Short-term practice effects in amnestic mild cognitive impairment: implications for diagnosis and treatment

Mild Cognitive Impairment: Quantifying a Qualitative Disorder

Mild cognitive impairment (MCI) has been described as a transitional state between normal aging and dementia, which can be both identified and tracked over time from qualitative and/or quantitative perspectives. Each definition of MCI involves some subjective cognitive complaint, some level of objective cognitive impairment, and generally intact daily functioning. Progression to dementia is common on follow-up in MCI, but stability and reversion to normal cognition can also occur. Quantitative methods might allow health care providers to evaluate and follow the subtle declines in MCI, as well as examine possible benefits of interventions with this at-risk condition.

Evaluating practice effects across learning trials - ceiling effects or something more?

BACKGROUND

Practice effects (PE) are traditionally considered improvements in performance observed resulting from repeated exposure to test materials across multiple testing sessions. While PE are commonly observed for memory tests, this effect has only been considered in summary total scores. The current objective was to consider PE in summary total scores, individual learning trials, and learning slopes.

METHOD

One-week PE for individual trial and learning slope performance was examined on the BVMT-R and HVLT-R in 151 cognitively intact participants and 131 participants with Mild Cognitive Impairment (MCI) aged 65 years and older.

RESULTS

One-week PE were observed across all trials and summary total scores for both memory measures and diagnostic classifications, despite the potential for ceiling effects to limit improvement on retesting. PE were largest on the first trial relative to subsequent learning trials. This effect was diminished - but not eliminated - in participants with MCI. Conversely, no PE were observed for learning slope scores, which was counter to expectations and likely confounded by ceiling effects.

CONCLUSIONS

PE were present across learning trials but not learning slopes, and the initial learning trial at follow-up tended to benefit most from PE relative to subsequent learning trials. Ceiling effects appeared to influence PE for learning slopes more than learning trials. These results highlight the potential diagnostic utility of PE across individual learning trials and inform how they are distributed at follow-up, while also suggesting that learning slopes may be generally stable during longitudinal assessment.

Validation of regression-based change formulae for mild cognitive impairment and Alzheimer's disease

INTRODUCTION

Identification of cognitive decline is critical in older adults at risk for dementia. In a 2020 study reported in Archives of Clinical Neuropsychology, Kiselica and colleagues developed standardized regression-based (SRB) change formulae for the Uniform Data Set 3.0 Neuropsychological Battery in cognitively unimpaired older adults. However, validation of their applicability in impaired individuals is needed.

METHODS

Using longitudinal data on 5974 participants (cognitively unimpaired, mild cognitive impairment, dementia) from the National Alzheimer's Coordinating Center, SRB change scores were calculated for each individual and compared across groups.

RESULTS

Across 6 to 24 months, minimal cognitive change was observed in cognitively unimpaired participants. Modest declines were seen in those with mild cognitive impairment and substantial declines in those with dementia. Change scores were negatively correlated with the Clinical Dementia Rating scale. In impaired individuals, SRB scores indicated more decline in those with positive amyloid scans.

DISCUSSION

Validation of SRB scores affords greater confidence in employing them in clinical and research settings.

Highlights

Validation of regression-based cognitive change scores in impaired samples.Clear differences on change scores across three groups (intact, MCI, dementia).Largely stable scores in intact participants, but notable decline in MCI and dementia.Moderate to strong relationship between change scores and the Clinical Dementia Rating scale sum of boxes.

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

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

Short-Term Practice Effects on Cognitive Tests Across the Late Life Cognitive Spectrum and How They Compare to Biomarkers of Alzheimer's Disease

Background

Practice effects on cognitive testing in mild cognitive impairment (MCI) and Alzheimer's disease (AD) remain understudied, especially with how they compare to biomarkers of AD.

Objective

The current study sought to add to this growing literature.

Methods

Cognitively intact older adults (n = 68), those with amnestic MCI (n = 52), and those with mild AD (n = 45) completed a brief battery of cognitive tests at baseline and again after one week, and they also completed a baseline amyloid PET scan, a baseline MRI, and a baseline blood draw to obtain APOE ɛ4 status.

Results

The intact participants showed significantly larger baseline cognitive scores and practice effects than the other two groups on overall composite measures. Those with MCI showed significantly larger baseline scores and practice effects than AD participants on the composite. For amyloid deposition, the intact participants had significantly less tracer uptake, whereas MCI and AD participants were comparable. For total hippocampal volumes, all three groups were significantly different in the expected direction (intact > MCI > AD). For APOE ɛ4, the intact had significantly fewer copies of ɛ4 than MCI and AD. The effect sizes of the baseline cognitive scores and practice effects were comparable, and they were significantly larger than effect sizes of biomarkers in 7 of the 9 comparisons.

Conclusion

Baseline cognition and short-term practice effects appear to be sensitive markers in late life cognitive disorders, as they separated groups better than commonly-used biomarkers in AD. Further development of baseline cognition and short-term practice effects as tools for clinical diagnosis, prognostic indication, and enrichment of clinical trials seems warranted.

