Cognitive markers preceding Alzheimer's dementia in the healthy oldest old

Protein intake and episodic memory: the moderating role of the apolipoprotein E ε4 status

BACKGROUND

This study investigated the correlation between protein intake and Alzheimer's disease (AD)-related cognitive decline, particularly in episodic memory, among older adults without dementia. Furthermore, we assessed the moderating effect of apolipoprotein ε4 (APOE4) on this association and analyzed its influence on other cognitive functions beyond memory.

METHODS

The study involved 196 participants who underwent assessments for protein intake, cognitive performance, APOE4 genotyping, and nutritional biomarkers. Protein intake was categorized into low, medium, and high based on the consumption of dairy, legumes, eggs, meat, and fish.

RESULTS

High protein intake was significantly associated with better episodic memory and overall cognition. Moreover, a significant interaction was found between high protein intake and APOE4, indicating that APOE4 moderates the association between high protein intake level and episodic memory. Sensitivity analysis confirmed these results among participants with stable food intake.

CONCLUSIONS

Our study results demonstrated that high protein intake is associated with better episodic memory among older adults without dementia. Furthermore, the findings highlight the significant role of APOE4 status in moderating the relationship between protein consumption and episodic memory. These results suggest that dietary interventions focusing on protein intake could be beneficial for cognitive health, particularly in individuals with a genetic predisposition to AD.

Manganese level and cognitive decline in older adults with the APOE e4 allele: a preliminary study

This study examined the relationship between serum manganese level and cognition, and the moderating effect of apolipoprotein E ε4 (APOE4) on this relationship. A total of 164 non-demented participants underwent clinical assessments including serum manganese level and cognition [episodic memory score (EMS), non-memory score (NMS) for executive function/attention/language/ visuospatial skill, and total score (TS)]. Serum manganese × APOE4 interaction had a significant effect on EMS and TS. Serum manganese level was inversely associated with EMS and TS in APOE4-positive but not APOE4-negative participants. APOE4 should be considered a key component in Alzheimer's disease studies that included manganese imbalance as a risk factor.

High-intensity walking in midlife is associated with improved memory in physically capable older adults

BACKGROUND

Little is known about the associations of midlife- and late life-initiated walking with Alzheimer's disease (AD)-related cognitive decline in humans. We aimed to investigate whether high-intensity, prolonged, midlife-initiated walking is associated with changes in AD-related cognitive decline in physically capable older adults.

METHODS

We studied 188 physically capable participants aged 65-90 years without dementia who underwent comprehensive clinical assessment, including of their walking modality (i.e., intensity, duration, midlife- or late life-onset), memory- or non-memory and total cognitive performance, and blood or nutritional biomarkers.

RESULTS

The walking group showed better episodic memory (B = 2.852, SE = 1.214, β = 0.144, p = 0.020), but not non-memory cognition, than the non-walking group. High-intensity walking starting in midlife was significantly associated with better episodic memory (B = 9.360, SE = 3.314, β = 0.446, p = 0.005) compared to the non-walking group. In contrast, there were no differences in cognition according to walking duration, regardless of the onset time. The walking group also showed a similar association with overall cognition.

CONCLUSIONS

Among physically capable older adults without dementia, walking, particularly at high intensity and starting in midlife, is associated with improved episodic memory, an AD-related cognitive domain. Further attention should be paid to the role of walking in terms of AD prevention.

Association between physical activity and episodic memory and the moderating effects of the apolipoprotein E ε4 allele and age

Background

An abundance of evidence indicates that physical activity may protect against Alzheimer's disease (AD) and related cognitive decline. However, little is known about the association between physical activity and AD-related cognitive decline according to age and the apolipoprotein E (APOE) ε4 allele (APOE4) as major risk factors. Therefore, we examined whether age and APOE4 status modulate the effects of physical activity on episodic memory as AD-related cognition in non-demented older adults.

Methods

We enrolled 196 adults aged between 65 and 90 years, with no dementia. All participants underwent comprehensive clinical assessments including physical activity evaluation and APOE genotyping. The AD-related cognitive domain was assessed by the episodic memory, as the earliest cognitive change in AD, and non-memory cognition for comparative purposes. Overall cognition was assessed by the total score (TS) of the Consortium to Establish a Registry for Alzheimer's Disease neuropsychological battery.

Results

We found significant physical activity × age and physical activity × APOE4 interaction effects on episodic memory. Subgroup analyses indicated that an association between physical activity and increased episodic memory was apparent only in subjects aged > 70 years, and in APOE4-positive subjects.

Conclusion

Our findings suggest that physical activity has beneficial effects on episodic memory, as an AD-related cognitive domain, in individuals aged > 70 years and in APOE4-positive individuals. Physicians should take age and APOE4 status account into when recommending physical activity to prevent AD-related cognitive decline.

Verbal memory formation across PET-based Braak stages of tau accumulation in Alzheimer's disease

A classical early sign of typical Alzheimer's disease is memory decline, which has been linked to the aggregation of tau in the medial temporal lobe. Verbal delayed free recall and recognition tests have consistently probed useful to detect early memory decline, and there is substantial debate on how performance, particularly in recognition tests, is differentially affected through health and disease in older adults. Using in vivo PET-Braak staging, we investigated delayed recall and recognition memory dysfunction across the Alzheimer's disease spectrum. Our cross-sectional study included 144 cognitively unimpaired elderly, 39 amyloid-β+ individuals with mild cognitive impairment and 29 amyloid-β+ Alzheimer's disease patients from the Translational Biomarkers in Aging and Dementia cohort, who underwent [¹⁸F]MK6240 tau and [¹⁸F]AZD4694 amyloid PET imaging, structural MRI and memory assessments. We applied non-parametric comparisons, correlation analyses, regression models and voxel-wise analyses. In comparison with PET-Braak Stage 0, we found that reduced, but not clinically significant, delayed recall starts at PET-Braak Stage II (adjusted P < 0.0015), and that recognition (adjusted P = 0.011) displayed a significant decline starting at PET-Braak Stage IV. While performance in both delayed recall and recognition related to tau in nearly the same cortical areas, further analyses showed that delayed recall rendered stronger associations in areas of early tau accumulation, whereas recognition displayed stronger correlations in mostly posterior neocortical regions. Our results support the notion that delayed recall and recognition deficits are predominantly associated with tau load in allocortical and neocortical areas, respectively. Overall, delayed recall seems to be more dependent on the integrity of anterior medial temporal lobe structures, while recognition appears to be more affected by tau accumulation in cortices beyond medial temporal regions.

