A clinicopathological comparison of community-based and clinic-based cohorts of patients with dementia

Different cohort, disparate results: Selection bias is a key factor in autopsy cohorts

INTRODUCTION

Research-oriented autopsy cohorts provide critical insights into dementia pathobiology. However, different studies sometimes report disparate findings, partially because each study has its own recruitment biases. We hypothesized that a straightforward metric, related to the percentage of research volunteers cognitively normal at recruitment, would predict other inter-cohort differences.

METHODS

The National Alzheimer's Coordinating Center (NACC) provided data on N = 7178 autopsied participants from 28 individual research centers. Research cohorts were grouped based on the proportion of participants with normal cognition at initial clinical visit.

RESULTS

Cohorts with more participants who were cognitively normal at recruitment contained more individuals who were older, female, had lower frequencies of apolipoprotein E ε4, Lewy body disease, and frontotemporal dementia, but higher rates of cerebrovascular disease. Alzheimer's disease (AD) pathology was little different between groups.

DISCUSSION

The percentage of participants recruited while cognitively normal predicted differences in findings in autopsy research cohorts. Most differences were in non-AD pathologies.

HIGHLIGHTS

Systematic differences exist between autopsy cohorts that serve dementia research. We propose a metric to use for gauging a research-oriented autopsy cohort. It is essential to consider the characteristics of autopsy cohorts.

Insights into the pathological basis of dementia from population-based neuropathology studies

The epidemiological neuropathology perspective of population and community-based studies allows unbiased assessment of the prevalence of various pathologies and their relationships to late-life dementia. In addition, this approach provides complementary insights to conventional case-control studies, which tend to be more representative of a younger clinical cohort. The Cognitive Function and Ageing Study (CFAS) is a longitudinal study of cognitive impairment and frailty in the general United Kingdom population. In this review, we provide an overview of the major findings from CFAS, alongside other studies, which have demonstrated a high prevalence of pathology in the ageing brain, particularly Alzheimer's disease neuropathological change and vascular pathology. Increasing burdens of these pathologies are the major correlates of dementia, especially neurofibrillary tangles, but there is substantial overlap in pathology between those with and without dementia, particularly at intermediate burdens of pathology and also at the oldest ages. Furthermore, additional pathologies such as limbic-predominant age-related TDP-43 encephalopathy, ageing-related tau astrogliopathy and primary age-related tauopathies contribute to late-life dementia. Findings from ageing population-representative studies have implications for the understanding of dementia pathology in the community. The high prevalence of pathology and variable relationship to dementia status has implications for disease definition and indicate a role for modulating factors on cognitive outcome. The complexity of late-life dementia, with mixed pathologies, indicates a need for a better understanding of these processes across the life-course to direct the best research for reducing risk in later life of avoidable clinical dementia syndromes.

The unique effect of TDP-43 on hippocampal subfield morphometry and cognition

•We explored postmortem TDP-43 burden and antemortem hippocampal surface deformation. •TDP-43 was uniquely associated with inward deformation in the hippocampus. •Deformation patterns account for co-existing disease showing TDP-43′s unique effect. •Deformation was significantly correlated with cognition scores.

Mixed dementia and hyperactive delirium: a diagnostic challenge

It is well recognised that acute confusion or delirium complicates up to 10% of acute medical admissions. Disorientation in time and place with an impaired short-term memory and conscious level are the hallmarks of an acute confusion. In delirium, disorders of perception may produce restlessness and agitation. A similar state during the final days of life is termed 'terminal delirium'. Less than 10% of affected individuals will have a primary neurological disorder, for example, dementia, a neurodegenerative disease with varying aetiologies. Currently there are at least 50 million people globally suffering from dementia rendering it a global healthcare problem. Mixed dementia (MD) can be defined as a cognitive decline sufficient to impair independent functioning in daily life resulting from the coexistence of Alzheimer's disease (AD) and cerebrovascular pathology. MD occurs in patients with a neurodegenerative disorder, such as AD, Lewy body or Pick's disease and additionally cerebrovascular disease. The mechanistic synergisms between the coexisting pathologies affecting dementia risk, progression and the ultimate clinical manifestations remain elusive. Although AD can be diagnosed with a considerable degree of accuracy, the distinction between isolated AD, vascular dementia and MD, when both pathologies coexist in the same patient remains one of the most difficult diagnostic challenges because their clinical presentation can overlap. Neuropathological studies indicate that mixed vascular Alzheimer's dementia (MD) has a prevalence of 22% in the elderly. The authors present the case of a 78-year-old man with a diagnosis of MD presenting to the emergency department with delirium, a common but serious acute neuropsychiatric syndrome with the core features of inattention and global cognitive dysfunction. This case demonstrates the challenges in establishing a diagnosis in patients presenting with MD and shows that a cognitive assessment at presentation in a delirious state offers very little diagnostic information. It is therefore suggested to conduct a routine cognitive function examination on patients with dementia to anticipate new neurological signs and/or symptoms thus allowing earlier diagnosis and treatment. However, a baseline cognitive assessment when the patient was well, duration and nature of deterioration as well as collateral history will help differentiate delirium from an underlying dementia.

