Cognitive decline and survival in Alzheimer's disease according to education level

Structural underpinnings and long-term effects of resilience in Parkinson's disease

Resilience in neuroscience generally refers to an individual's capacity to counteract the adverse effects of a neuropathological condition. While resilience mechanisms in Alzheimer's disease are well-investigated, knowledge regarding its quantification, neurobiological underpinnings, network adaptations, and long-term effects in Parkinson's disease is limited. Our study involved 151 Parkinson's patients from the Parkinson's Progression Marker Initiative Database with available Magnetic Resonance Imaging, Dopamine Transporter Single-Photon Emission Computed Tomography scans, and clinical information. We used an improved prediction model linking neuropathology to symptom severity to estimate individual resilience levels. Higher resilience levels were associated with a more active lifestyle, increased grey matter volume in motor-associated regions, a distinct structural connectivity network and maintenance of relative motor functioning for up to a decade. Overall, the results indicate that relative maintenance of motor function in Parkinson's patients may be associated with greater neuronal substrate, allowing higher tolerance against neurodegenerative processes through dynamic network restructuring.

Predictors for survival in patients with Alzheimer's disease: a large comprehensive meta-analysis

The prevalence of Alzheimer's disease (AD) is increasing as the population ages, and patients with AD have a poor prognosis. However, knowledge on factors for predicting the survival of AD remains sparse. Here, we aimed to systematically explore predictors of AD survival. We searched the PubMed, Embase and Cochrane databases for relevant literature from inception to December 2022. Cohort and case-control studies were selected, and multivariable adjusted relative risks (RRs) were pooled by random-effects models. A total of 40,784 reports were identified, among which 64 studies involving 297,279 AD patients were included in the meta-analysis after filtering based on predetermined criteria. Four aspects, including demographic features (n = 7), clinical features or comorbidities (n = 13), rating scales (n = 3) and biomarkers (n = 3), were explored and 26 probable prognostic factors were finally investigated for AD survival. We observed that AD patients who had hyperlipidaemia (RR: 0.69) were at a lower risk of death. In contrast, male sex (RR: 1.53), movement disorders (including extrapyramidal signs) (RR: 1.60) and cancer (RR: 2.07) were detrimental to AD patient survival. However, our results did not support the involvement of education, hypertension, APOE genotype, Aβ42 and t-tau in AD survival. Our study comprehensively summarized risk factors affecting survival in patients with AD, provided a better understanding on the role of different factors in the survival of AD from four dimensions, and paved the way for further research.

Moderating effects of cognitive reserve on the relationship between brain structure and cognitive abilities in middle-aged and older adults

The cognitive reserve (CR) hypothesis is reinforced by negative moderating effects, suggesting that those with higher CR are less reliant on brain structure for cognitive function. Previous research on CR's moderating effects yielded inconsistent results, motivating our 3 studies using UK Biobank data. Study I examined five CR proxies' moderating effects on global, lobar, and regional brain-cognition models; study II extended study I by using a larger sample size; and study III investigated age-related moderating effects on the hippocampal regions. In study I, most moderating effects were negative and none survived the multiple comparison correction, but study II identified 13 global-level models with significant negative moderating effects that survived correction. Study III showed age influenced CR proxies' moderating effects in hippocampal regions. Our findings suggest that the effects of CR proxies on brain integrity and cognition varied depending on the proxy used, brain integrity indicators, cognitive domain, and age group. This study offers significant insights regarding the importance of CR for brain integrity and cognitive outcomes.

Reading activities compensate for low education-related cognitive deficits

BACKGROUND

The incidence of cognitive impairment is increasing with an aging population. Developing effective strategies is essential to prevent dementia. Higher education level is associated with better baseline cognitive performance, and reading activities can slow down cognitive decline. However, it is unclear whether education and reading activities are synergistic or independent contributors to cognitive performance.

METHODS

This was a sub-study of an ongoing prospective community cohort of China National Clinical Research Center Alzheimer's Disease and Neurodegenerative Disorder Research (CANDOR). Demographic and clinical information, educational levels, and reading activities were collected. All participants finished neuropsychological testing batteries and brain MRIs. We analyzed cognitive performance and brain structures with education and reading activities.

RESULTS

Four hundred fifty-nine subjectively cognitively normal participants were enrolled in the study. One hundred sixty-nine (36.82%) of them had regular reading activities. Participants in the reading group had better performance in all cognitive tests compared with those in the non-reading group, but no difference in brain MRI variables. Participants with higher education levels (more than 13 years) had better cognitive performance and higher hippocampal volumes. In low education groups (less than 12 years), more reading activities were associated with better cognitive test scores.

CONCLUSIONS

Both education and reading activities are important and synergistic for baseline cognitive function. Higher education level is associated with larger hippocampal volumes. Education may stimulate the growth and development of the hippocampus. Reading activities help to maintain and improve cognitive function in people with low levels of education.

TRIAL REGISTRATION

NCT04320368.

The relationship between cognition, education, and employment in multiple sclerosis patients

Background

Processing speed decline is a common manifestation of multiple sclerosis (MS). The processing speed test (PST) is a validated electronic cognitive assessment based on the Symbol–Digit Modalities Test, which is routinely administered as part of the multi-institutional Multiple Sclerosis Partners Advancing Technology and Health Solutions (MS PATHS) initiative. The longitudinal relationship between education, processing speed, and employment is unclear.

Objectives

Determine the longitudinal impact of educational attainment on processing speed and employment.

Methods

MS PATHS data through March 2020 were analyzed. Repeat PST assessments at 1, 2, and 3 years were classified as improved, worsened, or stable. Linear regression was used to evaluate the relationship between education and baseline PST performance and logistic regression was used to determine the odds of PST worsening by educational attainment. Employment outcomes were analyzed by PST status and educational level.

Results

There were 13,732 patients analyzed. Education impacted baseline PST scores, but had a limited effect on PST performance over time. Education was protective with respect to employment in the setting of both PST worsening and improvement.

Conclusion

Greater education results in better baseline processing speed and is protective with respect to employment status. Its impact on processing speed over time is marginal.

Quantitative MRI Evidence for Cognitive Reserve in Healthy Elders and Prodromal Alzheimer's Disease

BACKGROUND

Cognitive reserve (CR) has been postulated to contribute to the variation observed between neuropathology and clinical outcomes in Alzheimer's disease (AD).

OBJECTIVE

We investigated the effect of an education-occupation derived CR proxy on biological properties of white matter tracts in patients with amnestic mild cognitive impairment (aMCI) and healthy elders (HC).

METHODS

Educational attainment and occupational complexity ratings (complexity with data, people, and things) from thirty-five patients with aMCI and twenty-eight HC were used to generate composite CR scores. Quantitative magnetic resonance imaging (qMRI) and multi-shell diffusion MRI were used to extract macromolecular tissue volume (MTV) across major white matter tracts.

RESULTS

We observed significant differences in the association between CR and white matter tract MTV in aMCI versus HC when age, gender, intracranial volume, and memory ability were held constant. Particularly, in aMCI, higher CR was associated with worse tract pathology (lower MTV) in the left and right dorsal cingulum, callosum forceps major, right inferior fronto-occipital fasciculus, and right superior longitudinal fasciculus (SLF) tracts. Conversely higher CR was associated with higher MTV in the right parahippocampal cingulum and left SLF in HC.

CONCLUSION

Our results support compensatory CR mechanisms in aMCI and neuroprotective mechanisms in HC and suggest differential roles for CR on white matter macromolecular properties in healthy elders versus prodromal AD patients.