Spicy food intake predicts Alzheimer-related cognitive decline in older adults with low physical activity

A plausible association exists among spicy food consumption, physical activity, and Alzheimer's disease (AD) or cognitive decline, but it remains poorly investigated. We aimed to examined the association between spicy food and AD-related memory decline or global cognitive decline in older adults under the moderating effect of physical activity. Total 196 non-demented older adults were included. Participants underwent comprehensive dietary and clinical assessments including spicy food intake, AD-related memory, global cognition, and physical activity. The strength of spicy food was stratified into three categories: 'not spicy' (reference), 'low spiciness', and 'high spiciness'. Multiple linear regression analyses were performed to examine the relationships between spicy level and cognition. The spicy level was the independent variable in each analysis; it was entered as a stratified categorical variable using the three categories. We found a significant association between a high level of spiciness in food and decreased memory ([Formula: see text] - 0.167, p < 0.001) or global cognition ([Formula: see text] - 0.122, p = 0.027), but not non-memory cognition. To explore the moderating effects of age, sex, apolipoprotein E ε4 allele-positivity, vascular risk score, body mass index, and physical activity on the associations between spicy level and memory or global cognition, the same regression analyses were repeated including two-way interaction terms between the spicy level and each of the six variables as an additional independent variable. An interactive effect was detected between a high level of spiciness in food and physical activity on the memory ([Formula: see text] 0.209, p = 0.029) or global cognition ([Formula: see text] 0.336, p = 0.001). Subgroup analyses showed that the association between a high level of spiciness in food and a lower memory ([Formula: see text] - 0.254, p < 0.001) and global score ([Formula: see text] - 0.222, p = 0.002) was present only in older adults with low physical activity, but not in older adults with high physical activity. Our findings suggest that spicy food intake is predictive of AD-related cognitive decline, i.e., episodic memory; this relationship is worsened by physically inactive lifestyle.

Ginseng intake and Alzheimer disease-specific cognition in older adults according to apolipoprotein 4 allele status

Background

The probable association among ginseng intake, Alzheimer's disease (AD)-specific cognition, and apolipoprotein ε4 (APOE4) remains poorly investigated. Hence, we examined the association between ginseng intake and AD-specific cognition in older adults under the moderating effect of APOE4 status.

Methods

This study enrolled 160 adults aged 65-90 years without dementia. All participants underwent comprehensive dietary and clinical assessments including ginseng intake, AD-related cognition (i.e., delayed episodic memory, as the earliest cognitive change in AD), and non-memory cognition for comparative purposes.

Results

Ginseng intake was associated with higher delayed episodic memory, but not non-memory cognition, compared to no ginseng intake. The interaction between ginseng intake and APOE4 status had a significant effect on delayed episodic memory. Subgroup analyses showed that ginseng intake was associated with higher delayed episodic memory in the APOE4-negative but not the APOE4-positive subgroup. The benefits of ginseng intake on delayed episodic memory were prominent in the high duration (≥5 years) and midlife onset (<65 years) groups.

Conclusion

Our study of older adults with no dementia suggests that ginseng intake (with high duration and midlife onset) had a beneficial effect on AD-specific cognitive decline, i.e., the delayed episodic memory. In addition, APOE4 status moderates the association between ginseng intake status and AD-specific cognitive decline.

Intraindividual Cognitive Variability and Magnetic Resonance Imaging in Aging American Indians: Data from the Strong Heart Study

BACKGROUND

American Indians have high prevalence of risk factors for Alzheimer's disease and related dementias (ADRD) compared to the general population, yet dementia onset and frequency in this population are understudied. Intraindividual cognitive variability (IICV), a measure of variability in neuropsychological test performance within a person at a single timepoint, may be a novel, noninvasive biomarker of neurodegeneration and early dementia.

OBJECTIVE

To characterize the cross-sectional associations between IICV and hippocampal, total brain volume, and white matter disease measured by magnetic resonance imaging (MRI) among older American Indians.

METHODS

IICV measures for memory, executive function, and processing speed, and multidomain cognition were calculated for 746 American Indians (aged 64-95) who underwent MRI. Regression models were used to examine the associations of IICV score with hippocampal volume, total brain volume, and graded white matter disease, adjusting for age, sex, education, body mass index, intracranial volume, diabetes, stroke, hypertension, hypercholesterolemia, alcohol use, and smoking.

RESULTS

Higher memory IICV measure was associated with lower hippocampal volume (Beta = -0.076; 95% CI -0.499, -0.023; p = 0.031). After adjustment for Bonferroni or IICV mean scores in the same tests, the associations were no longer significant. No IICV measures were associated with white matter disease or total brain volume.

CONCLUSION

These findings suggest that the IICV measures used in this research cannot be robustly associated with cross-sectional neuroimaging features; nonetheless, the results encourage future studies investigating the associations between IICV and other brain regions, as well as its utility in the prediction of neurodegeneration and dementia in American Indians.

Bidirectional relationship between nocturnal subjective sleep duration and cognitive performance in Chinese over 45 years old: a national representative longitudinal study

Introduction

Previous studies have inconsistent associations between changes in sleep duration and cognitive function and have not separated interindividual effects from intraindividual effects. This study aimed to examine the bidirectional associations between subjective night sleep duration and cognitive function while differing intraindividual and interindividual effects.

Methods

A national representative sample was obtained from China Health and Retirement Longitudinal Study during 2011–2018. Night sleep duration and potential confounders were assessed and collected by questionnaires. Cognition was assessed in three categories (orientation, executive function, and memory), and z scores were used for global cognitive performance. The random intercept cross-lagged panel model was used to examine the temporal associations during 2011–2018.

Results

Across 9404 participants over 45, at interindividual level, moderate (β= -0.014) and long sleepers (β= -0.06) had positive association between sleep duration and cognitive decline after adjusted covariates, but short sleepers had negative associations between sleep duration and cognitive decline (β = 0.87). At intraindividual level, prolonged sleep duration predicted better cognition for short (β= -0.021 at wave2-3; β= -0.04 at wave3-4) and moderate (β= -0.017 at wave3-4) sleepers.

Conclusion

For short sleepers, longer subjective nocturnal sleep duration predicted better cognitive performance; but moderate and long sleepers showed opposite results—short and moderate sleepers with prolonged subjective nocturnal sleep duration would have later cognitive decline. Our findings tentatively suggested that an increased subjective night sleep duration and subjective long sleep duration could be regarded as useful tools for identifying middle- and old adults at higher risks of progressing to cognitive decline.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03468-8.

Association between self-reported night sleep duration and cognitive function among older adults with intact global cognition

OBJECTIVES

The purpose of this study was to clarify the association between self-reported night sleep duration and cognitive functions such as word memory, story memory, attention, executive function, and processing speed of older adults with normal global cognitive function.

METHODS

A total of 241 functionally independent older adults (mean age, 75.5 ± 6.4 years) participated in this study. No participants had a history of dementia diagnosis, and each had a Mini-Mental State Examination (MMSE) score ≥ 24. Participants were evaluated for self-reported sleep duration and cognitive function using the National Center for Geriatrics and Gerontology-Functional Assessment Tool (NCGG-FAT).

