Practice effects in a longitudinal, multi-center Alzheimer's disease prevention clinical trial

Mid-term changes in cognitive functions in patients with atrial fibrillation: a longitudinal analysis of the Swiss-AF cohort

Background

Longitudinal association studies of atrial fibrillation (AF) and cognitive functions have shown an unclear role of AF-type and often differ in methodological aspects. We therefore aim to investigate longitudinal changes in cognitive functions in association with AF-type (non-paroxysmal vs. paroxysmal) and comorbidities in the Swiss-AF cohort.

Methods

Seven cognitive measures were administered up to five times between 2014 and 2022. Age-education standardized scores were calculated and association between longitudinal change in scores and baseline AF-type investigated using linear mixed-effects models. Associations between AF-type and time to cognitive drop, an observed score of at least one standard deviation below individual's age-education standardized cognitive scores at baseline, were studied using Cox proportional hazard models of each cognitive test, censoring patients at their last measurement. Models were adjusted for baseline covariates.

Results

2,415 AF patients (mean age 73.2 years; 1,080 paroxysmal, 1,335 non-paroxysmal AF) participated in this Swiss multicenter prospective cohort study. Mean cognitive scores increased longitudinally (median follow-up 3.97 years). Non-paroxysmal AF patients showed smaller longitudinal increases in Digit Symbol Substitution Test (DSST), Cognitive Construct Score (CoCo)and Trail Making Test part B (TMT-B) scores vs. paroxysmal AF patients. Diabetes, history of stroke/TIA and depression were associated with worse performance on all cognitive tests. No differences in time to cognitive drop were observed between AF-types in any cognitive test.

Conclusion

This study indicated preserved cognitive functioning in AF patients, best explained by practice effects. Smaller practice effects were found in non-paroxysmal AF patients in the DSST, TMT-B and the CoCo and could indicate a marker of subtle cognitive decline. As diabetes, history of stroke/TIA and depression-but not AF-type-were associated with cognitive drop, more attention should be given to risk factors and underlying mechanisms of AF.

Stability of Montreal Cognitive Assessment in Individuals with Mild Cognitive Impairment: Potential Influence of Practice Effect

Background: The Montreal Cognitive Assessment (MoCA) is a standard test for screening and monitoring cognitive functions. Objective: This study explored the two-year changes in MoCA scores in older adults. Methods: Fifty-seven participants with mild cognitive impairment (MCI) and 87 participants with normal cognition completed the baseline and two-year follow-up assessments. Apart from MoCA, tests on visuospatial judgment, memory, and motor-related executive function were administered. Results: The results identified three MCI subgroups based on the differential changes in MoCA scores. They were the consistently low, consistently high, and low-to-high between-time performances. These heterogeneous test performances are on contrary to the significant deteriorations in executive function and finger dexterity across all subgroups. Repeated exposure to MoCA tests during the follow-up period was found to be a plausible indicator of the MCI subgroup categorization. Conclusion: Findings raise concerns over adopting brief clinical instrument for repeated testing, such as MoCA, for monitoring MCI conditions among older adults.

HIV-Dementia Scale as a screening tool for the detection of subcortical cognitive deficits: validation of the Italian version

Mini-Mental State Examination (MMSE) lacks of sensitivity in detecting cognitive deficits associated with subcortical damage. The HIV-Dementia Scale (HDS), a screening tool originally created for detecting cognitive impairment due to subcortical damage in HIV + patients, has proved to be useful in other neurological diseases. Until now, an Italian version of the HDS is not available. We aimed at: (1) validating the HDS Italian version (HDS-IT) in a cohort of cognitively healthy subjects (CN); (2) exploring the suitability of HDS-IT in detecting cognitive impairment due to subcortical damage (scCI). The psychometric properties of the HDS-IT were assessed in 180 CN (mean age 67.6 ± 8.3, range 41-84) with regard to item-total correlation, test-retest reliability and convergent validity with MMSE. Item-total correlations ranged 0.44-0.72. Test-retest reliability was 0.70 (p < 0.001). The HDS-IT scores were positively associated with MMSE score (rS = 0.49, p < 0.001). Then, both the HDS-IT and the MMSE were administered to 44 scCI subjects (mean age 64.9 ± 10.6, range 41-84). Mean HDS-IT total score was close to the original version and significantly lower in the scCI group compared to CN (8.6 ± 3.6 vs. 12.6 ± 2.5, p < 0.001). ROC analysis yielded an optimal cutoff value of 11, with sensitivity of 0.70 and specificity of 0.82. Patients showed poorer scores on HDS-IT compared to CN (12.6 ± 2.5 vs. 8.6 ± 3.6, p < 0.001). Our results support the use of HDS-IT as a screening tool suitable for detecting cognitive deficits with prevalent subcortical pattern, being complementary to MMSE in clinical practice.

