Serial position effects in Alzheimer's disease, mild cognitive impairment, and normal aging: predictive value for conversion to dementia

Normative data beyond the total scores: a process score analysis of the Rey's 15 word test in healthy aging and Alzheimer's Disease

BACKGROUND

The Rey's 15 words test is currently the most frequently used task in Italy to detect memory deficits in AD. The current standardised version is however quite outdated and lacks some cognitive indexes which may highlight problems in recall or encoding processes. The aim of the study was to update the normative data of the test and to consider some variables which were not accounted for in the original study, that is, recognition, learning rate and forgetfulness. We also adopted the process scores approach to ascertain the effects of serial position (primacy and recency).

METHODS

Three hundred ninety-six healthy participants were recruited. To detect any variables useful for intercepting the early stages of dementia, a group of 208 patients in the very early stage of AD was also recruited. Linear models were used to calculate the corrections scores for age, education, and gender, and ROCs were used to calculate cut-offs based on the maximum sum of sensitivity and specificity and the positive and negative predictive values.

RESULTS

All main indexes showed excellent Area Under the Curve (0.90-1), strong sensitivity and PPVs for distinguishing between the HCs and AD participants. However, the Intrusions index performed poorly in all parameters.

CONCLUSION

The study provides updated, normative data which may be reliably used as a cognitive marker to detect early AD. The strength of the study is the large sample size and the number of indexes which make it possible to explore the utility of memory test process scores.

Contextual novelty detection and novelty-related memory enhancement in amnestic mild cognitive impairment

INTRODUCTION

Though novelty processing plays a critical role in memory function, little is known about how it influences learning in memory-impaired populations, such as amnestic Mild Cognitive Impairment (aMCI).

METHODS

21 aMCI patients and 22 age- and education-matched healthy older participants performed two tasks-(i) an oddball paradigm where fractals that were often repeated (60 % of the stimuli), less frequently repeated (20 %), or novel (presented once each) were shown to assess novelty preference (longer viewing time for novel than familiar stimuli), and (ii) a Von Restorff paradigm assessing novelty-related effects on memory. Participants studied 22 lists of 10 words. Among these lists, 18 contained an isolated word different from the others by its distinctive aspect, here the font size (90-point, 120-point or 150-point against 60-point for non-isolated words). The remaining four were control lists without isolated words. After studying each list, participants freely recalled the maximum words possible.

RESULTS

For the oddball task, a group-by-stimulus type ANOVA on median viewing times revealed a significant effect of stimulus type, but not of group. Both groups spent more time on novel stimuli. For the Von Restorff task, both aMCI and healthy controls recalled the isolated words (presented in 120-point or 150-point, but not 90-point) better than others (excluding primacy and recency effects). Novelty-related memory benefit-gain factor-was computed as the difference between the recall scores for isolated and other words. A group-by-font size ANOVA on gain factors revealed no group effect, nor interaction, suggesting that aMCI patients benefited from novelty, alike controls.

CONCLUSION

Novelty preference and the boosting effect of isolation-related novelty on subsequent recall seem preserved despite impaired episodic memory in aMCI patients. This is discussed in the light of contemporary divergent theories regarding the relationship between novelty and memory, as either being independent or parts of a continuum.

Disruption of the serial position effect as an early marker of Alzheimer's disease in Spanish-English bilinguals

OBJECTIVES

The present study examined if disruption of serial position effects in list recall could serve as an early marker of Alzheimer's disease (AD) in Spanish-English bilinguals.

METHODS

We tested 20 participants initially diagnosed as cognitively normal or with mild cognitive impairment who declined and eventually received a diagnosis of AD (decliners), and 37 who remained cognitively stable (controls) over at least 2 years. Participants were tested on the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word List Learning Test in English or Spanish as part of an annual neuropsychological evaluation.

RESULTS

Compared to controls, decliners exhibited significantly reduced recall including reduced primacy scores (i.e., items recalled from the first three list items on Trial 1), whereas recency scores (i.e., items recalled from the last 3 list items on Trial 1) were equivalent in decliners and controls. Further analyses suggested that the sensitivity of the primacy effect to preclinical AD was initially stronger in participants tested in Spanish, a surprising finding given that the CERAD was developed for English speakers. However, in the subsequent year of testing, primacy scores declined to the same level regardless of language of testing.