RESULTS

The longest sleep duration group (≥9 h) had lower MMSE scores (p = 0.010), Z-score of word list memory II (delayed recall; p = 0.001), and Z-score of story memory II (delayed recognition; p = 0.002) than the medium sleep duration group (7-8 h). Longest and long sleep duration (8-9 h) was significantly associated with impairment of story memory II (longest sleep duration: adjusted odds ratio [OR] = 3.58, 95% confidence interval [CI] = 1.13-11.37, long sleep duration: adjusted OR = 4.30, 95% CI = 1.34-13.82) with reference to medium sleep duration, but no impairment of MMSE according to multiple logistic regression analysis. Furthermore, short sleep duration (<7 h) was not associated with cognitive impairment.

CONCLUSIONS

This study suggests that long sleep duration is associated with cognitive impairment, especially of story memory (delayed recognition) in older adults with normal global cognitive function.

Can discourse processing performance serve as an early marker of Alzheimer’s disease and mild cognitive impairment? A systematic review of text comprehension

A number of linguistic and cognitive deficits have been reported during the course of Alzheimer’s disease (AD) and its preceding stage of mild cognitive impairment (MCI), with some deficits appearing years before onset of clinical symptoms. It continues to be a critical task to identify tools that may serve as an early marker of pathology that are also reliably able to distinguish AD from normal ageing. Given the limited success of classic psychometric cognitive testing, a novel approach in assessment is warranted. A potentially sensitive assessment paradigm is discourse processing. The aim of this review was to synthesize original research studies investigating comprehension of discourse in AD and MCI, and to evaluate the potential of this paradigm as a promising avenue for further research. A literature search targeting studies with AD or MCI groups over 60 years of age was conducted in PubMed, Web of Science, and PsycINFO databases. Eight articles with good quality were included in the review. Six measures of discourse comprehension—naming latency, summary, lesson, main idea, proportion of inferential clauses, true/false questions—were identified. All eight studies reported significant deficits in discourse comprehension in AD and MCI groups on five of the six measures, when compared to cognitively healthy older adults. Mixed results were observed for associations with commonly used cognitive measures. Given the consistent findings for discourse comprehension measures across all studies, we strongly recommend further research on its early predictive potential, and discuss different avenues for research.

Blood Hemoglobin, in-vivo Alzheimer Pathologies, and Cognitive Impairment: A Cross-Sectional Study

Background: Despite known associations between low blood hemoglobin level and Alzheimer's disease (AD) or cognitive impairment, the underlying neuropathological links are poorly understood. We aimed to examine the relationships of blood hemoglobin levels with in vivo AD pathologies (i.e., cerebral beta-amyloid [Aβ] deposition, tau deposition, and AD-signature degeneration) and white matter hyperintensities (WMHs), which are a measure of cerebrovascular injury. We also investigated the association between hemoglobin level and cognitive performance, and then assessed whether such an association is mediated by brain pathologies.

Methods: A total of 428 non-demented older adults underwent comprehensive clinical assessments, hemoglobin level measurement, and multimodal brain imaging, including Pittsburgh compound B-positron emission tomography (PET), AV-1451 PET, fluorodeoxyglucose (FDG)-PET, and magnetic resonance imaging. Episodic memory score and global cognition scores were also measured.

Results: A lower hemoglobin level was significantly associated with reduced AD-signature cerebral glucose metabolism (AD-CM), but not Aβ deposition, tau deposition, or WMH volume. A lower hemoglobin level was also significantly associated with poorer episodic memory and global cognition scores, but such associations disappeared when AD-CM was controlled as a covariate, indicating that AD-CM has a moderating effect.

Conclusion: The present findings suggest that low blood hemoglobin in older adults is associated with cognitive decline via reduced brain metabolism, which seems to be independent of those aspects of AD-specific protein pathologies and cerebrovascular injury that are reflected in PET and MRI measures.

Innovations in 3-Dimensional Tissue Models of Human Brain Physiology and Diseases

3-dimensional (3D) laboratory tissue cultures have emerged as an alternative to traditional 2-dimensional (2D) culture systems that do not recapitulate native cell behavior. The discrepancy between in vivo and in vitro tissue-cell-molecular responses impedes understanding of human physiology in general and creates roadblocks for the discovery of therapeutic solutions. Two parallel approaches have emerged for the design of 3D culture systems. The first is biomedical engineering methodology, including bioengineered materials, bioprinting, microfluidics and bioreactors, used alone or in combination, to mimic the microenvironments of native tissues. The second approach is organoid technology, in which stem cells are exposed to chemical and/or biological cues to activate differentiation programs that are reminiscent of human (prenatal) development. This review article describes recent technological advances in engineering 3D cultures that more closely resemble the human brain. The contributions of in vitro 3D tissue culture systems to new insights in neurophysiology, neurological diseases and regenerative medicine are highlighted. Perspectives on designing improved tissue models of the human brain are offered, focusing on an integrative approach merging biomedical engineering tools with organoid biology.

Serum Uric Acid, Alzheimer-Related Brain Changes, and Cognitive Impairment

Background

Despite known associations of lower serum uric acid (UA) with Alzheimer’s disease (AD) dementia or AD-related cognitive impairment, little is known regarding the underlying patho-mechanisms. We aimed to examine the relationships of serum UA with in vivo AD pathologies including cerebral beta-amyloid (Aβ) and tau deposition, AD-signature region cerebral glucose metabolism (AD-CM), and white matter hyperintensities (WMH). We also investigated the association between serum UA and cognitive performance, and then assessed whether such an association is mediated by the brain pathologies.

Methods

A total of 430 non-demented older adults underwent comprehensive clinical assessments, measurement of serum UA level, and multimodal brain imaging, including Pittsburgh compound B-positron emission tomography (PET), AV-1451 PET, fluorodeoxyglucose (FDG)-PET, and magnetic resonance imaging scans. Mini-Mental State Examination (MMSE) and word list recall (WLR) test scores were used to measure cognitive performance.

Results

Serum UA level was significantly associated with AD-CM, but not with Aβ deposition, tau deposition, or WMH volume. Serum UA levels also had significant association with WLR and marginal association with MMSE; such associations disappeared when AD-CM was controlled as a covariate, indicating that AD-CM has a mediating effect.

Conclusion

The findings of the present study indicate that there is an association of low serum UA with AD-related cerebral hypometabolism, and whether this represents a causal relationship remains to be determined.

Memory Decline and Depression Onset in U.S. and European Older Adults

Objectives: We explore the association between different patterns of change in depressive symptoms and memory trajectories in US and European Mediterranean (Spain, France, Italy, and Israel) and non-Mediterranean (Sweden, Denmark, Netherlands, Germany, Belgium, Switzerland, and Austria) older adults. Methods: Samples consisted of 3,466 participants from the Health Retirement Study (HRS) and 3,940 participants from the Survey of Health, Aging and Retirement (SHARE). Individuals were grouped as follows: non-case depression (NO DEP), persistent depression (DEP), depression onset (ONSET), depression recovery (RECOV), and fluctuating (FLUCT). Memory was measured using immediate and delayed recall tests. Linear mixed models were used. Results: DEP and RECOV had significantly lower baseline memory scores compared to NO DEP, at intercept level. At slope level, ONSET had a significantly faster decline in both tasks compared to NO DEP. Discussion: Cross-cohort robust and consistent new empirical evidence on the association between depression onset and faster decline in memory scores is provided.

