Practice effects predict cognitive outcome in amnestic mild cognitive impairment

Intraindividual variability in verbal fluency performance is moderated by and predictive of mild cognitive impairments

OBJECTIVE

The current study was designed to achieve 2 primary objectives: (a) determine the moderating effect of mild cognitive impairments (MCI) on intraindividual variability in semantic and letter fluency performance taking into account longitudinal annual assessments; and (b) establish predictive utility for intraindividual variability in semantic and letter fluency performance as a risk factor of incident MCI.

METHODS

Participants were community-residing older adults (n = 514; M age = 75.89 ± 6.45; 55.1% female). Sixty participants were diagnosed with MCI at baseline and 50 developed incident MCI during the follow-up. We operationalized intraindividual variability as word generation slopes derived from 3 consecutive time intervals during the standard 1-min administration of both letter and semantic fluency tasks (i.e., 0-20 s, 21-40 s, and 41-60 s).

RESULTS

Linear mixed effects models revealed significant within task slope effects for semantic (estimate = -8.350; p < .0001; 95% confidence interval [CI] = -8.604, -8.095) and letter (estimate = -5.068; p < .0001; 95% CI [-5.268, -4.869]) fluency indicating that word generation declined over the course of both tasks. The two-way interactions of MCI × Slope were significant for semantic (estimate = 1.34; p = .001; 95% CI [0.551, 2.126]) and letter (estimate = 0.733; p = .020; 95% CI [0.116, 1.350]) fluency indicating attenuated slopes among MCI participants compared to controls taking into account repeated annual assessments. Cox proportional-hazards models revealed that attenuated word generation slope, at baseline, in semantic (hazard ratio [HR] = 2.063; p = .015; 95% = 1.149 to 3.702) but not letter (HR = 0.704; p = .243; 95% CI [0.391, 1.269]) fluency was associated with increased risk of incident MCI.

CONCLUSION

Intraindividual variability in verbal fluency performance has clinical and predictive utility; it can be easily incorporated into testing batteries in clinical and research settings. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Behavioral studies of stimulus learning in zebrafish larvae

Within a week of fertilization, a zebrafish larva has developed a robust behavioral repertoire that includes the ability to learn about noncontingent stimuli. I begin this paper with a brief review of the t1-t2 framework in which groups receive different experiences at the first time point (t1) followed by a common assessment at the second time point (t2) and the strengths of this framework for studying stimulus learning. I then describe assays that have been implemented within the t1-t2 framework to demonstrate stimulus learning in the developing zebrafish. I discuss how these assays have been used to address three fundamental questions about stimulus learning: What are the conditions for stimulus learning? What is the content of stimulus learning? How is stimulus learning reflected in behavior? For each of these three questions, I also identify those issues regarding stimulus learning in the developing zebrafish that warrant further analysis at the behavioral level.

Reversion From Mild Cognitive Impairment To Normal Cognition: False-Positive Error Or True Restoration Thanks To Cognitive Control Ability?

PURPOSE

Relatively little attention has been paid to the meaning of reversion from mild cognitive impairment (MCI) to cognitively normal (CN), compared to MCI progression studies. The purpose of the study was to investigate the characteristics contributing to reversion from MCI to CN and to identify the associated factors with such reversion.

PATIENTS AND METHODS

We retrospectively identified 200 individuals who initially diagnosed as MCI and completed the second visit from the National Research Center for Dementia (NRCD) registry in Korea. Participants underwent comprehensive clinical and neuropsychological assessments. Factors associated with reversion were examined by a independent-samples t-test, χ² test, and logistic regression. Longitudinal change was examined by a repeated measures analysis of variance (rANOVA).

RESULTS

Based on the second assessment, 78 (39%) individuals were found to have reverted to CN (rMCI) and 118 (59%) remained with MCI (sMCI). Four (2%) progressed to Alzheimer's disease dementia and they were excluded from further analysis. Over a wide range of socio-demographic, clinical, and neuropsychological variables, group difference was significant only in neuropsychological tests of cognitive control. Both groups showed improvement in several neuropsychological tests, implying a practice effect, but the rMCI group showed greater improvement.

CONCLUSION

Reversion from MCI to CN might not be a false-positive error but a true recovery from cognitive impairment. Our results suggest that cognitive control ability may be a characteristic favorable for the restoration of cognitive function. Therefore, assessment of cognitive control might facilitate the development of appropriate interventions for MCI as well as prognosis evaluation.

Cognition or genetics? Predicting Alzheimer's disease with practice effects, APOE genotype, and brain metabolism

As practice effects are common in neuropsychological assessment, this study analyzed their utility to identify individuals with amnestic mild cognitive impairment (aMCI) at the greatest risk for Alzheimer's disease (AD-risk) and compared practice effects with APOE and brain metabolism biomarkers. We regressed Auditory Verbal Learning Test delayed recall (AVLT-DR) at 6 months on baseline AVLT-DR scores in 394 individuals with normal cognition from the Alzheimer's Disease Neuroimaging Initiative database and dichotomized 816 individuals with aMCI as showing practice effect or not showing practice effects (PE-) when the discrepancy between observed and predicted scores was found in less than 10%, 7%, and 5% of normal cognition. Cox regressions analyzed the AD-risk at 6 years. More than 60% of aMCI were showing practice effects. Controlling for age, sex, education, and baseline Mini-Mental State Examination and AVLT-DR scores, the AD-risk was associated with PE- [hazard ratio (HR) = 1.93], lower brain metabolism (HR = 0.95), and APOE genotype (HR = 1.92), with narrower risk estimates for PE-. The lack of practice effects during a 6-month period might be as precise as biomarkers for predicting the 6-year AD-risk.

