assessment tool.

Uncovering heterogeneous cognitive trajectories in relapsing-remitting multiple sclerosis: a longitudinal study

BACKGROUND

Cognitive impairment (CI) frequently occurs in relapsing-remitting multiple sclerosis (RRMS) and is assumed to be irreversible. Recent longitudinal studies highlighted the heterogeneity of CI in RRMS, challenging the traditional view of inevitable progression. Longitudinal studies exploring the baseline determinants of future cognitive decline are limited, and none yet explored the predictive value of patient-reported outcome measures (PROMs).

OBJECTIVE

To explore the evolutionary patterns of cognitive status in a cohort of RRMS patients initiating a new disease modifying treatment, and to determine whether PROMs may have a predictive value for future cognitive decline.

METHODS

This prospective study is a 36-month follow-up of 59 RRMS patients who underwent yearly a comprehensive, multiparametric assessment combining clinical, neuropsychological, MRI-derived metrics and a set of self-reported questionnaires. Lesion load and brain volumes were analyzed and processed by the automated MSmetrix® software (Icometrix®, Leuven, Belgium). A longitudinal logistic regression analysis was performed to investigate baseline predictors of future cognitive decline.

RESULTS

A total of 33 (56%) and 17 (35%) patients were defined as cognitively impaired at baseline and at the end of the study, respectively. Of these 33 patients, 20 showed either improvement and/or impairment in fewer cognitive domains at 36-month follow-up. Baseline physical disability as measured by EDSS was the best predictor for future cognitive decline (OR: 2.17; p = 0.03, 95% confidence interval = 1.07-4.38). None of the PROMs variables contributed to predict further cognitive decline.

CONCLUSIONS

Our findings highlight the importance of considering the evolution of CI in MS as a dynamic phenomenon with a substantial heterogeneity.

Ecological validity in neurocognitive assessment: Systematized review, content analysis, and proposal of an instrument

OBJECTIVES

The main objectives of this study are to identify the dimensions of Ecological Validity (EV) within the definitions of this concept, understand how they are operationalized in neurocognitive tests, and propose a checklist for EV attributes in neurocognitive tests.

METHOD

A systematized review was combined with content analysis of the selected papers, using the inductive method. We analyzed 82 studies on the EV of neurocognitive tests, 19 literature reviews and 63 empirical studies. Based on this review, we identified the relevant criteria for evaluating EV.

RESULTS

EV is a multidimensional concept with two main dimensions: representativeness and generalization. Representativeness involves the subdimensions simplicity-complexity and artificial-natural and several criteria organized on a continuum from low EV to high EV. Generalization is dependent on representativeness and is influenced by different cognitive and non-cognitive factors. We propose six stages for operationalizing EV, from defining the objectives of the neurocognitive assessment to the methodology for scoring and interpreting the results.

CONCLUSION

This systematized review helps to operationalize the concept of EV by providing a tool for evaluating and improving EV while developing new tests. Further studies with a longitudinal design can compare the predictive value of tests with higher versus lower EV-checklist scores.

Four year practice effects on the RBANS in a longitudinal study of older adults

OBJECTIVE

The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) is a widely used measure in neuropsychological assessment. Studies of practice effects on the RBANS have typically been assessed over one or two repeated assessments. The aim of the current study is to examine practice effects across four-years after baseline in a longitudinal study of cognitively healthy older adults.

METHOD

453 Participants from the Louisiana Aging Brain Study (LABrainS) completed the RBANS Form A on up to four annual assessments after baseline. Practice effects were calculated using a modified participants-replacement method where scores of returnees are compared to the baseline scores of matched participants with additional adjustment for attrition effects.

RESULTS

Practice effects were observed primarily in the immediate memory, delayed memory, and total score indices. These index scores continued to increase with repeated assessments.

CONCLUSIONS

These findings extend past work on the RBANS showing the susceptibility of memory measures to practice effects. Given that memory and total score indices of the RBANS have the most robust relationships with pathological cognitive decline, these findings raise concerns about the ability to recruit those at risk for decline from longitudinal studies using the same form of the RBANS for multiple years.

Identifying reversible psychiatric dementia mimics in new memory clinic outpatients

Background

Timely identification of reversible conditions that mimic dementia is critical in memory clinic practice. However, psychiatric conditions as potential dementia mimics have not been studied as thoroughly as neurological ones, and detailed data on their reversibility remain limited.

Objective

To identify reversible psychiatric dementia mimics.

Methods

A retrospective chart review was conducted on 749 new outpatients to investigate etiologies, progression rates, a neuropsychological assessment, cognitive and functional levels, and potential reversibility, categorized by psychiatric and neurological conditions. Cases showing cognitive reversibility following treatment were also identified. Comparisons were made based on the presence or absence of potential reversibility, as well as actual reversibility.

Results

Among the 749 individuals, 121 (16.2%) had potentially reversible conditions: 75 psychiatric and 46 neurological. Psychiatric conditions included depression, schizophrenia and delusional disorders, developmental disorders, alcohol use disorder, and dissociative and anxiety disorders. Compared to individuals without potentially reversible conditions, individuals with psychiatric conditions were younger, had a faster progression rate, and demonstrated higher cognitive function. Of the individuals who had mild cognitive impairment or dementia mimic, 6 (0.9%) showed complete cognitive resolution (3 cases) or partial cognitive improvement (3 cases). These 6 cases included two individuals with psychiatric conditions manifesting psychotic features.

Conclusions

While rare, reversible psychiatric dementia mimics highlight the importance of comprehensive evaluations in memory clinics, particularly for younger individuals experiencing rapid cognitive decline. The infrequency of reversibility may reflect a strong association between these potentially reversible conditions and dementia risk factors, or their role as prodromes of dementia itself.

Telomere length and cognitive changes in 7,877 older UK adults of European ancestry

Background

Telomere length (TL) has been linked to cognitive function, decline and dementia. This study aimed to explore whether both measured TL and genetic disposition for TL predict dimensions of cognitive performance in a longitudinal sample of older UK adults.

Methods

We analysed data from PROTECT study participants aged ≥50 years without a dementia diagnosis, who had completed longitudinal cognitive testing. We calculated polygenic scores for telomere length (PGS-TL) for 7,877 participants and measured relative telomere length (RTL) in a subgroup of 846 participants using DNA extracted from saliva samples collected within 6 months either side of their baseline cognitive testing. Latent growth models were used to examine whether RTL and PGS-TL predict both baseline and longitudinal changes in cognitive performance (4 time-points, annually).

Results

In the whole sample, we did not observe significant associations between either measure of telomere length and initial or longitudinal changes in cognitive performance. Stratifying by median age, in older adults (≥ ∼62 years), longer baseline RTL showed a nominal association with poorer baseline verbal reasoning performance (n = 423, M intercept = 47.58, B = -1.05, p = .011) and PGS-TL was associated with performance over time (n = 3,939; slope factor, M slope = 3.23, B = -0.45, p = .001; slope 2 factor, M slope 2 = 0.21, B = 0.13, p = .002).

Conclusion

Our findings suggest either the absence of a significant relationship between telomere length (RTL and PGS-TL) and cognitive performance (baseline and change over time), or possibly a weak age-dependent and domain-specific relationship, in older adults of European ancestry. More research is needed in representative and ancestrally diverse samples over a longer assessment period. Alternative biological ageing indicators may still provide utility in the early detection of individuals at risk for cognitive decline (e.g., pace-of ageing epigenetic clocks).

The Usefulness of the Regression-Based Normed SKT Short Cognitive Performance Test in Detecting Cognitive Impairment in a Community Sample

Background: The SKT is a short cognitive performance test designed to assess impairments in memory and cognitive abilities such as attention and speed of information processing. In 2019, new regression-based norms for the English version of the SKT were calculated. This study has two aims: to establish valid cut-offs for distinguishing between no cognitive impairment, mild cognitive impairment (MCI), and dementia (1) and to cross-validate the new norms for detecting MCI and dementia in a community sample of older adults with clinical diagnoses (2). Methods: The validation sample included 143 older adults (mean age = 87.7, SD = 3.55) from the Sydney Memory and Aging Study (MAS Study). Participants were classified as having normal cognition, MCI, or dementia solely based on a consensus diagnosis; in addition, three tests (SKT, Mini-Mental State Examination (MMSE), and Addenbrooke's Cognitive Examination III (ACE-III)) to measure cognitive impairment were applied. Sensitivity and specificity for all three tests, as well as bivariate correlations, were calculated. Results: The sensitivity of the SKT for the differentiation of cognitive impairment (MCI or dementia) from normal cognition was 80.6%. The convergence between the SKT and the consensus diagnoses was 70.3% for all three diagnostic groups. All correlations between the three tests and the consensus diagnosis were significant (p < 0.01). Conclusions: In sum, it can be stated that the SKT is a valid tool for detecting early stages of cognitive impairment, performing very well in discriminating between no cognitive impairment and cognitive impairment (MCI or dementia).