CONCLUSIONS

Several list learning measures may facilitate early diagnosis of AD in Spanish-English bilinguals, possibly including the relatively understudied primacy effect. Additional studies are needed to investigate the possibility that linguistic or demographic variables might modulate sensitivity of list learning tests to preclinical AD, which could lead to broader improvements in their utility for early diagnosis of AD in all populations.

Stricker Learning Span criterion validity: a remote self-administered multi-device compatible digital word list memory measure shows similar ability to differentiate amyloid and tau PET-defined biomarker groups as in-person Auditory Verbal Learning Test

OBJECTIVE

The Stricker Learning Span (SLS) is a computer-adaptive digital word list memory test specifically designed for remote assessment and self-administration on a web-based multi-device platform (Mayo Test Drive). We aimed to establish criterion validity of the SLS by comparing its ability to differentiate biomarker-defined groups to the person-administered Rey's Auditory Verbal Learning Test (AVLT).

METHOD

Participants (N = 353; mean age = 71, SD = 11; 93% cognitively unimpaired [CU]) completed the AVLT during an in-person visit, the SLS remotely (within 3 months) and had brain amyloid and tau PET scans available (within 3 years). Overlapping groups were formed for 1) those on the Alzheimer's disease (AD) continuum (amyloid PET positive, A+, n = 125) or not (A-, n = 228), and those with biological AD (amyloid and tau PET positive, A+T+, n = 55) vs no evidence of AD pathology (A-T-, n = 195). Analyses were repeated among CU participants only.

RESULTS

The SLS and AVLT showed similar ability to differentiate biomarker-defined groups when comparing AUROCs (p's > .05). In logistic regression models, SLS contributed significantly to predicting biomarker group beyond age, education, and sex, including when limited to CU participants. Medium (A- vs A+) to large (A-T- vs A+T+) unadjusted effect sizes were observed for both SLS and AVLT. Learning and delay variables were similar in terms of ability to separate biomarker groups.

CONCLUSIONS

Remotely administered SLS performed similarly to in-person-administered AVLT in its ability to separate biomarker-defined groups, providing evidence of criterion validity. Results suggest the SLS may be sensitive to detecting subtle objective cognitive decline in preclinical AD.

Using serial position effects to investigate memory dysfunction in homeless and precariously housed persons

Background: Homeless and precariously housed persons exhibit significant memory impairment, but the component processes underlying memory dysfunction have not been explored. We examined the serial position profile (i.e., primacy and recency effects) of verbal memory and its neuroanatomical correlates to identify the nature of memory difficulties in a large cohort of homeless and precariously housed adults. Method: The sample included 227 community-dwelling homeless and precariously housed adults. Serial position scores (primacy, middle, recency) were computed using the Hopkins Verbal Learning Test-Revised. Paired sample t-tests were used to compare percent recall from each word list region. Age-adjusted correlations assessed associations between serial position scores and other cognitive domains (attention, processing speed, executive functioning). Regression analyses were conducted to examine regional brain volumes of interest (hippocampus, entorhinal cortex, dorsolateral prefrontal cortex [DLPFC]) and their differential associations with serial position scores. Results: The serial position profile was characterized by a diminished recency effect in relation to the primacy effect. Serial position scores positively correlated with sustained attention and cognitive control. Larger hippocampal volume was associated with better primacy item recall. DLPFC volume was not associated with serial position recall after adjustment for false discovery rate. There were no associations between regional brain volumes and recency item recall. Conclusion: Our results suggest that commonly reported memory difficulties in homeless and precariously housed adults are likely secondary to a core deficit in executive control due to compromised frontal lobe functioning. These findings have implications for cognitive rehabilitation in this complex and vulnerable group.

Dissociating memory and executive function impairment through temporal features in a word list verbal learning task

The Rey Auditory Verbal Learning Test (RAVLT) is an established verbal learning test commonly used to quantify memory impairments due to Alzheimer's Disease (AD) both at a clinical dementia stage or prodromal stage of mild cognitive impairment (MCI). Focal memory impairment-as quantified e.g. by the RAVLT-at an MCI stage is referred to as amnestic MCI (aMCI) and is often regarded as the cognitive phenotype of prodromal AD. However, recent findings suggest that not only learning and memory but also other cognitive domains, especially executive functions (EF) and processing speed (PS), influence verbal learning performance. This research investigates whether additional temporal features extracted from audio recordings from a participant's RAVLT response can better dissociate memory and EF in such tasks and eventually help to better describe MCI subtypes. 675 age-matched participants from the H70 Swedish birth cohort were included in this analysis; 68 participants were classified as MCI (33 aMCI and 35 due to executive impairment). RAVLT performances were recorded and temporal features extracted. Novel temporal features were correlated with established neuropsychological tests measuring EF and PS. Lastly, the downstream diagnostic potential of temporal features was estimated using group differences and a machine learning (ML) classification scenario. Temporal features correlated moderately with measures of EF and PS. Performance of an ML classifier could be improved by adding temporal features to traditional counts. We conclude that RAVLT temporal features are in general related to EF and that they might be capable of dissociating memory and EF in a word list learning task.