Continuous theta-burst stimulation over the dorsolateral prefrontal cortex inhibits improvement on a working memory task

Theta-burst stimulation (TBS) over the dorsolateral prefrontal cortex (DLPFC) may be more effective for modulating cortical excitability compared to standard repetitive transcranial magnetic stimulation. However, the impact of intermittent (iTBS) and continuous TBS (cTBS) on working memory (WM) is poorly studied. The aim of our study was to compare the effects of iTBS and cTBS on WM over the left and right DLPFC. iTBS, cTBS or sham stimulation was administered over the right and left hemisphere of fifty-one healthy human subjects. WM was assessed before and after TBS using the 1-back, 2-back, and 3-back tasks. We found classical practice effects in the iTBS and the sham group: WM performance improved following stimulation as measured by the discriminability index. However, this effect could not be observed in the cTBS group. We did not find any hemisphere-dependent effects, suggesting that the practice effect is not lateralized, and TBS affects WM performance in a comparable manner if administered either over the left or the right hemisphere. We propose that our findings represent a useful addition to the literature of TBS-induced effects on WM. Moreover, these results indicate the possibility of clarifying processes underlying WM performance changes by using non-invasive brain stimulation.

Short-term repeat cognitive testing and its relationship to hippocampal volumes in older adults

BACKGROUND

Practice effects are improvements in cognitive test scores due to repeated exposure to testing materials. If practice effects provide information about Alzheimer's disease pathology, then they could be useful for clinical trials enrichment. The current study sought to add to the limited literature on short-term practice effects on cognitive tests and their relationship to neuroimaging biomarkers.

METHODS

Twenty-five, non-demented older adults (8 cognitively intact, 17 with mild cognitive impairment) received magnetic resonance imaging and two testing sessions across one week to determine practice effects on seven neuropsychological test scores. A series of correlations examined if hippocampal volume was associated with baseline, one-week, or practice effects scores on these tests. Next, a series of stepwise multiple regression models examined which of the three test scores best predicted hippocampal volumes RESULTS: In the correlation analysis, baseline scores on 5 of the 7 tests were significantly associated with hippocampal volumes, one week scores were significantly related for 7 of the 7 tests, and practice effects scores were significantly correlated for 4 of the 7 tests. In the stepwise regression models, 5 of the 7 tests indicated that one-week scores best predicted hippocampal volumes. For the other models, baseline score and practice effects score each best predicted hippocampal volume.

CONCLUSIONS

These results add to the growing body of evidence suggesting that diminished practice effects on short-term repeat testing is related to neuroimaging biomarkers of Alzheimer's disease and may serve as a screening tool for clinical practice and to enrich samples for research trials.

External validation of change formulae in neuropsychology with neuroimaging biomarkers: A methodological recommendation and preliminary clinical data

OBJECTIVE

Within neuropsychology, a number of mathematical formulae (e.g. reliable change index, standardized regression based) have been used to determine if change across time has reliably occurred. When these formulae have been compared, they often produce different results, but 'different' results do not necessarily indicate which formulae are 'best.' The current study sought to further our understanding of change formulae by comparing them to clinically relevant external criteria (amyloid deposition and hippocampal volume).

METHOD

In a sample of 25 older adults with varying levels of cognitive intactness, participants were tested twice across one week with a brief cognitive battery. Seven different change scores were calculated for each participant. An amyloid PET scan (to get a composite of amyloid deposition) and an MRI (to get hippocampal volume) were also obtained.

RESULTS

Deviation-based change formulae (e.g. simple discrepancy score, reliable change index with or without correction for practice effects) were all identical in their relationship to the two neuroimaging biomarkers, and all were non-significant. Conversely, regression-based change formulae (e.g. simple and complex indices) showed stronger relationships to amyloid deposition and hippocampal volume.

CONCLUSIONS

These results highlight the need for external validation of the various change formulae used by neuropsychologists in clinical settings and research projects. The findings also preliminarily suggest that regression-based change formulae may be more relevant than deviation-based change formulae in this context.

Underdiagnosis of mild cognitive impairment: A consequence of ignoring practice effects

INTRODUCTION

Longitudinal testing is necessary to accurately measure cognitive change. However, repeated testing is susceptible to practice effects, which may obscure true cognitive decline and delay detection of mild cognitive impairment (MCI).

METHODS

We retested 995 late-middle-aged men in a ∼6-year follow-up of the Vietnam Era Twin Study of Aging. In addition, 170 age-matched replacements were tested for the first time at study wave 2. Group differences were used to calculate practice effects after controlling for attrition effects. MCI diagnoses were generated from practice-adjusted scores.

RESULTS

There were significant practice effects on most cognitive domains. Conversion to MCI doubled after correcting for practice effects, from 4.5% to 9%. Importantly, practice effects were present although there were declines in uncorrected scores.

DISCUSSION

Accounting for practice effects is critical to early detection of MCI. Declines, when lower than expected, can still indicate practice effects. Replacement participants are needed for accurately assessing disease progression.

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

OBJECTIVES

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

DESIGN

Observational longitudinal study.

SETTING

Alzheimer's Disease Neuroimaging Initiative.

PARTICIPANTS

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

MEASUREMENTS

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

RESULTS

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

CONCLUSION

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

Neurodegenerative disease and cognitive retest learning

Retest learning impacts estimates of cognitive aging, but its bases are uncertain. Here, we test the hypothesis that dementia-related neurodegeneration impairs retest learning. Older persons without cognitive impairment at enrollment (n = 567) had annual cognitive testing for a mean of 11 years, died, and had a neuropathologic examination to quantify 5 neurodegenerative pathologies. Change point models were used to divide cognitive trajectories into an early retest sensitive component and a later component less sensitive to retest. Performance on a global cognitive measure (baseline mean = 0.227, standard deviation = 0.382) increased an estimated mean of 0.142-unit per year for a mean of 1.5 years and declined an estimated mean of 0.123-unit per year thereafter. No pathologic marker was related to cognitive change before the change point; each was related to cognitive decline after the change point. Results were comparable in analyses that used specific cognitive outcomes, included 220 individuals with mild cognitive impairment at enrollment, or allowed a longer retest learning period. The findings suggest that neurodegeneration does not impact cognitive retest learning.

Can there be learning potential in Parkinson's disease? A comparison with healthy older adults

Patients with Parkinson's disease may show certain cognitive impairments, although it is unclear how these deficits can affect their learning potential. The study aims to use the testing-the-limits technique to compare the potential for cognitive plasticity in a group of Patients with Parkinson's disease (N = 33) and a group of healthy older adults (N = 33). Sixty-six participants performed verbal learning test to analyze the learning potential. Repeated-measures analysis of variance showed significant main effects of time, group, and the interaction. There is a lower learning potential in subjects with Parkinson's disease; however, those still maintain a certain capacity for learning and, therefore, for cognitive plasticity.