Adjunctive methylphenidate extended release in patients with schizophrenia: Protocol of a single-centre fixed dose cross-over open-label trial to improve functional and cognitive outcomes

Background

Cognitive symptoms, among the core symptoms of schizophrenia, are associated with poor functional outcome and burden of illness. To date, there is no effective pharmacological treatment for these symptom clusters. Augmentation with psychostimulants has been proposed as a potential treatment option.

Objectives

The present study aims to assess off-label use of adjunctive methylphenidate extended release (ER) in patients with schizophrenia who are stable on antipsychotic medications, and to assess its efficacy on functioning and cognitive outcome.

Methods

This is a single centre study at the Royal Ottawa Mental Health Centre. An open-label fixed dose controlled cross-over trial is planned. Eligible participants will be randomized into one of two arms of the study: 1) four weeks of add-on methylphenidate ER 36 mg, or 2) four weeks of treatment as usual. At 4 weeks, participants will switch arms. The duration of the study includes 8 weeks of treatment and a follow-up visit at 12 weeks. Primary outcome measures include tablet-based tests of functioning and cognition (VRFCAT and BAC) and will be administered at baseline and every 4 weeks. We are aiming to recruit a total of 24 participants.

Expected outcomes

The proposed project intends to assess a potential treatment option for cognitive deficits of schizophrenia, for which there are no recommendations by current treatment guidelines. The novelty and significance of the current study is that it investigates this intervention and assess applicability of it in a "real world setting" in a tertiary care hospital.

Remote fitness assessment in younger and middle-aged to older adults: a comparison between laboratory- and videoconference-based assessment of selected measures of physical and cognitive fitness

BACKGROUND

Digital technologies can play an important role in improving the limited accessibility of healthcare services in rural regions (e.g., via remote assessment). However, whether remote fitness assessments (RFA) of selected physical and cognitive fitness parameters are feasible both in younger and older persons and whether they can reproduce laboratory tests needs yet to be established. Thus, this study aimed to address this knowledge gap by investigating the feasibility, and reproducibility of RFA in younger and middle-aged to older adults (MOA).

METHODS

A total of 31 younger adults and 32 MOAs participated in this study. At an interval of seven days, laboratory-based and remote assessments (via videoconferencing software) were conducted which included the quantification of the following parameters: (i) measurement of heart rate variability [HRV]; followed by (ii) cognitive testing to examine the level of attention, executive functions (oral Trail Making Test [A and B]), working memory, verbal short-term memory (digit span memory test and word list test (immediate recall)) and episodic memory (word list test (delayed recall)); followed by (iii) physical fitness assessments including performance tests of balance (balance test), functional strength ability of the lower limbs (5-time-sit-to-stand-test) and endurance capacity (3-min step test). Parameters of absolute and relative reliability were determined to assess the reproducibility of the laboratory-based and remote assessments.

RESULTS

The selected physical and cognitive fitness parameters showed moderate to excellent relative reliability (intraclass correlation coefficient [ICC] = 0.52-0.95). The parameters of absolute reliability (Bland-Altman plot and standard error of measurement [SEM]) provide evidence for good reproducibility of HRV parameters and measures of physical fitness, whereas measures of cognitive fitness showed moderate to good reproducibility. On a descriptive level, the absolute and relative reliability of the selected measures of physical and cognitive fitness did not vary as a function of participants' age.

CONCLUSION

Our results suggest that RFA of selected measures of physical and cognitive fitness is feasible and reproduces corresponding laboratory results to a moderate to excellent level in both younger adults and MOA. Data showed that the reproducibility of laboratory-based and remote assessments is not influenced by the age of the participants. These findings support the use of digital technologies to improve the accessibility of healthcare services (e.g., in remote areas). However, as the reproducibility varies considerably across the different parameters, further studies are needed to evaluate the effects of an optimised standardisation of the remote assessments and confounding factors.

Feasibility and reliability of online vs in-person cognitive testing in healthy older people

BACKGROUND

Early evidence in using online cognitive assessments show that they could offer a feasible and resource-efficient alternative to in-person clinical assessments in evaluating cognitive performance, yet there is currently little understanding about how these assessments relate to traditional, in-person cognitive tests.

OBJECTIVES

In this preliminary study, we assess the feasibility and reliability of NeurOn, a novel online cognitive assessment tool. NeurOn measures various cognitive domains including processing speed, executive functioning, spatial working memory, episodic memory, attentional control, visuospatial functioning, and spatial orientation.

DESIGN

Thirty-two participants (mean age: 70.19) completed two testing sessions, unsupervised online and in-person, one-week apart. Participants were randomised in the order of testing appointments. For both sessions, participants completed questionnaires prior to a cognitive assessment. Test-retest reliability and concurrent validity of the online cognitive battery was assessed using intraclass correlation coefficients (ICCs) and correlational analysis, respectively. This was conducted by comparing performance in repeated tasks across testing sessions as well as with traditional, in-person cognitive tests.

RESULTS

Global cognition in the NeurOn battery moderately validated against MoCA performance, and the battery demonstrated moderate test-retest reliability. Concurrent validity was found only between the online and paper versions of the Trail Making Test -A, as well as global cognitive performance between online and in-person testing sessions.

CONCLUSIONS

The NeurOn cognitive battery provides a promising tool for measuring cognitive performance online both longitudinally and across short retesting intervals within healthy older adults. When considering cost-effectiveness, flexible administration, and improved accessibility for wider populations, online cognitive assessments show promise for future screening of neurodegenerative diseases.

Inequalities in accelerated cognitive decline: Resolving observational window bias using nested non-linear regression

INTRODUCTION

Limited observational windows lead to conflicting results in studies examining educational differences in Alzheimer's disease and related dementias (ADRD) risk, due to observational window bias relative to onset of accelerated cognitive decline. This study tested a novel model to address observational window bias and tested for the presence and sources of disparities in accelerated cognitive declines due to ADRD.

METHODS

The sample examined 167,314 cognitive assessments from 32,441 Health and Retirement Study participants. We implemented a parametric non-linear nested longitudinal regression and reported multivariable-adjusted nodal incidence ratios (aNIR).

RESULTS

University degrees were associated with lower incidence (aNIR = 0.253, 95% confidence interval [CI] = [0.221 to 0.289], p < 0.001), while black participants had a higher incidence (aNIR = 1.995, [1.858 to 2.141], p < 0.001) of accelerated cognitive decline, adjusting for demographic, sociobehavioral, and medical risk factors. Sex-stratified analyses identified diminished educational returns for women and increased incidence among minoritized women.

DISCUSSION

Addressing observational window bias reveals large social inequalities in the onset of accelerated cognitive declines indicative of ADRD.

HIGHLIGHTS

This study identifies observational window bias as a source of conflicting results among previous studies of educational achievement in Alzheimer's disease and related dementias (ADRD) disparities. The study locates preclinical accelerated cognitive decline, which is indicative of ADRD while occurring 10+ years prior to symptom onset, as a site to study ADRD disparities that mitigates observational window bias. A novel method, nested non-linear regression, is developed to test for differences in the onset of accelerated cognitive decline. Educational and racial/ethnic disparities are demonstrated in the onset of accelerated cognitive decline, as are their intersecting differences with sex/gender.

Distinct effects of long-term Tai Chi Chuan and aerobic exercise interventions on motor and neurocognitive performance in early-stage Parkinson's disease: a randomized controlled trial

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative condition characterized by movement disorders and probable cognitive impairment. Exercise plays an important role in PD management, and recent studies have reported improvement in motor symptoms and cognitive function following aerobic and Tai Chi Chuan exercise.

AIM

To explore the different effects of Tai Chi Chuan and aerobic exercise on the clinical motor status and neurocognitive performance of patients with early-stage PD.

DESIGN

A randomized controlled trial.

SETTING

Parkinson's Disease Center at Kaohsiung Chang Gung Memorial Hospital and National Cheng Kung University Hospital.

POPULATION

Patients with idiopathic PD.