Primacy and recency effects in verbal memory are differentially associated with post-mortem frontal cortex p-tau 217 and 202 levels in a mixed sample of community-dwelling older adults

INTRODUCTION

Serial position effects in verbal memory are associated with in vivo fluid biomarkers and neuropathological outcomes in Alzheimer's disease (AD). To extend the biomarker literature, associations between serial position scores and postmortem levels of brain phosphorylated tau (p-tau) were examined, in the context of Braak stage of neurofibrillary tangle progression.

METHOD

Participants were 1091 community-dwelling adults (Mage = 80.2, 68.9% female) from the Rush University Religious Orders Study and Memory and Aging Project who were non-demented at enrollment and followed for a mean of 9.2 years until death. The CERAD Word List Memory test administered at baseline and within 1 year of death was used to calculate serial position (primacy, recency) and total recall scores. Proteomic analyses quantified p-tau 217 and 202 from dorsolateral prefrontal cortex samples. Linear regressions assessed associations between cognitive scores and p-tau with Braak stage as a moderator.

RESULTS

Cognitive status proximal to death indicated 34.7% were unimpaired, 26.2% met criteria for MCI, and 39.0% for dementia. Better baseline primacy recall, but not recency recall, was associated with lower p-tau 217 levels across Braak stages. Delayed recall showed a similar pattern as primacy. There was no main effect of immediate recall, but an interaction with Braak stages indicated a negative association with p-tau 217 level only in Braak V-VI. Within 1 year of death, there were no main effects for cognitive scores; however, recency, immediate and delayed recall scores interacted with Braak stage showing better recall was associated with lower p-tau 217 only in Braak V-VI. No associations were observed with p-tau 202.

CONCLUSIONS

Primacy recall measured in non-demented adults may be sensitive to emergent tau phosphorylation that occurs in the earliest stages of AD. Serial position scores may complement the routinely used delayed recall score and p-tau biomarkers to detect preclinical AD.

Serial position effects and mild cognitive impairment: a comparison of measures and scoring approaches

INTRODUCTION

Serial position effects (SPEs) have shown promise as predictors of future cognitive decline and conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD), even when accounting for total learning and memory scores. However, conflicting results have been found in the literature, which may be at least partially related to the many ways in which SPEs are calculated. The current study aimed to address the discrepancies in the literature by examining whether one method of analyzing SPEs is more sensitive at distinguishing those with and without psychometrically defined MCI.

METHOD

86 older adult participants (57 healthy comparison, 29 MCI) completed the California Verbal Learning Test, Third Edition (CVLT3) and the Rey Auditory Verbal Learning Test (RAVLT), along with measures assessing multiple cognitive domains. Each participant completed two visits, between 3 and 9 days apart, with a different memory measure administered on each day. The standard scoring approach and the regional scoring approach to calculating SPEs were compared.

RESULTS

Results showed that, when significant differences were found, SPEs were always reduced in the MCI group compared to the healthy comparison group when using regional scoring; however, results were not as consistent when using standard scoring. Further, lower primacy than recency scores were only consistently seen in the MCI group when using the RAVLT but not the CVLT3. ROC analyses showed that only regional scoring of SPEs from delayed recall of the RAVLT and the CVLT3 accurately discriminated between those with and without MCI.

CONCLUSION

Regional scoring of SPEs may be more sensitive at identifying subtle cognitive decline compared to standard scoring. However, the specific measure that is used to analyze SPEs can impact the interpretation of findings.

Gender differences in the serial position among older adults

INTRODUCTION

There are gender disparities in age of diagnosis with Mild Cognitive Impairment (MCI) or dementia, which may be related to general female advantages in verbal memory across aging. Further examination of the serial position effect (SPE) may provide an avenue for earlier diagnosis of MCI/dementia among women.