Potential implications of practice effects in Alzheimer's disease prevention trials

Introduction

Practice effects (PEs) present a potential confound in clinical trials with cognitive outcomes. A single-blind placebo run-in design, with repeated cognitive outcome assessments before randomization to treatment, can minimize effects of practice on trial outcome.

Methods

We investigated the potential implications of PEs in Alzheimer's disease prevention trials using placebo arm data from the Alzheimer's Disease Cooperative Study donepezil/vitamin E trial in mild cognitive impairment. Frequent ADAS-Cog measurements early in the trial allowed us to compare two competing trial designs: a 19-month trial with randomization after initial assessment, versus a 15-month trial with a 4-month single-blind placebo run-in and randomization after the second administration of the ADAS-Cog. Standard power calculations assuming a mixed-model repeated-measure analysis plan were used to calculate sample size requirements for a hypothetical future trial designed to detect a 50% slowing of cognitive decline.

Results

On average, ADAS-Cog 13 scores improved at first follow-up, consistent with a PE and progressively worsened thereafter. The observed change for a 19-month trial (1.18 points) was substantively smaller than that for a 15-month trial with 4-month run-in (1.79 points). To detect a 50% slowing in progression under the standard design (i.e., a 0.59 point slowing), a future trial would require 3.4 times more subjects than would be required to detect the comparable percent slowing (i.e., 0.90 points) with the run-in design.

Discussion

Assuming the improvement at first follow-up observed in this trial represents PEs, the rate of change from the second assessment forward is a more accurate representation of symptom progression in this population and is the appropriate reference point for describing treatment effects characterized as percent slowing of symptom progression; failure to accommodate this leads to an oversized clinical trial. We conclude that PEs are an important potential consideration when planning future trials.

Objective features of subjective cognitive decline in a United States national database

INTRODUCTION

Functional and cognitive features of subjective cognitive decline (SCD) were identified in a longitudinal database from the National Alzheimer's Coordinating Center.

METHODS

Cognitively normal older adults with (SCD+) and without (SCD-) self-reported memory complaints (N = 3915) were compared on (1) baseline Functional Assessment Questionnaire ratings, (2) baseline scores and longitudinal rate of change estimates from nine neuropsychological tests, and (3) final clinical diagnoses.

RESULTS

SCD+ had higher baseline ratings of functional impairment, reduced episodic memory practice effects and poorer performance on neuropsychological tests of psychomotor speed and language, and higher frequencies of mild cognitive impairment and dementia diagnoses at the end of follow-up compared with the SCD-group.

DISCUSSION

Subtle clinical features of SCD identified in this large cohort are difficult to detect at the individual level. More sensitive tests are needed to identify those with SCD who are vulnerable to cognitive decline and dementia.

Within-session and one-week practice effects on a motor task in amnestic mild cognitive impairment

Practice effects on neuropsychological tests, which are improvements in test scores due to repeated exposure to testing materials, are robust in healthy elders, but muted in older adults with cognitive disorders. Conversely, few studies have investigated practice effects on motor tasks involving procedural memory, particularly across test-retest periods exceeding 24 hours. The current study examined one-week practice effects on a novel upper extremity motor task in 54 older adults with amnestic mild cognitive impairment. Results indicate that these individuals with primary memory deficits did improve on this motor task within a brief training session as well as across one week. These practice effects were unrelated to demographic characteristics or global cognition. One-week practice effects were, however, negatively related to delayed memory function, with larger practice effects being associated with poorer delayed memory and potentially better visuospatial ability. The presence of longer term practice effects on a procedural motor task not only has implications for how longitudinal assessments with similar measures involving implicit memory might be interpreted, but may also inform future rehabilitative strategies for patients with more severe declarative memory deficits.

Hepatic Encephalopathy Is Associated with Persistent Learning Impairments Despite Adequate Medical Treatment: A Multicenter, International Study

BACKGROUND

Hepatic encephalopathy (HE) is considered reversible regarding mental status but may not be cognitively in single-center studies.

AIM

To evaluate persistence of learning impairment in prior HE compared to those who never experienced HE (no-HE) in a multicenter study.

METHODS

A total of 174 outpatient cirrhotics from three centers (94 Virginia, 30 Ohio, and 50 Rome; 36 prior HE) underwent psychometric hepatic encephalopathy score (PHES) and inhibitory control (ICT) testing at baseline and then at least 7 days apart. ICT learning (change in 2nd half lures compared to 1st half) was compared between patient groups at both visits. Change in the PHES individual sub-tests and total score between visits was compared in both groups. US versus Italian trends were also analyzed.

RESULTS

HE patients had worse PHES and ICT results compared to no-HE patients at baseline. Significant improvement (1st half 7.1 vs. 2nd half 6.2, p < 0.0001) was observed in no-HE, but not in HE (1st half 7.9 vs. 2nd half 7.8, p = 0.1) at baseline. At retesting (median 20 days later), no-HE patients continued with significant learning (1st half 6.0 vs. 2nd half 5.4, p < 0.0001), while HE patients again did not improve (1st half 7.8 vs. 2nd half 6.9, p = 0.37). Between visits, no-HE patients improved significantly on four PHES sub-tests and overall score, while HE patients only improved on two sub-tests with similar overall PHES score. Trends were similar between US and Italian subjects.

CONCLUSION

In this multicenter study, prior HE patients showed persistent significant learning impairment compared to those without prior HE, despite adequate medical therapy. This persistent change should increase efforts to reduce the first HE episode.

Screening for dementia in Arabic: normative data from an elderly Lebanese sample

OBJECTIVE

Prevention and treatment of dementia is a global concern that requires involvement of international samples. The purpose of this study is to develop culturally sensitive norms based on normal older Lebanese adults using multiple cognitive screening measures translated into Arabic for regional use.

METHODS

Participants were 164 community dwelling older Lebanese adults without cognitive complaints. They were administered the following cognitive measures in Arabic: Alzheimer's Disease 8-item questionnaire, Montreal Cognitive Assessment, Mini Mental Status Exam, Modified Mini Mental Status, Brief Visuospatial Memory Test-Revised, Lebanese Digit Span, Cross-Linguistic Naming Test, and phonemic and semantic fluency tests.