METHODS

Fifty-six patients with PD were recruited and divided into three groups: aerobic exercise (AE, N.=14), Tai Chi Chuan exercise (TE, N.=16), and control (CG, N.=13). Before and after a 12-week intervention period, we used unified Parkinson's disease rating scale Part III (UPDRS-III) scores and neuropsychological (e.g., accuracy rates [ARs] and reaction times [RTs]) and neurophysiological (e.g., event-related potential [ERP] N2 and P3 latencies and amplitudes) parameters to respectively assess the patients' clinical motor symptoms and neurocognitive performance when performing a working memory (WM) task.

RESULTS

Compared to baseline, UPDRS-III scores were significantly lower in the AE and TE groups after the intervention period, whereas those for the CG group were higher. In terms of the neurocognitive parameters, when performing the WM task after the intervention period, the AE group exhibited significantly faster RTs and larger ERP P3 amplitudes, the TE group exhibited an improvement only in ERP P3 amplitude, and the CG group exhibited a significantly reduced ERP P3 amplitude. However, neither the TE nor the AE group exhibited improved ARs and ERP N2 performance.

CONCLUSIONS

The present study supported the distinct effectiveness of Tai Chi Chuan and aerobic exercise for improving motor symptoms and providing neurocognitive benefits in PD patients.

CLINICAL REHABILITATION IMPACT

These results have important implications regarding the use of these exercise interventions for managing PD, particularly in the early stages.

Effect of Sleep Restriction on Adolescent Cognition by Adiposity: A Randomized Crossover Trial

Importance

Pediatric obesity is associated with impaired cognitive function; however, the mechanisms underlying this association demand assessment. Sleep may be a relevant moderator, as poor sleep predicts both increased adiposity and impaired cognitive function.

Objective

To determine the effects of adiposity and sleep on adolescent cognitive function.

Design, Setting, and Participants

This single-blind randomized crossover trial was conducted from September 2020 to October 2022. Parents or caregivers provided demographic information for adolescent participants. Body mass index percentile and bioelectrical impedance analysis assessed adiposity. Adolescents completed 2 actigraphy-confirmed sleep conditions, adequate and restricted, followed by in-person cognitive assessment. No additional follow-up was provided. Data collection for this population-based study took place in a behavioral medicine clinic in Birmingham, Alabama. A total of 323 participants were assessed for eligibility (ages 14-19 years and healthy). Of the 244 eligible adolescents, 157 declined participation. Eighty-seven were randomized and 26 dropped out postenrollment. The final sample included 61 adolescents, 31 with healthy weight and 30 with overweight or obesity. Data were analyzed from April to October 2023.

Interventions

Following a 2-day washout period of adequate sleep, adolescents completed 2 sleep conditions: adequate (mean [SD] duration, 8 hours, 54 minutes [58.0 minutes]) and restricted (mean [SD] duration, 4 hours, 12 minutes [50.7 minutes]).

Main Outcomes and Measures

The National Institutes of Health Cognitive Toolbox assessed global and fluid cognition, cognitive flexibility, working and episodic memory, attention, and processing speed. The Stroop Task assessed inhibition.

Results

The final sample included 61 adolescents (mean [SD] age, 16.3 [1.6] years; 35 [57.4%] female). Restricted sleep predicted poorer global cognition scores (restricted mean [SD], 98.0 [2.8]; adequate mean [SD], 103.2 [2.9]), fluid cognition scores (restricted mean [SD], 94.5 [3.2]; adequate mean [SD], 102.0 [3.6]), and cognitive flexibility scores (restricted mean [SD], 84.8 [3.0]; adequate mean [SD], 92.8 [3.0]) for adolescents with overweight or obesity. No differences emerged for adolescents with healthy weight. Adolescents with overweight or obesity also had poorer attention scores (mean [SD], 80.0 [2.3]) compared to adolescents with healthy weight (mean [SD], 88.4 [SD, 2.3]) following restricted sleep. No differences emerged following adequate sleep. Findings were similar for total body fat percentage (TBF%); however, for adolescents with TBF% above 42, restricted sleep also predicted poorer processing speed, and the association between sleep and attention did not vary based on TBF%.

Conclusions and Relevance

Adolescents with overweight or obesity may be more vulnerable to negative cognitive effects following sleep restriction. Improved sleep hygiene and duration in this group may positively impact their cognitive health.

Trial Registration

ClinicalTrials.gov Identifier: NCT04346433.

Amyloid and tau burden relate to longitudinal changes in the performance of complex everyday activities among cognitively unimpaired older adults: results from the performance-based Harvard Automated Phone Task

Background

Changes in everyday functioning constitute a clinically meaningful outcome, even in the early stages of Alzheimer's disease. Performance-based assessments of everyday functioning might help uncover these early changes. We aimed to investigate how changes over time in everyday functioning relate to tau and amyloid in cognitively unimpaired older adults.

Methods

Seventy-six cognitively unimpaired participants (72 ± 6 years old, 61% female) completed multiple Harvard Automated Phone Task (APT) assessments over 2.0 ± 0.9 years. The Harvard APT consists of three tasks, performed through an automated phone system, in which participants refill a prescription (APT-Script), select a new primary care physician (APT-PCP), and transfer money to pay a bill (APT-Bank). Participants underwent Pittsburgh compound-B and flortaucipir positron emission tomography scans at baseline. We computed distribution volume ratios for a cortical amyloid aggregate and standardized uptake volume ratios for medial temporal and neocortical tau regions. In separate linear mixed models, baseline amyloid by time and tau by time interactions were used to predict longitudinal changes in performance on the Harvard APT tasks. Three-way amyloid by tau by time interactions were also investigated. Lastly, we examined associations between tau and change in Harvard APT scores in exploratory voxel-wise whole-brain analyses. All models were adjusted for age, sex, and education.

Results

Amyloid [unstandardized partial regression coefficient estimate (β) = -0.007, 95% confidence interval (95% CI) = (-0.013, -0.001)], and medial temporal tau [β = -0.013, 95% CI = (-0.022, -0.004)] were associated with change over time in years on APT-PCP only, i.e., higher baseline amyloid and higher baseline tau were associated with steeper rate of decline of APT-PCP. Voxel-wise analyses showed widespread associations between tau and change in APT-PCP scores over time.

Conclusion

Even among cognitively unimpaired older adults, changes over time in the performance of cognitively complex everyday activities relate to cortical amyloid and widespread cerebral tau burden at baseline. These findings support the link between Alzheimer's disease pathology and function and highlight the importance of measuring everyday functioning in preclinical disease stages.

Digital Neuropsychology beyond Computerized Cognitive Assessment: Applications of Novel Digital Technologies

Compared with other health disciplines, there is a stagnation in technological innovation in the field of clinical neuropsychology. Traditional paper-and-pencil tests have a number of shortcomings, such as low-frequency data collection and limitations in ecological validity. While computerized cognitive assessment may help overcome some of these issues, current computerized paradigms do not address the majority of these limitations. In this paper, we review recent literature on the applications of novel digital health approaches, including ecological momentary assessment, smartphone-based assessment and sensors, wearable devices, passive driving sensors, smart homes, voice biomarkers, and electronic health record mining, in neurological populations. We describe how each digital tool may be applied to neurologic care and overcome limitations of traditional neuropsychological assessment. Ethical considerations, limitations of current research, as well as our proposed future of neuropsychological practice are also discussed.

Cognitive impairment and partnership status in the United States, 1998-2016, by sex, race/ethnicity, and education

Cognitively impaired adults without a partner are highly disadvantaged, as partners constitute an important source of caregiving and emotional support. With the application of innovative multistate models to the Health and Retirement Study, this paper is the first to estimate joint expectancies of cognitive and partnership status at age 50 by sex, race/ethnicity, and education in the United States. We find that women live a decade longer unpartnered than men. Women are also disadvantaged as they experience three more years as both cognitively impaired and unpartnered than men. Black women live over twice as long as cognitively impaired and unpartnered compared with White women. Lower-educated men and women live around three and five years longer, respectively, as cognitively impaired and unpartnered than more highly educated men and women. This study addresses a novel facet of partnership and cognitive status dynamics and examines their variations by key socio-demographic factors.

Prediction of cognitive decline in older breast cancer survivors: the Thinking and Living with Cancer study

PURPOSE

Cancer survivors commonly report cognitive declines after cancer therapy. Due to the complex etiology of cancer-related cognitive decline (CRCD), predicting who will be at risk of CRCD remains a clinical challenge. We developed a model to predict breast cancer survivors who would experience CRCD after systematic treatment.