A Comparison of Methods for Predicting Future Cognitive Status: Mixture Modeling, Latent Class Analysis, and Competitors

PURPOSE

The present work compares various methods for using baseline cognitive performance data to predict eventual cognitive status of longitudinal study participants at the University of Kentucky's Alzheimer's Disease Center.

METHODS

Cox proportional hazards models examined time to cognitive transition as predicted by risk strata derived from normal mixture modeling, latent class analysis, and a 1-SD thresholding approach. An additional comparator involved prediction directly from a numeric value for baseline cognitive performance.

RESULTS

A normal mixture model suggested 3 risk strata based on Consortium to Establish a Registry for Alzheimer's Disease (CERAD) T scores: high, intermediate, and low risk. Cox modeling of time to cognitive decline based on posterior probabilities for risk stratum membership yielded an estimated hazard ratio of 4.00 with 95% confidence interval 1.53-10.44 in comparing high risk membership to low risk; for intermediate risk membership versus low risk, the modeling yielded hazard ratio=2.29 and 95% confidence interval=0.98-5.33. Latent class analysis produced 3 groups, which did not have a clear ordering in terms of risk; however, one group exhibited appreciably greater hazard of cognitive decline. All methods for generating predictors of cognitive transition yielded statistically significant likelihood ratio statistics but modest concordance statistics.

CONCLUSION

Posterior probabilities from mixture modeling allow for risk stratification that is data-driven and, in the case of CERAD T scores, modestly predictive of later cognitive decline. Incorporating other covariates may enhance predictions.

Dietary Supplement Intake and Its Association with Cognitive Function, Physical Fitness, Depressive Symptoms, Nutritional Status and Biochemical Indices in a 3-Year Follow-Up Among Community Dwelling Older Adults: A Longitudinal Study

Purpose

Use of dietary supplements by older adults has been increasing for improving micronutrient deficiencies, cognitive function, and overall health status. Thus, the objective of this secondary investigation is to explore the longitudinal association of baseline supplement intake in improving cognitive function, biochemical parameters, anthropometric variables and physical fitness among older adults.

Methods

Towards Useful Aging (TUA) is a three-year longitudinal study conducted at baseline (2013–2014) and at follow-up (2015–2017) surveys. The number of participants dropped from 2322 during baseline study to 1787 and 1560 during the 18th and 36th month follow-up, respectively. Data on socio-demography, use of dietary supplement, biochemical indices, anthropometry, cognitive function, physical fitness and depressive symptoms were obtained. Longitudinal associations were done using the linear mixed model analysis among 1285 subjects with complete data.

Results

The most common vitamin and mineral supplementations consumed were multivitamin, B-complex, and calcium. Meanwhile, the herbal supplements consumed by participants were Eurycoma longifolia, Morinda citrifolia and Orthosiphon aristatus. Longitudinal analysis adjusted for multiple covariates showed improvement in both supplement users and non-users for global cognitive function, working memory, visual memory, 2-minute step test, chair stand test, chair sit and reach and time up and go test, waist circumference and hip circumference in both the supplement users and non-users.

Conclusion

Our findings indicated that dietary supplement intake is not associated with cognitive function, physical fitness, nutritional status, depressive symptoms or biochemical indices since improvement in the parameters was observed among both supplement users and non-users.

Assessing individual-level change in dementia research: a review of methodologies

Background

Whether in the context of monitoring disease progression or in assessing the effects of interventions, a major challenge in dementia research is determining when an individual has undergone meaningful change in symptoms and other relevant outcomes such as cognitive test performance. The challenge lies in differentiating genuine improvement or deterioration from change in scores due to random and systematic error.

Body

In this review, we discuss the advantages and limitations of available methods for assessing individual-level change in the context of key challenges, including imperfect and differential reliability of scores, and practice effects. We discuss indices of reliable change and the use of composite and item response theory (IRT) scores.