RESULTS

Sample characteristics and descriptive statistics for the demographically unadjusted raw scores are first presented (N = 164). Same-form test-retest reliability for each test were computed for 24 participants retested over 2-5 weeks, with reliabilities ranging from .55 to .90; Cronbach alpha coefficients ranged from .34 to .93. Two sets of normative data were constructed. First, base-rates for demographically unadjusted raw scores for the 5th, 10th and 15th percentiles are presented to identify relatively rare occurring performances. Second, using standardized regression-based procedures demographically corrected normative information adjusted for age, education and sex were generated for normative interpretation.

CONCLUSIONS

Adapting cognitive tests for use in culturally and linguistically diverse regions of the world not only requires careful translation of test instructions and materials, but construction of culturally sensitive local norms. Our normative data should allow for more accurate identification of cognitive impairment and dementia in Arabic-speaking patients, especially those living in Lebanon.

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.

[Formula: see text]Practice effects and longitudinal cognitive change in clinically normal older adults differ by Alzheimer imaging biomarker status

OBJECTIVE

The objective of this study was to examine practice effects and longitudinal cognitive change in 190 clinically normal elderly classified according to a two-feature biomarker model for Alzheimer's disease.

METHODS

All participants completed neuropsychological testing, MRI, FDG-PET, and PiB-PET at their baseline evaluation. We divided participants into four groups based on neuroimaging measures of amyloid (A+ or A-) and neurodegeneration (N+ or N-) and reexamined cognition at 15- and 30-month intervals.

RESULTS

The A-N- group showed significant improvements in the memory and global scores. The A+N- group also showed significant improvements in the memory and global scores as well as attention. The A-N+ group showed a significant decline in attention at 30 months. The A+N+ group showed significant improvements in memory and the global score at 15 months followed by a significant decline in the global score at 30 months.

CONCLUSION

Amyloidosis in the absence of neurodegeneration did not have an adverse impact on practice effects or the 30-month cognitive trajectories. In contrast, participants with neurodegeneration (either A-N+ or A+N+) had worse performance at the 30-month follow-up. Our results show that neurodegeneration has a more deleterious effect on cognition than amyloidosis in clinically normal individuals.

Practice Effects on Story Memory and List Learning Tests in the Neuropsychological Assessment of Older Adults

Two of the most commonly used methods to assess memory functioning in studies of cognitive aging and dementia are story memory and list learning tests. We hypothesized that the most commonly used story memory test, Wechsler's Logical Memory, would generate more pronounced practice effects than a well validated but less common list learning test, the Neuropsychological Assessment Battery (NAB) List Learning test. Two hundred eighty-seven older adults, ages 51 to 100 at baseline, completed both tests as part of a larger neuropsychological test battery on an annual basis. Up to five years of recall scores from participants who were diagnosed as cognitively normal (n = 96) or with mild cognitive impairment (MCI; n = 72) or Alzheimer's disease (AD; n = 121) at their most recent visit were analyzed with linear mixed effects regression to examine the interaction between the type of test and the number of times exposed to the test. Other variables, including age at baseline, sex, education, race, time (years) since baseline, and clinical diagnosis were also entered as fixed effects predictor variables. The results indicated that both tests produced significant practice effects in controls and MCI participants; in contrast, participants with AD declined or remained stable. However, for the delayed-but not the immediate-recall condition, Logical Memory generated more pronounced practice effects than NAB List Learning (b = 0.16, p < .01 for controls). These differential practice effects were moderated by clinical diagnosis, such that controls and MCI participants-but not participants with AD-improved more on Logical Memory delayed recall than on delayed NAB List Learning delayed recall over five annual assessments. Because the Logical Memory test is ubiquitous in cognitive aging and neurodegenerative disease research, its tendency to produce marked practice effects-especially on the delayed recall condition-suggests a threat to its validity as a measure of new learning, an essential construct for dementia diagnosis.

Use of an automated mobile application to assess effects of nicotine withdrawal on verbal fluency: A pilot study

Mild-to-moderate impairment in frontally mediated functions such as sustained attention, working memory, and inhibition have been found to occur during tobacco withdrawal and may present a barrier to successful cessation. These findings have led to studies evaluating cessation treatments that target nicotine withdrawal related cognitive impairment. The instruments currently used to assess cognitive function provide detailed and specific information but have limitations including being time consuming, cumbersome, anxiety provoking, and having poor ecological validity. The authors examined the feasibility of using a mobile computer application to test verbal fluency (VF) as a quick, easy-to-administer, and more ecologically valid method of measuring the effects of short-term smoking abstinence on frontally mediated cognitive functions. Thirty participants completed 2 assessments-1 during ad lib smoking and 1 after overnight abstinence. At each assessment, semantic and phonemic VF tests were administered using a mobile application and nicotine craving and withdrawal symptom severity was assessed. In repeated assessments, performance on both semantic and phonemic VF tests is expected to improve due to practice effects; however, significant improvements were observed only in semantic (p = .012) but not phonemic (p = .154) VF. In addition, the change between assessments in phonemic (but not semantic) score was significantly associated with withdrawal (p = .006) and craving (p = .037) severity measured postabstinence. This study demonstrates that nicotine withdrawal has differential effects on semantic versus phonemic VF suggesting impairments of working memory, attention, and inhibition. These effects were measured using methods easily used in large groups of participants, potentially with remote test administration and automated scoring. (PsycINFO Database Record

Short-term practice effects in mild cognitive impairment: Evaluating different methods of change

Practice effects are improvements on cognitive tests as a result of repeated exposure to testing material. However, variability exists in the literature about whether patients with amnestic mild cognitive impairment (MCI) display practice effects, which may be partially due to the methods used to calculate these changes on repeated tests. The purpose of the current study was to examine multiple methods of assessing short-term practice effects in 58 older adults with MCI. The cognitive battery, which included tests of memory (Hopkins Verbal Learning Test-Revised and Brief Visuospatial Memory Test-Revised) and processing speed (Symbol Digit Modalities Test and Trail Making Test Parts A and B), was administered twice across one week. Dependent t tests showed statistically significant improvement on memory scores (ps < .01, ds = 0.8-1.3), but not on processing speed scores. Despite this, the sample showed no clinically meaningful improvement on any cognitive scores using three different reliable change indices. Regression-based change scores did identify relatively large groups of participants who showed smaller than expected practice effects, which may indicate that this method is more sensitive in identifying individuals who may portend a declining trajectory. Practice effects remain a complex construct, worthy of continued investigation in diverse clinical conditions.