The Lifespan Human Connectome Project in Aging: An overview

The original Human Connectome Project yielded a rich data set on structural and functional connectivity in a large sample of healthy young adults using improved methods of data acquisition, analysis, and sharing. More recent efforts are extending this approach to include infants, children, older adults, and brain disorders. This paper introduces and describes the Human Connectome Project in Aging (HCP-A), which is currently recruiting 1200 + healthy adults aged 36 to 100+, with a subset of 600 + participants returning for longitudinal assessment. Four acquisition sites using matched Siemens Prisma 3T MRI scanners with centralized quality control and data analysis are enrolling participants. Data are acquired across multimodal imaging and behavioral domains with a focus on factors known to be altered in advanced aging. MRI acquisitions include structural (whole brain and high resolution hippocampal) plus multiband resting state functional (rfMRI), task fMRI (tfMRI), diffusion MRI (dMRI), and arterial spin labeling (ASL). Behavioral characterization includes cognitive (such as processing speed and episodic memory), psychiatric, metabolic, and socioeconomic measures as well as assessment of systemic health (with a focus on menopause via hormonal assays). This dataset will provide a unique resource for examining how brain organization and connectivity changes across typical aging, and how these differences relate to key characteristics of aging including alterations in hormonal status and declining memory and general cognition. A primary goal of the HCP-A is to make these data freely available to the scientific community, supported by the Connectome Coordination Facility (CCF) platform for data quality assurance, preprocessing and basic analysis, and shared via the NIMH Data Archive (NDA). Here we provide the rationale for our study design and sufficient details of the resource for scientists to plan future analyses of these data. A companion paper describes the related Human Connectome Project in Development (HCP-D, Somerville et al., 2018), and the image acquisition protocol common to both studies (Harms et al., 2018).

Adolescent Cognitive Aptitudes and Later-in-Life Alzheimer Disease and Related Disorders

IMPORTANCE

Low early-life cognitive ability is a potential early marker of dementia risk in later life. Previous studies use only global measures of general intelligence and/or study this relationship in gender-specific samples. The contribution of early-life performance on specific cognitive abilities, such as language, reasoning, and visualization aptitudes, to indicating future dementia risk is unknown.

OBJECTIVES

To investigate the association between adolescent cognitive ability and Medicare-recorded Alzheimer disease and related disorders (ADRD) using both general and specific measures of cognitive ability and to explore these associations separately in men and women.

DESIGN, SETTING, AND PARTICIPANTS

Population-based cohort study from the Project Talent-Medicare linked data set, a linkage of adolescent sociobehavioral data collected from high school students in 1960 to participants' 2012 to 2013 Medicare Claims and expenditures data. The association between adolescent cognitive ability and risk of ADRD in later life was assessed in a diverse sample of 43 014 men and 42 749 women aged 66 to 73 years using a series of logistic regressions stratified by sex, accounting for demographic characteristics, adolescent socioeconomic status, and regional effects. Data analysis was conducted from November 2017 to March 2018.

MAIN OUTCOMES AND MEASURES

Presence of Medicare-reported ADRD.

RESULTS

Overall, 1239 men (2.9%) and 1416 women (3.3%) developed ADRD. Lower mechanical reasoning was associated with increased odds of ADRD in men (odds ratio, 1.17; 95% CI, 1.05-1.29), and lower memory for words in adolescence was associated with increased odds of ADRD in women (odds ratio, 1.16; 95% CI, 1.05-1.28). Lower performance on several other language, reasoning, visualization, and mathematic aptitudes in adolescence showed prominent, but weaker, associations with odds of ADRD.

CONCLUSIONS AND RELEVANCE

This work contributes to the understanding of early-life origins of ADRD risk. The results suggest specific measures of cognitive ability may contribute to very early identification of at-risk subgroups who may benefit from prevention or intervention efforts.

Age-associated memory impairment and related disorders

Complaints of poor memory are common in the healthy elderly and to many it may seem unsurprising that cognitive function declines with ‘normal’ ageing. Virtually every biological system alters with age and, just as a 70-year-old cannot run as fast or hear as well as when he or she was 20, it is perhaps inevitable that cognitive function also becomes impaired. However, far from being straightforward, the nature, classification and clinical significance of age-related cognitive changes that fall short of dementia remain a most controversial and difficult area (see O'Brien & Beats, 1994; Dal Forno & Kawas, 1995). The recent emergence of new drugs for the treatment of Alzheimer's disease (donepezil and rivastigmine) and related disorders has emphasised the need to study groups with milder degrees of cognitive impairment. It is necessary to determine whether such conditions are benign and non-progressive, or harbingers of progressive dementia and so appropriate conditions to target for early therapeutic intervention. The presence of age-related cognitive changes raises other important issues including why such changes occur, how they should be classified and whether, even if ‘benign’, they can and should be treated.

Decline in Memory, Visuospatial Ability, and Crystalized Cognitive Abilities in Older Adults: Normative Aging or Terminal Decline?

The aim of this study is to explore the pattern of change in multiple measures of cognitive abilities in a sample of oldest-old adults, comparing two different time metrics (chronological age and time to death) and therefore examining both underlying conceptual assumptions (age-related change and terminal decline). Moreover, the association with individual characteristics as sex, education, and dementia diagnosis was also examined. Measures of cognitive status (Mini-Mental State Examination and the Swedish Clock Test) and tests of crystallized (knowledge and synonyms), memory (verbal memory, nonverbal long-term memory, recognition and correspondence, and short-term memory), and visuospatial ability were included. The sample consisted of 671 older Swedish adult participants of the OCTO Twin Study. Linear mixed models with random coefficients were used to analyse change patterns and BIC indexes were used to compare models. Results showed that the time to death model was the best option in analyses of change in all the cognitive measures considered (except for the Information Test). A significant cognitive decline over time was found for all variables. Individuals diagnosed with dementia had lower scores at the study entrance and a faster decline. More educated individuals performed better in all the measures of cognition at study entry than those with poorer education, but no differences were found in the rate of change. Differences were found in age, sex, or time to death at baseline across the different measures. These results support the terminal decline hypothesis when compared to models assuming that cognitive changes are driven by normative aging processes.

Alzheimer's Disease: Prototype of Cognitive Deterioration, Valuable Lessons to Understand Human Cognition

It is important for neurologists to become more familiar with neuropsychological evaluation for Alzheimer disease. The growth of this method in research, as an available, inexpensive, and noninvasive diagnostic approach, which can be administered even by non-specialist-trained examiners, makes this knowledge more necessary than ever. Such knowledge has a basic role in planning national programs in primary health care systems for prevention and early detection of Alzheimer disease. This is more crucial in developing countries, which have higher rates of dementia prevalence along with cardiovascular risk factors, lack of public knowledge about dementia, and limited social support. In addition compared to the neurological hard signs which are tangible and measurable, the concept of cognition seems to be more difficult for the neurologists to evaluate and for the students to understand. Dementia in general and Alzheimer's disease as the prototype of cognitive disorders specifically, play an important role to explore all domains of human cognition through its symptomatology and neuropsychological deficits.