Conclusion

We conclude that IRT-based approaches hold particular promise because they have the flexibility to accommodate solutions to a wide range of issues that influence the accuracy of judgements of meaningful change. We close by discussing the practical implications of adopting IRT-based approaches.

Do people with Alzheimer's disease improve with repeated testing? Unpacking the role of content and context in retest effects

Objective

retest effects may be attributed to 'repeated content' in neuropsychological tests such as words in word list-learning tests, or the 'testing context' which involves procedural memory and reduced test anxiety following repeated administration. Alzheimer's Disease (AD) severely impairs episodic memory, so longitudinal cognitive testing among people with dementia may reveal the relative contributions of content versus context to retest effects in neuropsychological testing.

Method

we used data from the Critical Path Institute's repository of placebo arm data from randomized controlled trials (RCTs) of dementia conducted by participating pharmaceutical companies (N = 990 people, 4,170 study visits, up to 2.4 years of follow-up). To estimate retest effects on the Mini-Mental State Examination (MMSE), we used linear regressions with random effects for people and time, adjusting for age, sex and race, and longitudinal quantile regressions.

Results

average MMSE score (16.6 points, SD = 5.5, range 1, 27) declined by 2.0 points/year (95% confidence interval, CI: -2.3, -1.8). Mean retest effect was 0.6 points (95% CI: 0.4, 0.8) at second assessment (average 4 months after baseline). Retest effects were similar among participants with and without any recall on the short-delay word recall subscale score at baseline, and at the 30th, 50th and 70th percentiles of the MMSE distribution, suggesting similar retest effects across the spectrum from mild to severe cases of dementia.

Conclusions

retest effects are apparent in people with dementia despite reduced episodic memory, suggesting a prominent role of the testing context in RCTs and cohort studies.

Healthy Aging and Dementia: Two Roads Diverging in Midlife?

Dementia, particularly Alzheimer’s disease (AD), is a growing pandemic that presents profound challenges to healthcare systems, families, and societies throughout the world. By 2050, the number of people living with dementia worldwide could almost triple, from 47 to 132 million, with associated costs rising to $3 trillion. To reduce the future incidence of dementia, there is an immediate need for interventions that target the disease process from its earliest stages. Research programs are increasingly starting to focus on midlife as a critical period for the beginning of AD-related pathology, yet the indicators of the incipient disease process in asymptomatic individuals remain poorly understood. We address this important knowledge gap by examining evidence for cognitive and structural brain changes that may differentiate, from midlife, healthy aging and pathological AD-related processes. This review crystallizes emerging trends for divergence between the two and highlights current limitations and opportunities for future research in this area.

A longitudinal study of cognitive trajectories and its factors for Koreans aged 60 and over: A latent growth mixture model

OBJECTIVE

The purpose of this study is twofold: first, to identify cognitive trajectories of older Koreans in a population-based longitudinal panel survey and, second, to investigate the main characteristics of the identified heterogeneous classes of cognitive trajectories.

METHODS

Data came from 2445 cognitively healthy persons aged 60 or older in the 2006 to 2012 Korean Longitudinal Study of Aging. Using Korean-mini mental status examination (K-MMSE) as a measure of global cognitive function, the latent growth mixture modeling approach examined potential heterogeneity of longitudinal changes over the 6 years.

RESULTS

This study found that older Koreans reported an average K-MMSE score of 27 at baseline and experienced a cognitive decline every 2 years by -1.6 (2006-2008) and -1.2 (2008-2010), followed by a slight increase of 0.7 in 2012. Results from the latent growth mixture modeling analysis indicated that there were 2 heterogeneous classes of longitudinal changes in the K-MMSE over a period of 6 years: class 1 with stable cognitive function and class 2 with sharp cognitive decline over time. The sharp decline was found among those older in age and with higher level of depression at baseline. On the contrary, being male, higher education, active social engagement, and regular exercise were main characteristics of stable cognitive function.

CONCLUSION

As the first to examine cognitive trajectories among older Koreans, this study highlighted heterogeneity of cognitive trajectories in the population that should be considered for developing differential intervention strategies aimed at both promoting healthy brain and delaying/preventing cognitive decline.