Reliability and concurrent validity of Alzheimer's disease assessment scale - Cognitive subscale, Chinese version (ADAS-Cog-C) among Chinese community-dwelling older people population

OBJECTIVE

To evaluate reliability and concurrent validity of the Alzheimer's Disease Assessment Scale - Cognitive Subscale, Chinese Version (ADAS-Cog-C) among Chinese community older adults.

METHOD

Three groups, comprising of 1,276 community-dwelling older adults, were included in this study: a normal control (NC), a mild cognitive impairment (MCI), and an Alzheimer's disease (AD) group. All participants were assessed through ADAS-Cog-C, clinical interviews, physical examinations, Mini Mental State Examination (MMSE), and the Clinical Dementia Rating Scale (CDR). Internal consistency was assessed to evaluate the reliability of ADAS-Cog-C. Pearson and Spearman correlation coefficients were calculated to evaluate the concurrent validity between ADAS-Cog-C, MMSE, and CDR.

RESULTS

Overall, the Cronbach's alpha coefficients of ADAS-Cog-C for the AD and MCI groups were 0.843 and 0.554, respectively. The split-half reliability coefficients for the AD and MCI groups were 0.860 and 0.539, respectively. ADAS-Cog-C scores were negatively correlated with MMSE scores (r = -0.706, p < 0.001) and positively associated with CDR scores (r = 0.546, p < 0.001). After excluding the MCI group from the analysis, the internal consistency of ADAS-Cog-C for the total population improved (α = 0.813, r _hh = 0.852, all p < 0.001), as did the correlation between ADAS-Cog-C and MMSE (r = -0.828, p < 0.001) and CDR (r = 0.429, all p < 0.001) scores.

CONCLUSIONS

ADAS-Cog-C has good internal consistency and concurrent validity for assessing Chinese community older adults with AD, but poor consistency, good concurrent validity with the MMSE while moderate concurrent validity with the CDR for MCI.

Clinical-Neuropathological Correlations of Alzheimer's Disease and Related Dementias in Latino Volunteers

Clinical, neuropsychological, and neurological procedures used to diagnose Alzheimer's disease (AD) and related dementias were largely developed and validated in well-educated, non-Latino, English-speaking populations. Sociocultural and genetic differences in Latinos might influence the accuracy of clinical diagnosis of AD and other dementias. We aim to compare the accuracy of the clinical diagnosis of AD and related dementias in Latinos with the corresponding neuropathological diagnosis. From the UCSD Alzheimer's Disease Research Center longitudinal cohort, we selected all Latino participants who had autopsy neuropathological studies from 1991 to 2017. Participants underwent annual neurological clinical evaluations, standard neuropsychological tests, neuroimaging, and genotyping of Apolipoprotein E. We calculated the sensitivity and specificity of the clinical diagnosis of AD against the primary pathological diagnosis. Of the 34 participants with a primary neuropathological diagnosis of AD, 33 (97.1%) were correctly clinically diagnosed as having AD at the last clinical evaluation, and 1 was incorrectly diagnosed with dementia with Lewy bodies. Of the 19 participants without a primary neuropathological diagnosis of AD, 8 were incorrectly clinically diagnosed with probable AD at the last clinic evaluation. The clinical diagnosis of AD at the last clinical evaluation had 97.1% sensitivity and 57.9% specificity for autopsy-verified AD. In this Latino cohort, clinicians predicted AD pathological findings with high sensitivity but moderate specificity. Tangle-only dementia was the most common misdiagnosis. Our study suggests that current procedures and instruments to clinically determine AD in Latinos have high sensitivity compared with neuropathology, but specificity needs to be improved.