METHODS

We used the Thinking and Living with Cancer study, a large ongoing multisite prospective study of older breast cancer survivors with complete assessments pre-systemic therapy, 12 months and 24 months after initiation of systemic therapy. Cognition was measured using neuropsychological testing of attention, processing speed, and executive function (APE). CRCD was defined as a 0.25 SD (of observed changes from baseline to 12 months in matched controls) decline or greater in APE score from baseline to 12 months (transient) or persistent as a decline 0.25 SD or greater sustained to 24 months. We used machine learning approaches to predict CRCD using baseline demographics, tumor characteristics and treatment, genotypes, comorbidity, and self-reported physical, psychosocial, and cognitive function.

RESULTS

Thirty-two percent of survivors had transient cognitive decline, and 41% of these women experienced persistent decline. Prediction of CRCD was good: yielding an area under the curve of 0.75 and 0.79 for transient and persistent decline, respectively. Variables most informative in predicting CRCD included apolipoprotein E4 positivity, tumor HER2 positivity, obesity, cardiovascular comorbidities, more prescription medications, and higher baseline APE score.

CONCLUSIONS

Our proof-of-concept tool demonstrates our prediction models are potentially useful to predict risk of CRCD. Future research is needed to validate this approach for predicting CRCD in routine practice settings.

Diet patterns and cognitive performance in a UK Female Twin Registry (TwinsUK)

BACKGROUND

Plant-based diets may provide protection against cognitive decline and Alzheimer's disease, but observational data have not been consistent. Previous studies include early life confounding from socioeconomic conditions and genetics that are known to influence both cognitive performance and diet behaviour. This study investigated associations between Mediterranean (MED) diet and MIND diets and cognitive performance accounting for shared genotype and early-life environmental exposures in female twins.

METHODS

Diet scores were examined in 509 female twins enrolled in TwinsUK study. The Cambridge Neuropsychological Test Automated Battery was used to assess cognition at baseline and 10 years later (in n = 275). A co-twin case-control study for discordant monozygotic (MZ) twins examined effects of diet on cognitive performance independent of genetic factors. Differences in relative abundance of taxa at 10-year follow-up were explored in subsamples.

RESULTS

Each 1-point increase in MIND or MED diet score was associated with 1.75 (95% CI: - 2.96, - 0.54, p = 0.005 and q = 0.11) and 1.67 (95% CI: - 2.71, - 0.65, p = 0.002 and q = 0.02) fewer respective errors in paired-associates learning. Within each MZ pair, the twin with the high diet score had better preservation in spatial span especially for MED diet (p = 0.02). There were no differences between diet scores and 10-year change in the other cognitive tests. MIND diet adherence was associated with higher relative abundance of Ruminococcaceae UCG-010 (0.30% (95% CI 0.17, 0.62), q = 0.05) which was also associated with less decline in global cognition over 10 years (0.22 (95% CI 0.06, 0.39), p = 0.01).

CONCLUSIONS

MIND or MED diets could help to preserve some cognitive abilities in midlife, particularly episodic and visuospatial working memory. Effects may be mediated by high dietary fibre content and increased abundance of short-chain fatty acid producing gut bacteria. Longer follow-up with repeated measures of cognition will determine whether diet can influence changes in cognition occurring in older age.

A Closer Look at Practice Effects in Mild Cognitive Impairment and Alzheimer's Disease

Practice effects have become a potentially important variable regarding the diagnosis, prognosis, and treatment recommendations in mild cognitive impairment (MCI) and Alzheimer's disease (AD). However, the understanding of these short-term changes in test scores remains unclear. The current observational study sought to examine variables that influence the magnitude of short-term practice effects in MCI and AD, including demographic information, cognitive performance, daily functioning, and medical comorbidities. One hundred sixty-six older adults classified as cognitively intact, amnestic MCI, or mild AD were tested twice across 1 week with a brief battery of neuropsychological tests. Correlational and regression analyses examined the relationship of practice effects with demographic and clinical variables. Results indicated that practice effects were minimally related to demographic variables and medical comorbidities, but they were significantly related to cognitive variables, depressive symptoms, and daily functioning. These findings expand our understanding of practice effects in MCI and AD, and they may allow a better appreciation of how they could affect clinical care and research.

Prodromal dementia with Lewy bodies in REM sleep behavior disorder: A multicenter study

INTRODUCTION

Isolated/idiopathic rapid eye movement sleep behavior disorder (iRBD) is a powerful early predictor of dementia with Lewy bodies (DLB) and Parkinson's disease (PD). This provides an opportunity to directly observe the evolution of prodromal DLB and to identify which cognitive variables are the strongest predictors of evolving dementia.

METHODS

IRBD participants (n = 754) from 10 centers of the International RBD Study Group underwent annual neuropsychological assessment. Competing risk regression analysis determined optimal predictors of dementia. Linear mixed-effect models determined the annual progression of neuropsychological testing.

RESULTS

Reduced attention and executive function, particularly performance on the Trail Making Test Part B, were the strongest identifiers of early DLB. In phenoconverters, the onset of cognitive decline began up to 10 years prior to phenoconversion. Changes in verbal memory best differentiated between DLB and PD subtypes.

DISCUSSION

In iRBD, attention and executive dysfunction strongly predict dementia and begin declining several years prior to phenoconversion.

HIGHLIGHTS

Cognitive decline in iRBD begins up to 10 years prior to phenoconversion. Attention and executive dysfunction are the strongest predictors of dementia in iRBD. Decline in episodic memory best distinguished dementia-first from parkinsonism-first phenoconversion.

Effect of cocoa extract supplementation on cognitive function: results from the clinic subcohort of the COSMOS trial

BACKGROUND

Some prior randomized clinical trials (RCTs) that tested the effects of cocoa extract (CE), a source of flavanols, on late-life cognition have yielded promising findings. A long-term RCT using in-person neuropsychological tests covering multiple cognitive domains may clarify the cognitive effects of CE.

OBJECTIVES

To test whether daily supplementation with CE, compared with placebo, produces better cognitive change over 2 y.

METHODS

The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) is a 2 × 2 factorial RCT of CE [500 mg flavanols/d, including 80 mg (-)-epicatechin] and/or a daily multivitamin-mineral supplement for cardiovascular disease and cancer prevention among 21,442 United States adults aged ≥60 y. There were 573 participants in the clinic subcohort of COSMOS (that is, COSMOS-Clinic) who completed all cognitive tests at baseline; of these, 492 completed 2-y follow-up assessments. The primary outcome was global cognition (averaging z-scores across 11 tests). Secondary outcomes were episodic memory and executive function/attention. Repeated measures models were used to compare randomized groups.

RESULTS

Participants' mean age (standard deviation) was 69.6 (5.3); 49.2% were females. Daily supplementation with CE, compared with placebo, had no significant effect on 2-y change in global cognition {mean difference [95% confidence interval (CI)]: -0.01 (-0.08, 0.05) standard deviation units (SU)}. CE, compared with placebo, had no significant effects on 2-y change in episodic memory [mean difference (95% CI): -0.01 (-0.13, 0.10) SU] or executive function/attention [mean difference (95% CI): 0.003 (-0.07, 0.08) SU]. Subgroup analyses uncorrected for multiple-testing suggested cognitive benefits of CE supplementation, compared with placebo among those with poorer baseline diet quality.

CONCLUSIONS

Among 573 older adults who underwent repeat in-person, detailed neuropsychological assessments over 2 y, daily CE supplementation, compared with placebo, showed no overall benefits for global or domain-specific cognitive function. Possible cognitive benefits of CE among those with poorer diet quality warrant further study.

TRIAL REGISTRATION

This trial was registered at clinicaltrials.gov with identifier - NCT02422745.

Validity and reliability of a digital solution for cognitive assessment: The Brain on Track®

Background

Cognitive assessment and the early detection of cognitive impairments have been enhanced by the use of remote digital solutions. The Brain on Track® is one of these digital solutions used in clinical practice for online screening and monitoring of cognitive functioning.

Objectives

This study aimed to explore the validity and reliability of the Brain on Track® computerized test on a tablet device in adults.

Methods

A community sample of 54 young adults, 51 middle-aged adults, and 50 older adults were invited to attend in two assessment sessions. The first session included data collection on sociodemographic data, user digital literacy, Brain on Track® on the computer and on the tablet device, and usability from the user and moderator perspective. The second session included the Montreal Cognitive Assessment Questionnaire (MoCA) and a second completion of the Brain on Track® on tablet to assess the criterion validity and test-retest reliability. Hypothesis testing was used to assess construct validity.

Results

A weak to moderate correlation was found between the Brain on Track® tablet score and the MoCA. The ICC was 0.72, 0.84, and 0.79, and Cronbach's alpha was 0.84, 0.83, and 0.89 in young adults, middle-aged adults, and older adults, respectively.