Modeling practice effects in healthy middle-aged participants of the Alzheimer and Families parent cohort

Introduction

Repetitive administration of neuropsychological tests can lead to performance improvement merely due to previous exposure. The magnitude of such practice effects (PEs) may be used as a marker of subtle cognitive impairment because they are diminished in healthy individuals subsequently developing Alzheimer's disease (AD).

Methods

To explore the relationship between sociodemographic factors, AD family history (FH), and APOE ε4 status, and the magnitude of PE, four subtests of the Wechsler Adult Intelligence Scale-IV were administered twice to 400 middle-aged healthy individuals, most of them first-degree descendants of AD patients.

Results

PEs were observed in all measures. Sociodemographic variables did not show a uniform effect on PE. Baseline score was the strongest predictor of change, being inversely related to PE magnitude. Significant effects of the interaction term APOE ε4^∗Age in processing speed and working memory were observed.

Discussion

PEs exert a relevant effect in cognitive outcomes at retest and, accordingly, they must be taken into consideration in clinical trials. The magnitude of PE in processing speed and working memory could be of special interest for the development of cognitive markers of preclinical AD.

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.

Short-Term Practice Effects and Brain Hypometabolism: Preliminary Data from an FDG PET Study

Practice effects are improvements in cognitive test scores due to repeated exposure to the same tests. Typically viewed as error, short-term practice effects have been shown to provide valuable clinical information about diagnosis, prognosis, and treatment outcomes in older patients with mild cognitive impairments. This study examined short-term practice effects across one week and brain hypometabolism on fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) in 25 older adults (15 intact, 10 Mild Cognitive Impairment). Averaged cerebral brain metabolism on FDG PET was correlated with multiple cognitive scores at baseline in those with Mild Cognitive Impairment, and short-term practice effects accounted for additional variance in these same subjects. The relationship between brain metabolism and cognition (either at baseline or practice effects) was minimal in the intact individuals. Although needing replication in larger samples, short-term practice effects on tests of executive functioning and memory may provide valuable information about biomarkers of Alzheimer's disease.

Diabetes, glycaemia, and cognition-a secondary analysis of the Finnish Diabetes Prevention Study

BACKGROUND

Type 2 diabetes is linked with cognitive dysfunction and dementia in epidemiological studies, but these observations are limited by lack of data on the exact timing of diabetes onset. We investigated diabetes, dysglycaemia, and cognition in the Finnish Diabetes Prevention Study, in which the timing and duration of diabetes are well documented.

METHODS

The Finnish Diabetes Prevention Study comprised middle-aged, overweight participants with impaired glucose tolerance but no diabetes at baseline (n = 522), randomized to lifestyle intervention or a control group. After an intervention period (mean duration 4 years) and follow-up (additional 9 years), cognitive assessment with the CERAD test battery and Trail Making Test A (TMT) was executed twice within a 2-year interval. Of the 364 (70%) participants with cognitive assessments, 171 (47%) had developed diabetes.

RESULTS

Cognitive function did not differ between those who developed diabetes and those who did not. Lower mean 2-h glucose at an oral glucose tolerance test (OGTT) and HbA1C during the intervention period predicted better performance in the TMT (p = 0.012 and 0.024, respectively). Those without diabetes or with short duration of diabetes improved in CERAD total score between the two assessments (p = 0.001) whereas those with long duration of diabetes did not (p = 0.844).

CONCLUSIONS

Better glycemic control among persons with baseline impaired glucose tolerance predicted better cognitive performance 9 years later in this secondary analysis of the Finnish Diabetes Prevention Study population. In addition, learning effects in cognitive testing were not evident in people with long diabetes duration. Copyright © 2015 John Wiley & Sons, Ltd.

Metformin in Amnestic Mild Cognitive Impairment: Results of a Pilot Randomized Placebo Controlled Clinical Trial

Diabetes and hyperinsulinemia may be risk factors for Alzheimer's disease (AD). We conducted a pilot study of metformin, a medication efficacious in treating and preventing diabetes while reducing hyperinsulinemia, among persons with amnestic mild cognitive impairment (aMCI) with the goal of collecting preliminary data on feasibility, safety, and efficacy. Participants were 80 men and women aged 55 to 90 years with aMCI, overweight or obese, without treated diabetes. We randomized participants to metformin 1000 mg twice a day or matching placebo for 12 months. The co-primary clinical outcomes were changes from baseline to 12 months in total recall of the Selective Reminding Test (SRT) and the score of the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog). The secondary outcome was change in relative glucose uptake in the posterior cingulate-precuneus in brain fluorodeoxyglucose positron emission tomography. Change in plasma Aβ42 was an exploratory outcome. The mean age of participants was 65 years. Fifty percent of participants were women. The only baseline variable that was different between the arms was the ADAS-Cog. Metformin could not be tolerated by 7.5% of participants; 15% tolerated 500 mg/day, 35% tolerated 1000 mg/day, 32.5% tolerated 1500 mg/day, and only 10% tolerated the maximum dose. There were no serious adverse events related to metformin. The 7.5% of persons who did not tolerate metformin reported gastrointestinal symptoms. After adjusting for baseline ADAS-cog, changes in total recall of the SRT favored the metformin group (9.7±8.5 versus 5.3±8.5; p = 0.02). Differences for other outcomes were not significant. A larger trial seems warranted to evaluate the efficacy and cognitive safety of metformin in prodromal AD.

