The utility of placing recollection in opposition to familiarity in early discrimination of healthy aging and very mild dementia of the Alzheimer's type

The Utility of the National Alzheimer's Coordinating Center's Database for the Rapid Assessment of Evolving Neuropathologic Conditions

The field of dementia research is rapidly evolving, especially with regards to our understanding of the diversity of neuropathologic changes that underlie cognitive decline. Definitions and criteria for known conditions are being periodically revised and refined, and new findings are being made about neuropathologic features associated with dementia status. The database maintained by the National Alzheimer's Coordinating Center (NACC) offer researchers a robust, rapid, and statistically well-powered method to evaluate the implications of newly identified neuropathologic conditions with regards to comorbidities, demographic associations, cognitive status, neuropsychologic tests, radiographic findings, and genetics. NACC data derive from dozens of excellent US Alzheimer disease research centers, which collectively follow thousands of research volunteers longitudinally. Many of the research participants are autopsied using state-of-the-art methods. In this article, we describe the NACC database and give examples of its use in evaluating recently revised neuropathologic diagnoses, including primary age-related tauopathy (PART), limbic predominant age-related TDP-43 encephalopathy (LATE), and the preclinical stage of Alzheimer disease neuropathologic change, based on the National Institute on Aging-Alzheimer's Association consensus guidelines. The dementia research community is encouraged to make use of this readily available database as new neuropathologic changes are recognized and defined in this rapidly evolving field.

Selective familiarity deficits in otherwise cognitively intact aging individuals with genetic risk for Alzheimer's disease

Introduction

Familiarity has been associated with integrity of the rhinal cortex. Thus, impairment in familiarity is expected in very early stages of Alzheimer's disease (AD). The apolipoprotein E (APOE) ε4 allele is a major risk factor for AD. Here, we investigated the effect of the APOE ε4 status on familiarity in cognitively normal aging individuals.

Methods

Eighty-one individuals aged between 55 and 80 years, 21 carriers and 60 noncarriers, were used in these analyses. A cognitive evaluation was performed on all participants to document the absence of objective cognitive deficits. The effect of APOE ε4 status on familiarity was tested using independent sample t test and an analysis of covariance controlling for age, gender, and education.

Results

The groups did not differ in term of age, education, and male/female ratio. APOE ε4 carriers showed a significant reduction in familiarity. No other cognitive deficit was observed in the group of ε4 carriers, relative to noncarriers.

Discussion

APOE ε4 is associated with a reduction in familiarity in the absence of other cognitive deficits. These results suggest that performance in familiarity could represent an early cognitive marker for individuals at risk of AD.

The Interaction Between Memory Trace and Memory Judgment in Age-Related Decline

BACKGROUND/STUDY CONTEXT

Associative memory deficit and executive functioning deficit are two alternative--but nonexclusive--accounts of the episodic memory deficit observed in aging. The first explain the episodic memory decline generally observed in aging by an associative memory deficit (memory decline per se), whereas the second explains it by an executive functioning deficit. This distinction could be critical in early discrimination between healthy aging and very mild Alzheimer's-type dementia.

METHODS

Memory performance was measured in older adults (n = 20) and paired younger participants (n = 20), whereas the facial expression and auditory context (spoken voice) associated with the face were manipulated between study and test. Recollection and familiarity were estimated using a remember/know judgment, and source memory performance was obtained depending on the information to retrieve.

RESULTS

Although no between-group difference was observed for correctly recognized old faces, older participants made more false alarms than younger ones, thus revealing lower discriminability (d'). Facial expression change decreased recognition for all participants, whereas auditory context change decreased recognition only for younger participants. Remember/know judgments revealed age-related deficits in both recollection and familiarity, the relative decrease in familiarity reported by older adults was particularly large in the expression change conditions, and a disadvantage in source memory performance was particularly pronounced when the task was to retrieve auditory context associated with the face at study.

CONCLUSIONS

The present findings show that age-related associative memory differences occur with familiarity as well as recollection and are observed in situations that do not necessarily require conscious retrieval. This age-related decline is more prominent for multimodal (face-auditory context) than for intraitem (face-expression) associations. The value of exploring both memory trace and memory judgment was discussed, and potential applications for the development of neuropsychological tools for memory assessment in aging were highlighted.