Heterogeneity in longitudinal trajectories of cognitive performance among middle-aged and older individuals with hypertension: Growth mixture modeling across an 8-year cohort study

Hypertension is one of the most prevalent chronic conditions and has been proven to be related to cognitive function. However, there is no evidence regarding the heterogeneity in cognitive trajectories among persons with hypertension. The aims of the current study were to characterize the heterogeneity in longitudinal trajectories of cognitive performance among Chinese middle-aged and older individuals with hypertension and to explore the potential determinants of trajectory memberships. Data from the 2011 to 2018 Chinese Health and Retirement Longitudinal Study (CHARLS) were utilized. Two cognitive measures of executive function and episodic memory were assessed, and conditional growth mixture modeling (GMM) was performed to identify the trajectories of cognitive performance and explore the related factors of cognitive change. The findings revealed three trajectory classes of executive function (stable, sharp decline, smooth decline) and two trajectory classes of episodic memory (stable, decline). Individuals with hypertension who had a higher educational level, moderate nighttime sleep duration, and lower depressive symptoms as well as those who reported consuming alcohol at least once a month were more likely to belong to the optimal stable executive function group. Subjects with a higher educational level, adequate daytime napping duration, and higher BMI were more likely to exhibit stable episodic memory over time. Other factors, including age, sex, community type, marital status, and hypertension treatment, exhibited class-specific effects on growth parameters of cognitive trajectory. Targeting intervention designation is proposed to ameliorate the burdens of cognitive impairment among individuals with hypertension.

Chinese herbal medicine for mild cognitive impairment using mini-mental state examination: A systematic review and meta-analysis

INTRODUCTION

The prevalence of mild cognitive impairment (MCI) in the elderly population aged 60 to 84 years ranges from 6.7% to 25.2%, and the effective prevention and reversal of MCI progression to Alzheimer disease (AD) is crucial. The mini mental state examination (MMSE) is the most commonly used screening tool in Chinese outpatient clinics, with sufficient sensitivity and specificity to allow useful stratification from average to abnormal with adequate consideration of age and education.

OBJECTIVE

To investigate the clinical significance of Chinese herbs on MMSE scores in MCI patients and discuss the effectiveness of Chinese herbs through pharmacology.

METHODS

Three English databases and 4 Chinese databases we have searched, and the risk of bias was assessed according to the Cochrane tool. Statistics will be used for heterogeneity assessment, sensitivity analysis, data synthesis, funnel plot generation and subgroup analysis. If sufficiently homogeneous studies are found, a Meta-analysis will be performed, with subgroups describing any differences.

RESULTS

A total of 21 studies were included, 4 studies were placebo-controlled, 14 Chinese Herbal Medicines (CHMs) were compared with other cognitive improvements, 3 CHMs were combined with other medications, and the results of 17 studies favored the herbal group.

CONCLUSION

The results indicate that herbal medicine can improve MMSE scores, and herbal medicine combined with other drugs that can improve cognition can significantly improve MMSE scores, but there are methodological flaws in the study. Experimental studies have found a basis for the ability of herbs to improve cognition and memory impairment, and herbal medicine has great potential to improve MCI cognition. Keywords mild cognitive impairment, herbal medicine, MMSE, systematic evaluation, meta-analysis. PROSPERO international prospective register of systematic reviews protocol registration number: CRD42020202368.

Association Between Immune Response to Cytomegalovirus and Cognition in the Health and Retirement Study

Chronic infections and the subsequent immune response have recently been shown to be risk factors for cognitive decline and Alzheimer disease and related dementias (ADRD). While some studies have shown an association between cytomegalovirus (CMV), a chronic and highly prevalent infection, and cognition and/or ADRD, these studies have been limited by nonrepresentative and small samples. Using 2016 data on 5,617 adults aged 65 years or more from the Health and Retirement Study, we investigated the cross-sectional associations of both CMV serostatus and immunoglobulin G (IgG) antibody response with cognitive function using linear regression models adjusting for age, sex, race/ethnicity, and educational attainment. We further investigated potential effect-measure modification by educational attainment. Overall, both CMV seropositivity and higher IgG antibody response were associated with lower cognitive function, though the relationship was not statistically significant in adjusted models. Among participants with less than a high school diploma, CMV seropositivity and being in the first tertile of IgG response, relative to seronegative persons, were associated with lower scores on the Telephone Interview for Cognitive Status (-0.56 points (95% confidence interval: -1.63, 0.52) and -0.89 points (95% confidence interval: -2.07, 0.29), respectively), and the relationship was attenuated among those with higher education. Our results suggest that CMV may be a risk factor for cognitive impairment, particularly among persons with fewer educational resources.

Disease progression modeling of Alzheimer's disease according to education level

To develop a disease progression model of Alzheimer’s disease (AD) that shows cognitive decline from subjective cognitive impairments (SCI) to the end stage of AD dementia (ADD) and to investigate the effect of education level on the whole disease spectrum, we enrolled 565 patients who were followed up more than three times and had a clinical dementia rating sum of boxes (CDR-SB). Three cohorts, SCI (n = 85), amnestic mild cognitive impairment (AMCI, n = 240), and ADD (n = 240), were overlapped in two consecutive cohorts (SCI and AMCI, AMCI and ADD) to construct a model of disease course, and a model with multiple single-cohorts was estimated using a mixed-effect model. To examine the effect of education level on disease progression, the disease progression model was developed with data from lower (≤ 12) and higher (> 12) education groups. Disease progression takes 274.3 months (22.9 years) to advance from 0 to 18 points using the CDR-SB. Based on our predictive equation, it takes 116.5 months to progress from SCI to AMCI and 56.2 months to progress from AMCI to ADD. The rate of CDR-SB progression was different according to education level. The lower-education group showed faster CDR-SB progression from SCI to AMCI compared to the higher-education group, and this trend disappeared from AMCI to ADD. In the present study, we developed a disease progression model of AD spectrum from SCI to the end stage of ADD. Our disease modeling provides us with more understanding of the effect of education on cognitive trajectories.

Interaction between Cognitive Reserve and Biomarkers in Alzheimer Disease

Patients with comparable degree of neuropathology could show different cognitive impairments. This could be explained with the concept of cognitive reserve (CR), which includes a passive and an active component. In particular, CR is used to explain the gap between tissue damage and clinical symptoms that has been observed in dementia and, in particular, in patients affected by Alzheimer disease (AD). Different studies confirm brain neuroplasticity. Our preliminary study demonstrated that AD patients with high education showed a CR inversely associated with glucose uptake measured in fluorodeoxyglucose positron emission tomography (FDG-PET), whereas the inverse correlation was observed in AD patients with low education. In other words, our findings suggest that CR compensates the neurodegeneration and allows the maintenance of patients’ cognitive performance. Best understanding of the concept of CR could lead to interventions to slow cognitive aging or reduce the risk of dementia.