Tracking discourse complexity preceding Alzheimer's disease diagnosis: a case study comparing the press conferences of Presidents Ronald Reagan and George Herbert Walker Bush

Changes in some lexical features of language have been associated with the onset and progression of Alzheimer's disease. Here we describe a method to extract key features from discourse transcripts, which we evaluated on non-scripted news conferences from President Ronald Reagan, who was diagnosed with Alzheimer's disease in 1994, and President George Herbert Walker Bush, who has no known diagnosis of Alzheimer's disease. Key word counts previously associated with cognitive decline in Alzheimer's disease were extracted and regression analyses were conducted. President Reagan showed a significant reduction in the number of unique words over time and a significant increase in conversational fillers and non-specific nouns over time. There was no significant trend in these features for President Bush.

The Times They Are a-Changin': Clock Drawing and Prediction of Dementia

Identification of individuals who will eventually develop dementia is critical for early intervention, treatment, and care planning. The clock drawing test (CDT) is a widely used cognitive screening tool that has been well accepted among clinicians and patients for its ease of use and short administration time. This review explores the value of the CDT for predicting the later development of dementia in cognitively intact older adults and patients with mild cognitive impairment (MCI). Additionally, we reviewed studies that examined the ability of the CDT to monitor declines in cognitive functioning over time. A PubMed literature search for articles that included a longitudinal analysis of the CDT was conducted. The search included articles published up to June 2013 and manual cross-referencing of bibliographies. Relevant studies were categorized, summarized, and critiqued. The consensus from the studies reviewed suggests that the CDT is a useful measure of cognitive decline over time. Conceptual clock drawing errors (eg, misrepresentation of time) detected this decline most effectively. In addition, the CDT appears to differentiate at baseline between cognitively intact older adults who will develop dementia up to 2 years postbaseline. Finally, the CDT has been found to differentiate between patients with MCI who will progress to dementia up to 6 years postbaseline. The CDT appears useful for the longitudinal assessment of cognitive impairment and together with other validated measures may be helpful for predicting conversion to dementia. Cost-effective and practical ways of predicting risk of dementia will become increasingly critical as we develop disease-modifying treatments.

CANTAB object recognition and language tests to detect aging cognitive decline: an exploratory comparative study

Objective

The recognition of the limits between normal and pathological aging is essential to start preventive actions. The aim of this paper is to compare the Cambridge Neuropsychological Test Automated Battery (CANTAB) and language tests to distinguish subtle differences in cognitive performances in two different age groups, namely young adults and elderly cognitively normal subjects.

Method

We selected 29 young adults (29.9±1.06 years) and 31 older adults (74.1±1.15 years) matched by educational level (years of schooling). All subjects underwent a general assessment and a battery of neuropsychological tests, including the Mini Mental State Examination, visuospatial learning, and memory tasks from CANTAB and language tests. Cluster and discriminant analysis were applied to all neuropsychological test results to distinguish possible subgroups inside each age group.

Results

Significant differences in the performance of aged and young adults were detected in both language and visuospatial memory tests. Intragroup cluster and discriminant analysis revealed that CANTAB, as compared to language tests, was able to detect subtle but significant differences between the subjects.

Conclusion

Based on these findings, we concluded that, as compared to language tests, large-scale application of automated visuospatial tests to assess learning and memory might increase our ability to discern the limits between normal and pathological aging.

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.

Mild cognitive impairment

PURPOSE OF REVIEW

The term mild cognitive impairment (MCI) is used to describe older subjects with demonstrable cognitive impairment who have not crossed the threshold for dementia. Because patients with MCI have an increased risk of developing dementia, especially Alzheimer disease (AD), there is significant interest in the clinical characterization of these subjects and in understanding the pathophysiology of the transition from MCI to AD.

RECENT FINDINGS

The MCI syndrome, as an expression of an incipient disorder that may lead to dementia, is extremely heterogeneous and may coexist with systemic, neurologic, or psychiatric disorders that can cause cognitive deficits. Recent clinical criteria were designed to take into account the different forms of clinical presentation of the syndrome, and introduced the possible contribution of biomarkers to the clinical diagnosis. Bedside diagnosis of MCI can be difficult, since patients who report having cognitive problems may have normal scores in global cognitive scales or in brief neuropsychological instruments.

SUMMARY

This article presents the evolution of the clinical concept of MCI, the operationalization of its current definitions, the development of biomarkers that can help to identify an underlying neurodegenerative process as the etiology of the syndrome, and its proposed treatments.

Cognitive predictors for five-year conversion to dementia in community-dwelling Chinese older adults

BACKGROUND

This study evaluates which cognitive measure is best for predicting incident dementia in a population-based random sample of Chinese older adults without dementia over a five-year period.

METHODS

A total of 787 community-dwelling Chinese older adults without dementia in Hong Kong were assessed at baseline (T0), at two years (T1), and at five years (T2).

RESULTS

The annual conversion rate to dementia was 1.6% and 6.3% for baseline normal participants and baseline mild cognitive impairment (MCI) participants, respectively. The Cantonese version of Mini-mental State Examination (CMMSE) scores declined significantly over time. In participants who progressed to dementia, Category Verbal Fluency Test (CVFT) scores dropped significantly from T0 to T1. A 1-SD drop of either CMMSE or CVFT in two years predicted dementia at five years with 91.5% sensitivity and 62.0% specificity. A stable CMMSE and CVFT at two years predicted a 91% chance of not progressing to clinical dementia at five years.

CONCLUSION

In this community sample of Chinese older adults, a decline in cognitive screening tests in short term (two years) offered useful information in predicting dementia conversion over a longer period.

Which neuropsychological tests predict progression to Alzheimer's disease in Hispanics?

OBJECTIVE

To investigate which neuropsychological tests predict eventual progression to Alzheimer's disease (AD) in both Hispanic and non-Hispanic individuals. Although our approach was exploratory, we predicted that tests that underestimate cognitive ability in healthy aging Hispanics might not be sensitive to future cognitive decline in this cultural group.

METHOD

We compared first-year data of 22 older adults (11 Hispanic) who were diagnosed as cognitively normal but eventually developed AD (decliners), to 60 age- and education-matched controls (27 Hispanic) who remained cognitively normal. To identify tests that may be culturally biased in our sample, we compared Hispanic with non-Hispanic controls on all tests and asked which tests were sensitive to future decline in each cultural group.