Potential Factors Associated with Cognitive Improvement of Individuals Diagnosed with Mild Cognitive Impairment or Dementia in Longitudinal Studies

Despite the progressive nature of Alzheimer's disease and other dementias, it is observed that many individuals that are diagnosed with mild cognitive impairment (MCI) in one clinical assessment, may return back to normal cognition (CN) in a subsequent assessment. Less frequently, such 'back-transitions' are also observed in people that had already been diagnosed with later stages of dementia. In this study, an analysis was performed on two longitudinal cohort datasets provided by 1) the Alzheimer's Disease Neuroimaging Initiative (ADNI) and 2) the National Alzheimer's Coordinating Centre (NACC). The focus is on the observed improvement of individuals' clinical condition recorded in these datasets to explore potential associations with different factors. It is shown that, in both datasets, transitions from MCI to CN are significantly associated with younger age, better cognitive function, and the absence of ApoE ɛ4 alleles. Better cognitive function and in some cases the absence of ApoE ɛ4 alleles are also significantly associated with transitions from types of dementia to less severe clinical states. The effect of gender and education is not clear-cut in these datasets, although highly educated people who reach MCI tend to be more likely to show an improvement in their clinical state. The potential effect of other factors such as changes in symptoms of depression is also discussed. Although improved clinical outcomes can be associated with many factors, better diagnostic tools are required to provide insight into whether such improvements are a result of misdiagnosis, and if they are not, whether they are linked to improvements in the underlying neuropathological condition.

Social cognition psychometric evaluation (SCOPE) in people with early psychosis: A preliminary study

Social cognition is an important outcome in schizophrenia research. Unfortunately, there has been a lack of consensus regarding which measures of social cognition best capture this domain of functioning. The Social Cognition Psychometric Evaluation (SCOPE) study was developed to address the need for a battery of measures that have sound psychometric properties and can be implemented in clinical trials for individuals with chronic schizophrenia. The current study expands upon the SCOPE study by examining the psychometric properties of the eight candidate measures administered to individuals early in the course of psychosis. Thirty-eight stable outpatients with first episode psychosis and thirty-nine healthy controls completed the battery at baseline and one-month follow-up assessments. The SCOPE battery was evaluated on a collection of psychometric properties, including: (1) Reliability - including test-retest and internal consistency, (2) Between group differences, (3) Utility as a repeated measure, (4) Relationship to social and occupational functioning, (5) Incremental validity - variance in functioning beyond neurocognition, and (6) Feasibility - including practicality of administration and tolerability. Social cognition accounted for substantially more variance in functional outcome than neurocognition. Only one measure, the Hinting task, displayed adequate psychometric properties to be recommended for use in clinical research with first episode psychosis. The remaining candidate measures would require modifications before implementation or cannot be recommended for use in clinical research with first episode psychosis.

Tai Chi for Posttraumatic Stress Disorder and Chronic Musculoskeletal Pain: A Pilot Study

PURPOSE

Explore the feasibility of a Tai Chi intervention to improve musculoskeletal pain, emotion, cognition, and physical function in individuals with posttraumatic stress disorder.

DESIGN

Two-phase, one-arm quasi-experimental design.

METHOD

Phase 1: 11 participants completed one Tai Chi session, feasibility questionnaire, and were offered participation in Phase 2, a 12-week Tai Chi intervention. Ten participants participated in Phase 2. Pain intensity, interference, physical function scales, an emotional battery, and cognition tests were used for pre- and postintervention outcome measures. Paired t tests and thematic analysis were used for analysis.

FINDINGS

In Phase 1, most felt Tai Chi would benefit health (90.9%) and expressed interest in continuing Tai Chi (6.73 out of 7). Phase 2 results showed improvement in fear-affect (raw t = -2.64, p = .03; age adjusted t = -2.90, p = .02), fear-somatic arousal (raw t = -2.53, p = .035), List Sorting Working Memory (raw t = 2.62, p = .031; age adjusted t = 2.96, p = .018), 6-Minute Walk Test ( t = 3.541, p = .008), and current level of Pain Intensity ( t = -4.00, p = .004).

CONCLUSIONS

Tai Chi is an acceptable, holistic treatment to individuals with musculoskeletal pain and posttraumatic stress disorder. It may reduce pain, improve emotion, memory, and physical function.