Education and Cognitive Functioning Across the Life Span

Cognitive abilities are important predictors of educational and occupational performance, socioeconomic attainment, health, and longevity. Declines in cognitive abilities are linked to impairments in older adults' everyday functions, but people differ from one another in their rates of cognitive decline over the course of adulthood and old age. Hence, identifying factors that protect against compromised late-life cognition is of great societal interest. The number of years of formal education completed by individuals is positively correlated with their cognitive function throughout adulthood and predicts lower risk of dementia late in life. These observations have led to the propositions that prolonging education might (a) affect cognitive ability and (b) attenuate aging-associated declines in cognition. We evaluate these propositions by reviewing the literature on educational attainment and cognitive aging, including recent analyses of data harmonized across multiple longitudinal cohort studies and related meta-analyses. In line with the first proposition, the evidence indicates that educational attainment has positive effects on cognitive function. We also find evidence that cognitive abilities are associated with selection into longer durations of education and that there are common factors (e.g., parental socioeconomic resources) that affect both educational attainment and cognitive development. There is likely reciprocal interplay among these factors, and among cognitive abilities, during development. Education-cognitive ability associations are apparent across the entire adult life span and across the full range of education levels, including (to some degree) tertiary education. However, contrary to the second proposition, we find that associations between education and aging-associated cognitive declines are negligible and that a threshold model of dementia can account for the association between educational attainment and late-life dementia risk. We conclude that educational attainment exerts its influences on late-life cognitive function primarily by contributing to individual differences in cognitive skills that emerge in early adulthood but persist into older age. We also note that the widespread absence of educational influences on rates of cognitive decline puts constraints on theoretical notions of cognitive aging, such as the concepts of cognitive reserve and brain maintenance. Improving the conditions that shape development during the first decades of life carries great potential for improving cognitive ability in early adulthood and for reducing public-health burdens related to cognitive aging and dementia.

Determining Middle-Aged and Older Adults' Health Beliefs to Change Lifestyle and Health Behavior for Dementia Risk Reduction

BACKGROUND

Global population is getting older and the prevalence of dementia continuously increases. Understanding the related health beliefs is bound to enable lifestyle-based interventions that maximize public engagement in dementia risk reduction behaviors. The aim of this study was to determine health beliefs on dementia prevention behaviors and lifestyle changes and to determine the factors influencing these beliefs among middle-aged and older people in Turkey.

MATERIALS AND METHODS

This descriptive and cross-sectional study was conducted with 284 individuals aged 40 years and older, using nonprobability convenience sampling. Data were collected using a demographic characteristic form and the Turkish version of the Motivation for Changing Lifestyle and Health Behavior for Reducing the Risk of Dementia scale. The study utilized the value, mean, percentage frequency distribution, correlation, independent t test, and the one-way analysis of variance test.

RESULTS

The mean age of the participants included in the study was 56.99 ± 12.05, 68.7% of individuals were males. The mean education years of the participants were 11.22 ± 4.55. The majority (72.2%) of participants expressed subjective memory complaints. Presence of family history of dementia was 28.2%. Age, gender, education years, subjective memory complaints, presence family history of dementia, prior experience as a caregiver of dementia, and willingness to know their own risk were determined as essential factors that influence several health belief factors related to dementia risk reduction.

CONCLUSION

Our findings indicate that males, older adults, and lower-educated and income are priority groups that should be guided for lifestyle and behavioral changes regarding dementia risk reduction.

The Role of Cognitive Reserve in Alzheimer's Disease and Aging: A Multi-Modal Imaging Review

Comforts in modern society have generally been associated with longer survival rates, enabling individuals to reach advanced age as never before in history. With the increase in longevity, however, the incidence of neurodegenerative diseases, especially Alzheimer's disease, has also doubled. Nevertheless, most of the observed variance, in terms of time of clinical diagnosis and progression, often remains striking. Only recently, differences in the social, educational and occupational background of the individual, as proxies of cognitive reserve (CR), have been hypothesized to play a role in accounting for such discrepancies. CR is a well-established concept in literature; lots of studies have been conducted in trying to better understand its underlying neural substrates and associated biomarkers, resulting in an incredible amount of data being produced. Here, we aimed to summarize recent relevant published work addressing the issue, gathering evidence for the existence of a common path across research efforts that might ease future investigations by providing a general perspective on the actual state of the arts. An innovative model is hereby proposed, addressing the role of CR across structural and functional evidences, as well as the potential implementation of non-invasive brain stimulation techniques in the causal validation of such theoretical frame.

Reserve and Alzheimer's disease genetic risk: Effects on hospitalization and mortality

INTRODUCTION

Cognitive reserve predicts delayed diagnosis of Alzheimer's disease (AD) and faster postdiagnosis decline. The net impact of cognitive reserve, combining both prediagnosis and postdiagnosis risk, on adverse AD-related outcomes is unknown. We adopted a novel approach, using AD genetic risk scores (AD-GRS), to evaluate this.

METHODS

Using 242,959 UK Biobank participants age 56+ years, we evaluated whether cognitive reserve (operationalized as education) modified associations between AD-GRS and mortality or hospitalization (total count, fall-related, and urinary tract infection-related).

RESULTS

AD-GRS predicted mortality and hospitalization outcomes. Education did not modify AD-GRS effects on mortality, but had a nonsignificantly (interaction P = .10) worse effect on hospitalizations due to urinary tract infection or falls among low education (OR = 1.07 [95% CI: 1.02, 1.12]) than high education (OR = 1.01 [0.95, 1.07]) individuals.

DISCUSSION

Education did not convey differential survival advantages to individuals with higher genetic risk of AD, but may reduce hospitalization risk associated with AD genetic risk.

Cognitive reserve and dementia A scientometric review

Research into cognitive reserve (CR) and dementia is advancing rapidly. This paper analyses the intellectual structure, emerging trends and relevant shifts in the development of available knowledge. Data collected from the Web-of-Science produced an expanded network of 564 articles and 12,504 citations in the 1998-2017 period. The co-citation network visualized was characterized by a scientometric review using CiteSpace. The results revealed that author Stern Y had the highest number of publications and citations. The network of journals, institutions and countries showed a central-peripheral structure with Neurology, Harvard University and the USA ranked first, respectively. While cognitive reserve remains the most prominent area of research in this field, studies related to functional ability, executive control, mortality data and reserve mechanisms have grown considerably. The identification of critical articles and the development of emerging trends highlights new insights in the area of research, better communicating key findings and facilitating the exploration of data.

Bayesian adaptive group lasso with semiparametric hidden Markov models

This paper presents a Bayesian adaptive group least absolute shrinkage and selection operator method to conduct simultaneous model selection and estimation under semiparametric hidden Markov models. We specify the conditional regression model and the transition probability model in the hidden Markov model into additive nonparametric functions of covariates. A basis expansion is adopted to approximate the nonparametric functions. We introduce multivariate conditional Laplace priors to impose adaptive penalties on regression coefficients and different groups of basis expansions under the Bayesian framework. An efficient Markov chain Monte Carlo algorithm is then proposed to identify the nonexistent, constant, linear, and nonlinear forms of covariate effects in both conditional and transition models. The empirical performance of the proposed methodology is evaluated via simulation studies. We apply the proposed model to analyze a real data set that was collected from the Alzheimer's Disease Neuroimaging Initiative study. The analysis identifies important risk factors on cognitive decline and the transition from cognitive normal to Alzheimer's disease.

APOE ε4 Genotype and Cognitive Reserve Effects on the Cognitive Functioning of Healthy Elders

AIM

To test the association between cognitive performance and APOE genotype, and to assess potential modifications of this association by sociodemographic and neuroanatomical factors in a sample of 74 healthy elders.

METHODS

Firstly, we explored the isolated role of the APOE ɛ4 genotype (i.e., APOE4) in different neuropsychological tests, and then the effects of its interaction with sociodemographic (i.e., age, gender, and educational level) and neuroanatomical (i.e., hippocampal volumes) variables. Subsequently, we performed the same analyses after dividing the sample into two subgroups according to their Mini-Mental State Examination scores (control-high group ≥29 and control-low group < 29).