Mixed dementia: A review of the evidence

Mixed dementia is the coexistence of Alzheimer's disease and cerebrovascular disease (CVD) in the same demented patient. Currently, its diagnosis and treatment remains a challenge for practitioners. To provide an overview of the epidemiology, pathogenesis, natural history, diagnosis, and therapy of Mixed Vascular-Alzheimer Dementia (MVAD). The literature was reviewed for articles published between 1990-2016 by using the keywords linked to MVAD. Neuropathological studies indicate that MVAD is a very common pathological finding in the elderly with a prevalence about of 22%. The distinction between Alzheimer's dementia and vascular dementia (VD) is complex because their clinical presentation can overlap. There are international criteria for the MVAD diagnosis. The pharmacologic therapy shows modest clinical benefits that are similar among all drugs used in patients with Alzheimer's dementia and VD. The non-pharmacologic therapy includes the rigorous management of cardiovascular risk factors (especially hypertension) and the promotion of a healthy diet. The diagnosis and treatment of MVAD cannot be improved without further studies. Currently available medications provide only modest clinical benefits once a patient has developed MVAD. In subjects at risk, the antihypertensive therapy and healthy diet should be recommend for preventing or slowing the progression of MVAD.

Considering sex and gender in Alzheimer disease and other dementias

Suffering related to dementia is multifaceted because cognitive and physical functioning slowly deteriorates. Advanced age and sex, two of the most prominent risk factors for dementia, are not modifiable. Lifestyle factors such as smoking, excessive alcohol use, and poor diet modulate susceptibility to dementia in both males and females. The degree to which the resulting health conditions (eg, obesity, type 2 diabetes, and cardiovascular disease) impact dementia risk varies by sex. Depending on the subtype of dementia, the ratio of male to female prevalence differs. For example, females are at greater risk of developing Alzheimer disease dementia, whereas males are at greater risk of developing vascular dementia. This review examines sex and gender differences in the development of dementia with the goal of highlighting factors that require further investigation. Considering sex as a biological variable in dementia research promises to advance our understanding of the pathophysiology and treatment of these conditions.

Antimicrobial Use in Patients with Dementia: Current Concerns and Future Recommendations

Infections are common in people with dementia, and antibiotic use is widespread, albeit highly variable, across healthcare settings and countries. The few studies conducted to date that consider the appropriateness of antibiotic prescribing specifically for people with dementia focus on people with advanced dementia and suggest that much of the prescribing of antibiotics for these patients may be potentially inappropriate. We suggest that clinicians must consider a number of factors to determine appropriateness of antimicrobial prescribing for people with dementia, including the risks and benefits of assessing and treating infections, the uncertainty regarding the effects of antibiotics on patient comfort, goals of care and treatment preferences, hydration status, dementia severity and patient prognosis. Future research should examine antibiotic prescribing and its appropriateness across the spectrum of common infections, dementia severities, care settings and countries, and should consider how antibiotic therapy should be considered in discussions regarding treatment preferences, goals of care and/or advance care planning between clinicians, patients and families.

Population-based analysis of pathological correlates of dementia in the oldest old

Objective

The aim of this study was to analyze brain pathologies which cause dementia in the oldest old population.

Methods

All 601 persons aged ≥85 years living in the city of Vantaa (Finland), on April 1st, 1991 formed the study population of the Vantaa85 +  study, 300 of whom were autopsied during follow‐up (79.5% females, mean age‐at‐death 92 ± 3.7 years). Alzheimer's disease (AD) pathology (tau and beta‐amyloid [Aβ]), cerebral amyloid angiopathy (CAA) and Lewy‐related pathologies were analyzed. Brain infarcts were categorized by size (<2 mm, 2–15 mm, >15 mm) and by location. Brain hemorrhages were classified as microscopic (<2 mm) and macroscopic.

Results

195/300 (65%) were demented. 194/195 (99%) of the demented had at least one neuropathology. Three independent contributors to dementia were identified: AD‐type tau‐pathology (Braak stage V‐VI), neocortical Lewy‐related pathology, and cortical anterior 2–15 mm infarcts. These were found in 34%, 21%, and 21% of the demented, respectively, with the multivariate odds ratios (OR) for dementia 5.5, 4.5, and 3.4. Factor analysis investigating the relationships between different pathologies identified three separate factors: (1) AD‐spectrum, which included neurofibrillary tau, Aβ plaque, and neocortical Lewy‐related pathologies and CAA (2) >2 mm cortical and subcortical infarcts, and (3) <2 mm cortical microinfarcts and microhemorrhages. Multipathology was common and increased the risk of dementia significantly.