Rapid Responsiveness to Practice Predicts Longer-Term Retention of Upper Extremity Motor Skill in Non-Demented Older Adults

Skill acquisition is a form of motor learning that may provide key insights into the aging brain. Although previous work suggests that older adults learn novel motor tasks slower and to a lesser extent than younger adults, we have recently demonstrated no significant effect of chronological age on the rates and amounts of skill acquisition, nor on its long-term retention, in adults over the age of 65. To better understand predictors of skill acquisition in non-demented older adults, we now explore the relationship between early improvements in motor performance due to practice (i.e., rapid responsiveness) and longer-term retention of an upper extremity motor skill, and whether the extent of rapid responsiveness was associated with global cognitive status. Results showed significant improvements in motor performance within the first five (of 150) trials, and that this “rapid responsiveness” was predictive of skill retention 1 month later. Notably, the extent of rapid responsiveness was not dependent on global cognitive status, as measured by the Montreal Cognitive Assessment (MoCA). Thus, rapid responsiveness appears to be an important variable in longer-term neurorehabilitative efforts with older adults, regardless of their cognitive status.

Cognitive Effects of Hormone Therapy Continuation or Discontinuation in a Sample of Women at Risk for Alzheimer Disease

OBJECTIVE

Use of estrogen-based hormone therapy (HT) as a protection from cognitive decline and Alzheimer disease (AD) is controversial, although cumulative data support HT use when initiated close to menopause onset with estrogen formulations containing 17β-estradiol preferable to conjugated equine estrogen formulations. Little is known regarding specific populations of women who may derive benefit from HT.

METHODS

Women with heightened risk for AD (aged 49-69), all of whom were taking HT for at least 1 year and most of whom initiated HT close to menopause onset, underwent cognitive assessment followed by randomization to continue or discontinue HT. Assessments were repeated at 2 years after randomization.

RESULTS

Women who continued HT performed better on cognitive domains composed of measures of verbal memory and combined attention, working memory, and processing speed measures. Women who used 17β-estradiol versus conjugated equine estrogen, whether randomized to continue or discontinue HT, showed better verbal memory performance at the 2-year follow-up assessment. An interaction was also found with HT randomization and family history of AD in a first-degree relative. All female offspring of patients with AD declined in verbal memory; however, women who continued HT declined less than women who discontinued HT. Women without a first-degree relative with AD showed verbal memory improvement (likely because of practice effects) with continuance and declined with discontinuance of HT.

CONCLUSION

Continuation of HT use appears to protect cognition in women with heightened risk for AD when initiated close to menopause onset.

Age Moderates the Association of Aerobic Exercise with Initial Learning of an Online Task Requiring Cognitive Control

The aim of this study was to examine whether people differed in change in performance across the first five blocks of an online flanker task and whether those trajectories of change were associated with self-reported aerobic or resistance exercise frequency according to age. A total of 8752 men and women aged 13-89 completed a lifestyle survey and five 45-s games (each game was a block of ~46 trials) of an online flanker task. Accuracy of the congruent and incongruent flanker stimuli was analyzed using latent class and growth curve modeling adjusting for time between blocks, whether the blocks occurred on the same or different days, education, smoking, sleep, caffeinated coffee and tea use, and Lumosity training status ("free play" or part of a "daily brain workout"). Aerobic and resistance exercise were unrelated to first block accuracies. For the more cognitively demanding incongruent flanker stimuli, aerobic activity was positively related to the linear increase in accuracy [B=0.577%, 95% confidence interval (CI), 0.112 to 1.25 per day above the weekly mean of 2.8 days] and inversely related to the quadratic deceleration of accuracy gains (B=-0.619% CI, -1.117 to -0.121 per day). An interaction of aerobic activity with age indicated that active participants younger than age 45 had a larger linear increase and a smaller quadratic deceleration compared to other participants. Age moderates the association between self-reported aerobic, but not self-reported resistance, exercise and changes in cognitive control that occur with practice during incongruent presentations across five blocks of a 45-s online, flanker task.

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.

A 2 year multidomain intervention of diet, exercise, cognitive training, and vascular risk monitoring versus control to prevent cognitive decline in at-risk elderly people (FINGER): a randomised controlled trial

BACKGROUND

Modifiable vascular and lifestyle-related risk factors have been associated with dementia risk in observational studies. In the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER), a proof-of-concept randomised controlled trial, we aimed to assess a multidomain approach to prevent cognitive decline in at-risk elderly people from the general population.

METHODS

In a double-blind randomised controlled trial we enrolled individuals aged 60-77 years recruited from previous national surveys. Inclusion criteria were CAIDE (Cardiovascular Risk Factors, Aging and Dementia) Dementia Risk Score of at least 6 points and cognition at mean level or slightly lower than expected for age. We randomly assigned participants in a 1:1 ratio to a 2 year multidomain intervention (diet, exercise, cognitive training, vascular risk monitoring), or a control group (general health advice). Computer-generated allocation was done in blocks of four (two individuals randomly allocated to each group) at each site. Group allocation was not actively disclosed to participants and outcome assessors were masked to group allocation. The primary outcome was change in cognition as measured through comprehensive neuropsychological test battery (NTB) Z score. Analysis was by modified intention to treat (all participants with at least one post-baseline observation). This trial is registered at ClinicalTrials.gov, number NCT01041989.

FINDINGS

Between Sept 7, 2009, and Nov 24, 2011, we screened 2654 individuals and randomly assigned 1260 to the intervention group (n=631) or control group (n=629). 591 (94%) participants in the intervention group and 599 (95%) in the control group had at least one post-baseline assessment and were included in the modified intention-to-treat analysis. Estimated mean change in NTB total Z score at 2 years was 0·20 (SE 0·02, SD 0·51) in the intervention group and 0·16 (0·01, 0·51) in the control group. Between-group difference in the change of NTB total score per year was 0·022 (95% CI 0·002-0·042, p=0·030). 153 (12%) individuals dropped out overall. Adverse events occurred in 46 (7%) participants in the intervention group compared with six (1%) participants in the control group; the most common adverse event was musculoskeletal pain (32 [5%] individuals for intervention vs no individuals for control).

INTERPRETATION

Findings from this large, long-term, randomised controlled trial suggest that a multidomain intervention could improve or maintain cognitive functioning in at-risk elderly people from the general population.

FUNDING

Academy of Finland, La Carita Foundation, Alzheimer Association, Alzheimer's Research and Prevention Foundation, Juho Vainio Foundation, Novo Nordisk Foundation, Finnish Social Insurance Institution, Ministry of Education and Culture, Salama bint Hamdan Al Nahyan Foundation, Axa Research Fund, EVO funding for University Hospitals of Kuopio, Oulu, and Turku and for Seinäjoki Central Hospital and Oulu City Hospital, Swedish Research Council, Swedish Research Council for Health, Working Life and Welfare, and af Jochnick Foundation.