RESULTS

Compared to age-, education-, and gender-matched non-Hispanic controls, Hispanic controls obtained lower scores on tests of language, executive function, and some measures of global cognition. Consistent with our predictions, some tests identified non-Hispanic, but not Hispanic, decliners (vocabulary, semantic fluency). Contrary to our predictions, a number of tests on which Hispanics obtained lower scores than non-Hispanics nevertheless predicted eventual progression to AD in both cultural groups (e.g., Boston Naming Test [BNT], Trails A and B).

CONCLUSIONS

Cross-cultural variation in test sensitivity to decline may reflect greater resistance of medium difficulty items to decline and bilingual advantages that initially protect Hispanics against some aspects of cognitive decline commonly observed in non-Hispanics with preclinical AD. These findings highlight a need for further consideration of cross-cultural differences in neuropsychological test performance and development of culturally unbiased measures.

Evidence of altered corticomotor system connectivity in early-stage Alzheimer's disease

BACKGROUND AND PURPOSE

There is increasing evidence for subtle motor dysfunction early in Alzheimer disease (AD), including common motor behaviors that were once considered unaffected early in the disease process. Our objective was to assess whether functional neural networks underlying motor behavior are altered by AD.

METHODS

We investigated AD-related differences in regional brain activation during motor performance. Nine older adults with early-stage AD and 10 without dementia underwent functional magnetic resonance imaging while performing a visually directed simple motor task (hand squeeze).

RESULTS

Despite some similarity in brain activation during motor performance, we found that individuals without dementia exhibited greater activation in accessory motor regions, supplementary motor area, and cerebellum compared with those with AD. We also assessed disease-related differences in regions where activity was functionally integrated with primary motor cortex. Using a psychophysiological interaction analysis, we found that those with AD displayed increased coactivation with primary motor cortex of bilateral motor and visual regions.

DISCUSSION AND CONCLUSIONS

These AD-related differences in regional coactivation during motor execution may represent inefficiency in the motor network as a consequence of the disease process. Alternatively, they may represent compensatory activation. These findings provide further evidence that in early stages of AD, neuromotor function is altered even during simple motor behaviors. The results may have implications for performance of more complex tasks and may be associated with the well-characterized decline in dual-task performance in those with AD.

The neuropsychological profile of Alzheimer disease

Neuropsychological assessment has featured prominently over the past 30 years in the characterization of dementia associated with Alzheimer disease (AD). Clinical neuropsychological methods have identified the earliest, most definitive cognitive and behavioral symptoms of illness, contributing to the identification, staging, and tracking of disease. With increasing public awareness of dementia, disease detection has moved to earlier stages of illness, at a time when deficits are both behaviorally and pathologically selective. For reasons that are not well understood, early AD pathology frequently targets large-scale neuroanatomical networks for episodic memory before other networks that subserve language, attention, executive functions, and visuospatial abilities. This chapter reviews the pathognomonic neuropsychological features of AD dementia and how these differ from "normal," age-related cognitive decline and from other neurodegenerative diseases that cause dementia, including cortical Lewy body disease, frontotemporal lobar degeneration, and cerebrovascular disease.

The micron stroke hypothesis of Alzheimer's disease and dementia

Alzheimer's disease as currently described in the medical literature is often more a description of dementia rather than a specific disease. In over a century of scientific work there has been no proven theory as to the precise pathogenesis of Alzheimer's disease and dementia. As there is no efficient treatment for patients with Alzheimer's disease, prevention or attenuation of the disease is of substantial value. An intricate collection of hypotheses, studies, research, and experience has made it complicated for one to completely understand this disease. The purpose of this hypothesis is to illustrate new concepts and work to link those concepts to the present understanding of an obscure disease. The search for a single unifying hypothesis on the etiology of Alzheimer's disease has been elusive. Many hypotheses associated to Alzheimer's disease have not survived their testing to become theory. Suggested here is that the elusive nature of etiology of dementia is not from one cause, but rather the causes are numerous. Medical terminology used freely for decades is rarely evaluated in the light of a new hypothesis. At the foundation of this work is the suggestion of a new medical term: Micron Strokes. The Micron Stroke Hypothesis of Alzheimer's Disease and Dementia include primary and secondary factors. The primary factors can be briefly described as baseline brain tissue, atrial fibrillation, hypercoaguable state, LDL, carotid artery stenosis, tobacco exposure, hypertension diabetes mellitus, and the presence of systemic inflammation. Dozens of secondary factors contribute to the development of dementia. Most dementia is caused by nine primary categories of factors as they interact to cause micron strokes to the brain.

A comparison of screening tools for the assessment of mild cognitive impairment: preliminary findings

We report a pilot investigation into the utility of screening tools in Mild Cognitive Impairment (MCI). The Addenbrooke's Cognitive Examination-Revised (ACE-R), Montreal Cognitive Assessment (MoCA) and the novel Computer-Administered Neuropsychological Screen for Mild Cognitive Impairment (CANS-MCI) were administered to 20 elderly controls and 15 MCI cases. Non-parametric Mann-Whitney U-tests showed significant differences between groups (p < .0001) on the CANS-MCI and MoCA. The ACE-R and MoCA total scores showed high sensitivity (90%) to MCI. Area under the curve was consistently significant in discriminating controls and MCI for memory scores across all screening instruments. A useful profile of quantitative and qualitative information pertaining to cognitive functioning in MCI can be obtained with the MoCA, ACE-R, and CANS-MCI.

Evaluation of a summary score of cognitive performance for use in trials in perioperative and critical care

BACKGROUND/AIMS

Cognitive dysfunction after medical treatment is increasingly being recognized. Studies on this topic require repeated cognitive testing within a short time. However, with repeated testing, practice effects must be expected. We quantified practice effects in a demographically corrected summary score of a neuropsychological test battery repeatedly administered to healthy elderly volunteers.

METHODS

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Neuropsychological Assessment Battery (for which a demographically corrected summary score was developed), phonemic fluency tests, and trail-making tests were administered in healthy volunteers aged 65 years or older on days 0, 7, and 90. This battery allows calculation of a demographically adjusted continuous summary score.

RESULTS

Significant practice effects were observed in the CERAD total score and in the word list (learning and recall) subtest. Based on these volunteer data, we developed a threshold for diagnosis of postoperative cognitive dysfunction (POCD) with the CERAD total score.

CONCLUSION

Practice effects with repeated administration of neuropsychological tests must be accounted for in the interpretation of such tests. Ignoring practice effects may lead to an underestimation of POCD. The usefulness of the proposed demographically adjusted continuous score for cognitive function will have to be tested prospectively in patients.

Kernels for longitudinal data with variable sequence length and sampling intervals

We develop several kernel methods for classification of longitudinal data and apply them to detect cognitive decline in the elderly. We first develop mixed-effects models, a type of hierarchical empirical Bayes generative models, for the time series. After demonstrating their utility in likelihood ratio classifiers (and the improvement over standard regression models for such classifiers), we develop novel Fisher kernels based on mixture of mixed-effects models and use them in support vector machine classifiers. The hierarchical generative model allows us to handle variations in sequence length and sampling interval gracefully. We also give nonparametric kernels not based on generative models, but rather on the reproducing kernel Hilbert space. We apply the methods to detecting cognitive decline from longitudinal clinical data on motor and neuropsychological tests. The likelihood ratio classifiers based on the neuropsychological tests perform better than than classifiers based on the motor behavior. Discriminant classifiers performed better than likelihood ratio classifiers for the motor behavior tests.