Interpretation

These results indicate that AD‐type neurodegenerative processes play the most prominent role in twilight cognitive decline. The high prevalence of both neurodegenerative and vascular pathologies indicates that multiple preventive and therapeutic approaches are needed to protect the brains of the oldest old.

Two novel loci, COBL and SLC10A2, for Alzheimer's disease in African Americans

INTRODUCTION

African Americans' (AAs) late-onset Alzheimer's disease (LOAD) genetic risk profile is incompletely understood. Including clinical covariates in genetic analyses using informed conditioning might improve study power.

METHODS

We conducted a genome-wide association study (GWAS) in AAs employing informed conditioning in 1825 LOAD cases and 3784 cognitively normal controls. We derived a posterior liability conditioned on age, sex, diabetes status, current smoking status, educational attainment, and affection status, with parameters informed by external prevalence information. We assessed association between the posterior liability and a genome-wide set of single-nucleotide polymorphisms (SNPs), controlling for APOE and ABCA7, identified previously in a LOAD GWAS of AAs.

RESULTS

Two SNPs at novel loci, rs112404845 (P = 3.8 × 10-8), upstream of COBL, and rs16961023 (P = 4.6 × 10-8), downstream of SLC10A2, obtained genome-wide significant evidence of association with the posterior liability.

DISCUSSION

An informed conditioning approach can detect LOAD genetic associations in AAs not identified by traditional GWAS.

Regularized Linear Discriminant Analysis of EEG Features in Dementia Patients

The present study explores if EEG spectral parameters can discriminate between healthy elderly controls (HC), Alzheimer's disease (AD) and vascular dementia (VaD) using. We considered EEG data recorded during normal clinical routine with 114 healthy controls (HC), 114 AD, and 114 VaD patients. The spectral features extracted from the EEG were the absolute delta power, decay from lower to higher frequencies, amplitude, center and dispersion of the alpha power and baseline power of the entire frequency spectrum. For discrimination, we submitted these EEG features to regularized linear discriminant analysis algorithm with a 10-fold cross-validation. To check the consistency of the results obtained by our classifiers, we applied bootstrap statistics. Four binary classifiers were used to discriminate HC from AD, HC from VaD, AD from VaD, and HC from dementia patients (AD or VaD). For each model, we measured the discrimination performance using the area under curve (AUC) and the accuracy of the cross-validation (cv-ACC). We applied this procedure using two different sets of predictors. The first set considered all the features extracted from the 22 channels. For the second set of features, we automatically rejected features poorly correlated with their labels. Fairly good results were obtained when discriminating HC from dementia patients with AD or VaD (AUC = 0.84). We also obtained AUC = 0.74 for discrimination of AD from HC, AUC = 0.77 for discrimination of VaD from HC, and finally AUC = 0.61 for discrimination of AD from VaD. Our models were able to separate HC from dementia patients, and also and to discriminate AD from VaD above chance. Our results suggest that these features may be relevant for the clinical assessment of patients with dementia.

Stroke risk interacts with Alzheimer's disease biomarkers on brain aging outcomes

Alzheimer's disease (AD) biomarkers and stroke risk factors independently predict cognitive impairment, likely through independent disease pathways. However, limited work has sought to describe the dynamic interplay between these important risk factors. This article evaluated the interaction between stroke risk and AD biomarkers on hippocampal volume and cognitive performance. We first evaluated the interaction between stroke risk factors and AD biomarkers using data from the Alzheimer's Disease Neuroimaging Initiative (ADNI, n = 1202). We then extended our findings to an independent autopsy data set from the National Alzheimer's Coordinating Center (NACC, n = 1122) using measures of AD pathology. Stroke risk was quantified using the Framingham Stroke Risk Profile. In ADNI, stroke risk interacted with tau and amyloid levels in relation to baseline and longitudinal cognitive performance. Similarly, in NACC, stroke risk interacted with amyloid and tau positivity on cognitive performance. The effect of stroke risk factors on cognition was strongest in the absence of AD biomarkers or neuropathology, providing additional evidence that AD biomarkers and stroke risk factors relate to cognition through independent pathways.