The utility of a non-verbal prospective memory measure as a sensitive marker for early-stage Alzheimer's disease in Hong Kong

ABSTRACT Background: With the proportion of older adults in Hong Kong projected to double in size in the next 30 years, it is important to develop measures for detecting individuals in the earliest stage of Alzheimer's disease (AD, 0.5 in Clinical Dementia Rating, CDR). We tested the utility of a non-verbal prospective memory task (PM, ability to remember what one has to do when a specific event occurs in the future) as an early marker for AD in Hong Kong Chinese. Methods: A large community dwelling sample of older adults who are healthy controls (CDR 0, N = 125), in the earliest stage of AD (CDR 0.5, N = 125), or with mild AD (CDR 1, N = 30) participated in this study. Their reaction time/accuracy data were analyzed by mixed-factor analyses of variance to compare the performance of the three CDR groups. Logistic regression analyses were performed to test the discriminative power of these measures for CDR 0 versus 0.5 participants. Results: Prospective memory performance declined as a function of AD severity: CDR 0 > CDR 0.5 > CDR 1, suggesting the effects of early-stage AD and AD progression on PM. After partialling out the variance explained by psychometric measures (e.g., ADAS-Cog), reaction time/accuracy measures that reflected the PM still significantly discriminated between CDR 0 versus 0.5 participants in most of the cases. Conclusion: The effectiveness of PM measures in discriminating individuals in the earliest stage of AD from healthy older adults suggests that these measures should be further developed as tools for early-stage AD discrimination.

Alzheimer disease biomarkers, attentional control, and semantic memory retrieval: Synergistic and mediational effects of biomarkers on a sensitive cognitive measure in non-demented older adults

OBJECTIVE

Past studies have shown that measures of attentional control and semantic memory are sensitive markers of Alzheimer's disease (AD). The effects of established biomarkers of AD (cerebrospinal fluid tau and amyloid-beta42, positron emission tomography Pittsburgh compound-B, and apolipoprotein E [APOE] genotype) on concurrent cognitive performance in cognitively normal individuals have been mixed. The present study examined the utility of combining attentional control with semantic retrieval as a sensitive correlate of AD biomarkers and used mediation analyses to examine possible mechanisms by which the biomarkers influence cognition.

METHOD

Three hundred sixty-three participants completed a category verification task (CVT), and 113 of them concurrently underwent biomarker assessments. On each trial, participants viewed a category (e.g., "unit of time") and verified whether a subsequent target item was an exemplar of the category ("hour") or not ("clock"). Importantly, the nonmembers of the category were associatively related to the category (e.g., "clock" is not "a unit of time," but is highly related), and demanded attentional control to reject.

RESULTS

Accuracy to the foil items was the strongest discriminator between healthy aging and very mild symptomatic AD. Cerebrospinal fluid biomarkers had independent yet synergistic influence on CVT performance in cognitively healthy older adults. Furthermore, the influence of the biomarkers and APOE genotype was mediated primarily through increased levels of PIB.

CONCLUSION

The combined influence of attentional control with semantic retrieval is a marker of symptomatic AD and a sensitive correlate of established biomarkers for AD risk in cognitively healthy participants. The biomarkers influenced cognition primarily through increased levels of amyloid in the brain.

The effects of healthy aging, amnestic mild cognitive impairment, and Alzheimer's disease on recollection and familiarity: a meta-analytic review

It is well established that healthy aging, amnestic Mild Cognitive Impairment (aMCI), and Alzheimer's Disease (AD) are associated with substantial declines in episodic memory. However, there is still debate as to how two forms of episodic memory - recollection and familiarity - are affected by healthy and pathological aging. To address this issue we conducted a meta-analytic review of the effect sizes reported in studies using remember/know (RK), receiver operating characteristic (ROC) and process dissociation (PD) methods to examine recollection and familiarity in healthy aging (25 published reports), aMCI (9 published reports), and AD (5 published reports). The results from the meta-analysis revealed that healthy aging is associated with moderate-to-large recollection impairments. Familiarity was not impaired in studies using ROC or PD methods but was impaired in studies that used the RK procedure. aMCI was associated with large decreases in recollection whereas familiarity only tended to show a decrease in studies with a patient sample comprised of both single-domain and multiple-domain aMCI patients. Lastly, AD was associated with large decreases in both recollection and familiarity. The results are consistent with neuroimaging evidence suggesting that the hippocampus is critical for recollection whereas familiarity is dependent on the integrity of the surrounding perirhinal cortex. Moreover, the results highlight the relevance of method selection when examining aging, and suggest that familiarity deficits might be a useful behavioral marker for identifying individuals that will develop dementia.

Neuropsychological changes in asymptomatic persons with Alzheimer disease neuropathology

OBJECTIVE

To determine whether asymptomatic persons with Alzheimer disease (AD) neuropathologic change differ in the trajectory of their cognitive performance compared to asymptomatic persons without AD neuropathologic change.