Impact of Age on Cognitive Testing Practice Effects and Cardiorespiratory Responses

Objective: This study tested the hypothesis that healthy aging attenuates cognitive practice effects and, consequently, limits the familiarity-associated reductions in heart rate (HR) and breathing frequency (BF) responses during retesting. Methods: Twenty-one cognitively normal older and younger adults (65 ± 2 vs. 26 ± 1 years old) participated in the study. Mini-Mental State Examination (MMSE), Digit-Span-Test (DST), Trail Making Test (TMT-B), and California Verbal Learning Test (CVLT-II) were administered twice at 3-week intervals, while HR and BF were monitored by electrocardiography and plethysmography, respectively. Results: Cognitive performances were not affected by the age factor, and the retest factor only affected CVLT-II. HR and BF increased only in the younger adults (p < .01) during cognitive tests; retesting attenuated these responses (retest factor p < .01). Long-delay free-recall in CVLT-II was unchanged in cognitively normal older versus younger adults. Healthy aging did not diminish short-term memory assessed by DST and CVLT-II short-delay or long-delay free-recalls. Conclusions: Only CVLT-II, but not MMSE, DST or TMT-B, demonstrated cognitive retesting practice effects in the younger and older adults. Cognitive testing at 3-week intervals in cognitively normal older and younger subjects revealed divergent cardiorespiratory responses to MMSE, DST, and TMT-B cognitive testing, particularly HR, which increased only in younger adults and to a lesser extent during retesting despite the absence of practice effects.

Validation of one-year reliable change in the RBANS for community-dwelling older adults with amnestic mild cognitive impairment

Objective: The current study sought to externally validate previously published standardized regression-based (SRB) equations for the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Indexes administered twice over a one-year period. Method: Hammers and colleagues' SRB prediction equations were applied to two independent samples of community-dwelling older adults with amnestic Mild Cognitive Impairment (MCI), including those recruited from the community (n = 64) and those recruited from a memory disorders clinic (n = 58). Results: While Observed Baseline and Observed Follow-up performances were generally comparable for both MCI samples over one year, both samples possessed significantly lower Observed One-Year Follow-up scores than were predicted based on Hammers and colleagues' development sample across many RBANS Indexes. Relatedly, both amnestic MCI samples possessed a greater percentage of participants either "declining" or failing to exhibit a long-term practice effect over one year relative to expectation across most Indexes. Further, the clinic-recruited amnestic MCI sample displayed worse baseline performances, smaller long-term practice effects, and greater proportions of individual participants exhibiting a decline across one year relative to the community amnestic MCI sample. Conclusions: These findings validate Hammers and colleagues' SRB prediction equations by (1) indicating their ability to identify clinically meaningful change across RBANS Indexes in independent samples, and (2) discriminating rates of cognitive change among cognitively nuanced samples.

Patients with amnestic MCI Fail to Adapt Executive Control When Repeatedly Tested with Semantic Verbal Fluency Tasks

OBJECTIVE

Semantic verbal fluency (SVF) tasks require individuals to name items from a specified category within a fixed time. An impaired SVF performance is well documented in patients with amnestic Mild Cognitive Impairment (aMCI). The two leading theoretical views suggest either loss of semantic knowledge or impaired executive control to be responsible.

METHOD

We assessed SVF 3 times on 2 consecutive days in 29 healthy controls (HC) and 29 patients with aMCI with the aim to answer the question which of the two views holds true.

RESULTS

When doing the task for the first time, patients with aMCI produced fewer and more common words with a shorter mean response latency. When tested repeatedly, only healthy volunteers increased performance. Likewise, only the performance of HC indicated two distinct retrieval processes: a prompt retrieval of readily available items at the beginning of the task and an active search through semantic space towards the end. With repeated assessment, the pool of readily available items became larger in HC, but not patients with aMCI.

CONCLUSION

The production of fewer and more common words in aMCI points to a smaller search set and supports the loss of semantic knowledge view. The failure to improve performance as well as the lack of distinct retrieval processes point to an additional impairment in executive control. Our data did not clearly favour one theoretical view over the other, but rather indicates that the impairment of patients with aMCI in SVF is due to a combination of both.

Examining the role of repeated test exposure over 12 months across ADNI protocols

Objective: Changes to study protocols during longitudinal research may alter cognitive testing schedules over time. Unlike in prior Alzheimer's Disease Neuroimaging Initiative (ADNI) protocols, where testing occurred twice annually, participants enrolled in the ADNI-3 are no longer exposed to cognitive materials at 6 months. This may affect their 12-month performance relative to earlier ADNI cohorts, and potentially confounds data harmonization attempts between earlier and later ADNI protocols. Method: Using data from participants enrolled across multiple ADNI protocols, this study investigated whether test exposure during 6-month cognitive evaluation influenced scores on subsequent 12-month evaluation. Results: No interaction effects were observed between test exposure group and time at 12 months on cognitive performance. No improvements, and limited declines, were seen between baseline and 12-month follow-up scores on most measures. Conclusions: The 6-month testing session had minimal impact on 12-month performance in ADNI. Collapsing longitudinal data across ADNI protocols in future research appears appropriate.