RESULTS

In the whole group, APOE4 carriers exhibited a significantly poorer execution in several cognitive domains including global cognitive functioning, episodic memory, verbal fluency, and naming. This effect was more noticeable in older and less educated subjects. The separated analyses revealed that APOE4 carriers in the control-low group exhibited lower scores in global cognitive functioning and episodic memory, while no effects were observed in the control-high group. Neither gender nor hippocampal volumes showed a significant interaction effect with APOE genotype.

CONCLUSIONS

Current results point out that APOE4 genotype influences healthy aged cognition, although factors such age or educational attainment seem to modulate its effects.

The Impact of a Long-Term Rivastigmine and Donepezil Treatment on All-Cause Mortality in Patients With Alzheimer's Disease

Cholinesterase inhibitors (ChEIs) are the mainstays of symptomatic treatment of Alzheimer's disease (AD); however, their efficacy is limited, and their use was associated with deaths in some groups of patients. The aim of the current study was to assess the impact of the long-term use of ChEIs on mortality in patients with AD. This observational, longitudinal study included 1171 adult patients with a diagnosis of AD treated with donepezil or rivastigmine. Each patient was observed for 24 months or until death. The cognitive and functional assessments, the use of ChEIs, memantine, antipsychotics, antidepressants, and anxiolytics were recorded. The total number of deaths at the end of the observational period was 99 (8.45%). The patients who had received rivastigmine treatment were at an increased risk of death in the follow-up period. The higher risk of death in the rivastigmine group remained significant in multivariate Cox regression models.

Cognitive Reserve Relates to Functional Network Efficiency in Alzheimer's Disease

Alzheimer’s disease (AD) is the most common form of dementia, with no means of cure or prevention. The presence of abnormal disease-related proteins in the population is, in turn, much more common than the incidence of dementia. In this context, the cognitive reserve (CR) hypothesis has been proposed to explain the discontinuity between pathophysiological and clinical expression of AD, suggesting that CR mitigates the effects of pathology on clinical expression and cognition. fMRI studies of the human connectome have recently reported that AD patients present diminished functional efficiency in resting-state networks, leading to a loss in information flow and cognitive processing. No study has investigated, however, whether CR modifies the effects of the pathology in functional network efficiency in AD patients. We analyzed the relationship between CR, pathophysiology and network efficiency, and whether CR modifies the relationship between them. Fourteen mild AD, 28 amnestic mild cognitive impairment (aMCI) due to AD, and 28 controls were enrolled. We used education to measure CR, cerebrospinal fluid (CSF) biomarkers to evaluate pathophysiology, and graph metrics to measure network efficiency. We found no relationship between CR and CSF biomarkers; CR was related to higher network efficiency in all groups; and abnormal levels of CSF protein biomarkers were related to more efficient networks in the AD group. Education modified the effects of tau-related pathology in the aMCI and mild AD groups. Although higher CR might not protect individuals from developing AD pathophysiology, AD patients with higher CR are better able to cope with the effects of pathology—presenting more efficient networks despite pathology burden. The present study highlights that interventions focusing on cognitive stimulation might be useful to slow age-related cognitive decline or dementia and lengthen healthy aging.

Feasibility and Safety of Perilla Seed Oil as an Additional Antioxidative Therapy in Patients with Mild to Moderate Dementia

Dementia is a broad-spectrum terminology for a degenerate in cognitive function severe enough to intervene in activities of daily living. Oxidative stress plays a major role in the neurodegenerative cascade, leading to the irreversible mechanism in dementia. Perilla seed oil is extracted from its seeds and contains a high source of antioxidative substances such as omega-3 fatty acid. With its prominent antioxidative property, perilla seed oil demonstrates neuroprotective effects against dementia in preclinical studies. We aim to prove the feasibility and safety of perilla seed oil as an additional antioxidative therapy in patients with dementia. This single-centered, double-blinded, placebo-controlled trial randomized 239 patients with clinical diagnosis of mild to moderate dementia according to the Thai Mini-Mental State Examination (TMSE) score of 10 to 23 or the Thai Montreal Cognitive Assessment score of 12 to 25. Either two capsules containing 500 milligrams of perilla seed oil or similarly appearing two capsules containing 500 milligrams of olive oil (placebo) four times daily was added to conventional standard treatment of dementia for six months. Clinical side effects and routine laboratory results at baseline and after treatment were compared between both groups. Nausea and vomiting were the most common clinical side effects (3%) found equally in both groups. Three patients in the placebo group prematurely discontinued the medication, while only one patient in the treatment group quit the medication early. However, about 5% of patients in both groups could not comply with the regimen of the treatment. The routine laboratory results, including complete blood counts, kidney function tests, and liver function panels, at baseline and after treatment, were not significantly different in both groups. In conclusion, perilla seed oil was feasible and safe to add on with standard treatment in patients with mild to moderate dementia. Further study is needed to confirm its benefit to use as additional antioxidative therapy in patients with dementia.

Effects of cognitive reserve depend on executive and semantic demands of the task

BACKGROUND

Cognitive reserve (CR) is one factor that helps to maintain cognitive function in patients with Alzheimer's disease (AD). Whether the effects of CR depend on the semantic/executive components of the task remains unknown.

METHODS

470 patients (138 with AD, 332 with mild cognitive impairment (MCI)) were selected from the Alzheimer's Disease Neuroimaging Initiative database. Linear regression models were used to determine the effects of CR (years of education) on cognitive performance after controlling for demographic factors and regional cortical atrophy. First, we assessed memory tasks with low (Auditory Verbal Learning Test (AVLT) discriminability), moderate (AVLT delayed recall) and high (Logical Memory Test (LMT) delayed recall) executive/semantic components. Next, we assessed tasks with lower (digit span forward, Trails A) or higher (digit span backwards, Trails B) executive demands, and lower (figure copying) or higher (naming, semantic fluency) semantic demands.

RESULTS

High CR was significantly associated with performance on the LMT delayed recall, approached significance in the AVLT delayed recall and was not significantly associated with performance on AVLT discriminability. High CR was significantly associated with performance on the Trails B and digit span backwards, mildly associated with Trails A performance and was not associated with performance on digit span forwards. High CR was associated with performance on semantic but not visuospatial tasks. High CR was associated with semantic tasks in patients with both MCI and AD, but was only associated with executive functions in patients with MCI.

CONCLUSION

CR may relate to executive functioning and semantic knowledge, leading to preserved cognitive performance in patients with AD pathology.

Education and Genetic Risk Modulate Hippocampal Structure in Alzheimer's Disease

Genetic and environmental protective factors and risks modulate brain structure and function in neurodegenerative diseases and their preclinical stages. We wanted to investigate whether the years of formal education, a proxy measure for cognitive reserve, would influence hippocampal structure in Alzheimer’s disease patients, and whether apolipoprotein Eε4 (APOE4) carrier status and a first-degree family history of the disease would change a possible association. Fifty-eight Alzheimer’s disease patients underwent 3T magnetic resonance imaging. We applied a cortical unfolding approach to investigate individual subregions of the medial temporal lobe. Among patients homozygous for the APOE4 genotype or carrying both APOE4 and family history risks, lower education was associated with a thinner cortex in multiple medial temporal regions, including the hippocampus. Our data suggest that the years of formal education and genetic risks interact in their influence on hippocampal structure in Alzheimer’s disease patients.