Role of cognitive enhancer therapy in Alzheimer's disease with concomitant cerebral white matter disease: findings from a long-term naturalistic study

Background

Evidence is lacking for cognitive enhancer therapy in patients with Alzheimer’s disease (AD) and concomitant cerebrovascular disease (mixed AD) as such patients would have been excluded from clinical trials. Earlier studies of mixed AD have focused on large vessel cerebrovascular disease. The influence of small vessel cerebrovascular disease (svCVD) in the form of white matter hyperintensity (WMH) on treatment outcomes in mixed AD has not been addressed.

Objective

In this long-term naturalistic study, we evaluated the effectiveness of cognitive enhancers in patients with mixed AD with svCVD.

Methods

We conducted a retrospective analysis of a prospective clinical database from a memory clinic of a tertiary hospital. Magnetic resonance imaging WMH was used as a marker of svCVD. Demographic, cognitive, and treatment data were analysed. Linear mixed models with patient-specific random effects were used to evaluate cognitive outcomes over time while adjusting for confounders.

Results

Patients with mixed AD (n = 137) or AD without svCVD (pure AD) (n = 28) were studied over a median duration of 28.7 months. Patients with mixed AD had a higher prevalence of hypertension (62.8 vs. 35.7 %, p = 0.011). The majority (75.2 %) of the study sample were managed with monotherapy. Mini Mental State Examination (MMSE) scores decreased over time (−0.04, p = 0.007), and the decrease was similar for both diagnosis groups (−0.03, p = 0.246). Annual estimated mean MMSE decline was 0.84 for pure AD and 0.48 for mixed AD. Similar trends were observed with Montreal Cognitive Assessment (MoCA) scores, with annual estimated mean reduction of 0.72 and 0.48 for pure AD and mixed AD, respectively.

Conclusion

Cognitive enhancers are effective in slowing the rate of cognitive decline in patients with AD with svCVD. These findings would need to be confirmed in randomized clinical trials.

EEG Spectral Features Discriminate between Alzheimer's and Vascular Dementia

Alzheimer's disease (AD) and vascular dementia (VaD) present with similar clinical symptoms of cognitive decline, but the underlying pathophysiological mechanisms differ. To determine whether clinical electroencephalography (EEG) can provide information relevant to discriminate between these diagnoses, we used quantitative EEG analysis to compare the spectra between non-medicated patients with AD (n = 77) and VaD (n = 77) and healthy elderly normal controls (NC) (n = 77). We use curve-fitting with a combination of a power loss and Gaussian function to model the averaged resting-state spectra of each EEG channel extracting six parameters. We assessed the performance of our model and tested the extracted parameters for group differentiation. We performed regression analysis in a multivariate analysis of covariance with group, age, gender, and number of epochs as predictors and further explored the topographical group differences with pair-wise contrasts. Significant topographical differences between the groups were found in several of the extracted features. Both AD and VaD groups showed increased delta power when compared to NC, whereas the AD patients showed a decrease in alpha power for occipital and temporal regions when compared with NC. The VaD patients had higher alpha power than NC and AD. The AD and VaD groups showed slowing of the alpha rhythm. Variability of the alpha frequency was wider for both AD and VaD groups. There was a general decrease in beta power for both AD and VaD. The proposed model is useful to parameterize spectra, which allowed extracting relevant clinical EEG key features that move toward simple and interpretable diagnostic criteria.

PROGRESS IN CLINICAL NEUROSCIENCES: Canadian Guidelines for the Development of Antidementia Therapies: A Conceptual Summary

The magnitude of the problems faced by an aging Canadian society has been clearly identified. Perhaps the single most important problem is the increasing incidence of dementia. Alzheimer's disease (AD) accounts for 50-60% of the dementias in later life within a spectrum of other contributing dementias. Regulatory approval has been given to Acetylcholinesterase inhibitors for the symptomatic treatment of mild to moderate AD, and conditional approval to memantine for the symptoms of moderate to severe AD. There has been no regulatory approval for the treatment of the degenerative dementias beyond AD. The very rapid progress in the past decade in biotechnology and in the molecular biology of the dementias is supporting a new generation of innovative treatment strategies that will more directly target the underlying disease pathogenic mechanisms. Such treatments will foreseeably include immunotherapies, anti-aggregants that may prevent misfolding and deposition of proteins, and neuroregenerative interventions. These Guidelines follow the 2nd Canadian Conference on the Development of Antidementia Therapies, held in 2004, which covered a range of design, methodological and ethical issues facing clinical researchers and regulatory authorities. They are intended to provide a common point of reference and guidance in Canada for therapeutic development of the dementias.