METHOD

338 cognitively healthy adults aged 50⁺ (110 men; 228 women) were administered the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) List Learning task as part of dementia screening. We examined whether the SPE could be demonstrated on Trial 1 and delayed recall, and whether SPE patterns were consistent across genders, using mixed measure ANOVAs. Using regression, we also examined whether gender, SPE components, or their interactions predicted RBANS Delayed Memory Index (DMI) performance. Using cluster analyses, we identified a group with reduced primacy relative to recency on Trial 1 and a group without. We used ANOVA to examine whether clusters differed in DMI scores and whether this was moderated by gender.

RESULTS

We demonstrated the prototypical SPE on Trial 1. On delayed recall, we found reduced recency compared to primacy and middle performance. As expected, men exhibited worse performance on the DMI. However, gender did not interact with SPE. Primacy and middle, but not recency, performance on Trial 1 predicted DMI scores, as did the recency ratio. These relationships were not moderated by gender. Finally, participants with better primacy than recency on Trial 1 (N = 187) exhibited higher performance on DMI than participants with better recency than primacy (N = 151). Gender did not interact with cluster membership.

CONCLUSION

Our results have important clinical implications in assessment, where focusing on Trial 1 primacy performance and loss of recency between Trial 1 and delayed recall may help to address gender-related delays in age of diagnosis of MCI or dementia.

Longitudinal change in serial position scores in older adults with entorhinal and hippocampal neuropathologies

OBJECTIVE

Serial position scores on verbal memory tests are sensitive to early Alzheimer's disease (AD)-related neuropathological changes that occur in the entorhinal cortex and hippocampus. The current study examines longitudinal change in serial position scores as markers of subtle cognitive decline in older adults who may be in preclinical or at-risk states for AD.

METHODS

This study uses longitudinal data from the Religious Orders Study and the Rush Memory and Aging Project. Participants (n = 141) were included if they did not have dementia at enrollment, completed follow-up assessments, and died and were classified as Braak stage I or II. Memory tests were used to calculate serial position (primacy, recency), total recall, and episodic memory composite scores. A neuropathological evaluation quantified AD, vascular, and Lewy body pathologies. Mixed effects models were used to examine change in memory scores. Neuropathologies and covariates (age, sex, education, APOE e4) were examined as moderators.

RESULTS

Primacy scores declined (β = -.032, p < .001), whereas recency scores increased (β = .021, p = .012). No change was observed in standard memory measures. Greater neurofibrillary tangle density and atherosclerosis explained 10.4% of the variance in primacy decline. Neuropathologies were not associated with recency change.

CONCLUSIONS

In older adults with hippocampal neuropathologies, primacy score decline may be a sensitive marker of early AD-related changes. Tangle density and atherosclerosis had additive effects on decline. Recency improvement may reflect a compensatory mechanism. Monitoring for changes in serial position scores may be a useful in vivo method of tracking incipient AD.

The Role of Entropy in Construct Specification Equations (CSE) to Improve the Validity of Memory Tests: Extension to Word Lists

Metrological methods for word learning list tests can be developed with an information theoretical approach extending earlier simple syntax studies. A classic Brillouin entropy expression is applied to the analysis of the Rey’s Auditory Verbal Learning Test RAVLT (immediate recall), where more ordered tasks—with less entropy—are easier to perform. The findings from three case studies are described, including 225 assessments of the NeuroMET2 cohort of persons spanning a cognitive spectrum from healthy older adults to patients with dementia. In the first study, ordinality in the raw scores is compensated for, and item and person attributes are separated with the Rasch model. In the second, the RAVLT IR task difficulty, including serial position effects (SPE), particularly Primacy and Recency, is adequately explained (Pearson’s correlation R=0.80) with construct specification equations (CSE). The third study suggests multidimensionality is introduced by SPE, as revealed through goodness-of-fit statistics of the Rasch analyses. Loading factors common to two kinds of principal component analyses (PCA) for CSE formulation and goodness-of-fit logistic regressions are identified. More consistent ways of defining and analysing memory task difficulties, including SPE, can maintain the unique metrological properties of the Rasch model and improve the estimates and understanding of a person’s memory abilities on the path towards better-targeted and more fit-for-purpose diagnostics.

A Comparison of Serial Position Effects in Patients with Mild Cognitive Impairment due to Parkinson's Disease or to Alzheimer's Disease

OBJECTIVE

The first (primacy region) and last (recency region) items of a word list are generally better memorized than items from the middle region. The recency effect depends on short-term memory (STM) and the primacy effect on long-term memory (LTM), where verbal information is transferred from STM into LTM by maintenance rehearsal. We compared the serial position effects (SPE) between patients with mild cognitive impairment (MCI) due to Parkinson's disease (PD), i.e., PD-MCI, and patients with MCI due to Alzheimer's disease (AD-MCI), and evaluated the influence of SPE and frontostriatal deficits on verbal memory recall.