Predictive factors for disease progression in patients with early-onset Alzheimer's disease

BACKGROUND

Only a few studies have investigated disease progression in patients with early-onset Alzheimer's disease (EOAD). Therefore, the aim of this study was to investigate disease progression in patients with EOAD and the influence of various factors, such as gender, education, and apolipoprotein E (APOE) genotype on disease progression.

METHODS

A total of 288 EOAD patients were enrolled in the study. Linear mixed models were used to investigate the rate of cognitive and functional decline in terms of age at onset, gender, education, follow-up period, and APOE genotype.

RESULTS

EOAD patients showed an annual decline of -1.54 points/years in the Korean version mini-mental examination score, an annual increase of 3.46 points/year in the Seoul instrumental activities of daily living (SIADL) score, and an annual increase of 1.15 points/year in the clinical dementia rating scale-sum of boxes score. After stratification, higher educated patients showed faster disease progression in all three parameters, and female patients demonstrated faster disease progression as assessed by the SIADL score. Age at onset and APOE genotype had no influence on disease progression.

CONCLUSION

We confirmed the rate of disease progression in Korean patients with EOAD in real-life hospital-based clinical practice. The results of this study suggest that education and female gender, not APOE genotype, may be important as independent strong predictive factors for disease progression in patients with EOAD.

Education is associated with sub-regions of the hippocampus and the amygdala vulnerable to neuropathologies of Alzheimer's disease

We evaluated the correlation of educational attainment with structural volume and shape morphometry of the bilateral hippocampi and amygdalae in a sample of 110 non-demented, older adults at elevated sociodemographic risk for cognitive and functional declines. In both men and women, no significant education-volume correlation was detected for either structure. However, when performing shape analysis, we observed regionally specific associations with education after adjusting for age, intracranial volume, and race. By sub-dividing the hippocampus and the amygdala into compatible subregions, we found that education was positively associated with size variations in the CA1 and subiculum subregions of the hippocampus and the basolateral subregion of the amygdala (p < 0.05). In addition, we detected a greater left versus right asymmetric pattern in the shape-education correlation for the hippocampus but not the amygdala. This asymmetric association was largely observed in men versus women. These findings suggest that education in youth may exert direct and indirect influences on brain reserve in regions that are most vulnerable to the neuropathologies of aging, dementia, and specifically, Alzheimer disease.

Socioeconomic Disparities and Mortality After a Diagnosis of Dementia: Results From a Nationwide Registry Linkage Study

Low socioeconomic status (SES) has been linked to a higher incidence of dementia. Less is known about the association between SES and mortality in persons with dementia. We studied this association in a prospective cohort of 15,558 patients in the Netherlands between 2000 and 2010. SES was measured using disposable household income and divided in tertiles. Overall, there was a negative relationship between SES and mortality in both sexes and both settings of care. For men who visited a day clinic, the 5-year mortality rate was 74% among those in the lowest tertile of SES and 57% among those in the highest; for women, the rates were 60% and 50%, respectively. The differences in median survival times between persons in the lower and upper tertiles of SES were 260 days for men and 300 days for women. For men who were admitted to the hospital, the 5-year mortality rate was 89% among those in the lowest tertile of SES and 86% among those in the highest; for women, the rates were 83% and 77%, respectively. The differences in median survival times between persons in the lower and upper tertiles of SES were 80 days for men and 130 days for women. Among patients who visited a day clinic, for patients in the lowest tertile of SES versus those in the highest, the adjusted hazard ratio was 1.41 (95% confidence interval: 1.26, 1.57); for those admitted to the hospital, it was 1.14 (95% confidence interval: 1.07, 1.20). In summary, lower SES was associated with a higher mortality risk in both men and women with dementia. The results of the present study should raise awareness in clinicians and caregivers about the unfavorable prognosis in the most deprived patients.

Cognitive Reserve and the Prevention of Dementia: the Role of Physical and Cognitive Activities

PURPOSE OF REVIEW

The article discusses the two most significant modifiable risk factors for dementia, namely, physical inactivity and lack of stimulating cognitive activity, and their effects on developing cognitive reserve.

RECENT FINDINGS

Both of these leisure-time activities were associated with significant reductions in the risk of dementia in longitudinal studies. In addition, physical activity, particularly aerobic exercise, is associated with less age-related gray and white matter loss and with less neurotoxic factors. On the other hand, cognitive training studies suggest that training for executive functions (e.g., working memory) improves prefrontal network efficiency, which provides support to brain functioning in the face of cognitive decline. While physical activity preserves neuronal structural integrity and brain volume (hardware), cognitive activity strengthens the functioning and plasticity of neural circuits (software), thus supporting cognitive reserve in different ways. Future research should examine whether lifestyle interventions incorporating these two domains can reduce incident dementia.

Episodic memory in normal aging and Alzheimer disease: Insights from imaging and behavioral studies

Age-related cognitive changes often include difficulties in retrieving memories, particularly those that rely on personal experiences within their temporal and spatial contexts (i.e., episodic memories). This decline may vary depending on the studied phase (i.e., encoding, storage or retrieval), according to inter-individual differences, and whether we are talking about normal or pathological (e.g., Alzheimer disease; AD) aging. Such cognitive changes are associated with different structural and functional alterations in the human neural network that underpins episodic memory. The prefrontal cortex is the first structure to be affected by age, followed by the medial temporal lobe (MTL), the parietal cortex and the cerebellum. In AD, however, the modifications occur mainly in the MTL (hippocampus and adjacent structures) before spreading to the neocortex. In this review, we will present results that attempt to characterize normal and pathological cognitive aging at multiple levels by integrating structural, behavioral, inter-individual and neuroimaging measures of episodic memory.

Risk factors that affect life expectancy in Alzheimer's disease: a 15-year follow-up

BACKGROUNDS/AIMS

Future disease-modifying therapies might affect the expected life span in Alzheimer's disease (AD). Our aim was to identify factors that influence life expectancy in cholinesterase inhibitor (ChEI)-treated patients.

METHODS

This study included 791 deceased individuals with a clinical diagnosis of AD and a Mini-Mental State Examination score of 10-26 at baseline who were recruited from a 3-year, prospective, multicenter study of ChEI therapy in clinical practice. The participants' date of death was recorded and their survival was compared with the gender- and age-matched general population.

RESULTS

The mean survival time after the start of ChEI therapy (time of AD diagnosis) was 5.10 years for men and 6.12 years for women. Better cognitive ability, less impaired basic functional capacity, and fewer medications, but not education level or apolipoprotein E (APOE) genotype, were independent prognostic factors of longer survival after diagnosis, after controlling for gender and age.

CONCLUSION

AD shortens life expectancy in ChEI-treated patients diagnosed before the age of 85 years, similar to that reported previously for untreated individuals. A longer life span was observed in the eldest patients (≥85 years) compared with untreated cohorts, which did not differ from that observed in the general population. Higher education or carrying two APOE ε4 alleles were risk factors for earlier death.

Higher education affects accelerated cortical thinning in Alzheimer's disease: a 5-year preliminary longitudinal study

BACKGROUND

Epidemiological studies have reported that higher education (HE) is associated with a reduced risk of incident Alzheimer's disease (AD). However, after the clinical onset of AD, patients with HE levels show more rapid cognitive decline than patients with lower education (LE) levels. Although education level and cognition have been linked, there have been few longitudinal studies investigating the relationship between education level and cortical decline in patients with AD. The aim of this study was to compare the topography of cortical atrophy longitudinally between AD patients with HE (HE-AD) and AD patients with LE (LE-AD).