Neuropsychological Decline Stratifies Dementia Risk in Cognitively Unimpaired and Impaired Older Adults

Objective

Validation and widespread use of markers indicating decline in serial neuropsychological exams has remained elusive despite potential value in prognostic and treatment decision-making. This study aimed to operationalize neuropsychological decline, termed "neuropsychological (NP) decline," in older adults followed over 12 months in order to aid in the stratification of dementia risk along the cognitively unimpaired-to-mild cognitive impairment (MCI) spectrum.

Methods

A prospective cohort study utilized 6,794 older adults from the National Alzheimer's Coordinating Center (NACC) database with a baseline diagnosis of normal cognition, impaired without MCI or with MCI. Operationalization of NP decline over 12-month follow-up used regression-based norms developed in a robustly normal reference sample. The extent to which each participant's 12-month follow-up score deviated from norm-referenced expectations was quantified and standardized to an NP decline z-score. Cox regression evaluated whether the NP decline metric predicted future dementia.

Results

Participant's NP decline scores predicted future all-cause dementia in the total sample, χ² = 110.71, hazard ratio (HR) = 1.989, p < 0.001, and in the subset diagnosed with normal cognition, χ² = 40.84, HR = 2.006, p < 0.001, impaired without MCI diagnosis, χ² = 14.89, HR = 2.465, p < 0.001, and impaired with MCI diagnosis, χ² = 55.78, HR = 1.916, p < 0.001.

Conclusion

Operationalizing NP decline over 12 months with a regression-based norming method allows for further stratification of dementia risk along the cognitively unimpaired-to-MCI spectrum. The use of NP decline as an adjunctive marker of risk beyond standard cognitive diagnostic practices may aid in prognosis and clinical decision-making.

A Lack of Practice Effects on Memory Tasks Predicts Conversion to Alzheimer Disease in Patients With Amnestic Mild Cognitive Impairment

The aim of the current study was to test the accuracy of practice effects, that is, improvement in test performance due to repeated neuropsychological evaluations, in identifying patients with amnestic mild cognitive impairment (a-MCI) at greater risk of conversion to Alzheimer disease (AD). For this purpose, we conducted a longitudinal study of 54 patients diagnosed with a-MCI at the first assessment and followed-up for 4 years. During this time, 18 patients converted to AD. Baseline and 6- to 12-month follow-up performances on a large set of neuropsychological tests were analyzed to determine their diagnostic ability to predict later conversion to dementia. Results demonstrate that a lack of practice effects on episodic memory tests is an accurate prognostic indicator of late conversion to AD in a-MCI patients. In fact, even though the performance of both groups was substantially comparable at the baseline evaluation, stable a-MCI patients greatly improved their memory performance at retest after 6 to 12 months; instead, scores of converter a-MCI remained stable or decreased passing from baseline to follow-up. Standardized z-change scores on memory tasks, which were computed as a reliable measure of performance change, classified group membership with very good overall accuracy, which was higher than the classification of converter and stable a-MCIs provided by baseline or follow-up scores. We hypothesize that the lack of practice effects on memory tasks mirrors the early involvement of medial temporal lobe areas in converter a-MCI that are fundamental for the consolidation of new memory traces.

Prospective Evaluation of an Abbreviated Test Battery to Screen for Neurocognitive Impairment in HIV-Positive Military Members

Human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND) affects around 20-50% of people living with HIV (PLWH). Although batteries of tests are used to identify neurocognitive impairment (NCI), they are long and difficult to perform during a routine clinic visit, thus impairing the ability to diagnose HAND. Therefore, a brief yet sensitive screening tool to identify NCI is necessary. This study prospectively evaluated an abbreviated screening battery with reported 86.5%/87.1% sensitivity/specificity, identified from a planned post-hoc analysis in a prior neurocognitive study among military PLWH. Adult HIV-positive military beneficiaries in the U.S. Military HIV Natural History Study, who agreed to undergo a comprehensive seven-domain neuropsychological battery (16 tests), and who completed an additional 20-min abbreviated battery (AB), comprised of four tests, prior to the full battery (FB) were included in this analysis. A group of 169 individuals completed both tests, of which 25.4% had a positive AB and 17.8% had NCI on FB (global deficit score ≥ 0.5). With the FB as the reference standard, the specificity for the AB was 79.9% (73.2-86.5), however the sensitivity was 50.0% (32.1-67.9). In those with NCI by FB but not AB, the most common impaired domains were executive function (73.3%) and memory (73.3%), both being domains not fully tested by the AB. An abbreviated HAND screening battery of four tests requiring approximately 20 min provided a relatively high level of specificity but lacked sensitivity for detection of NCI. Inclusion of additional domains or alternative scoring approaches may improve sensitivity but require further study. Continued efforts are needed to develop an effective brief screening test for HAND.

Repetitive Transcranial Magnetic Stimulation as an Add-On Treatment for Cognitive Impairment in Alzheimer's Disease and Its Impact on Self-Rated Quality of Life and Caregiver's Burden

Alzheimer’s disease (AD) is associated with progressive memory loss and decline in executive functions, as well as neuropsychiatric symptoms. Patients usually consider quality of life (QoL) and mood as more important for their health status than disease-specific physical and mental symptoms. In this open-label uncontrolled trial, 12 subjects diagnosed with AD underwent 10 sessions of repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (10 Hz, 20 min, 2000 pulses/day, 110% MT). Outcomes were measured before and 30 days after treatment. Our primary objective was to test the efficacy of rTMS as an add-on treatment for AD on the global cognitive function, assessed through the Mini-Mental State Examination (MMSE) and the Mattis Dementia Rating Scale (MDRS). As secondary objectives, the detailed effect on cognitive functions, depression and anxiety symptoms, QoL, and functionality in daily life activities were evaluated, as well as correlations between QoL and cognition, depression and anxiety scores. The treatment significantly enhanced semantic memory and reduced anxiety. Improvement of these features in AD could become an important target for treatment strategies. Although limited by its design, this trial may contribute with another perspective on the analysis and the impact of rTMS on AD.