METHODS

Four similar groups of subjects participated in the study: 26 PD-MCI patients, 26 cognitively normal patients with PD (PD-CN), 26 AD-MCI patients, and 26 normal controls (NC). Verbal episodic memory, verbal span, attentional capacity, executive functions, and verbal working memory performance were assessed. Measures for primacy and recency regions were defined at the first trial of a 16-items word list. Hierarchical regression models were used to investigate the contribution of frontostriatal deficits beyond SPE on verbal memory recall performance ("long-delay free recall") in PD and AD patients.

RESULTS

Primacy effects were significantly diminished in both PD-MCI and AD-MCI patients relative to NC and PD-CN (all p < 0.01). Compared to PD-MCI patients, AD-MCI patients exhibited significantly worse "delayed-recall 'savings'." Reduced primacy effect was predictive for decreased recall performance in PD and AD. The conducted hierarchical regression model revealed that in PD, but not in AD patients, performance of attention and executive function significantly increased the prediction of free recalled words.

CONCLUSIONS

Reduced recall performance is likely due to impaired transition of newly learned material from STM into LTM in AD and in PD. Whereas AD-MCI patients suffer from a storage deficit, the similarly reduced recall performance found in patients with PD-MCI may additionally be related to deficient attentional and executive capacity.

Evidence and implications of abnormal predictive coding in dementia

The diversity of cognitive deficits and neuropathological processes associated with dementias has encouraged divergence in pathophysiological explanations of disease. Here, we review an alternative framework that emphasizes convergent critical features of cognitive pathophysiology. Rather than the loss of ‘memory centres’ or ‘language centres’, or singular neurotransmitter systems, cognitive deficits are interpreted in terms of aberrant predictive coding in hierarchical neural networks. This builds on advances in normative accounts of brain function, specifically the Bayesian integration of beliefs and sensory evidence in which hierarchical predictions and prediction errors underlie memory, perception, speech and behaviour. We describe how analogous impairments in predictive coding in parallel neurocognitive systems can generate diverse clinical phenomena, including the characteristics of dementias. The review presents evidence from behavioural and neurophysiological studies of perception, language, memory and decision-making. The reformulation of cognitive deficits in terms of predictive coding has several advantages. It brings diverse clinical phenomena into a common framework; it aligns cognitive and movement disorders; and it makes specific predictions on cognitive physiology that support translational and experimental medicine studies. The insights into complex human cognitive disorders from the predictive coding framework may therefore also inform future therapeutic strategies.

Association of serial position scores on memory tests and hippocampal-related neuropathologic outcomes

OBJECTIVE

To determine whether serial position scores in verbal memory differentiate hippocampal-related neuropathologic outcomes, we examined these associations in a sample of older adults without dementia who underwent autopsy.

METHODS

We used data from the Rush Memory and Aging Project, a longitudinal clinical-pathologic cohort study of community-dwelling adults. A total of 701 participants (mean age 82.7, 71.2% female) completed baseline cognitive evaluations and underwent brain autopsy to identify pathologic Alzheimer disease (AD), TDP-43 inclusions (defining limbic-predominant age-related TDP-43 encephalopathy [LATE]), and hippocampal sclerosis. The Consortium to Establish a Registry for Alzheimer's Disease word list memory test immediate recall trials provided serial position scores, which index the proportion of words recalled from the beginning (primacy scores) and end (recency scores) of a word list. Binary and ordinal logistic regressions examined associations between serial position scores and neuropathologic outcomes. Secondary outcomes included Alzheimer dementia and mild cognitive impairment proximate to death.

RESULTS

Primacy and recency scores were uncorrelated (r = 0.07). Each SD of better primacy score was associated with lower likelihood of neuropathologic changes (24% lower LATE, 31% lower pathologic AD, 37% lower hippocampal sclerosis). For pathologic AD, better baseline primacy scores were associated with a 36% lower likelihood of comorbidity with LATE or hippocampal sclerosis. Primacy scores better discriminated between clinical diagnoses proximate to death, including those with mild cognitive impairment compared to no impairment. Recency scores showed weaker or no associations.

CONCLUSIONS

Primacy scores may be particularly sensitive markers of AD and related hippocampal neuropathologies. The differential predictive value of serial position scores suggests they offer complementary information about disease outcomes in addition to the routinely used total recall scores.