Evidence of practice effect in CANTAB spatial working memory test in a cohort of patients with mild cognitive impairment

The Cambridge Neuropsychological Test Automated Battery (CANTAB) is a system of neuropsychological tests frequently used to track the progression of cognitive deficits in mild cognitive impairment (MCI) and Alzheimer's disease (AD). We investigated test-retest reliability in seven CANTAB tests. Twenty-five MCI patients, with either AD-like or conflicting/normal cerebrospinal fluid profiles underwent three testing sessions at 6-month intervals, including the following tests: Reaction Time and Rapid Visual Information Processing (assessing attention and reaction times); Delayed Matching-to-Sample, Paired Associates Learning, Spatial Recognition Memory and Pattern Recognition Memory (assessing memory); Spatial Working Memory (assessing executive functions). No significant difference was found when comparing the two groups. Many CANTAB measures obtained low or marginal test-retest coefficients. We observed a marked improvement in Spatial Working Memory (SWM) in both groups when comparing the baseline performance with the 6-month follow-up, but no difference in performance between 6- and 12-month follow-ups. A similar trend was documented in Paired Associates Learning (PAL), but the effect size was small. Such improvement may result from a practice effect, likely due to the learning of an effective strategy. Our evidence raised an important issue concerning the need for methodological caution when interpreting the results of longitudinal studies using SWM and PAL.

Longitudinal assessment of the Edinburgh Cognitive and Behavioural Amyotrophic Lateral Sclerosis Screen (ECAS): lack of practice effect in ALS patients?

OBJECTIVE

The study objective was to assess whether controls and ALS patients show a practice effect in the Edinburgh Cognitive and Behavioural ALS Screen (ECAS) on repeated longitudinal testing and if the ECAS detects progression of cognitive or behavioural changes over time.

METHODS

The ECAS was administered serially to ALS patients (n = 24 after six months, n = 10 after 12-18 months) and controls (n = 21 after six months). The ECAS was fully performed by all participants. For comparison purposes the Frontal Assessment Battery (FAB) was administered to a subgroup of 14 patients and 14 controls.

RESULTS

After six months controls showed a significantly higher overall score (p < 0.001) and significantly higher scores in all subdomains of the ECAS, except for visuospatial function and fluency. ALS patients showed no significant difference in any score of the ECAS after six months and up to18 months. Behavioural changes were increasingly, but not statistically, significant, noted by patient carers. The FAB was no longer applicable due to progressive motor deficits in 20% of ALS patients.

CONCLUSIONS

In conclusion, in contrast to healthy controls, ALS patients show no practice effects. This could reflect 'pre-symptomatic' cognitive decline and progressive behavioural symptoms.

Jump, Hop, or Skip: Modeling Practice Effects in Studies of Determinants of Cognitive Change in Older Adults

Improvements in cognitive test scores upon repeated assessment due to practice effects (PEs) are well documented, but there is no empirical evidence on whether alternative specifications of PEs result in different estimated associations between exposure and rate of cognitive change. If alternative PE specifications produce different estimates of association between an exposure and rate of cognitive change, this would be a challenge for nearly all longitudinal research on determinants of cognitive aging. Using data from 3 cohort studies-the Three-City Study-Dijon (Dijon, France, 1999-2010), the Normative Aging Study (Greater Boston, Massachusetts, 1993-2007), and the Washington Heights-Inwood Community Aging Project (New York, New York, 1999-2012)-for 2 exposures (diabetes and depression) and 3 cognitive outcomes, we compared results from longitudinal models using alternative PE specifications: no PEs; use of an indicator for the first cognitive visit; number of prior testing occasions; and square root of the number of prior testing occasions. Alternative specifications led to large differences in the estimated rates of cognitive change but minimal differences in estimated associations of exposure with cognitive level or change. Based on model fit, using an indicator for the first visit was often (but not always) the preferred model. PE specification can lead to substantial differences in estimated rates of cognitive change, but in these diverse examples and study samples it did not substantively affect estimated associations of risk factors with change.

Longitudinal Change in Performance on the Montreal Cognitive Assessment in Older Adults

OBJECTIVE

The Montreal Cognitive Assessment (MoCA) is a brief screening measure commonly used to determine cognitive status among older adults. Despite the popularity of the MoCA, there has been little research into how performance on the MoCA changes over time in healthy older adults.

METHODS

The present study examined a sample of older adults (n = 53) recruited for a longitudinal study of healthy aging. Change in total MoCA score at three time points (baseline, 12 months, and 48 months) and scores from the Repeatable Battery for the Assessment of Neuropsychological Status at five time points (RBANS; baseline 12 months, 24 months, 36 months, and 48 months) were assessed using repeated measures analyses.