Autopsy as Gold Standard in FDG-PET Studies in Dementia

Positron emission tomography (PET) imaging with F18-fluorodeoxyglucose (FDG) is increasingly used as an adjunct to clinical evaluation in the diagnosis of dementia. Considering that most FDG-PET studies in dementia use clinical diagnosis as gold standard and that clinical diagnosis is approximately 80% sensitive or accurate, we aim to review the evidence-based data on the diagnostic accuracy of brain FDG-PET in dementia when cerebral autopsy is used as gold standard. We searched the PubMed and Medline databases for dementia-related articles that correlate histopathological diagnosis at autopsy with FDG-PET imaging and found 47 articles among which there were only 5 studies of 20 patients or more. We were able to conclude that sensitivity and specificity of FDG-PET for Alzheimer's disease are good, but more studies using histopathological diagnosis at autopsy as gold standard are needed in order to evaluate what FDG-PET truly adds to premortem diagnostic accuracy in dementia.

Correcting the MoCA for Education: Effect on Sensitivity

Objective:

The goal of this study was to quantify the impact of the suggested education correction on the sensitivity and specificity of the Montreal Cognitive Assessment (MoCA).

Method:

Twenty-five outpatients with dementia and 39 with amnestic mild cognitive impairment (aMCI) underwent a diagnostic evaluation, which included the MoCA. Thirty-seven healthy controls also completed the MoCA and psychiatric, medical, neurological, functional, and cognitive difficulties were ruled out.

Results:

For the total MoCA score, unadjusted for education, a cut-off score of 26 yielded the best balance between sensitivity and specificity (80% and 89% respectively) in identifying cognitive impairment (people with either dementia or aMCI, versus controls). When applying the education correction, sensitivity decreased from 80% to 69% for a small specificity increase (89% to 92%). The cut-off score yielding the best balance between sensitivity and specificity for the education adjusted MoCA score fell to 25 (61% and 97%, respectively).

Conclusions:

Adjusting the MoCA total score for education had a detrimental effect on sensitivity with only a slight increase in specificity. Clinically, this loss in sensitivity can lead to an increased number of false negatives, as education level does not always correlate to premorbid intellectual function. Clinical judgment about premorbid status should guide interpretation. However, as this effect may be cohortspecific, age and education corrected norms and cut-offs should be developed to help guide MoCA interpretation.

Neuropathologic correlates of cognition in a population-based sample

Many cognitively normal older adults have underlying neuropathologic changes of Alzheimer's disease (AD), vascular brain injury (VBI), or Lewy body disease (LBD), which confer an increased risk of dementia. The current study focused on the association between multiple neuropathologic indices and performance on specific cognitive domains in a community sample of older adults. Of 438 participants in the Adult Changes in Thought population-based study of brain aging who were autopsied, 363 subjects had cognitive testing at their final study visit and were included. Associations were measured between performance on the Cognitive Abilities Screening Instrument prior to death and neuropathologic endpoints, including AD neuropathologic changes, LBD, cerebral amyloid angiopathy, and measures of VBI. Braak stage for neurofibrillary tangles, lower brain weight, and VBI as measured by cerebral cortical microvascular lesions (μVBI) explained a significant proportion of the variance associated with global cognitive test performance (R2 = 0.31, p < 0.0001) both in the entire sample and when analysis was restricted to non-demented subjects (R2 = 0.23, p < 0.0001). Specific cognitive domains were differentially related to neuropathologic lesion type: memory and executive function with AD pathologic changes and cortical μVBI, executive function with subcortical μVBI, and visuospatial construction with LBD. Thus, neuropathologic lesions of LBD and μVBI are associated with poorer cognitive performance over and above AD neuropathologic changes in subjects without dementia in this cohort. These findings underscore that cognitive impairment is a complex convergent trait that has important implications for clinical investigation and medical management of older adults.

Amyloid deposition, hypometabolism, and longitudinal cognitive decline

OBJECTIVE

Using data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) population, we examined (1) cross-sectional relationships between amyloid deposition, hypometabolism, and cognition, and (2) associations between amyloid and hypometabolism measurements and longitudinal cognitive measurements.