Predicting Early Mild Cognitive Impairment With Free Recall: The Primacy of Primacy

OBJECTIVES

Serial position effects have been found to discriminate between normal and pathological aging, and to predict conversion from Mild Cognitive Impairment (MCI) to Alzheimer's disease (AD). Different scoring methods have been used to estimate the accuracy of these predictions. In the current study, we investigated delayed primacy as predictor of progression to early MCI over established diagnostic memory methods. We also compared three serial position methods (regional, standard and delayed scores) to determine which measure is the most sensitive in differentiating between individuals who develop early MCI from a baseline of cognitively intact older adults.

METHOD

Data were analyzed with binary logistic regression and with receiver-operating characteristic (ROC). Baseline serial position scores were collected using the Rey's Auditory Verbal Learning Test and used to predict conversion to early MCI. The diagnosis of early MCI was obtained through statistical algorithm and consequent consensus conference. One hundred and ninety-one participants were included in the analyses. All participants were aged 60 or above and cognitively intact at baseline.

RESULTS

The binary logistic regression showed that delayed primacy was the only predictor of conversion to early MCI, when compared to total and delayed recall. ROC curves showed that delayed primacy was still the most sensitive predictor of progression to early MCI when compared to other serial position measures.

CONCLUSIONS

These findings are consistent with previous studies and support the hypothesis that delayed primacy may be a useful cognitive marker of early detection of neurodegeneration.

Screen position effects on task performance in a delayed match to sample task

Studies of working memory have used immediate and delayed recall of lists of items. Serial position effects are the phenomena where items at the beginning and end of a studied list are recalled differentially from items in the middle of the list. In matching versions of the task, study items may be presented serially or simultaneously in a grid. After a delay a single probe item is presented for which the participant determines whether or not it was in the study set. The effects of the position of an item when studied on a screen are currently not well understood and are the focus of the current work. Findings from a delayed match to sample task in 49 healthy young adults with 1 to 9 items presented in a 3 by 3 grid, demonstrate that the column of the studied items affect response time and accuracy. The effects of position on accuracy also significantly interact with task demands. The importance of screen position effects is demonstrated with simulations using the mean accuracies split by task demands and screen locations. Simulations demonstrate the possible range of accuracies based on screen effects when the number of trials presented to an individual is less than 20 for each task demand. This has important implications when a small number of trials are administered using randomly generated stimuli which is often the case in neuroimaging studies where tasks are delivered under constrained time limits.

Is there a specific memory signature associated with Aβ-PET positivity in patients with amnestic mild cognitive impairment?

Amnestic mild cognitive impairment (aMCI) is a clinical entity with various potential etiologies including but not limited to Alzheimer's disease. We examined whether a positive ([18F]Florbetapir) beta amyloid positron emission tomography scan, supporting underlying Alzheimer's disease pathophysiology, was associated with specific memory deficits in 48 patients with aMCI (33 beta amyloid positive, 15 beta amyloid negative). Memory was evaluated using an autobiographical fluency task and a word-list learning task with 2 different encoding types (shallow/incidental versus deep/intentional). Compared with 40 beta amyloid-negative controls, both aMCI subgroups demonstrated severe deficits in the global memory score and in most subscores of both tasks. Finer-grained analyses of memory tests showed subtle association with beta amyloid status, revealing a stronger impairment of the primacy effect in beta amyloid-positive patients. Structural magnetic resonance imaging showed that both aMCI subgroups exhibited comparable atrophy patterns, with similar degrees of medial temporal volume loss compared with controls. Specifically assessing the primacy effect might complement global memory scores in identifying beta amyloid-positive patients with aMCI.

Immediate verbal recall and familial dementia risk: population-based study of over 4000 twins

OBJECTIVE

To investigate the effect of familial risk for dementia on verbal learning by comparing cognitively healthy twins who had demented co-twins with cognitively healthy twins who had cognitively healthy co-twins.

METHODS

4367 twins aged ≥65 years including 1375 twin pairs (533 monozygotic (MZ), 823 dizygotic (DZ) and 19 unknown zygosity pairs) from a population-based Finnish Twin Cohort participated in a cross-sectional telephone assessment for dementia and in a single free recall trial of a 10-item word list.