Short-Term Retest Performance in Young versus Older Adults: Consideration of Integrated Speed-Accuracy Measures

Objectives: The current research addressed gaps in the literature regarding short-term computerized cognitive retest performance in young and older adults using two integrated speed-accuracy metrics. The aims were: (a) to advance the aging literature on short-term retest performance using a computerized cognitive battery and a retest schedule that included both within- and between-day time points, and (b) to assess the test-retest reliability of two integrated speed-accuracy metrics, inverse efficiency scores (IES) and balanced integration scores (BIS).Method: Twenty young (18-23 years) and thirty older (65-71 years) men completed a battery measuring a range of cognitive functions, six times over three testing days, each 1 week apart.Results: Compared to young adults, older adults exhibited steeper within- and between-day performance gains in IES and BIS, which may reflect a combination of lower initial cognitive ability and familiarity, indicating that older adults may require more familiarization on computerized tests. Relative to unadjusted reaction times, IES reliability appeared comparable in older adults, but slightly lower among young adults. The reliability of BIS was lower than unadjusted reaction times and IES in both age groups.Discussion: Our findings provide guidance for researchers wanting to combine speed and accuracy into a single performance metric in repeated testing contexts.

Serial Tap Test of patients with idiopathic normal pressure hydrocephalus: impact on cognitive function and its meaning

Background

Idiopathic normal pressure hydrocephalus (INPH) is characterized by gait disturbance, urinary incontinence and cognitive decline. Symptoms are potentially reversible and treatment is based on cerebrospinal fluid shunting. The tap test (TT) is used to identify patients that will benefit from surgery. This procedure consists of the withdrawal of 20 to 50 mL of cerebrospinal fluid (CSF) through a lumbar puncture (LP) after which the symptoms of the triad are tested. Improvement in the quality and speed of gait are already recognized but cognitive improvement depends on several factors such as tests used, the time elapsed after LP for re-testing, and the number of punctures. Serial punctures may trigger similar conditions as external lumbar drainage (ELD) to the organism.

Objective

This study aimed to identify how serial punctures affect cognition to increase the sensitivity of the test and consequently the accuracy of surgical indication.

Methods

Sixty-one patients with INPH underwent baseline memory and executive tests repeatedly following the 2-Step Tap Test protocol (2-STT – two procedures of 30 mL lumbar CSF drainage separated by a 24-h interval). The baseline scores of INPH patients were compared with those of 55 healthy controls, and with intragroup post-puncture scores of the 2-STT.

Results

The group with INPH had lower performance than the control group in all cognitive tests (RAVLT, Stroop, CFT, FAR-COWA, FAB, MMSE, orientation, mental control), except for the forward digit span test (p = 0.707). After conducting LP procedures, the Stroop test (words, colors and errors), RAVLT (stage A1, A6 and B1), and CFT (immediate and delayed R) scores were equal to those of the control group (p > 0.05). The INPH group presented significant improvement after the first puncture in MMSE (p = 0.031) and in the Stroop Test (points) (p < 0.001). After the second puncture, subjects improved in orientation, MMSE, RAVLT (B1), Stroop (points, words, errors) and CFT (IR).

Conclusion

Progressive cognitive improvement occurred over the 2-STT and changes were more significant after the second LP in all cognitive domains except for RAVLT (A7). Encephalic alert system ‘arousal’ seems to participate in early improvements observed during 2-STT. The second LP increased the sensitivity of the drainage test to detect changes in cognitive variables, and consequently improved the quality of the method.

Reliable change in cognition over 1 week in community-dwelling older adults: a validation and extension study

OBJECTIVE

Reliable change methods can aid neuropsychologists in understanding if performance differences over time represent clinically meaningful change or reflect benefit from practice. The current study sought to externally validate the previously published standardized regression-based (SRB) prediction equations developed by Duff for commonly administered cognitive measures.

METHOD

This study applied Duff's SRB prediction equations to an independent sample of community-dwelling participants with amnestic mild cognitive impairment (MCI) assessed twice over a 1-week period. A comparison of MCI subgroups (e.g., single v. multi domain) on the amount of change observed over 1 week was also examined.

RESULTS

Using pairwise t-tests, large and statistically significant improvements were observed on most measures across 1 week. However, the observed follow-up scores were consistently below expectation compared with predictions based on Duff's SRB algorithms. In individual analyses, a greater percentage of MCI participants showed smaller-than-expected practice effects based on normal distributions. In secondary analyses, smaller-than-expected practice effects were observed in participants with worse baseline memory impairment and a greater number of impaired cognitive domains, particularly for measures of executive functioning/speeded processing.