METHODS

Longitudinal performance on standard neuropsychological tests was examined in participants who died within 2 years of their last cognitive assessment and who were never diagnosed with mild cognitive impairment or dementia (Clinical Dementia Rating global score of 0 at all assessments). Using cognitive and neuropathologic data collected between 2005 and 2013 from the 34 National Institute on Aging-sponsored Alzheimer's Disease Centers, cognitive trajectories were compared for persons with and without evidence of AD neuropathologic change. We evaluated rates of decline in 4 domains (episodic memory, language, attention/working memory, executive function). The significance of the differences (β) in rates of decline was tested using linear regression, adjusting for age, education, sex, and other neuropathologic lesions.

RESULTS

Participants who had low to high levels of AD neuropathologic change (n = 131) showed a greater rate of decline on the attention/working memory domain score (β = -0.11; 95% confidence interval = -0.19, -0.02; p = 0.02) when compared to 80 participants who died without evidence of AD neuropathologic change.

CONCLUSIONS

Clinically normal individuals who come to autopsy with AD neuropathologic change exhibit subtle evidence of declining cognitive trajectories for attention/working memory.

Item familiarity and controlled associative retrieval in Alzheimer's disease: an fMRI study

Typical Alzheimer's disease (AD) is characterized by an impaired form of associative memory, recollection, that includes the controlled retrieval of associations. In contrast, familiarity-based memory for individual items may sometimes be preserved in the early stages of the disease. This is the first study that directly examines whole-brain regional activity during one core aspect of the recollection function: associative controlled episodic retrieval (CER), contrasted to item familiarity in AD patients. Cerebral activity related to associative CER and item familiarity in AD patients and healthy controls (HCs) was measured with functional magnetic resonance imaging during a word-pair recognition task to which the process dissociation procedure was applied. Some patients had null CER estimates (AD-), whereas others did show some CER abilities (AD+), although significantly less than HC. In contrast, familiarity estimates were equivalent in the three groups. In AD+, as in controls, associative CER activated the inferior precuneus/posterior cingulate cortex (PCC). When performing group comparisons, no region was found to be significantly more activated during CER in HC than AD+ and vice versa. However, during associative CER, functional connectivity between this region and the hippocampus, the inferior parietal and dorsolateral prefrontal cortex (DLPFC) was significantly higher in HC than in AD+. In all three groups, item familiarity was related to activation along the intraparietal sulcus (IPS). In conclusion, whereas the preserved automatic detection of an old item (without retrieval of accurate word association) is related to parietal activation centred on the IPS, the inferior precuneus/PCC supports associative CER ability in AD patients, as in HC. However, AD patients have deficient functional connectivity during associative CER, suggesting that the residual recollection function in these patients might be impoverished by the lack of some recollection-related aspects such as autonoetic quality, episodic details and verification.

The process-dissociation approach two decades later: convergence, boundary conditions, and new directions

The process-dissociation procedure was developed to separate the controlled and automatic contributions of memory. It has spawned the development of a host of new measurement approaches and has been applied across a broad range of fields in the behavioral sciences, ranging from studies of memory and perception to neuroscience and social psychology. Although it has not been without its shortcomings or critics, its growing influence attests to its utility. In the present article, we briefly review the factors motivating its development, describe some of the early applications of the general method, and review the literature examining its underlying assumptions and boundary conditions. We then highlight some of the specific issues that the methods have been applied to and discuss some of the more recent applications of the procedure, along with future directions.

Frequent false hearing by older adults: the role of age differences in metacognition

In two experiments testing age differences in the subjective experience of listening, which we call meta-audition, young and older adults were first trained to learn pairs of semantic associates. Following training, both groups were tested on identification of words presented in noise, with the critical manipulation being whether the target item was congruent, incongruent, or neutral with respect to prior training. Results of both experiments revealed that older adults compared to young adults were more prone to "false hearing," defined as mistaken high confidence in the accuracy of perception when a spoken word had been misperceived. These results were obtained even when performance was equated across age groups on control items by reducing the noise level for older adults. Such false hearing is shown to reflect older adults' heavier reliance on context. Findings suggest that older adults' greater ability to benefit from semantic context reflects their bias to respond consistently with the context, rather than their greater skill in using context. Procedures employed are unique in measuring the subjective experience of hearing as well as its accuracy. Both theoretical and applied implications of the findings are discussed. Convergence of results with those showing higher false memory, and false seeing are interpreted as showing that older adults are less able to constrain their processing in ways that are optimal for performance of a current task. That lessened constraint may be associated with decline in frontal-lobe functioning.

Role of family history for Alzheimer biomarker abnormalities in the adult children study

OBJECTIVE

To assess whether family history (FH) of Alzheimer disease (AD) alone influences AD biomarker abnormalities.