RESULTS

Cognitively healthy twins with demented co-twins (n=101 pairs) recalled less words than cognitively healthy twins with cognitively healthy co-twins (n=770 pairs) after adjusting for age, sex and education, B=- 0.44, 95%  CI (-0.73 to -0.14), p=0.003. The effect size was similar in MZ (n=31) twins (3.88 vs 4.29 words, B=-0.41, 95%  CI (-0.96 to 0.13)) and DZ (n=66) twins (3.70 vs 4.17 words, B=-0.47, 95%  CI (-0.84 to -0.10)). The heritability estimate of immediate recall (IR) was 0.37, 95%  CI (0.21 to 0.43).

CONCLUSIONS

The results demonstrate that familial risk for dementia is reflected in the IR performance of cognitively healthy older persons. The finding of poorer IR performance in non-affected siblings compared with the general population, together with substantial heritability of IR, supports IR as a useful endophenotype for molecular genetic studies of dementia.

The effects of age on the learning and forgetting of primacy, middle, and recency components of a multi-trial word list

The serial position effect reveals that recall of a supraspan list of words follows a predictable pattern, whereby words at the beginning (primacy) and end (recency) of a list are recalled more easily than words in the middle. This effect has typically been studied using single list-learning trials, but in neuropsychology, multi-trial list-learning tests are more commonly used. The current study examined trends in learning for primacy, middle, and recency effects across multiple trials in younger and older age cohorts. Participants were 158 volunteers, including 79 adults aged 17-36 ("younger" group) and 79 adults aged 54-89 years ("older" group). Each participant completed four learning trials and one delayed (5-10 min) recall trial from the Memory Assessment Scales. Scores were divided into primacy (first four words), middle (middle four words), and recency (final four words) scores for all trials. For list acquisition, mixed effects modeling examined the main effects of and interactions between learning slope (logarithmic), age group, and serial position. Rate of learning increased logarithmically over four trials and varied by serial position, with growth of middle and recency word acquisition increasing more rapidly than recall of primacy words; this interaction did not differ by age group. Delayed retention differed according to age group and serial position; both older and younger adults demonstrated similar retention for primacy words, but older adults showed reduced retention for middle and recency words. Although older adults acquired less information across learning trials, the reason for this reduced acquisition was related to initial learning, not to rate of learning over time. Older compared to younger adults were less efficient at transferring middle and recency words from short-term to long-term memory.

The Primacy Effect in Amnestic Mild Cognitive Impairment: Associations with Hippocampal Functional Connectivity

Background: The “primacy effect,” i.e., increased memory recall for the first items of a series compared to the following items, is reduced in amnestic mild cognitive impairment (aMCI). Memory task-fMRI studies demonstrated that primacy recall is associated with higher activation of the hippocampus and temporo-parietal and frontal cortical regions in healthy subjects. Functional magnetic resonance imaging (fMRI) at resting state revealed that hippocampus functional connectivity (FC) with neocortical brain areas, including regions of the default mode network (DMN), is altered in aMCI. The present study aimed to investigate whether resting state fMRI FC between the hippocampus and cortical brain regions, especially the DMN, is associated with primacy recall performance in aMCI.

Methods: A number of 87 aMCI patients underwent resting state fMRI and verbal episodic memory assessment. FC between the left or right hippocampus, respectively, and all other voxels in gray matter was mapped voxel-wise and used in whole-brain regression analyses, testing whether FC values predicted delayed primacy recall score. The delayed primacy score was defined as the number of the first four words recalled on the California Verbal Learning Test. Additionally, a partial least squares (PLS) analysis was performed, using DMN regions as seeds to identify the association of their functional interactions with delayed primacy recall.

Results: Voxel-based analyses indicated that delayed primacy recall was mainly (positively) associated with higher FC between the left and right hippocampus. Additionally, significant associations were found for higher FC between the left hippocampus and bilateral temporal cortex, frontal cortical regions, and for higher FC between the right hippocampus and right temporal cortex, right frontal cortical regions, left medial frontal cortex and right amygdala (p < 0.01, uncorr.). PLS analysis revealed positive associations of delayed primacy recall with FC between regions of the DMN, including the left and right hippocampus, as well as middle cingulate cortex and thalamus (p < 0.04). In conclusion, in the light of decreased hippocampus function in aMCI, inter-hemispheric hippocampus FC and hippocampal FC with brain regions predominantly included in the DMN may contribute to residual primacy recall in aMCI.