Aging, Practice Effects, and Genetic Risk in the Wisconsin Registry for Alzheimer's Prevention

BACKGROUND

In the last five years, a consensus has developed that Alzheimer's disease (AD) may begin years before overt cognitive impairment. Accordingly, the focus has shifted to identifying preclinical disease in order to match treatments to those most likely to benefit. Subtle cognitive changes, including reduced benefit from practice, may be one such preclinical sign. In this study, we explore cognitive aging trajectories within a large cohort of clinically intact late middle-aged adults.

METHOD

Longitudinal cognitive data were analyzed from 594 participants in the Wisconsin Registry for Alzheimer's Prevention. Mixed models were used to examine trajectories, adjusting for prior exposure, and the moderation thereof by markers of dementia risk, APOE-ε4 status, and family history of AD.

RESULTS

Practice effects were observed for Verbal Learning & Memory, Working Memory, Speed & Flexibility, and Visual Learning. However, for Working Memory and Speed & Flexibility, these effects were attenuated for FH + subjects.

CONCLUSION

Reduced practice effects have previously been observed in clinical groups. These results in middle-aged adults suggest that they may also indicate preclinical changes on the path to AD.

Absence of practice effects in preclinical Alzheimer's disease

OBJECTIVE

To describe how practice effects influence cognitive trajectories and determine if a reduction in practice effects is a potential marker of Stage-III preclinical Alzheimer's disease (AD).

METHOD

Participants included 263 older adults who were cognitively normal at baseline (i.e., had a Clinical Dementia Rating [CDR] of 0; Morris, 1993) and returned for an average of 9.5 annual visits. Participants completed standard tests of episodic memory, visuospatial ability, semantic memory, and executive function. Progressors (n = 66) converted to CDR > 0 with a diagnosis of symptomatic AD after a minimum of 3 visits and stable participants (n = 197) never progressed to CDR > 0. Practice effects, defined as the slope of performance across Visits 1-3, were compared between groups and used within subjects to predict risk of conversion. Change-point models that accounted for retest were contrasted with linear models that ignored retest.

RESULTS

The stable group showed practice effects on episodic-memory measures (β = 0.14, SE = .02, p < .0001) but the progressor group did not (β = 0.03, SE = .03, p = .343). Across all participants, practice effects on episodic-memory tests were associated with a decreased risk of progression to AD as indicated by the subdistribution hazards model (SHR; Fine & Gray, 1999); SHR = .110, 95% CI [.032, .384], p = .001). Finally, use of change-point models dramatically altered rate-of-change estimates compared with models that ignored practice.

CONCLUSION

Our results indicate that preclinical AD is marked by a reduction in practice effects in episodic memory and that the magnitude of gain from retesting is inversely related to progression risk. Assessment of practice effects may be a face-valid indicator of Stage-III preclinical AD.

Practice effects and amyloid deposition: preliminary data on a method for enriching samples in clinical trials

Clinical trials in Alzheimer disease are moving toward prevention studies in prodromal individuals with amyloid burden. However, methods are needed to identify individuals expected to be amyloid positive for these studies to be feasible and cost-effective. The current study sought to determine whether short-term practice effects on cognitive tests can identify those with notable uptake on amyloid imaging. Twenty-five, nondemented older adults (15 cognitively intact, 10 with mild cognitive impairment) underwent amyloid imaging through F-flutemetamol and 2 cognitive testing sessions across 1 week to determine practice effects on a visual memory test. Results indicated that, whereas F-flutemetamol uptake showed little association with baseline performance on a visual memory test (r=-0.04, P=0.85), it was significantly correlated with practice effects across 1 week on that same memory measure (r=-0.45, P=0.02), with greater uptake being associated with lower practice effects. The odds ratio of notable F-flutemetamol uptake was 5 times higher in individuals with low practice effects compared with high practice effects. Although these preliminary results need to be replicated in larger samples, short-term practice effects on cognitive tests may provide an affordable screening method to identify individuals who are amyloid positive, which could enrich samples for preventative clinical trials in Alzheimer disease.

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

Introduction

Practice effects are characteristic of nearly all standard cognitive tasks when repeated during serial assessments and are frequently important confounders in clinical trials.

Methods

We summarize evidence that gains in neuropsychological test performance scores associated with practice effects occur as artifactual changes associated with serial testing within clinical trials. We identify and emphasize such gains in older, non–cognitively impaired individuals and estimate an effect size of 0.25 for composite cognitive measures in older populations assessed three times in a 6- to 12-month period.

Results

We identified three complementary approaches that can be used to attenuate practice effects: (1) massed practice in a prebaseline period to reduce task familiarity effects; (2) tests designed to reduce practice-related gains so that item-specific driven improvements are minimized by using tasks that minimize strategy and/or maximize interitem interference; and (3) well-matched alternate forms.

Discussion

We have drawn attention to and increased awareness of practice effect–related gains that could result in type 1 or type 2 errors in trials. Successfully managing practice effects will eliminate a large source of error and reduce the likelihood of misinterpretation of clinical trials outcomes.

Prodromal posterior cortical atrophy: clinical, neuropsychological, and radiological correlation

We present longitudinal clinical, cognitive, and neuroimaging data from a 63-year-old woman who enrolled in research as a normal control and evolved posterior cortical atrophy (PCA) over 5 year follow-up. At baseline she reported only subtle difficulty driving and performed normally on cognitive tests, but already demonstrated atrophy in left visual association cortex. With follow-up she developed insidiously progressive visuospatial and visuoperceptual deficits, correlating with progressive atrophy in bilateral visual areas. Amyloid PET was positive. This case tracks the evolution of PCA from the prodromal stage, and illustrates challenges to early diagnosis as well as the utility of imaging biomarkers.

Cognitive and emotional dysfunction in mild cognitive impairment

Although mild cognitive impairment (MCI) is a widely accepted construct both clinically and in the research literature, it remains a heterogeneous condition that varies in presentation and prognosis. This article first reviews the evolution of the diagnosis of MCI, followed by examination of pros and cons of cognitive assessments commonly used to assess for MCI. Emotional changes commonly seen in MCI are also reviewed. Finally, the relation between cognitive and emotional dysfunction is examined, including a discussion of specific psychological symptoms seen in subtypes of MCI, and how the presence of neuropsychiatric symptoms may affect the risk for progression to dementia.