CONCLUSIONS

These findings help to further support the validity of Duff's 1-week SRB prediction equations in MCI samples and extend previous research by showing incrementally smaller-than-expected benefit from practice for increasingly impaired amnestic MCI subtypes.

Validating 1-Year Reliable Change Methods

OBJECTIVE

reliable change methods can assist in the determination of whether observed changes in performance are meaningful. The current study sought to validate previously published 1-year standardized regression-based (SRB) equations for commonly administered neuropsychological measures that incorporated baseline performances, demographics, and 1-week practice effects.

METHOD

Duff et al.'s SRB prediction equations were applied to an independent sample of 70 community-dwelling older adults with either normal cognition or mild cognitive impairment, assessed at baseline, at 1 week, and at 1 year.

RESULTS

minimal improvements or declines were seen between observed baseline and observed 1-year follow-up scores, or between observed 1-year and predicted 1-year scores, on most measures. Relatedly, a high degree of predictive accuracy was observed between observed 1-year and predicted 1-year scores across cognitive measures in this repeated battery.

CONCLUSIONS

these results, which validate Duff et al.'s SRB equations, will permit clinicians and researchers to have more confidence when predicting cognitive performance on these measures over 1 year.

Diminished Learning Over Repeated Exposures (LORE) in preclinical Alzheimer's disease

INTRODUCTION

We determine whether diminished Learning Over Repeated Exposures (LORE) identifies subtle memory decrements in cognitively unimpaired (CU) older adults with Alzheimer's disease (AD) biomarker burden.

METHODS

Ninety-four CU participants (mean age = 77.6 ± 5.02) completed a challenging associative memory test, at home, monthly, for up to 1 year (mean = 9.97 months) on a study-issued iPad. Learning curves for face-name memory were computed for two versions completed monthly: same face-name pairs (A-A-A) and alternate face-name pairs (B-C-D). Positron emission tomography (PET) imaging characterized global amyloid (Pittsburgh Compound-B (PiB); amyloid beta (Aβ)+/-) and regional tau burden (flortaucipir).

RESULTS

Diminished LORE for same (but not alternate) face-name pairs was associated with greater amyloid and tau burden. Aβ+/- group differences for same face-name pairs emerged by the fourth exposure and was of medium-to-large magnitude (Cohen's d = 0.66; 95% confidence interval [CI] = 0.25-1.08).

DISCUSSION

Subtle decrements in learning related to AD pathological burden in CU are detectable over short time-intervals (ie, months). Implications for prevention trial design are discussed.

Lower practice effects as a marker of cognitive performance and dementia risk: A literature review

BACKGROUND

Practice effects (PEs) are improvements in performance after repeated exposure to test materials, and typically viewed as a source of bias in repeated cognitive assessments. We aimed to determine whether characterizing PEs could also provide a useful marker of early cognitive decline.

METHODS

We conducted a systematic review of the literature, searching PsycInfo (Ebsco) and PubMed databases for articles studying PEs in aging and dementia populations. Articles published between 1920 and 2019 were included.

RESULT

We identified 259 articles, of which 27 studied PEs as markers of cognitive performance. These studies consistently showed that smaller, less-robust PEs were associated with current diagnostic status and/or future cognitive decline. In addition, lower PEs were associated with Alzheimer's disease risk factors and neurodegeneration biomarkers.

CONCLUSION

PEs provide a potentially useful marker of cognitive decline, and could prove valuable as part of a cost-effective strategy to select individuals who are at-risk for dementia for future interventions.

Practice effects in mild cognitive impairment: A validation of Calamia et al. (2012)

Objective: In a meta-analysis examining practice effects on repeated neuropsychological testing, Calamia et al. (2012) provided information to predict practice effects in healthy and clinical samples across a range of cognitive domains. However, these estimates have not been validated.Method: This study used these prediction estimate calculations to predict follow-up scores across one year on a brief battery of neuropsychological tests in a sample of 93 older adults with amnestic mild cognitive impairment. The predicted follow-up scores were compared to observed follow-up scores.Results: Using Calamia et al. model's intercept, age, retest interval, clinical status, and specific cognitive tests, three of the seven observed follow-up scores in this cognitive battery were significantly lower than the Calamia et al. predicted follow-up scores. Differences between individual participants' observed and predicted follow-up scores were more striking. For example, on Delayed Recall of the Hopkins Verbal Learning Test - Revised, 40% of the sample had Calamia et al. predicted scores that were one or more standard deviations above their observed scores. These differences were most notable on tests that were not in Calamia et al.'s cognitive battery, suggesting the meta-analysis results may not generalize as well to other tests.Conclusions: Although Calamia et al. provided a method for predicting practice effects and follow-up scores, these results raise caution when using them in MCI, especially on cognitive tests that were not in their meta-analysis.

Forgetting in Alzheimer's disease: Is it fast? Is it affected by repeated retrieval?

OBJECTIVES

Whether people with Alzheimer's Disease present with accelerated long term forgetting compared to healthy controls is still debated. Typically, accelerated long term forgetting implies testing the same participants repeatedly over several delays. This testing method raises the issue of confounding repetition effects with forgetting rates. We used a novel procedure to disentangle the two effects.