Reducing case ascertainment costs in U.S. population studies of Alzheimer's disease, dementia, and cognitive impairment-Part 1

Establishing methods for ascertainment of dementia and cognitive impairment that are accurate and also cost-effective is a challenging enterprise. Large population-based studies often using administrative data sets offer relatively inexpensive and reliable estimates of severe conditions including moderate to advanced dementia that are useful for public health planning, but they can miss less severe cognitive impairment which may be the most effective point for intervention. Clinical and epidemiological cohorts, intensively assessed, provide more sensitive detection of less severe cognitive impairment but are often costly. In this article, several approaches to ascertainment are evaluated for validity, reliability, and cost. In particular, the methods of ascertainment from the Health and Retirement Study are described briefly, along with those of the Aging, Demographics, and Memory Study (ADAMS). ADAMS, a resource-intense sub-study of the Health and Retirement Study, was designed to provide diagnostic accuracy among persons with more advanced dementia. A proposal to streamline future ADAMS assessments is offered. Also considered are algorithmic and Web-based approaches to diagnosis that can reduce the expense of clinical expertise and, in some contexts, can reduce the extent of data collection. These approaches are intended for intensively assessed epidemiological cohorts where goal is valid and reliable case detection with efficient and cost-effective tools.

Alzheimer-signature MRI biomarker predicts AD dementia in cognitively normal adults

OBJECTIVE

Since Alzheimer disease (AD) neuropathology is thought to develop years before dementia, it may be possible to detect subtle AD-related atrophy in preclinical AD. Here we hypothesized that the "disease signature" of AD-related cortical thinning, previously identified in patients with mild AD dementia, would be useful as a biomarker to detect anatomic abnormalities consistent with AD in cognitively normal (CN) adults who develop AD dementia after longitudinal follow-up.

METHODS

We studied 2 independent samples of adults who were CN when scanned. In sample 1, 8 individuals developing AD dementia (CN-AD converters) after an average of 11.1 years were compared to 25 individuals who remained CN (CN-stable). In sample 2, 7 CN-AD converters (average follow-up 7.1 years) were compared to 25 CN-stable individuals.

RESULTS

AD-signature cortical thinning in CN-AD converters in both samples was remarkably similar, about 0.2 mm (p < 0.05). Despite this small absolute difference, Cohen d effect sizes for these differences were very large (> 1). Of the 11 CN individuals with baseline low AD-signature thickness (≥ 1 SD below cohort mean), 55% developed AD dementia over nearly the next decade, while none of the 9 high AD-signature thickness individuals (≥ 1 SD above mean) developed dementia. This marker predicted time to diagnosis of dementia (hazard ratio = 3.4, p < 0.0005); 1 SD of thinning increased dementia risk by 3.4.

CONCLUSIONS

By focusing on cortical regions known to be affected in AD dementia, subtle but reliable atrophy is identifiable in asymptomatic individuals nearly a decade before dementia, making this measure a potentially important imaging biomarker of early neurodegeneration.

Neuropsychological features of mild cognitive impairment and preclinical Alzheimer's disease

Detectable cognitive decline occurs in patients with Alzheimer's disease (AD) well before the clinical diagnosis can be made with any certainty. Studies examining this preclinical period identify decline in episodic memory as the earliest manifestation of the disease (i.e., a condition of amnestic Mild Cognitive Impairment). The episodic memory impairment is characterized by deficits in a number of processes including delayed recall, the recollective aspect of recognition memory, associative memory necessary for "binding" representations of two or more stimuli, pattern separation necessary to distinguish between two similar memory representations, prospective memory required to remember a delayed intention to act at a certain time in the future, and autobiographical memory for specific episodes that occurred in one's past. A growing body of evidence suggests that cognitive changes in preclinical AD may be more global in nature. Deterioration of semantic knowledge is evident on demanding naming and category fluency tasks, and "executive" dysfunction is apparent on tasks that require concurrent mental manipulation of information (e.g., working memory) or cue-directed behavior (e.g., set-shifting). Asymmetric cognitive test performance may also be apparent prior to significant decline in cognitive ability. The pattern and progression of these neuropsychological changes fit well with the proposed distribution and spread of AD pathology and serve as important cognitive markers of early disease.

Serial position effects in mild cognitive impairment

Mild cognitive impairment (MCI) is often associated with the preclinical phase of Alzheimer's disease (AD). Special scoring of word-list recall data for serial position has been suggested to improve discrimination of normal aging from dementia. We examined serial position effects in word-list recall for MCI participants compared to Alzheimer patients and controls. Individuals with MCI, like Alzheimer patients, had a diminished primacy effect in recalling words from a list. No alternative scoring system was better than standard scoring of word-list recall in distinguishing MCI patients from controls. Retention weighted scoring improved the discrimination of MCI and AD groups.

Brain aging in the oldest-old

Nonagenarians and centenarians represent a quickly growing age group worldwide. In parallel, the prevalence of dementia increases substantially, but how to define dementia in this oldest-old age segment remains unclear. Although the idea that the risk of Alzheimer's disease (AD) decreases after age 90 has now been questioned, the oldest-old still represent a population relatively resistant to degenerative brain processes. Brain aging is characterised by the formation of neurofibrillary tangles (NFTs) and senile plaques (SPs) as well as neuronal and synaptic loss in both cognitively intact individuals and patients with AD. In nondemented cases NFTs are usually restricted to the hippocampal formation, whereas the progressive involvement of the association areas in the temporal neocortex parallels the development of overt clinical signs of dementia. In contrast, there is little correlation between the quantitative distribution of SP and AD severity. The pattern of lesion distribution and neuronal loss changes in extreme aging relative to the younger-old. In contrast to younger cases where dementia is mainly related to severe NFT formation within adjacent components of the medial and inferior aspects of the temporal cortex, oldest-old individuals display a preferential involvement of the anterior part of the CA1 field of the hippocampus whereas the inferior temporal and frontal association areas are relatively spared. This pattern suggests that both the extent of NFT development in the hippocampus as well as a displacement of subregional NFT distribution within the Cornu ammonis (CA) fields may be key determinants of dementia in the very old. Cortical association areas are relatively preserved. The progression of NFT formation across increasing cognitive impairment was significantly slower in nonagenarians and centenarians compared to younger cases in the CA1 field and entorhinal cortex. The total amount of amyloid and the neuronal loss in these regions were also significantly lower than those reported in younger AD cases. Overall, there is evidence that pathological substrates of cognitive deterioration in the oldest-old are different from those observed in the younger-old. Microvascular parameters such as mean capillary diameters may be key factors to consider for the prediction of cognitive decline in the oldest-old. Neuropathological particularities of the oldest-old may be related to "longevity-enabling" genes although little or nothing is known in this promising field of future research.