Conclusions

This study suggested that the Brain on Track® administered using a tablet device has criterion validity, particularly in middle-aged and older adults, and internal consistency and test-retest reliability in adults of any age group.

A Longitudinal Study on Memory Enhancement in Subjective Cognitive Decline Patients: Clinical and Neuroimaging Perspectives

BACKGROUND

Subjective cognitive decline (SCD) refers to the self-reported persistent cognitive decline despite normal objective testing, increasing the risk of dementia compared to cognitively normal individuals.

OBJECTIVE

This study aims to investigate the attributes of SCD patients who demonstrated memory function improvement.

METHODS

In this prospective study of SCD, a total of 120 subjects were enrolled as part of a multicenter cohort study aimed at identifying predictors for the clinical progression to mild cognitive impairment or dementia (CoSCo study). All subjects underwent 18F-florbetaben PET and brain MRI scans at baseline and annual neuropsychological tests. At the 24-month follow-up, we classified SCD patients based on changes in memory function, the z-score of the Seoul verbal learning test delayed recall.

RESULTS

Of the 120 enrolled patients, 107 successfully completed the 24-month follow-up assessment. Among these, 80 patients (74.8%) with SCD exhibited memory function improvements. SCD patients with improved memory function had a lower prevalence of coronary artery disease at baseline and performed better in the trail-making test part B compared to those without improvement. Anatomical and biomarker analysis showed a lower frequency of amyloid PET positivity and larger volumes in the left and right superior parietal lobes in subjects with improved memory function.

CONCLUSIONS

Our prospective study indicates that SCD patients experiencing memory improvement over a 24-month period had a lower amyloid burden, fewer cardiovascular risk factors, and superior executive cognitive function. Identifying these key factors associated with cognitive improvement may assist clinicians in predicting future memory function improvements in SCD patients.

Cognitive improvement following endovascular embolization in patients with intracranial dural arteriovenous fistula: The Neuropsychology in dural ArterIal Fistula (NAIF) Study

BACKGROUND

Cognitive improvement after endovascular embolization of an intracranial dural arteriovenous fistula (dAVF) remains unexplored. We aim to investigate cognitive changes following endovascular embolization of dAVFs.

METHODS

Neuropsychology in dural ArterIal Fistula (NAIF) was a prospective multicentric study including patients with an angiographic diagnosis of dAVF who underwent endovascular embolization over the course of 4 years. A complete neuropsychological evaluation comprising five cognitive domains (attention and executive functions, memory, language, praxis, gnosis) was performed at baseline and 3 months follow-up. Mean Z scores for cognitive tests were compared pre- and post-treatment using paired sample t-tests, where higher Z scores indicate better cognition. Effect sizes were computed as Cohen's d.

RESULTS

A total of 32 patients (mean age 61.1±15.4 years, 10 (31.3%) females) were included. Patients exhibited improved performance in attention and executive functions: executive functions-attention (+0.282, P=0.009, d=0.29), executive functions-fluencies (+0.283, P=0.029, d=0.4), and executive functions-processing speed (+0.471, P=0.039, d=0.41). There was an increase in memory: verbal learning and verbal delayed recall scores (+0.513, P<0.001, d=0.55, and +0.385, P=0.001, d=0.41, respectively), while verbal recognition parameters (+0.839, P=0.086, d=0.37) and visual memory (delayed recall) (+0.430, P=0.060, d=0.35) displayed trends toward improved performance. Regarding language, there was significant overall improvement (+0.300, P=0.014, d=0.24), but neither praxis nor gnosis changed significantly. These cognitive outcomes were independent of the severity (measured as Cognard classification), and no patient experienced cognitive worsening.

CONCLUSION

This study suggests that endovascular embolization confers cognitive benefits on dAVF patients undergoing endovascular embolization and may be beneficial even for patients with a low risk of hemorrhage.

Assessing cognitive function in longitudinal studies of ageing worldwide: some practical considerations

Over 55 million people live with dementia worldwide. With 40% of modifiable risk factors estimated to contribute to dementia, the potential for prevention is high, and preventive measures, at an early stage of cognitive decline, are likely to positively influence future dementia trends. Countries need reliable health data and adequate measurement tools to quantify, monitor and track early changes in cognitive capacity in the general population. Many cognitive tests exist; however, there is no consensus to date about which instruments should be employed, and important variations in measurement have been observed. In this narrative review, we present a number of cognitive tests that have been used in nationally representative population-based longitudinal studies of ageing. Longitudinal panel studies of ageing represent critical platforms towards capturing the process of cognitive ageing and understanding associated risk and protective factors. We highlight optimal measures for use at a population level and for cross-country comparisons, taking into consideration instrument reliability, validity, duration, ease of administration, costs, literacy and numeracy requirements, adaptability to sensory and fine motor impairments and portability to different cultural and linguistic milieux. Drawing upon the strengths and limitations of each of these tests, and the experience gained and lessons learnt from conducting a nationally representative study of ageing, we indicate a comprehensive battery of tests for the assessment of cognitive capacity, designed to facilitate its standardised operationalisation worldwide.

Concordance Between Logical Memory and Craft Story 21 in Community-Dwelling Older Adults: The Role of Demographic Factors And Cognitive Status

OBJECTIVE

Episodic memory loss, a hallmark symptom of Alzheimer's Disease, is frequently quantified by story memory performance. The National Alzheimer's Coordinating Center Uniform Data Set Neuropsychological Battery (UDSNB) replaced Logical Memory with Craft Story 21 in UDSNB Version 3. The concordance between these story memory tasks is poorly characterized in demographically diverse older adults, possibly jeopardizing the integrity of longitudinal data in aging cohorts.

METHOD

Einstein Aging Study participants (n = 298; Mage = 76.6; Meducation = 15; 66.4% women; 43.3% Non-Hispanic White) completed UDSNB measures, including Craft Story and Logical Memory. Classification as normal cognition (n = 206) or mild cognitive impairment (n = 90) was based on Jak/Bondi criteria. Analyses included correlations, linear regression, and equipercentile equating methods to characterize the relationship between Logical Memory and Craft Story. Multivariate linear mixed effects models explored the association of covariates and practice effects over follow-up, stratified by cognitive status and race/ethnicity.

RESULTS

Immediate (r = 0.54) and delayed (r = 0.56) versions of Logical Memory and Craft Story were moderately correlated. Age, education, depression, and female sex were associated with Logical Memory, while age, education, cognitive status, and male sex were associated with Craft Story. Significant differential effects of sex on story memory were observed.

CONCLUSIONS

We demonstrated that Logical Memory and Craft Story may be used largely interchangeably; however, memory may be enhanced for stories with a protagonist of the same sex as the participant. Craft Story was somewhat more associated with mild cognitive impairment in the overall sample, but especially in non-Hispanic Black participants. We discuss how results inform test selection considerations.

Feasibility of common, enjoyable game play for assessing daily cognitive functioning in older adults

Background

Frequent digital monitoring of cognition is a promising approach for assessing endpoints in prevention and treatment trials of Alzheimer's disease and related dementias (ADRD). This study evaluated the feasibility of the MIND GamePack© for recurrent semi-passive assessment of cognition across a longitudinal interval.

Methods

The MIND GamePack consists of four iPad-based games selected to be both familiar and enjoyable: Word Scramble, Block Drop, FreeCell, and Memory Match. Participants were asked to play 20 min/day for 5 days (100 min) for 4 months. Feasibility of use by older adults was assessed by measuring gameplay time and game performance. We also evaluated compliance through semi-structured surveys. A linear generalized estimating equation (GEE) model was used to analyze changes in gameplay time, and a regression tree model was employed to estimate the days it took for game performance to plateau. Subjective and environmental factors associated with gameplay time and performance were examined, including daily self-reported questions of memory and thinking ability, mood, sleep, energy, current location, and distractions prior to gameplay.

Results

Twenty-six cognitively-unimpaired older adults participated (mean age ± SD = 71.9 ± 8.6; 73% female). Gameplay time remained stable throughout the 4-months, with an average compliance rate of 91% ± 11% (1946 days of data across all participants) and weekly average playtime of 210 ± 132 min per participant. We observed an initial learning curve of improving game performance which on average, plateaued after 22-39 days, depending on the game. Higher levels of self-reported memory and thinking ability were associated with more gameplay time and sessions.

Conclusion

MIND GamePack is a feasible and well-designed semi-passive cognitive assessment platform which may provide complementary data to traditional neuropsychological testing in research on aging and dementia.