METHODS

Four short stories were presented during an initial in-person assessment of 40 patients with Alzheimer's Disease and 42 age-matched healthy controls. Our aim was for participants to reach a score of 70% correct (9 out of 13 questions) at encoding. If this criterion was not achieved after the first trial, the four stories were presented again (in a different order); participants took the 1 min filler task again and were then retested. We repeated this process until participants reached the 70% criterion or to a maximum of four trials. Cued recall memory tests were completed during follow-up telephone call(s) at different delay intervals. Study material was presented only at encoding, then probed with different question sets on all other delays. Each question set tested different sub-parts of the material. The experiment employed a mixed design. Participants were randomly allocated to either a condition without retrieval practice or a condition with retrieval practice. Participants in the condition without retrieval practice were only tested at two delays: post encoding filled delay and at one month. Participants in the condition with retrieval practice were tested at four delays: post encoding filled delay, one day, one week and one month. Our methodological design allowed us to separate the effects of retesting from the effects of delay.

RESULTS

Alzheimer's Disease patients showed a significant encoding deficit reflected in the higher number of trials required to reach criterion. Using Linear Mixed Models, we found no group by delay interactions between the post encoding filled delay retrieval and one month delays, with Alzheimer's Disease groups having a similar decline in performance to healthy controls, irrespective of testing condition. Significant condition by delay interactions were found for both groups (Alzheimer's Disease and healthy controls), with better performance at one month in the condition with retrieval practice.

CONCLUSIONS

Our data showed that Alzheimer's Disease is not characterised by accelerated long term forgetting, patients in our sample forgot at the same rate as healthy controls. Given the additional trials required by Alzheimer's patients to reach the 70% correct criterion, their memory impairment appears to be one of encoding. Moreover, Alzheimer's Disease patients benefited from repeated testing to the same extent as healthy controls. Due to our methodological design, we were also able to show that performance improved under repeated testing conditions, even with partial testing (sampling different features from each narrative on every test session/delay) in both healthy controls and Alzheimer's Disease.

Test-retest reliability in an fMRI study of naming in dementia

fMRI has been used as an outcome measure in dementia treatment studies, with many previous studies comparing only single pre- and post-treatment fMRI scans to determine treatment-induced neural changes, while utilizing single subject experimental designs. The purpose of the current study was to evaluate fMRI test-retest reliability in dementia patients and typical older adults using noun and verb confrontation naming to evaluate the validity of using a single pre/post-treatment scan comparison. Seven individuals with dementia and 9 control participants were tested three times over two months using the same fMRI procedures. Differences in individual and group level activation patterns were observed that varied across time. Additionally, the extent of variability fluctuated across individuals, groups, and the grammatical category of target words. Our findings suggested that one time fMRI scanning may inadequately represent an individual's typical brain activation pattern, particularly an individual with dementia. Thus, multiple imaging baselines are recommended.

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.

Age-related differences in default-mode network connectivity in response to intermittent theta-burst stimulation and its relationships with maintained cognition and brain integrity in healthy aging

The default-mode network (DMN) is affected by advancing age, where particularly long-range connectivity has been consistently reported to be reduced as compared to young individuals. We examined whether there were any differences in the effects of intermittent theta-burst stimulation (iTBS) in DMN connectivity between younger and older adults, its associations with cognition and brain integrity, as well as with long-term cognitive status. Twenty-four younger and 27 cognitively normal older adults were randomly assigned to receive real or sham iTBS over the left inferior parietal lobule between two resting-state functional magnetic resonance imaging (rs-fMRI) acquisitions. Three years later, those older adults who had received real iTBS underwent a cognitive follow-up assessment. Among the younger adults, functional connectivity increased following iTBS in distal DMN areas from the stimulation site. In contrast, older adults exhibited increases in connectivity following iTBS in proximal DMN regions. Moreover, older adults with functional responses to iTBS resembling those of the younger participants exhibited greater brain integrity and higher cognitive performance at baseline and at the 3-year follow-up, along with less cognitive decline. Finally, we observed that 'young-like' functional responses to iTBS were also related to the educational background attained amongst older adults. The present study reveals that functional responses of the DMN to iTBS are modulated by age. Furthermore, combining iTBS and rs-fMRI in older adults may allow characterizing distinctive cognitive profiles in aging and its progression, probably reflecting network plasticity systems that may entail a neurobiological substrate of cognitive reserve.

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.

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.

Reversion From Mild Cognitive Impairment to Normal Cognition: A Meta-Analysis

The initiation of Alzheimer disease (AD) prevention studies has placed greater emphasis on the need to accurately detect individuals with amnestic mild cognitive impairment (aMCI) given their increased risk for developing AD. Several studies reporting on the incidence and prevalence of aMCI have also found that a substantial number of aMCI cases at baseline assessments revert to normal cognition at subsequent assessments. This instability presents a major challenge to intervention studies aimed at preventing the onset of clinical symptoms associated with aMCI. Reversion rates from 25 studies were used for this meta-analysis which found an overall reversion rate of approximately 24%. When the studies were separated by their setting (community vs. clinic), substantial differences in reversion rates were noted with clinic-based studies having a much lower reversion rate (14%) than community-based studies (31%). North American and European studies had high heterogeneity of reversion rates, whereas Asian studies had moderate levels of heterogeneity and significantly lower rates of reversion. Continued improvement in diagnostic and classification methodologies may help in more accurately identifying aMCI cases which are less likely to revert to normal cognition.