METHODS

We prospectively recruited 36 patients with early-stage AD and 14 normal controls. The patients were classified into two groups according to educational level, 23 HE-AD (>9 years) and 13 LE-AD (≤9 years).

RESULTS

As AD progressed over the 5-year longitudinal follow-ups, the HE-AD showed a significant group-by-time interaction in the right dorsolateral frontal and precuneus, and the left parahippocampal regions compared to the LE-AD.

CONCLUSION

Our study reveals that the preliminary longitudinal effect of HE accelerates cortical atrophy in AD patients over time, which underlines the importance of education level for predicting prognosis.

Response to cholinesterase inhibitors affects lifespan in Alzheimer's disease

BACKGROUND

A varying response to cholinesterase inhibitor (ChEI) treatment has been reported among patients with Alzheimer's disease (AD). Whether the individual-specific response, specific ChEI agent or dose affects mortality is unclear. We aimed to examine the relationship between the 6-month response to ChEI and lifespan.

METHODS

Six hundred and eighty-one deceased patients with a clinical AD diagnosis and a Mini-Mental State Examination (MMSE) score of 10-26 at the start of ChEI therapy (baseline) were included in a prospective, observational, multicentre study in clinical practice. At baseline and after 6 months of treatment, the participants were assessed using the MMSE, the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog), the Clinician's Interview-Based Impression of Change (CIBIC), the Instrumental Activities of Daily Living (IADL) scale, and the Physical Self-Maintenance Scale (PSMS). The individuals' socio-demographic characteristics, ChEI dose, and date of death were recorded. Responses to ChEI and the association of possible risk factors with survival were analysed using general linear models.

RESULTS

A longer lifespan (mean of 0.5 years) was observed among the improved/unchanged patients, as measured by MMSE or CIBIC score, but not by ADAS-cog score, after 6 months of ChEI therapy. In the multivariate models, increased survival time was independently related to a better 6-month response in MMSE, CIBIC, IADL, and PSMS scores, female sex, no antihypertensive/cardiac or antidiabetic therapy, younger age, lower education, milder disease stage at baseline, and higher ChEI dose. Apolipoprotein E genotype did not affect mortality significantly. The patients who received a higher ChEI dose during the first 6 months had a mean lifespan after baseline that was 15 months longer than that of those who received a lower dose.

CONCLUSIONS

A better short-term response to ChEI might prolong survival in naturalistic AD patients. In individuals who received and tolerated higher ChEI doses, a longer lifespan can be expected.

Can leisure activities slow dementia progression in nursing home residents? A cluster-randomized controlled trial

BACKGROUND

To examine the effects of complex cognitive (mahjong) and physical (Tai Chi) activities on dementia severity in nursing home residents with dementia.

METHODS

Cluster-randomized open-label controlled design. 110 residents were randomized by nursing home into three conditions: mahjong, Tai Chi, and simple handicrafts (control). Activities were conducted three times a week for 12 weeks. Clinical Dementia Rating (CDR) was taken at 0 (baseline), 3 (post-treatment), 6, and 9 months. The outcome measure was CDR sum-of-box, which is a composite measure of both cognitive and functional deterioration in dementia.

RESULTS

Intent-to-treat analyses were performed using multilevel regression models. Apolipoprotein E ε4 allele and education were included as covariates. Neither treatments had effects on the cognitive and functional components of the CDR, but mahjong had a significant interaction with time on the CDR sum-of-box total, suggesting a slower rate of global deterioration in the mahjong group as compared with the control group.

CONCLUSIONS

Mahjong led to a gradual improvement in global functioning and a slightly slower rate of dementia progression over time. The effect was generalized and was not specific to cognition or daily functioning.

Double compression: a vision for compressing morbidity and caregiving in dementia

The anticipated rise of dementia prevalence due to global aging may be tackled by morbidity compression through lifestyle changes (i.e., consistent participation in physical and intellectual activities) that promote cognitive reserve. A hypothetical model of cognitive decline due to Alzheimer's disease (AD) and modulation of the clinical trajectory by cognitive reserve is presented. People with higher cognitive reserve are expected to show delay of the mild cognitive impairment phase but faster conversion to AD thereafter. Once conversion to AD is evident, there would be even faster deterioration, resulting in compression of morbidity. When morbidity is compressed, not only is prevalence reduced but the caregiving load is also compressed; this is referred to as "double compression." Research and policy directions are discussed.

Factors determining disease duration in Alzheimer's disease: a postmortem study of 103 cases using the Kaplan-Meier estimator and Cox regression

Factors associated with duration of dementia in a consecutive series of 103 Alzheimer's disease (AD) cases were studied using the Kaplan-Meier estimator and Cox regression analysis (proportional hazard model). Mean disease duration was 7.1 years (range: 6 weeks–30 years, standard deviation = 5.18); 25% of cases died within four years, 50% within 6.9 years, and 75% within 10 years. Familial AD cases (FAD) had a longer duration than sporadic cases (SAD), especially cases linked to presenilin (PSEN) genes. No significant differences in duration were associated with age, sex, or apolipoprotein E (Apo E) genotype. Duration was reduced in cases with arterial hypertension. Cox regression analysis suggested longer duration was associated with an earlier disease onset and increased senile plaque (SP) and neurofibrillary tangle (NFT) pathology in the orbital gyrus (OrG), CA1 sector of the hippocampus, and nucleus basalis of Meynert (NBM). The data suggest shorter disease duration in SAD and in cases with hypertensive comorbidity. In addition, degree of neuropathology did not influence survival, but spread of SP/NFT pathology into the frontal lobe, hippocampus, and basal forebrain was associated with longer disease duration.

Different patterns of gray matter atrophy in early- and late-onset Alzheimer's disease

We assessed patterns of gray matter atrophy according to-age-at-onset in a large sample of 215 Alzheimer's disease (AD) patients and 129 control subjects with voxel-based morphometry using 3-Tesla 3D T1-weighted magnetic resonance imaging. Local gray matter amounts were compared between late- and early-onset AD patients and older and younger control subjects, taking into account the effect of apolipoprotein E. Additionally, combined effects of age and diagnosis on volumes of hippocampus and precuneus were assessed. Compared with age-matched control subjects, late-onset AD patients exhibited atrophy of the hippocampus, right temporal lobe, and cerebellum, whereas early-onset AD patients showed gray matter atrophy in hippocampus, temporal lobes, precuneus, cingulate gyrus, and inferior frontal cortex. Direct comparisons between late- and early-onset AD patients revealed more pronounced atrophy of precuneus in early-onset AD patients and more severe atrophy in medial temporal lobe in late-onset AD patients. Age and diagnosis independently affected the hippocampus; moreover, the interaction between age and diagnosis showed that precuneus atrophy was most prominent in early-onset AD patients. Our results suggest that patterns of atrophy might vary in the spectrum of AD.

Effects of education on the progression of early- versus late-stage mild cognitive impairment

BACKGROUND

Highly educated participants with normal cognition show lower incidence of Alzheimer's disease (AD) than poorly educated participants, whereas longitudinal studies involving AD have reported that higher education is associated with more rapid cognitive decline. We aimed to evaluate whether highly educated amnestic mild cognitive impairment (aMCI) participants show more rapid cognitive decline than those with lower levels of education.