Reliability of remote National Alzheimer's Coordinating Center Uniform Data Set data

INTRODUCTION

The National Alzheimer's Coordinating Center (NACC) Uniform Data Set (UDS) neuropsychological battery is being used to track cognition in participants across the country, but it is unknown if scores obtained through remote administration can be combined with data obtained in person.

METHODS

The remote UDS battery includes the blind version of the Montreal Cognitive Assessment (MoCA), Number Span, Semantic and Phonemic Fluency, and Craft Story. For these tests, we assessed intraclass correlation coefficients (ICCs) between in-person and remote scores in 3838 participants with both in-person and remote UDS assessments, and we compared annual score changes between modalities in a subset that had two remote assessments.

RESULTS

All tests exhibited moderate to good reliability between modalities (ICCs = 0.590-0.787). Annual score changes were also comparable between modalities except for Craft Story Immediate Recall, Semantic Fluency, and Phonemic Fluency.

DISCUSSION

Our findings generally support combining remote and in-person scores for the majority of UDS tests.

Racial, Ethnic, Nativity, and Educational Disparities in Cognitive Impairment and Activity Limitations in the United States, 1998-2016

Despite extensive research on cognitive impairment and limitations in basic activities of daily living, no study has investigated the burden of their co-occurrence (co-impairment). Using the Health and Retirement Study data and incidence-based multistate models, we study the population burden of co-impairment using three key indicators: mean age at onset, lifetime risk, and health expectancy. We examine patterns by gender, race, ethnicity, nativity, education, and their interactions for U.S. residents aged 50-100. Furthermore, we analyze what fractions of racial, ethnic, and nativity disparities in co-impairment are attributable to inequalities in educational attainment. Results reveal that an estimated 56% of women and 41% of men aged 50 will experience co-impairment in their remaining life expectancy. Men experience an earlier onset of co-impairment than women (74 vs. 77 years), and women live longer in co-impairment than men (3.4 vs. 1.9 years). Individuals who are Black, Latinx, and lower educated, especially those experiencing intersecting disadvantages, have substantially higher lifetime risk of co-impairment, earlier co-impairment onset, and longer life in co-impairment than their counterparts. Up to 75% of racial, ethnic, and nativity disparity is attributable to inequality in educational attainment. This study provides novel insights into the burden of co-impairment and offers evidence of dramatic disparities in the older U.S. population.

Cognitive Trajectories in Preclinical and Prodromal Alzheimer's Disease Related to Amyloid Status and Brain Atrophy: A Bayesian Approach

Background

Cognitive decline is a key outcome of clinical studies in Alzheimer's disease (AD).

Objective

To determine effects of global amyloid load as well as hippocampus and basal forebrain volumes on longitudinal rates and practice effects from repeated testing of domain specific cognitive change in the AD spectrum, considering non-linear effects and heterogeneity across cohorts.

Methods

We included 1,514 cases from three cohorts, ADNI, AIBL, and DELCODE, spanning the range from cognitively normal people to people with subjective cognitive decline and mild cognitive impairment (MCI). We used generalized Bayesian mixed effects analysis of linear and polynomial models of amyloid and volume effects in time. Robustness of effects across cohorts was determined using Bayesian random effects meta-analysis.

Results

We found a consistent effect of amyloid and hippocampus volume, but not of basal forebrain volume, on rates of memory change across the three cohorts in the meta-analysis. Effects for amyloid and volumetric markers on executive function were more heterogeneous. We found practice effects in memory and executive performance in amyloid negative cognitively normal controls and MCI cases, but only to a smaller degree in amyloid positive controls and not at all in amyloid positive MCI cases.

Conclusions

We found heterogeneity between cohorts, particularly in effects on executive functions. Initial increases in cognitive performance in amyloid negative, but not in amyloid positive MCI cases and controls may reflect practice effects from repeated testing that are lost with higher levels of cerebral amyloid.

Understanding the impact of radical changes in diet and the gut microbiota on brain function and structure: rationale and design of the EMBRACE study

BACKGROUND

Bariatric surgery leads to profound changes in gut microbiota and dietary patterns, both of which may interact to impact gut-brain communication. Though cognitive function improves postsurgery, there is a large variability in outcomes. How bariatric surgery-induced modifications in the gut microbiota and dietary patterns influence the variability in cognitive function is still unclear.

OBJECTIVES

To elucidate the associations between bariatric surgery-induced changes in dietary and gut microbiota patterns with cognition and brain structure.

SETTING

University hospital.

METHODS

A total of 120 adult patients (≥30 years) scheduled to undergo a primary bariatric surgery along with 60 age-, sex-, and body mass index-matched patients on the surgery waitlist will undergo assessments 3-months presurgery and 6- and 12-month postsurgery (or an equivalent time for the waitlist group). Additionally, 60 age-and sex-matched nonbariatric surgery eligible individuals will complete the presurgical assessments only. Evaluations will include sociodemographic and health behavior questionnaires, physiological assessments (anthropometrics, blood-, urine-, and fecal-based measures), neuropsychological cognitive tests, and structural magnetic resonance imaging. Cluster analyses of the dietary and gut microbiota changes will define the various dietary patterns and microbiota profiles, then using repeated measures mixed models, their associations with global cognitive and structural brain alterations will be explored.

RESULTS

The coordinating study site (Centre intégré universitaire de santé et de services sociaux du Nord-de-l'Île-de-Montréal, QC, Canada), provided the primary ethical approval (Research Ethics Board#: MP-32-2022-2412).

CONCLUSIONS

The insights generated from this study can be used to develop individually-targeted neurodegenerative disease prevention strategies, as well as providing critical mechanistic information.

Effect of tDCS targeting the M1 or left DLPFC on physical performance, psychophysiological responses, and cognitive function in repeated all-out cycling: a randomized controlled trial

BACKGROUND

Despite reporting the positive effects of transcranial direct current stimulation (tDCS) on endurance performance, very few studies have investigated its efficacy in anaerobic short all-out activities. Moreover, there is still no consensus on which brain areas could provide the most favorable effects on different performance modalities. Accordingly, this study aimed to investigate the effects of anodal tDCS (a-tDCS) targeting the primary motor cortex (M1) or left dorsolateral prefrontal cortex (DLPFC) on physical performance, psychophysiological responses, and cognitive function in repeated all-out cycling.

METHODS

In this randomized, crossover, and double-blind study, 15 healthy physically active men underwent a-tDCS targeting M1 or the left DLPFC or sham tDCS in separate days before performing three bouts of all-out 30s cycling anaerobic test. a-tDCS was applied using 2 mA for 20 min. Peak power, mean power, fatigue index, and EMG of the quadriceps muscles were measured during each bout. Heart rate, perceived exertion, affective valence, and arousal were recorded two minutes after each bout. Color-word Stroop test and choice reaction time were measured at baseline and after the whole anaerobic test.

RESULTS

Neither tDCS montage significantly changed peak power, mean power, fatigue index, heart rate, affective valence, arousal, and choice reaction time (p> 0.05). a-tDCS over DLPFC significantly lowered RPE of the first bout (compared to sham; p=0.048, Δ=-12.5%) and third bout compared to the M1 (p=0.047, Δ=-12.38%) and sham (p=0.003, Δ=-10.5%), increased EMG of the Vastus Lateralis muscle during the second (p=0.016, Δ= +40.3%) and third bout (p=0.016, Δ= +42.1%) compared to sham, and improved the score of color-word Stroop test after the repeated all-out task (p=0.04, Δ= +147%). The qualitative affective response (valence and arousal) was also higher under the M1 and DLPFC compared to the sham.

CONCLUSION

We concluded that tDCS targeting M1 or DLPFC does not improve repeated anaerobic performance. However, the positive effect of DLPFC montage on RPE, EMG, qualitative affective responses, and cognitive function is promising and paves the path for future research using different tDCS montages to see any possible effects on anaerobic performance.

TRIAL REGISTRATION

This study was approved by the Ethics Committee of Razi University (IR.RAZI.REC.1400.023) and registered in the Iranian Registry of Clinical Trials (IRCT id: IRCT20210617051606N5; Registration Date: 04/02/2022).