One-week practice effects in older adults: tools for assessing cognitive change

Although neuropsychologists are frequently asked to evaluate cognitive change in a patient, this can be a complex determination. Using data from 167 non-demented older adults tested twice across one week, the current study sought to provide a variety of reliable change indices for a brief battery of commonly used neuropsychological measures. Statistically significant improvements were observed on seven of nine scores examined over this short retest interval, with the largest changes occurring on memory measures. Information is provided on simple discrepancy scores, standard deviation index, reliable change index (with and without correcting for practice effects), and standardized regression based change formulae for each cognitive score. Even though a one-week retesting interval is a less typical clinical scenario, these results may give clinicians and researchers more options for assessing short-term change in a variety of settings.

Memory consolidation in aging and MCI after 1 week

OBJECTIVE

To assess consolidation in amnestic mild cognitive impairment (aMCI), controlling for differences in initial learning and using a protracted delay period for recall.

METHOD

15 individuals with aMCI were compared with 15 healthy older adult controls on a story learning task. Subjects were trained to criteria to equalize initial learning across subjects. Recall was tested at both the 30-min typically used delay and a 1-week delay used to target consolidation.

RESULTS

Using repeated measures ANOVAs adjusted for age, we found group × time point interactions across the entire task between the final trial and 30-min delay, and again between the 30-min and 1-week delay periods, with aMCI having greater declines in recall as compared with controls. Significant group main effects were also found, with aMCI recalling less than controls.

CONCLUSION

Consolidation was impaired in aMCI as compared with controls. Our findings indicate that aMCI-related performance typically measured at 30 min underestimates aMCI-associated memory deficits. This is the first study to isolate consolidation by controlling for initial learning differences and using a protracted delay period to target consolidation in an aMCI sample.

Practice effects and longitudinal cognitive change in normal aging vs. incident mild cognitive impairment and dementia in the Mayo Clinic Study of Aging

The objective of this study was to examine practice effects and longitudinal cognitive change in a population-based cohort classified as clinically normal at their initial evaluation. We examined 1390 individuals with a median age of 78.1 years and re-evaluated them up to four times at approximate 15-month intervals, with an average follow-up time of 5 years. Of the 1390 participants, 947 (69%) individuals remained cognitively normal, 397 (29%) progressed to mild cognitive impairment (MCI), and 46 (3%) to dementia. The stable normal group showed an initial practice effect in all domains which was sustained in memory and visuospatial reasoning. There was only a slight decline in attention and language after visit 3. We combined individuals with incident MCI and dementia to form one group representing those who declined. The incident MCI/dementia group showed an unexpected practice effect in memory from baseline to visit 2, with a significant decline thereafter. This group did not demonstrate practice effects in any other domain and showed a downward trajectory in all domains at each evaluation. Modeling cognitive change in an epidemiologic sample may serve as a useful benchmark for evaluating cognitive change in future intervention studies.

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

Background

Practice effects are a known threat to reliability and validity in clinical trials. Few studies have investigated the potential influence of practice on repeated screening measures in longitudinal clinical trials with a focus on dementia prevention. The current study investigates whether practice effects exist on a screening measure commonly used in aging research, the Memory Impairment Screen (MIS).

Methods

The PREADViSE trial is a clinical intervention study evaluating the efficacy of vitamin E and selenium for Alzheimer’s disease prevention. Participants are screened annually for incident dementia with the MIS. Participants with baseline and three consecutive follow-ups who made less than a perfect score at one or more assessments were included in the current analyses (N=1,803). An additional subset of participants with four consecutive assessments but who received the same version of the MIS at baseline and first follow-up (N=301) was also assessed to determine the effects of alternate forms on mitigating practice. We hypothesized that despite efforts to mitigate practice effects with alternate versions, MIS scores would improve with repeated screening. Linear mixed models were used to estimate mean MIS scores over time.

Results

Among men with four visits and alternating MIS versions, although there is little evidence of a significant practice effect at the first follow-up, mean scores clearly improve at the second and third follow-ups for all but the oldest participants. Unlike those who received alternate versions, men given the same version at first follow-up show significant practice effects.

Conclusion

While increases in the overall means were small, they represent a significant number of men whose scores improved with repeated testing. Such improvements could bias case ascertainment if not taken into account.

Practice effects: a unique cognitive variable

Practice effects are improvements in cognitive test performance due to repeated evaluation with the same or similar test materials. Prior studies have reported that these improvements can vary with age, education/intellect, and disease status. However, additional information is needed about variables that influence practice effects. The current study prospectively quantified short-term practice effects in 268 community-dwelling older adults and compared these practice effects to demographic variables, global cognition, premorbid intellect, depression, and individual cognitive domains. Overall, practice effects were not significantly related to most demographic and clinical characteristics or individual cognitive domains, which was contrary to our hypotheses. However, since practice effects appear to be uninfluenced by many variables that typically affect cognitive scores, they may be a unique and valuable tool that could be applied in a number of diverse patient groups.

Within-session practice effects in patients referred for suspected dementia

BACKGROUND

Practice effects are improvements in cognitive test performance associated with repeated administrations of same or similar measures and are traditionally seen as error variance. However, there is growing evidence that practice effects provide clinically useful information.

METHODS

Within-session practice effects (WISPE) across 2 h were collected from 61 non-consecutive patients referred for suspected dementia and compared to the Mini Mental Status Examination (MMSE), a screening measure of dementia severity.

RESULTS

In all patients, WISPE on two cognitive measures were significantly correlated with MMSE, even after controlling for baseline cognitive scores (partial r = 0.47, p < 0.001; partial r = 0.26, p = 0.046). In patients diagnosed with probable Alzheimer's disease, the trend was even stronger (partial r = 0.72, p < 0.01; partial r = 0.58, p = 0.046). In both groups, lower WISPE were associated with lower MMSE scores (i.e. greater dementia severity), even after controlling for initial cognitive scores.

CONCLUSION

If future research validates these findings with longitudinal studies, then WISPE may have important clinical applications in dementia evaluations.