Verbal list learning and memory profiles in HIV-infected adults, Alzheimer's disease, and Parkinson's disease: An evaluation of the "cortical hypothesis" of NeuroAIDS

HIV+ population is getting older because of progress in treatments. Yet, there are concerns that Older HIV+ individuals (OHIV+) may be more vulnerable for developing a "cortical" dementia such as Alzheimer Disease (AD). Our aim was to explore the hypothesis that the cognitive deficit extends to ''cortical'' functions in OHIV+ by comparing serial position effects (SPE) in different groups of participants affected by "cortical" or "subcortical" damage. We enrolled a total of 122 subjects: 22 OHIV+ (≥60 years of age), 31 Younger HIV+ (YHIV+) (<60 years of age), 18 participants with AD, 23 subjects with Parkinson Disease (PD), and 28 healthy subjects. All subjects performed verbal learning tasks (VLT) to explore SPE. Factorial analysis of covariance showed a significant effect of "group" (p < 0.001) and "task" (Primacy vs Recency) (p < 0.001), but no significant group*task (p = 0.257) interaction. Compared with healthy subjects (p = 0.003), AD had the most severe reduction of Primacy, confirming a primary "encoding deficit," while PD confirmed a "frontal pattern." OHIV+ showed a memory profile similar to that of PD with a worsening of the cognitive performance in comparison with YHIV+. In conclusion, we did not confirm the "cortical" hypothesis in OHIV+, at least in terms of learning and memory functions.

Confirmatory factor analysis of the Spanish version of the California Verbal Learning Test in a sample of middle-aged and older adults with subjective memory complaints

INTRODUCTION

Assessment of the ability to retain new information is of special interest in the second half of life because of age-related changes, especially in those individuals at risk of cognitive impairment. The California Verbal Learning Test (CVLT) is one of the most common auditory-verbal learning tests used to test episodic memory. The objective of this paper is to study the stability of the factorial structure of the Spanish version of CVLT in a sample of adults aged 50-87 years with subjective memory complaints (SMCs).

METHOD

Performance at baseline and follow-up assessment (about 18 months later) was analyzed in 301 participants. Models including one, two, three, and four factors were tested, by comparing the results of confirmatory factor analysis and structural equation models of relations between the factors at baseline and follow-up.

RESULTS

The two-factor models (accurate and inaccurate memory) yielded the best fit. The model establishing a relationship between these two factors at baseline and follow-up provided a good fit.

CONCLUSION

CVLT performance in a sample of middle-aged and old adults with SMCs was separated into two factors differentiating accurate recollection and errors. A structural equation modeling (SEM) model relating data from both assessments replicated these findings.

Early neuropsychological detection of Alzheimer's disease

Lifestyle modification offers a promising way of preventing or delaying Alzheimer's disease (AD). In particular, nutritional interventions can contribute to decrease the risk of dementia. The efficacy of such interventions should be assessed in individuals thought to be prone to AD. It is therefore necessary to identify markers that may help detecting AD as early as possible. This review will focus on subtle neuropsychological changes that may already exist in the predementia phase, and that could point to individuals at risk of dementia. Episodic memory decline appears consistently as the earliest sign of incipient typical AD. An episodic memory test that ensures deep encoding of information and assesses retrieval with free as well as cued recall appears as a useful tool to detect patients at an early stage of AD. Beyond the memory domain, category verbal fluency has been shown to decline early and to predict progression to AD. Moreover, in line with current diagnosis criteria for prodromal AD, combining neuropsychological scores and neuroimaging data allows a better discrimination of future AD patients than neuroimaging or neuropsychological data alone. Altogether, the detection of cognitive changes that are predictive of the typical form of probable AD already in the predementia stage points to at risk people who are the best target for therapeutic interventions, such as nutrition or physical exercise counseling or dietary interventions.

Serial position effects are sensitive predictors of conversion from MCI to Alzheimer's disease dementia

BACKGROUND

It is unclear whether the predictive strength of established cognitive variables for progression to Alzheimer's disease (AD) dementia from mild cognitive impairment (MCI) varies depending on time to conversion. We investigated which cognitive variables were best predictors, and which of these variables remained predictive for patients with longer times to conversion.

METHODS

Seventy-five participants with MCI were assessed on measures of learning, memory, language, and executive function. Relative predictive strengths of these measures were analyzed using Cox regression models.

RESULTS

Measures of word-list position-namely, serial position scores-together with Short Delay Free Recall of word-list learning best predicted conversion to AD dementia. However, only serial position scores predicted those participants with longer time to conversion.

CONCLUSIONS

Results emphasize that the predictive strength of cognitive variables varies depending on time to conversion to dementia. Moreover, finer measures of learning captured by serial position scores were the most sensitive predictors of AD dementia.