Longitudinal Assessment of Verbal Learning and Memory in Amnestic Mild Cognitive Impairment: Practice Effects and Meaningful Changes

Objectives: To identify learning effects and meaningful changes in amnestic mild cognitive impairment (aMCI) at a follow-up assessment.

Method: The Spanish version of the California Verbal Learning Test (CVLT) was administered to a sample of 274 adults of age over 50 years with subjective memory complains (SMC), including single and multiple domain aMCI groups and participants with SMC but without cognitive impairment (SMC group). The Wilcoxon test was used to compare results at baseline and after 18 months in short and long recall, and standardized regression-based (SRB) methods were used to study meaningful changes.

Results: Scores were significantly higher at follow-up for short and long-delayed recall in all groups indicating generalized practice effect. SRB scores indicated a significant decline in recall in a higher proportion of participants with aMCI than in SMC group.

Discussion: Patients with multiple and single domain aMCI benefit from practice in a verbal learning memory test. The SRB approach revealed a higher incidence of meaningful decline in short and long-delay recall and recognition in the aMCI groups than in the SMC group. Specifically, compared to SMC participants, single-domain aMCI individuals declined in a higher proportion in all measures, and multiple-domain aMCI individuals in long delay free recall.

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.

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.

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.

Learning Ability as a Function of Practice: Does It Apply to Farmworkers?

OBJECTIVE

Farmworkers experience significant work-related health risks including pesticide-associated cognitive impairment. Practice effect is a surrogate for learning ability. This study examined differences in cognitive function and learning capacity in Latino farmworkers and nonfarmworkers.

METHODS

Tasks of learning and short-term memory, executive function and working memory, perceptual coding, and psychomotor function were assessed at baseline and 3-month follow-up in 136 farmworkers and 116 nonfarmworkers.

RESULTS

Farmworkers had better performance on visuospatial learning and short-term memory at baseline (P < 0.05). Nevertheless, nonfarmworkers showed more practice effects, or improvement on cognitive performance, at 3-month follow-up relative to farmworkers. Furthermore, the amount of improvement on visuospatial learning ability, short-term visuospatial memory, and perceptual coding ability was significantly higher in nonfarmworkers than in farmworkers.

CONCLUSIONS

Practice effects may serve as an additional cognitive readout to differentiate healthy individuals from those with cognitive impairment.

Neuropsychological Practice Effects in the Context of Cognitive Decline: Contributions from Learning and Task Novelty

Although cognitive decline is typically associated with decreasing practice effects (PEs) (presumably due to declining memory), some studies show increased PEs with declines in cognition. One explanation for these inconsistencies is that PEs reflect not only memory, but also rebounds from adapting to task novelty (i.e., novelty effect), leading to increased PEs. We examined a theoretical model of relationships among novelty effects, memory, cognitive decline, and within-session PEs. Sixty-six older adults ranging from normal to severely impaired completed measures of memory, novelty effects, and two trials each of Wechsler Adult Intelligence Scale, 4 th Edition Symbol Search and Coding. Interrelationships among variables were examined using regression analyses. PEs for Symbol Search and Coding (a) were related to different proposed PE components (i.e., memory and novelty effects), such that novelty effect predicted Symbol Search PE (R2 =.239, p<.001) and memory predicted Coding PE (R2 =.089, p=.015), and (b) showed different patterns across stages of cognitive decline, such that the greatest cognitive decline was associated with smallest Coding PE (R2 =.125, p=.004), whereas intermediate cognitive decline was associated with the greatest Symbol Search PE (R2 =.097, p=.040). The relationship between cognitive decline and PE for Symbol Search was partially mediated by novelty effect among older adults with abnormal cognitive decline (model R2 =.286, p<.001). These findings (a) suggest that PE is not a unitary construct, (b) offer an explanation for contradictory findings in the literature, and (c) highlight the need for a better understanding of component processes of PE across different neuropsychological measures.

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.

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.

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.

Diagnostic accuracy and practice effects in the National Alzheimer's Coordinating Center Uniform Data Set neuropsychological battery

INTRODUCTION

The Uniform Data Set (UDS) neuropsychological battery is frequently used in clinical studies. However, practice effects, effectiveness as a measure of global cognitive functioning, and detection of mild cognitive impairment have not been examined.

METHODS

A normative total score for the UDS has been developed. Linear discriminant analysis determined classification accuracy in identifying cognitively normal and impaired groups. Practice effects were examined in cognitively normal and cognitively impaired groups.

RESULTS

The total score differentiates between cognitively normal participants and those with dementia, but does not accurately identify individuals with mild cognitive impairment (MCI). Mean total scores for test-exposed participants were significantly higher than test-naive participants in both the normal and MCI groups and were higher, but not significantly so, in the dementia group.

CONCLUSION

The total score's classification accuracy discriminates between cognitively normal versus participants who have dementia. The total score appears subject to practice effects.

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.