RESULTS

Total MoCA score significantly increased across time, particularly between the first and second administrations. Scores did not significantly differ between the second (12 month) and third (48 month) administrations. When grouped by baseline performance, individuals who scored low at baseline significantly improved performance at 12-month testing, but had little change between 12- and 48-month testing. Conversely, individuals who scored high at baseline did not significantly change between baseline and 12-month testing, but improved between 12- and 48-month testing. RBANS scores did not significantly change over time.

CONCLUSIONS

These results suggest that the MoCA may be susceptible to practice effects, particularly between the first and second administrations. These practice effects should be taken into consideration when repeatedly employing the MoCA to screen for cognitive status in healthy older adults.

Hippocampal Sclerosis of Aging Can Be Segmental: Two Cases and Review of the Literature

Hippocampal sclerosis of aging (HS-Aging) is a neurodegenerative disease that mimics Alzheimer disease (AD) clinically and has a prevalence rivaling AD in advanced age. Whereas clinical biomarkers are not yet optimized, HS-Aging has distinctive pathological features that distinguish it from other diseases with "hippocampal sclerosis" pathology, such as epilepsy, cerebrovascular perturbations, and frontotemporal lobar degeneration. By definition, HS-Aging brains show neuronal cell loss and gliosis in the hippocampal formation out of proportion to AD-type pathology; it is strongly associated with aberrant TDP-43 pathology and arteriolosclerosis. Here, we describe 2 cases of "segmental" HS-Aging in which "sclerosis" in the hippocampus was evident only in a subset of brain sections by hematoxylin and eosin (H&E) stain. In these cases, TDP-43 pathology was more widespread on immunostained sections than the neuronal cell loss and gliosis seen in H&E stains. The 2 patients were cognitively intact at baseline and were tracked longitudinally over a decade using cognitive studies with at least 1 neuroimaging scan. We discuss the relevant HS-Aging literature, which indicates the need for a clearer consensus-based delineation of "hippocampal sclerosis" and TDP-43 pathologies in aged subjects.

Predictors of Retest Effects in a Longitudinal Study of Cognitive Aging in a Diverse Community-Based Sample

Better performance due to repeated testing can bias long-term trajectories of cognitive aging and correlates of change. We examined whether retest effects differ as a function of individual differences pertinent to cognitive aging: race/ethnicity, age, sex, language, years of education, literacy, and dementia risk factors including apolipoprotein E ε4 status, baseline cognitive performance, and cardiovascular risk. We used data from the Washington Heights-Inwood Columbia Aging Project, a community-based cohort of older adults (n=4073). We modeled cognitive change and retest effects in summary factors for general cognitive performance, memory, executive functioning, and language using multilevel models. Retest effects were parameterized in two ways, as improvement between the first and subsequent testings, and as the square root of the number of prior testings. We evaluated whether the retest effect differed by individual characteristics. The mean retest effect for general cognitive performance was 0.60 standard deviations (95% confidence interval [0.46, 0.74]), and was similar for memory, executive functioning, and language. Retest effects were greater for participants in the lowest quartile of cognitive performance (many of whom met criteria for dementia based on a study algorithm), consistent with regression to the mean. Retest did not differ by other characteristics. Retest effects are large in this community-based sample, but do not vary by demographic or dementia-related characteristics. Differential retest effects may not limit the generalizability of inferences across different groups in longitudinal research.

Neural substrates of cognitive subtypes in Parkinson's disease: a 3-year longitudinal study

BACKGROUND

The neuropsychological features and neuropathological progression patterns associated with rapidly evolving cognitive decline or dementia in Parkinson's disease (PD) remain to be elucidated.

METHODS

Fifty-three PD patients without dementia were recruited to participate in a 3-year longitudinal cohort study. The patients were grouped according to the Clinical Dementia Rating (CDR). Group-wise comparisons were made with regard to demographic characteristics, motor symptoms, neuropsychological performances and 18F-fluorodeoxyglucose positron emission tomography.

RESULTS

Patients who had memory-plus cognitive impairment (patients whose CDR was 0 at baseline and 0.5 in memory and other domains at follow-up, and those whose baseline CDR was 0.5 in memory and other domains) exhibited higher age at onset, visuoperceptual impairment, non-tremor-dominant motor disturbance, rapid symptomatic progression and posterior neocortical hypometabolism. In patients who were cognitively unimpaired and those who had memory-dominant cognitive impairment (patients whose CDR was 0 at baseline and 0.5 only in memory domain at follow-up, and those whose baseline CDR was 0.5 only in memory domain), the posterior neocortex was relatively unaffected until a later stage of the disease.