METHODS

A total of 249 aMCI patients enrolled from 31 memory clinics using the standard assessment and diagnostic processes were followed with neuropsychological evaluation (duration 17.2 ± 8.8 months). According to baseline performances on memory tests, participants were divided into early-stage aMCI (-1.5 to -1.0 standard deviation (SD)) and late-stage aMCI (below -1.5 SD) groups. Risk of AD conversion and changes in neuropsychological performances according to the level of education were evaluated.

RESULTS

Sixty-two patients converted to AD over a mean follow-up of 1.43 years. The risk of AD conversion was higher in late-stage aMCI than early-stage aMCI. Cox proportional hazard models showed that aMCI participants, and late-stage aMCI participants in particular, with higher levels of education had a higher risk of AD conversion than those with lower levels of education. Late-stage aMCI participants with higher education showed faster cognitive decline in language, memory, and Clinical Dementia Rating Sum of Boxes (CDR-SOB) scores. On the contrary, early-stage aMCI participants with higher education showed slower cognitive decline in MMSE and CDR-SOB scores.

CONCLUSIONS

Our findings suggest that the protective effects of education against cognitive decline remain in early-stage aMCI and disappear in late-stage aMCI.

Factors that influence survival in a probable Alzheimer disease cohort

Introduction

This longitudinal study examined multiple factors that influence survival in a cohort of Alzheimer patients followed over two decades.

Methods

Time to death after symptom onset was determined in 641 probable AD patients who were evaluated annually until death or loss to follow-up, and information was entered into a longitudinal database. Date of death was available for everyone including those eventually lost. Baseline variables included age, sex, race, disease severity, a calculated index of rate of initial cognitive decline from symptom onset to cohort entry (pre-progression rate or PPR), years of education, and medical comorbidities (diabetes, hypertension, hyperlipidemia, coronary disease, cerebrovascular disease). Multivariable Cox proportional hazard regression analysis was used to analyze the baseline and/or time dependent association in Mini-mental Status Exam (MMSE) severity, Physical Self Maintenance Scale (PSMS), Persistency Index (PI) of exposure to antipsychotic and antidementia drugs, and psychotic symptoms (hallucinations, delusions) with mortality.

Results

Baseline covariates significantly associated with increased survival were younger age (p = .0016), female sex (p = .0001), and a slower PPR (p < .0001). Overall disease severity at baseline, medical comorbidities, and education did not influence time to death. Time-dependent changes in antipsychotic drug use, development of psychotic symptoms, antidementia drug use, and observed MMSE change were not predictive. In the final model the only time-dependent covariate that significantly decreased survival was worsening of functional ability on the PSMS (hazard ratio = 1.10; CI: 1.07-1.11).

Conclusions

In this large AD cohort survival is influenced by age, sex, and the development of functional disability during follow-up. The most important predictor of mortality was a faster rate of cognitive decline at the initial patient visit (PPR). The currently available antidementia drugs do not prolong survival in Alzheimer patients.

Alzheimer's disease: a clinical practice-oriented review

Investigation in the field of Alzheimer's disease (AD), the commonest cause of dementia, has been very active in recent years and it may be difficult for the clinician to keep up with all the innovations and to be aware of the implications they have in clinical practice. The authors, thus, reviewed recent literature on the theme in order to provide the clinician with an updated overview, intended to support decision-making on aspects of diagnosis and management. This article begins to focus on the concept of AD and on its pathogenesis. Afterward, epidemiology and non-genetic risk factors are approached. Genetics, including genetic risk factors and guidelines for genetic testing, are mentioned next. Recommendations for diagnosis of AD, including recently proposed criteria, are then reviewed. Data on the variants of AD is presented. First approach to the patient is dealt with next, followed by neuropsychological evaluation. Biomarkers, namely magnetic resonance imaging, single photon emission tomography, FDG PET, PiB PET, CSF tau, and Aβ analysis, as well as available data on their diagnostic accuracy, are also discussed. Factors predicting rate of disease progression are briefly mentioned. Finally, non-pharmacological and pharmacological treatments, including established and emerging drugs, are addressed.

Functional connectivity tracks clinical deterioration in Alzheimer's disease

While resting state functional connectivity has been shown to decrease in patients with mild and/or moderate Alzheimer's disease, it is not yet known how functional connectivity changes in patients as the disease progresses. Furthermore, it has been noted that the default mode network is not as homogenous as previously assumed and several fractionations of the network have been proposed. Here, we separately investigated the modulation of 3 default mode subnetworks, as identified with group independent component analysis, by comparing Alzheimer's disease patients to healthy controls and by assessing connectivity changes over time. Our results showed decreased connectivity at baseline in patients versus controls in the posterior default mode network, and increased connectivity in the anterior and ventral default mode networks. At follow-up, functional connectivity decreased across all default mode systems in patients. Our results suggest that earlier in the disease, regions of the posterior default mode network start to disengage whereas regions within the anterior and ventral networks enhance their connectivity. However, as the disease progresses, connectivity within all systems eventually deteriorates.

[Cognitive reserve and its relevance for the prevention and diagnosis of dementia]

Progressive brain damage is undoubtedly the main cause of clinical symptoms of dementia in neurodegenerative disorders such as Alzheimer's disease. However, the association between brain damage and cognitive symptoms is not linear. Certain interindividual differences such as a good school education or a greater brain volume are associated with a higher resilience against brain damage that is usually referred to as cognitive reserve (CR). Individuals with high CR have a diminished risk for dementia and both active and passive concepts for this phenomenon are discussed. In the concept of passive CR, peculiarities of brain structure such as higher synapse or neuron counts are regarded as buffers against brain damage. Symptoms of dementia do not occur until a certain threshold of damage is passed. In addition to the passive concepts, active mechanisms are also discussed that are associated with the ability to maintain a certain level of cognitive performance in the face of progressive neurodegeneration for a longer period. In subjects with healthy cognitive function, these active mechanisms contribute to the adaptation of brain activity when task difficulty level is increased. Confronted with progressive neurodegeneration, these active mechanisms help to compensate for brain damage. Individuals with higher CR show more efficient activation for solving the same task, which helps them to preserve normal levels of cognitive performance for a longer period.

Psychometric properties of the Spanish QoL-AD with institutionalized dementia patients and their family caregivers in Spain

OBJECTIVES

To evaluate the psychometric attributes of the Spanish version of the Quality of Life-Alzheimer's Disease Scale (QoL-AD) in institutionalized patients and family caregivers in Spain.

METHOD

101 patients (88.1% women; mean age, 83.2  ±  6.3) with Alzheimer's disease (AD) (n = 82) and mixed dementia (n = 19) and their closest family caregivers. Patient-related variables included severity of dementia, cognitive status, perceived general health, quality of life, behavior, apathy, depression, and functional status. QoL-AD acceptability, reliability, and construct validity were analyzed.

RESULTS

The mean Mini-Mental State Examination (MMSE) score was 7.2  ±  6.1 and Global Deterioration Scale was: stage four (4%); five (21.2%); six (34.3%); and seven (40.4%). Both, QoL-AD patient version (QoL-ADp) (n = 40; MMSE = 12.0  ±  4.5) and QoL-AD caregiver version (QoL-ADc) (n = 101) lacked significant floor and ceiling effects and the Cronbach α index was 0.90 and 0.86, respectively. The corrected item-total correlation was 0.11-0.68 (QoL-ADc) and 0.28-0.84 (QoL-ADp). Stability was satisfactory for QoL-ADp (intraclass correlation coefficient [ICC]=0.83) but low for QoL-ADc (ICC = 0.51); the standard error of measurement was 2.72 and 4.69. Construct validity was moderate/high for QoL-ADc (QUALID=-0.43; EQ-5D = 0.65), but lower for QoL-ADp. No significant correlations were observed between QoL-ADp and patient variables or QoL-ADc. A low to high association (r = 0.18-0.55) was obtained between QoL-ADc and patient-related measures of neuropsychiatric, function, and cognitive status.