Emergence of mild cognitive impairment in late middle-aged adults in the wisconsin registry for Alzheimer's prevention

AIM

It is difficult to reliably detect the earliest signs of Alzheimer's disease (AD)-associated cognitive impairment. Our aim was to compare 3 psychometric methods of identifying amnestic mild cognitive impairment (aMCI) in a middle-aged longitudinal cohort enriched for AD risk.

METHODS

Wisconsin Registry for Alzheimer's Prevention (WRAP) participants with 3 waves of cognitive assessment over approximately 6 years were coded as meeting each of 3 psychometric aMCI definitions: (a) 'aMCI standard-baseline' used published norms to establish cutoffs for baseline performance; (b) 'aMCI robust-baseline' applied WRAP-specific robust norms to baseline, and (c) 'aMCI robust-multiwave' applied these robust norms across 3 waves of assessment. Each group was compared to a cognitively healthy subset.

RESULTS

Half the aMCI standard-baseline and one third of the aMCI robust-baseline group reverted to normal ranges at follow-up. Only the aMCI robust-multiwave method had an aMCI × age interaction showing significantly worse age-related memory declines in the aMCI group compared to the cognitively healthy group over 6 years of follow-up.

CONCLUSION

Both cross-sectional methods showed instability over time, with many reverting to normal performance after baseline. The multiwave approach identified a group who showed progressive memory declines over 3 visits. Being able to detect progressive decline in late middle age is a critical step in improving prevention efforts.

Effects of age and ability on components of cognitive change

Prior experience with a cognitive task is often associated with higher performance on a second assessment, and these experience effects can complicate the interpretation of cognitive change. The current study was designed to investigate experience effects by obtaining measures of cognitive performance separated by days and by years. The analyses were based on data from 2017 adults with two longitudinal occasions, of whom 948 had also completed a third occasion, with each occasion consisting of three parallel versions of the tests on separate sessions. Change across short intervals was typically positive, and greater among older adults and adults with low levels of cognitive ability, whereas change over intervals of approximately three years was often negative, particularly at older ages. In contrast to the expectation that change over short intervals might be informative about change over longer intervals, relations between short-term change and long-term change were negative, as the individuals who gained the most with assessments separated by days tended to experience the greatest losses across assessments separated by years.

The robust reliability of neuropsychological measures: meta-analyses of test-retest correlations

Test-retest reliability is an important psychometric property relevant to assessment instruments typically used in neuropsychological assessment. This review presents a quantitative summary of test-retest reliability coefficients for a variety of widely used neuropsychological measures. In general, the meta-analytic test-retest reliabilities of the test scores ranged from adequate to high (i.e., r=.7 and higher). Furthermore, the reliability values were largely robust across factors such as age, clinical diagnosis, and the use of alternate forms. The values for some of the memory and executive functioning scores were lower (i.e., less than r=.7). Some of the possible reasons for these lower values include ceiling effects, practice effects, and across time variability in cognitive abilities measured by those tests. In general, neuropsychologists who use these measures in their assessments can be encouraged by the magnitude of the majority of the meta-analytic test-retest correlations obtained.

Demographic corrections for the modified telephone interview for cognitive status

Despite the growing use of the modified Telephone Interview for Cognitive Status (mTICS) as a cognitive screening instrument, it does not yet have demographic corrections. Demographic data, mTICS, and a neuropsychological battery were collected from 274 community-dwelling older adults with intact cognition or mild cognitive impairments. Age, education, premorbid intellect, and depression were correlated with mTICS scores. Using regression equations, age and education significantly predicted mTICS total score, and depression and premorbid intellect further enhanced this prediction. These results were comparable when only examining the 153 cognitively intact subjects. By using these corrections, clinicians and researchers can more accurately predict an individual's cognitive status with this telephone screening measure.

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.

Evidence-based indicators of neuropsychological change in the individual patient: relevant concepts and methods

Repeated assessments are a relatively common occurrence in clinical neuropsychology. The current paper will review some of the relevant concepts (e.g., reliability, practice effects, alternate forms) and methods (e.g., reliable change index, standardized based regression) that are used in repeated neuropsychological evaluations. The focus will be on the understanding and application of these concepts and methods in the evaluation of the individual patient through examples. Finally, some future directions for assessing change will be described.

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.

Practice effects predict cognitive outcome in amnestic mild cognitive impairment

OBJECTIVE

Practice effects on cognitive tests have been shown to further characterize patients with amnestic mild cognitive impairment (aMCI) and may provide predictive information about cognitive change across time. We tested the hypothesis that a loss of practice effects would portend a worse prognosis in aMCI.

DESIGN

Longitudinal, observational design following participants across 1 year.

SETTING

Community-based cohort.

PARTICIPANTS

Three groups of older adults: 1) cognitively intact (n = 57), 2) aMCI with large practice effects across 1 week (MCI + PE, n = 25), and 3) aMCI with minimal practice effects across 1 week (MCI - PE, n = 26).

MEASUREMENTS

Neuropsychological tests.

RESULTS

After controlling for age and baseline cognitive differences, the MCI - PE group performed significantly worse than the other groups after 1 year on measures of immediate memory, delayed memory, language, and overall cognition.

CONCLUSIONS

Although these results need to be replicated in larger samples, the loss of short-term practice effects portends a worse prognosis in patients with aMCI.