Recommendations on the Selection, Development, and Modification of Performance Outcome Assessments: A Good Practices Report of an ISPOR Task Force

In evaluating the clinical benefit of new therapeutic interventions, it is critical that the treatment outcomes assessed reflect aspects of health that are clinically important and meaningful to patients. Performance outcome (PerfO) assessments are measurements based on standardized tasks actively undertaken by a patient that reflect physical, cognitive, sensory, and other functional skills that bring meaning to people's lives. PerfO assessments can have substantial value as drug development tools when the concepts of interest being measured best suit task performance and in cases where patients may be limited in their capacity for self-report. In their development, selection, and modification, including the evaluation and documentation of validity, reliability, usability, and interpretability, the good practice recommendations established for other clinical outcome assessment types should continue to be followed, with concept elicitation as a critical foundation. In addition, the importance of standardization, and the need to ensure feasibility and safety, as well as their utility in patient groups, such as pediatric populations, or those with cognitive and psychiatric challenges, may enhance the need for structured pilot evaluations, additional cognitive interviewing, and evaluation of quantitative data, such as that which would support concept confirmation or provide ecological evidence and other forms of construct evidence within a unitary approach to validity. The opportunity for PerfO assessments to inform key areas of clinical benefit is substantial and establishing good practices in their selection or development, validation, and implementation, as well as how they reflect meaningful aspects of health is critical to ensuring high standards and in furthering patient-focused drug development.

Video Teleconference Administration of the Addenbrooke's Cognitive Examination-III for the Assessment of Neuropsychological Status: An Experience in Indian Subjects with Cognitive Dysfunction

Objective

To determine the feasibility, reliability, and acceptability of video teleconference (VTC)-based neuropsychological assessment using Addenbrooke's cognitive examination-III (ACE-III).

Methods

This study was performed from January 2022 to April 2022, during the third wave of the COVID-19 pandemic in India. We administered ACE-III using video-teleconferencing and compared the scores to face-to-face (FTF) testing for the eligible participants. We also conducted a participant's satisfaction survey of VTC-administered ACE-III compared to FTF-administered ACE-III, using a 7-point Likert scale.

Results

We screened 37 participants and 24 (64.9%) successfully underwent ACE-III testing through VTC. We included 20 patients (mean age: 62.7 ± 10 years, mean education: 12.0 ± 4.6 years, 85% men) for final analysis, (who completed both VTC and FTF-administered ACE-III). Nine patients had major neurocognitive disorder (dementia), eight had mild neurocognitive disorder (MCI), and three had subjective cognitive decline (SCD). The two tests were administered at a median gap of 36 (18,74.5) days. The Intraclass correlation coefficients (ICC) of ACE-3 total scores (0.97) and the subdomain scores was high (>0.8). There was "very low" to "no" bias on the Bland-Altman plots, across all domains. The mean overall satisfaction score was 4.1, indicating that VTC is "as good as" FTF.

Conclusions

Results support the feasibility and acceptability of remote administration of ACE-III via VTC. There is a good agreement between the ACE-III scores across VTC and in-person conditions.

Misinterpreting cognitive change over multiple timepoints: When practice effects meet age-related decline

OBJECTIVE

Practice effects (PE) on cognitive testing have been shown to delay detection of impairment and impede our ability to assess change. When decline over time is expected, as with older adults or progressive diseases, failure to adequately address PEs may lead to inaccurate conclusions because PEs artificially boost scores while pathology- or age-related decline reduces scores. Unlike most methods, a participant-replacement approach can separate pathology- or age-related decline from PEs; however, this approach has only been used across two timepoints. More than two timepoints make it possible to determine if PEs level out after the first follow-up, but it is analytically challenging because individuals may not be assessed at every timepoint.

METHOD

We examined 1,190 older adults who were cognitively unimpaired (n = 809) or had mild cognitive impairment (MCI; n = 381). Participants completed six neuropsychological measures at three timepoints (baseline, 12-month, 24-month). We implemented a participant-replacement method using generalized estimating equations in comparisons of matched returnees and replacements to calculate PEs.

RESULTS

Without accounting for PEs, cognitive function appeared to improve or stay the same. However, with the participant-replacement method, we observed significant PEs within both groups at all timepoints. PEs did not uniformly decrease across time; some-specifically on episodic memory measures-continued to increase beyond the first follow-up.

CONCLUSION

A replacement method of PE adjustment revealed significant PEs across two follow-ups. As expected in these older adults, accounting for PEs revealed cognitive decline. This, in turn, means earlier detection of cognitive deficits, including progression to MCI, and more accurate characterization of longitudinal change. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Intensive assessment of executive functions derived from performance in cognitive training games

Traditional neuropsychological tests accurately describe the current cognitive state but fall short to characterize cognitive change over multiple short time periods. We present an innovative approach to remote monitoring of executive functions on a monthly basis, which leverages the performance indicators from self-administered computerized cognitive training games (NUP-EXE). We evaluated the measurement properties of NUP-EXE in N = 56 individuals (59% women, 60-80 years) at increased risk of Alzheimer's disease (APOE-ϵ4 carriers with subjective cognitive decline) who completed a 12-month multimodal intervention for preventing cognitive decline. NUP-EXE presented good psychometric properties and greater sensitivity to change than traditional tests. Improvements in NUP-EXE correlated with improvements in functionality and were affected by participants' age and gender. This novel data collection methodology is expected to allow a more accurate characterization of an individual's response to a cognitive decline preventive intervention and to inform development of outcome measures for a new generation of intervention trials.

Specific but not general declines in attention and executive function with aging: Converging cross-sectional and longitudinal evidence across the adult lifespan

Objective

Attention and executive function (EF) are vulnerable to aging. However, whether all these functions generally decline with aging is not known. Furthermore, most evidence is based on cross-sectional data and fewer follow-up data are available in the literature. Longitudinal follow-up studies are necessary to characterize individualized and precise changes in cognitive function. Additionally, relatively few aging studies have included middle-aged adults to examine age-related differences in attention and EF. Therefore, this study aims to examine whether general or specific attention and EF decline with aging from adulthood to old age by combining cross-sectional and longitudinal follow-up approaches.

Methods

This study recruited 253 participants aged 20 to 78  years. passing a prescreening procedure (see main text for detail) for the baseline session, and 123 of them were invited to return 1 ~ 2  years after their first visit to participate in the follow-up session. The participants completed a series of attention and EF tasks at both the baseline and follow-up sessions, which measured alerting, orienting, conflict control, stopping, memory updating, and switching abilities. We applied linear and nonlinear regression models to evaluate the cross-sectional age effect on attention and EF and employed a modified Brinley plot to inspect follow-up performance against baseline in attention and EF.

Results

The results of cross-sectional data showed that older adults exhibited decreased efficiency in alerting, stopping, and memory updating but paradoxically increased efficiency in conflict control and switching abilities and no changes in orienting efficiency with age. However, the results of longitudinal data showed that only alerting and memory updating continued to show decreased efficiency. Furthermore, conflict control and switching showed increased efficiency with aging, whereas the orienting network, and stopping no longer showed decreased efficiency.

Conclusion

Thus, converging the cross-sectional and longitudinal data showed that the alerting and memory updating function exhibited the most robust deficit with age (cross-sectional) and aging (longitudinal). Alerting and memory updating abilities are crucial survival skills for human beings. Therefore, developing methods to prevent and improve an individual’s alertness and working memory ability is an important practical issue in aging research.

A Pilot Study of Near-Infrared Light Treatment for Alzheimer's Disease

BACKGROUND

Laboratory investigations have demonstrated that near-infrared (NIR) light treatment can reduce amyloid-β burden in models of Alzheimer's disease (AD). However, previous clinical studies are rather insufficient.

OBJECTIVE

Before starting a large-scale clinical trial, we performed a pilot study to characterize the efficacy of NIR light for AD patients.

METHODS

Twenty participants with mild to moderate AD were assigned randomly to the intervention (1060-1080 nm and 800-820 nm NIR light treatment for 12 weeks) or control group (without sham treatment). Safety and efficacy were evaluated at baseline, week 4, 8, and 12, and 4 weeks after treatment.

RESULTS

In the intervention and control groups at week 12, mean changes from baseline on the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog) were -3.1 and -1.3 (p = 0.5689). Mean changes from baseline on the Activities of Daily Living (ADL) were -3.6 versus 3.1 (p = 0.0437). Mean changes from baseline on the Mini-Mental State Examination (MMSE) were 4.4 versus 1.0 (p = 0.0253). The percentage of participants who exhibited a change larger than 4 points from baseline to week 12 was determined for the intervention and control groups on the ADAS-Cog (57% versus 29%), ADL (29% versus 0%), and MMSE (57% versus 14%). Treatment with NIR light did not increase the incidence of adverse events in participants.

CONCLUSION

NIR light treatment appears to be safe and potentially beneficial for AD patients. It improved cognitive function and activities of daily living. The preliminary data encouraged us to launch a large-sample, multicenter, double-blind clinical trial.