CONCLUSION

Differences in their psychometric attributes, and discrepancy between them, were found for QoL-ADp and QoL-ADc. In patients with AD and advanced dementia, the QoL perceived by the patient could be based on a construct that is different from the traditional QoL construct.

Cognitive lifestyle and long-term risk of dementia and survival after diagnosis in a multicenter population-based cohort

An active cognitive lifestyle has been linked to dementia incidence and survival, but the separate and combined effects of its subcomponents are not clear. Data were derived from the Medical Research Council Cognitive Function and Ageing Study, a population-based study of 13,004 individuals in England and Wales first interviewed in 1991-1992 and followed over a 10-year period for dementia incidence and 12 years for mortality. A Cognitive Lifestyle Score (CLS), defined as a composite of cognitive activity including education, occupational complexity, and social engagement, was available for 12,600 individuals in 3 stages of life. A higher CLS was protective of dementia (odds ratio = 0.6, 95% confidence interval: 0.4, 0.9). Sensitivity analyses found this main effect to be reliable and replicable even when considering just 2 components of the score, either education and occupation or education and late-life social engagement. No single CLS factor was associated with dementia incidence on its own. Survival differences did not reach statistical significance. Our data suggest that more years of education, as well as further stimulatory experiences in either midlife or late life. are necessary for a protective link with dementia incidence. There was little evidence of an effect of cognitive lifestyle on survival after dementia diagnosis.

Cognitive reserve and Alzheimer's disease biomarkers are independent determinants of cognition

The objective of this study was to investigate how a measure of educational and occupational attainment, a component of cognitive reserve, modifies the relationship between biomarkers of pathology and cognition in Alzheimer's disease. The biomarkers evaluated quantified neurodegeneration via atrophy on magnetic resonance images, neuronal injury via cerebral spinal fluid t-tau, brain amyloid-β load via cerebral spinal fluid amyloid-β1-42 and vascular disease via white matter hyperintensities on T2/proton density magnetic resonance images. We included 109 cognitively normal subjects, 192 amnestic patients with mild cognitive impairment and 98 patients with Alzheimer's disease, from the Alzheimer's Disease Neuroimaging Initiative study, who had undergone baseline lumbar puncture and magnetic resonance imaging. We combined patients with mild cognitive impairment and Alzheimer's disease in a group labelled 'cognitively impaired' subjects. Structural Abnormality Index scores, which reflect the degree of Alzheimer's disease-like anatomic features on magnetic resonance images, were computed for each subject. We assessed Alzheimer's Disease Assessment Scale (cognitive behaviour section) and mini-mental state examination scores as measures of general cognition and Auditory-Verbal Learning Test delayed recall, Boston naming and Trails B scores as measures of specific domains in both groups of subjects. The number of errors on the American National Adult Reading Test was used as a measure of environmental enrichment provided by educational and occupational attainment, a component of cognitive reserve. We found that in cognitively normal subjects, none of the biomarkers correlated with the measures of cognition, whereas American National Adult Reading Test scores were significantly correlated with Boston naming and mini-mental state examination results. In cognitively impaired subjects, the American National Adult Reading Test and all biomarkers of neuronal pathology and amyloid load were independently correlated with all cognitive measures. Exceptions to this general conclusion were absence of correlation between cerebral spinal fluid amyloid-β1-42 and Boston naming and Trails B. In contrast, white matter hyperintensities were only correlated with Boston naming and Trails B results in the cognitively impaired. When all subjects were included in a flexible ordinal regression model that allowed for non-linear effects and interactions, we found that the American National Adult Reading Test had an independent additive association such that better performance was associated with better cognitive performance across the biomarker distribution. Our main conclusions included: (i) that in cognitively normal subjects, the variability in cognitive performance is explained partly by the American National Adult Reading Test and not by biomarkers of Alzheimer's disease pathology; (ii) in cognitively impaired subjects, the American National Adult Reading Test, biomarkers of neuronal pathology (structural magnetic resonance imaging and cerebral spinal fluid t-tau) and amyloid load (cerebral spinal fluid amyloid-β1-42) all independently explain variability in general cognitive performance; and (iii) that the association between cognition and the American National Adult Reading Test was found to be additive rather than to interact with biomarkers of Alzheimer's disease pathology.

The impact of brain size on pilot performance varies with aviation training and years of education

Previous studies have consistently reported age-related changes in cognitive abilities and brain structure. Previous studies also suggest compensatory roles for specialized training, skill, and years of education in the age-related decline of cognitive function. The Stanford/VA Aviation Study examines the influence of specialized training and skill level (expertise) on age-related changes in cognition and brain structure. This preliminary report examines the effect of aviation expertise, years of education, age, and brain size on flight simulator performance in pilots aged 45-68 years. Fifty-one pilots were studied with structural magnetic resonance imaging, flight simulator, and processing speed tasks. There were significant main effects of age (p < .01) and expertise (p < .01), but not of whole brain size (p > .1) or education (p > .1), on flight simulator performance. However, even though age and brain size were correlated (r = -0.41), age differences in flight simulator performance were not explained by brain size. Both aviation expertise and education were involved in an interaction with brain size in predicting flight simulator performance (p < .05). These results point to the importance of examining measures of expertise and their interactions to assess age-related cognitive changes.

Predictors of the progression of dementia severity in brazilian patients with Alzheimer's disease and vascular dementia

Introduction. This study evaluates the progression of dementia and identifies prognostic risk factors for dementia. Methods. A group of 80 Brazilian community residents with dementia (34 with Alzheimer's disease and 46 with vascular dementia) was assessed over the course of 2 years. Data were analyzed with Cox regression survival analysis. Results. The data showed that education predicted cognitive decline (HR = 1.2; P < .05) when analyzed without controlling for vascular risk factors. After the inclusion of vascular risk factors, education (HR = 1.32; P < .05) and hypertension were predictive for cognitive decline (HR = 38; P < .05), and Alzheimer's disease diagnosis was borderline predictive (P = .055). Conclusion. Vascular risk factors interacted with the diagnosis of vascular dementia. Education was a strong predictor of decline.

Systematic review of the effect of education on survival in Alzheimer's disease

BACKGROUND

According to the cognitive reserve model, higher levels of education compensate for the neuropathology of Alzheimer's disease (AD), delaying its clinical manifestations. This model suggests that for any level of cognitive impairment, people with more education have worse neuropathology than those with less education and will therefore have shorter survival post-diagnosis. This is the first systematic review of the relationship between more education and decreased survival in people with AD.

METHODS

We reviewed the literature systematically, searching electronic databases and reference lists of included studies. We used Centre for Evidence Based Medicine criteria for inclusion and rating of the validity of cohort studies that reported the relationship of education to survival in people with AD.

RESULTS

22 studies met inclusion criteria. We found Grade A evidence (highest evidence level) that more education was not associated with decreased survival post-diagnosis in AD. Only one of 11 studies rated 1b (highest level of quality) supported our hypothesis that more education predicted reduced survival after adjusting for age, gender and dementia severity; it comprised African-Caribbean participants, who had on average more severe cognitive impairment than other studies' participants.

CONCLUSIONS

Education delays the onset of the dementia syndrome in AD, but does not lead to earlier death after diagnosis.