DESIGN

Adult Children Study.

SETTING

Washington University's Charles F. and Joanne Knight Alzheimer's Disease Research Center.

PARTICIPANTS

A total of 269 cognitively normal middle- to older-aged individuals with and without an FH for AD.

MAIN OUTCOME MEASURES

Clinical and cognitive measures, magnetic resonance imaging-based brain volumes, diffusion tensor imaging-based white matter microstructure, cerebrospinal fluid biomarkers, and molecular imaging of cerebral fibrillar amyloid with positron emission tomography using the [(11)C] benzothiazole tracer, Pittsburgh compound B.

RESULTS

A positive FH for AD was associated with an age-related decrease of cerebrospinal fluid Aβ42; the ε4 allele of apolipoprotein E (APOE4) did not alter this effect. Age-adjusted cerebrospinal fluid Aβ42 was decreased for individuals with APOE4 compared with the level for those without, and the decrease was larger for individuals with a positive FH compared with the decrease for those without. The variation of cerebrospinal fluid tau and Pittsburgh compound B mean cortical binding potential increased by age. For individuals younger than 55, an age-related increase in mean cortical binding potential was associated with APOE4 but not FH. For individuals older than 55, a positive FH and a positive APOE4 implied the fastest age-related increase in mean cortical binding potential. A positive FH was associated with decreased fractional anisotropy from diffusion tensor imaging in the genu and splenium of the corpus callosum.

CONCLUSION

Independent of APOE4, FH is associated with age-related change of several cerebrospinal fluid, Pittsburgh compound B, and diffusion tensor imaging biomarkers in cognitively normal middle- to older-aged individuals, suggesting that non- APOE susceptibility genes for AD influence AD biomarkers.

The development of memory efficiency and value-directed remembering across the life span: a cross-sectional study of memory and selectivity

Although attentional control and memory change considerably across the life span, no research has examined how the ability to strategically remember important information (i.e., value-directed remembering) changes from childhood to old age. The present study examined this in different age groups across the life span (N = 320, 5-96 years old). A selectivity task was used in which participants were asked to study and recall items worth different point values in order to maximize their point score. This procedure allowed for measures of memory quantity/capacity (number of words recalled) and memory efficiency/selectivity (the recall of high-value items relative to low-value items). Age-related differences were found for memory capacity, as young adults recalled more words than the other groups. However, in terms of selectivity, younger and older adults were more selective than adolescents and children. The dissociation between these measures across the life span illustrates important age-related differences in terms of memory capacity and the ability to selectively remember high-value information.

The utility of Stroop task switching as a marker for early-stage Alzheimer's disease

Past studies have suggested attentional control tasks such as the Stroop task and the task-switching paradigm may be sensitive for the early detection of dementia of the Alzheimer's type (DAT). The authors of the current study combined these tasks to create a Stroop switching task. Performance was compared across young adults, older adults, and individuals diagnosed with very mild dementia. Results indicated that this task strongly discriminated individuals with healthy aging from those with early-stage DAT. In a logistic regression analysis, incongruent error rates from the Stroop switching task discriminated healthy aging from DAT better than any of the other 18 cognitive tasks given in a psychometric battery.

Effects of healthy aging and early stage dementia of the Alzheimer's type on components of response time distributions in three attention tasks

OBJECTIVE

The characteristics of response time (RT) distributions beyond measures of central tendency were explored in 3 attention tasks across groups of young adults, healthy older adults, and individuals with very mild dementia of the Alzheimer's type (DAT).

METHOD

Participants were administered computerized Stroop, Simon, and switching tasks, along with psychometric tasks that tap various cognitive abilities and a standard personality inventory (NEO-FFI). Ex-Gaussian (and Vincentile) analyses were used to capture the characteristics of the RT distributions for each participant across the 3 tasks, which afforded 3 components: mu and sigma (mean and standard deviation of the modal portion of the distribution) and tau (the positive tail of the distribution).

RESULTS

The results indicated that across all 3 attention tasks, healthy aging produced large changes in the central tendency mu parameter of the distribution along with some change in sigma and tau (mean etap(2) = .17, .08, and .04, respectively). In contrast, early stage DAT primarily produced an increase in the tau component (mean etap(2) = .06). tau was also correlated with the psychometric measures of episodic/semantic memory, working memory, and processing speed, and with the personality traits of neuroticism and conscientiousness. Structural equation modeling indicated a unique relation between a latent tau construct (-.90), as opposed to sigma (-.09) and mu constructs (.24), with working memory measures.

CONCLUSIONS

The results suggest a critical role of attentional control systems in discriminating healthy aging from early stage DAT and the utility of RT distribution analyses to better specify the nature of such change.