METHODS

We examined associations between mean cortical florbetapir uptake, mean (18) F-fluorodeoxyglucose-positron emission tomography (FDG-PET) within a set of predefined regions, and Alzhiemer's Disease Assessment Scale (ADAS-cog) performance in 426 ADNI participants (126 normal, 162 early mild cognitive impairment [EMCI], 85 late MCI [LMCI], 53 Alzheimer disease [AD] patients). For a subset of these (76 normal, 81 LMCI) we determined whether florbetapir and FDG-PET were associated with retrospective decline in longitudinal ADAS-cog measurements.

RESULTS

Twenty-nine percent of normal subjects, 43% of EMCI patients, 62% of LMCI patients, and 77% of AD patients were categorized as florbetapir positive. Florbetapir was negatively associated with concurrent FDG and ADAS-cog in both MCI groups. In longitudinal analyses, florbetapir-positive subjects in both normal and LMCI groups had greater ongoing ADAS-cog decline than those who were florbetapir negative. However, in normal subjects, florbetapir positivity was associated with greater ADAS-cog decline than FDG, whereas in LMCI, FDG positivity was associated with greater decline than florbetapir.

INTERPRETATION

Although both hypometabolism and β-amyloid (Aβ) deposition are detectable in normal subjects and all diagnostic groups, Aβ showed greater associations with cognitive decline in normal participants. In view of the minimal cognitive deterioration overall in this group, this suggests that amyloid deposition has an early and subclinical impact on cognition that precedes metabolic changes. At moderate and later stages of disease (LMCI/AD), hypometabolism becomes more pronounced and more closely linked to ongoing cognitive decline.

Duke Twins Study of Memory in Aging in the NAS-NRC Twin Registry

The Duke Twins Study of Memory in Aging is an ongoing, longitudinal study of cognitive change and dementia in the population-based National Academy of Sciences-National Research Council (NAS-NRC) Twin Registry of World War II Male Veterans. The primary goal of this study has been to estimate the overall genetic and environmental contributions to dementia with a specific focus on Alzheimer's disease. An additional goal has been to examine specific genetic and environmental antecedents of cognitive decline and dementia. Since 1989, we have completed 4 waves of data collection. Each wave included a 2-phase telephone cognitive screening protocol, followed by an in-home standardized clinical assessment for those with suspected dementia. For many participants, we have obtained postmortem neuro-pathological confirmation of the diagnosis of dementia. In addition to data on cognition, we have also collected information on occupational history, medical history, medications and other lifetime experiences that may influence cognitive function in late life. We provide an overview of the study's methodology and describe the focus of recent research.

Effectiveness and safety of 18F-FDG PET in the evaluation of dementia: a review of the recent literature

Imaging that can detect pathophysiologic change in the brain holds great promise for diagnostic assessment of patients with Alzheimer disease (AD) and dementia. Although a previous metaanalysis centering on literature from 1990 to 2000 showed a summary accuracy of 86% for (18)F-FDG PET for AD diagnosis, the clinical value was considered uncertain because of methodologic shortcomings. Review of the recent literature since 2000 demonstrates that the evidence for (18)F-FDG PET in assessment of dementia has increased with new studies that include autopsy confirmation, wide-diagnostic-spectrum recruitment in primary care settings, historical and prospective cohort studies, and multicenter data analyses. These data support the role of (18)F-FDG PET as an effective and useful adjunct to other diagnostic information in the assessment of patients with symptoms of dementia. Findings are in line with recently revised diagnostic criteria of AD that for the first time recognize the unique role of biomarker evidence in disease definition.

Evolution of the diagnostic criteria for degenerative and cognitive disorders

PURPOSE OF REVIEW

This review describes the evolution of the clinical criteria for Alzheimer's disease over the past 25 years, with special emphasis on those recently published that have incorporated the use of biomarkers.

RECENT FINDINGS

One of the most important advances in the knowledge of Alzheimer's disease was the development of cerebrospinal fluid, PET and MRI biomarkers. These have shown that the Alzheimer's disease is present in cognitively normal individuals, suggesting that there is a long incubation process that precedes the onset of the symptoms. Although there are diagnostic criteria for Alzheimer's disease, the National Institute on Aging and the Alzheimer's Association has proposed a set of diagnostic criteria oriented to provide a unified vision of the pathological process from preclinical, to mild cognitive impairment, and to full-blown dementia. These new criteria take advantage of different biomarkers to support the clinical diagnosis of the different stages of the disease.