CONCLUSIONS

These results suggest that visuoperceptual impairment and the early involvement of the posterior neocortex may be risk factors for rapid symptomatic progression and dementia in PD.

Influence of multiple APOE genetic variants on cognitive function in a cohort of older men - results from the Normative Aging Study

BACKGROUND

APOE is the biomarker with the greatest known influence on cognitive function; however, the effect of complex haplotypes involving polymorphisms rs449647, rs405509, rs440446, rs429358 and rs7412 has never been studied in older populations.

METHODS

We evaluated APOE polymorphisms using multiplex PCR for genotyping and Mini-Mental State Examination (MMSE) to evaluate cognitive function in 819 individuals from VA Normative Aging Study.

RESULTS

Combinatorial analysis of all polymorphisms and individual analysis of polymorphisms rs449647, rs405509, rs440446 and rs7412 did not show any association with cognitive performance. Polymorphism rs429358 was associated with better cognitive performance (odds of MMSE ≤ 25 = 0.63, 95% CI 0.42-0.95; p = 0.03) in the oldest subsample (5th quintile of age) (odds of MMSE ≤ 25 = 0.34; 95% CI 0.13-0.86; p = 0.02). APOE allele ε4 was also associated with better cognitive performance (odds of MMSE ≤ 25 = 0.61, 95% CI 0.40-0.94; p = 0.02), also in the oldest subsample (odds of MMSE ≤ 25 = 0.35, 95% CI 0.14-0.90; p = 0.03).

CONCLUSIONS

These results suggest a beneficial effect of polymorphism rs429358 in the oldest men.

Normal cognitive aging

Even those who do not experience dementia or mild cognitive impairment may experience subtle cognitive changes associated with aging. Normal cognitive changes can affect an older adult's everyday function and quality of life, and a better understanding of this process may help clinicians distinguish normal from disease states. This article describes the neurocognitive changes observed in normal aging, followed by a description of the structural and functional alterations seen in aging brains. Practical implications of normal cognitive aging are then discussed, followed by a discussion of what is known about factors that may mitigate age-associated cognitive decline.

Brain training: rationale, methods, and pilot data for a specific visuomotor/visuospatial activity program to change progressive cognitive decline

INTRODUCTION

Research in the field of the aging brain has evolved to the extent that it is now commonly understood that actively engaging in cognitive tasks provides the potential of being beneficial in affecting the trajectory of age-related cognitive decline. What remains to be examined is the extent, and type, of program required to effect change in aging cognitively impaired individuals.

METHODS

To address this issue, a cognitive program focusing on the use of visuospatial (VS)/visuomotor (VM) elements was applied to a group of six older individuals with identified progressive cognitive impairments. It was hypothesized that using tasks with VS and VM components may be beneficial in supporting overall brain performance, and subsequently assist individuals to perform well in various cognitive and behavioral tasks.

RESULTS

Results showed that on many evaluative measures individuals remained stable, or improved in performance with medium-to-large effect sizes (e.g., 0.3-1.0). Thus, in a cognitively impaired population sample where decline would be the norm, our participants improved or remained stable.

CONCLUSION

The novel application of a VS/VM training program shows promise in addressing global cognitive decline, by targeting a brain area susceptible to early disruptions and providing it with additional and ongoing stimulative tasks in an effort to bolster its functioning and subsequently overall brain functioning.

Simulating effects of biomarker enrichment on Alzheimer's disease prevention trials: conceptual framework and example

BACKGROUND

We present a conceptual framework for simulations to determine the utility of biomarker enrichment to increase statistical power to detect a treatment effect in future Alzheimer's disease prevention trials. We include a limited set of simulation results to illustrate aspects of this framework.

METHODS

We simulated data based on the Alzheimer's Disease Anti-Inflammatory Prevention Trial, and a range of sample sizes, biomarker positive predictive values, and treatment effects. We also investigated the consequences of assuming homogeneity of parameter estimates as a function of dementia outcome.

RESULTS

Use of biomarkers to increase the sample fraction that would develop Alzheimer's disease in the absence of intervention from 0.5 to 0.8 would increase power from 0.35 to 0.69 with n = 200. Ignoring sample heterogeneity resulted in overestimation of power.

CONCLUSION

Biomarker enrichment can increase statistical power, but estimates of the expected increase are sensitive to a variety of assumptions outlined in the framework.