Computerized cognitive practice effects in relation to amyloid and tau in preclinical Alzheimer's disease: Results from a multi-site cohort

Scalable cognitive paradigms that provide metrics such as the Computerized Cognitive Composite (C3) may be sensitive enough to relate to Alzheimer's disease biomarkers in the preclinical clinically unimpaired (CU) stage. We examined CU older adults (n = 3287) who completed alternate versions of the C3 approximately 51 days apart. A subset of CU with abnormal amyloid also completed tau positron emission tomography (PET) imaging. C3 initial performance and practice effects were examined in relation to amyloid status and continuous regional tau burden. Initial C3 performance was associated with amyloid status across all participants, and with tau burden in the medial temporal lobe and early cortical regions in CU with abnormal amyloid. Short-term practice effects were associated with reduced tau in these regions in CU with abnormal amyloid, but were not associated with amyloid status. Thus, computerized cognitive testing repeated over a short follow-up period provides additional insights into early Alzheimer's disease processes.

Safety, Feasibility, and Potential Clinical Efficacy of 40 Hz Invisible Spectral Flicker versus Placebo in Patients with Mild-to-Moderate Alzheimer's Disease: A Randomized, Placebo-Controlled, Double-Blinded, Pilot Study

BACKGROUND

Recent studies suggested induction of 40 Hz neural activity as a potential treatment for Alzheimer's disease (AD). However, prolonged exposure to flickering light raises adherence and safety concerns, encouraging investigation of tolerable light stimulation protocols.

OBJECTIVE

To investigate the safety, feasibility, and exploratory measures of efficacy.

METHODS

This two-stage randomized placebo-controlled double-blinded clinical trial, recruited first cognitive healthy participants (n = 3/2 active/placebo), and subsequently patients with mild-to-moderate AD (n = 5/6, active/placebo). Participants were randomized 1:1 to receive either active intervention with 40 Hz Invisible Spectral Flicker (ISF) or placebo intervention with color and intensity matched non-flickering white light.

RESULTS

Few and mild adverse events were observed. Adherence was above 86.1% of intended treatment days, with participants remaining in front of the device for >51.3 min (60 max) and directed gaze >34.9 min. Secondary outcomes of cognition indicate a tendency towards improvement in the active group compared to placebo (mean: -2.6/1.5, SD: 6.58/6.53, active/placebo) at week 6. Changes in hippocampal and ventricular volume also showed no tendency of improvement in the active group at week 6 compared to placebo. At week 12, a potential delayed effect of the intervention was seen on the volume of the hippocampus in the active group compared to placebo (mean: 0.34/-2.03, SD: 3.26/1.18, active/placebo), and the ventricular volume active group (mean: -0.36/2.50, SD: 1.89/2.05, active/placebo), compared to placebo.

CONCLUSION

Treatment with 40 Hz ISF offers no significant safety or adherence concerns. Potential impact on secondary outcomes must be tested in larger scale clinical trials.

Models of depressive pseudoamnestic disorder

Objective

Little effort has been made in the past to validate depressive pseudodementia based on hypothesis-driven approaches. We extended this concept to individuals with amnestic Mild Cognitive Impairment and Major Depression, that is, pseudodepressive amnestic disorder. We tested two hypotheses consistent with the presentations and mechanisms associated with this potential syndrome: improvements in cognition would be significantly correlated with improvements in depression after treatment (Hypothesis 1), and if not confirmed, the presence of such an association could be identified once moderator variables were taken into account (Hypothesis 2).

Methods

Within a clinical trial, 61 individuals received open label serotonin reuptake inhibitor (citalopram or venlafaxine) treatment over a 16-week period. Selective Reminding Test and Hamilton Depression scale were conducted serially to measure change in memory and depression, respectively. Magnetic resonance imaging, other cognitive measures (Alzheimer's Disease Assessment Scale-Cognitive and speed of processing tests), and additional depression measure (Beck Depression Inventory [BDI]) were also administered.

Results

No significant associations between improvement in depression and improvement in cognition were observed. Sensitivity analyses with other cognitive measures, the BDI, and exclusion of possible "placebo" responders were negative as well. There were no significant moderation effects for baseline Hamilton Rating Scale for Depression as a measure of symptom severity or age. APOE ε4 genotype and white matter hyperintensity burden yielded counter-intuitive, albeit marginally significant results.

Conclusions

Negative findings cast doubt on the frequency of depressive pseudoamnestic disorder in older populations with documented depression and memory impairments.

Challenging neurovascular coupling through complex and variable duration cognitive paradigms: A subcomponent analysis

A similar pattern of cerebral blood velocity (CBv) response has been observed for neurovascular coupling (NVC) assessment with cognitive tasks of varying complexity and duration. This lack of specificity could result from parallel changes in arterial blood pressure (BP) and PaCO₂, which could confound the estimates of NVC integrity. Healthy participants (n = 16) underwent recordings at rest (5 min sitting) and during randomized paradigms of different complexity (naming words (NW) beginning with P-, R-, V- words and serial subtractions (SS) of 100-2, 100-7, 1000-17, with durations of 5, 30 and 60 s). Bilateral CBv (middle cerebral arteries, transcranial Doppler), end-tidal CO₂ (EtCO₂, capnography), blood pressure (BP, Finapres) and heart rate (HR, ECG) were recorded continuously. The bilateral CBv response to all paradigms was classified under objective criteria to select only responders, then the repeated data were averaged between visits. Bilateral CBv change to tasks was decomposed into the relative contributions (subcomponents) of arterial BP (V_BP; neurogenic), critical closing pressure (V_CrCP; metabolic) and resistance area product (V_RAP; myogenic). A temporal effect was demonstrated in bilateral V_BP and V_RAP during all tasks (p<0.002), increased V_BP early (between 0 and 10 s) and followed by decreases of V_RAP late (25-35 s) in the response. V_CrCP varied by complexity and duration (p<0.046). The main contributions to CBv responses to cognitive tasks of different complexity and duration were V_BP and V_RAP, whilst a smaller contribution from V_CrCP would suggest sensitivity to metabolic demands. Further studies are needed to assess the influence of different paradigms, ageing and cerebrovascular conditions.

Repeated forms, testing intervals, and SDMT performance in a large multiple sclerosis dataset

BACKGROUND

The Symbol Digit Modalities Test (SDMT), the most reliable and sensitive measure of cognition in people with multiple sclerosis (PwMS), is increasingly used in clinical trials and care.

OBJECTIVES

We aimed to establish how SDMT performance is influenced by repeating forms and frequency of use in PwMS.

METHODS

A retrospective analysis was completed on a large database of PwMS (n = 740) with multiple SDMT administrations. Change in SDMT performance was analyzed, accounting for frequency of tests and utilization of alternate- versus same-form conditions.

RESULTS

SDMT administrations ranged from 2 to 14 per subject over a mean (SD) of 5.9 (4.5) years. Accounting for demographics, the mixed effects model revealed a significant main effect of SDMT exposures (1.8 point improvement per repetition, p = 0.001) and an interaction between time since previous SDMT and whether the same test form was administered in the previous administration (estimate=-1.1, p = 0.037). As well, SDMT decline is observed when testing intervals exceed two years (F = 9.69, p<0.001).

CONCLUSION

Improvements in SDMT performance with repeated exposure, likely reflecting practice effects, were greatest when repeating the same SDMT form over briefer intervals. We recommend the use of alternate forms or analogous versions of timed symbol-digit coding particularly where samples are saturated with many administrations.

Future Directions for the HRS Harmonized Cognitive Assessment Protocol

In the absence of effective pharmacological treatment to halt or reverse the course of Alzheimer's disease and related dementias (ADRDs), population-level research on the modifiable determinants of dementia risk and outcomes for those living with ADRD is critical. The Harmonized Cognitive Assessment Protocol (HCAP), fielded in 2016 as part of the U.S. Health and Retirement Study (HRS) and multiple international counterparts, has the potential to play an important role in such efforts. The stated goals of the HCAP are to improve our ability to understand the determinants, prevalence, costs, and consequences of cognitive impairment and dementia in the U.S. and to support cross-national comparisons. The first wave of the HCAP demonstrated the feasibility and value of the more detailed cognitive assessments in the HCAP compared to the brief cognitive assessments in the core HRS interviews. To achieve its full potential, we provide eight recommendations for improving future iterations of the HCAP. Our highest priority recommendation is to increase the representation of historically marginalized racial/ethnic groups disproportionately affected by ADRDs. Additional recommendations relate to the timing of the HCAP assessments; clinical and biomarker validation data, including to improve cross-national comparisons; dropping lower performing items; enhanced documentation; and the addition of measures related to caregiver impact. We believe that the capacity of the HCAP to achieve its stated goals will be greatly enhanced by considering these changes and additions.