Reliability and validity of an algorithm for the diagnosis of normal cognition, mild cognitive impairment, and dementia: implications for multicenter research studies

BACKGROUND

The traditional consensus diagnosis (ConsDx) of normal cognition, mild cognitive impairment (MCI), and dementia relies on the reconciliation of an informant-based report of cognitive and functional impairment by a physician diagnosis (PhyDx), and a neuropsychological diagnosis (NPDx). As this procedure may be labor intensive and influenced by the philosophy and biases of a clinician, the diagnostic algorithm (AlgDx) was developed to identify individuals as cognitively normal, with MCI, or dementia.

METHODS

The AlgDx combines the PhyDx with the NPDx, using a diagnostic algorithm that provides cognitive diagnoses, as defined by the National Alzheimer Coordinating Center/Uniform Data Set nomenclature. Reliability of the AlgDx was assessed in 532 community-dwelling elderly subjects by its concordance with the ConsDx and association with two biomarkers, medial temporal atrophy (MTA) scores of brain magnetic resonance imaging scans, and Apolipoprotein E (ApoE)-epsilon4 genotype.

RESULTS

A high degree of concordance was observed between ConsDx and AlgDx with a weighted Cohen's kappa of 0.84. Concordance of the AlgDx to the same ConsDx categories ranged from 85% to 92%. Excellent discriminative validity was observed using AlgDx, MTA scores, and ApoE-epsilon4 allele frequencies, each of which distinguished subjects with amnestic MCI and dementia from normal subjects.

CONCLUSION

The AlgDx of normal cognition, MCI, and dementia is a valid alternative that reduces time, effort, and biases associated with the ConsDx. The inherent reliability of a fixed algorithm, together with its efficiency and avoidance of individual bias, suggests the AlgDx may be used in longitudinal, multisite clinical trials, and population studies of MCI and dementia.

Longitudinal study of the transition from healthy aging to Alzheimer disease

BACKGROUND

Detection of the earliest cognitive changes signifying Alzheimer disease is difficult.

OBJECTIVE

To model the cognitive decline in preclinical Alzheimer disease.

DESIGN

Longitudinal archival study comparing individuals who became demented during follow-up and people who remained nondemented on each of 4 cognitive factors: global, verbal memory, visuospatial, and working memory.

SETTING

Alzheimer Disease Research Center, Washington University School of Medicine, St Louis, Missouri.

PARTICIPANTS

One hundred thirty-four individuals who became demented during follow-up and 310 who remained nondemented.

MAIN OUTCOME MEASURES

Inflection point in longitudinal cognitive performance.

RESULTS

The best-fitting model for each of the 4 factors in the stable group was linear, with a very slight downward trend on all but the Visuospatial factor. In contrast, a piecewise model with accelerated slope after a sharp inflection point provided the best fit for the group that progressed. The optimal inflection point for all 4 factors was prior to diagnosis of dementia: Global, 2 years; Verbal and Working Memory, 1 year; and Visuospatial, 3 years. These results were also obtained when data were limited to the subset (n = 44) with autopsy-confirmed Alzheimer disease.

CONCLUSIONS

There is a sharp inflection point followed by accelerating decline in multiple domains of cognition, not just memory, in the preclinical period in Alzheimer disease when there is insufficient cognitive decline to warrant clinical diagnosis using conventional criteria. Early change was seen in tests of visuospatial ability, most of which were speeded. Research into early detection of cognitive disorders using only episodic memory tasks may not be sensitive to all of the early manifestations of disease.

Language performance in Alzheimer's disease and mild cognitive impairment: a comparative review

Mild cognitive impairment (MCI) manifests as memory impairment in the absence of dementia and progresses to Alzheimer's disease (AD) at a rate of around 15% per annum, versus 1-2% in the general population. It thus constitutes a primary target for investigation of early markers of AD. Language deficits occur early in AD, and performance on verbal tasks is an important diagnostic criterion for both AD and MCI. We review language performance in MCI, compare these findings to those seen in AD, and identify the primary issues in understanding language performance in MCI and selecting tasks with diagnostic and prognostic value.

Functional abnormalities of the visual processing system in subjects with mild cognitive impairment: an fMRI study

Subjects with mild cognitive impairment (MCI) have a higher risk of developing Alzheimer's disease compared with healthy controls (HC). Sensory impairment can contribute to the severity of cognitive impairment. We measured the activation changes in the visual system between MCI and HC subjects. There were 16 MCI subjects with either amnestic MCI or multiple-domain+amnestic MCI and an HC group of 19 subjects. There were two tasks: (a) a face matching and (b) a location matching task. Brain activation was measured using functional magnetic resonance imaging. There were no differences in task performance. The HC group selectively activated the ventral and dorsal pathways during the face and location matching tasks, respectively, while the MCI group did not. The MCI group had greater activation than the HC group in the left frontal lobe during the location matching task. There were no areas of increased activation in the HC group compared with the MCI group. The MCI group, as a compensatory mechanism, activated both visual pathways and increased activation in the left frontal lobe during the location matching task compared with the healthy controls. To our knowledge, this is the first study that has examined visual processing in MCI.

Clinicopathologic correlates in the oldest-old: Commentary on "No disease in the brain of a 115-year-old woman"

den Dunnen et al. [den Dunnen, W.F.A., Brouwer, W.H., Bijlard, E., Kamphuis, J., van Linschoten, K., Eggens-Meijer, E., Holstege, G., 2008. No disease in the brain of a 115-year-old woman. Neurobiol. Aging] had the opportunity to follow up the cognitive functioning of one of the world's oldest woman during the last 3 years of her life. They performed two neuropsychological evaluations at age 112 and 115 that revealed a striking preservation of immediate recall abilities and orientation. In contrast, working memory, retrieval from semantic memory and mental arithmetic performances declined after age 112. Overall, only a one-point decrease of MMSE score occurred (from 27 to 26) reflecting the remarkable preservation of cognitive abilities. The neuropathological assessment showed few neurofibrillary tangles (NFT) in the hippocampal formation compatible with Braak staging II, absence of amyloid deposits and other types of neurodegenerative lesions as well as preservation of neuron numbers in locus coeruleus. This finding was related to a striking paucity of Alzheimer disease (AD)-related lesions in the hippocampal formation. The present report parallels the early descriptions of rare "supernormal" centenarians supporting the dissociation between brain aging and AD processes. In conjunction with recent stereological analyses in cases aged from 90 to 102 years, it also points to the marked resistance of the hippocampal formation to the degenerative process in this age group and possible dissociation between the occurrence of slight cognitive deficits and development of AD-related pathologic changes in neocortical areas. This work is discussed in the context of current efforts to identify the biological and genetic parameters of human longevity.