SUMMARY

The new guidelines provide a definition of the dementia syndrome and core diagnostic features to be used in research and clinical practice, although they caution about the use of biomarkers, since they still require validation, and the longitudinal interaction and dynamics of these biomarkers in relationship to the manifestation of the symptoms are not fully understood.

White matter lesions defined by diffusion tensor imaging in older adults

OBJECTIVE

The cellular and molecular mechanisms underlying magnetic resonance imaging-defined white matter (WM) changes associated with age-related cognitive decline remain poorly defined. We tested the hypothesis that WM lesions in older adults, defined by diffusion tensor imaging (DTI), arise in the setting of vascular brain injury (VBI) and are characterized by increased free radical injury and aberrant oligodendrocyte lineage (OL) cell response to injury.

METHODS

We undertook a multimodal analysis of prefrontal cortex (PFC) WM from 25 autopsies derived from a population-based cohort where VBI and Alzheimer disease (AD) frequently coincide. Ex vivo high field strength DTI measurements of fractional anisotropy (FA), apparent diffusion coefficient, and axial and radial (D(⊥) ) diffusivity were measured at high magnetic field strength (11.7T) and analyzed relative to quantitative in vivo biomarkers of free radical injury, an OL-specific marker Olig2, and histologic evaluation of hyaluronan (HA), an inhibitor of OL maturation.

RESULTS

Coincident AD and VBI showed significant association with lower FA and a robust relationship between decreasing FA and increasing D(⊥) . Free radical injury to docosahexaenoate and adrenate in PFC WM was significantly elevated in cases with VBI independent of AD, and was inversely correlated with FA. Similarly, increased density of Olig2-immunoreactive cells in PFC WM was significantly associated with VBI independent of AD and colocalized with regions enriched in HA.

INTERPRETATION

DTI-defined PFC WM lesions in older individuals are characterized by free radical injury to myelin and neuroaxonal elements that coincides with pronounced expansion of the pool of OL cells in HA-rich regions.

Ecology of the aging human brain

BACKGROUND

Alzheimer disease, cerebral vascular brain injury, and isocortical Lewy body disease (LBD) are the major contributors to dementia in community- and population-based studies.

OBJECTIVE

To estimate the prevalence of clinically silent forms of these diseases in cognitively normal (CN) adults.

DESIGN

Autopsy study.

SETTING

Community- and population based.

PARTICIPANTS

A total of 1672 brain autopsies from the Adult Changes in Thought study, Honolulu-Asia Aging Study, Nun Study, and Oregon Brain Aging Study, of which 424 met the criteria for CN.

MAIN OUTCOME MEASURES

Of these, 336 cases had a comprehensive neuropathologic examination of neuritic plaque density, Braak stage for neurofibrillary tangles, LB distribution, and number of cerebral microinfarcts.

RESULTS

Forty-seven percent of CN cases had moderate or frequent neuritic plaque density; of these, 6% also had Braak stage V or VI for neurofibrillary tangles. Fifteen percent of CN cases had medullary LBD; 8% also had nigral and 4% isocortical LBD. The presence of any cerebral microinfarcts was identified in 33% and of high-level cerebral microinfarcts in 10% of CN individuals. Overall, the burden of lesions in each individual and their comorbidity varied widely within each study but were similar across studies.

CONCLUSIONS

These data show an individually varying complex convergence of subclinical diseases in the brain of older CN adults. Appreciating this ecology should help guide future biomarker and neuroimaging studies and clinical trials that focus on community- and population-based cohorts.

Progression of cognitive, functional, and neuropsychiatric symptom domains in a population cohort with Alzheimer dementia: the Cache County Dementia Progression study

OBJECTIVES

Progression of Alzheimer dementia (AD) is highly variable. Most estimates derive from convenience samples from dementia clinics or research centers where there is substantial potential for survival bias and other distortions. In a population-based sample of incident AD cases, we examined progression of impairment in cognition, function, and neuropsychiatric symptoms, and the influence of selected variables on these domains.

DESIGN

Longitudinal, prospective cohort study.

SETTING

Cache County (Utah).

PARTICIPANTS

Three hundred twenty-eight persons with a diagnosis of possible/probable AD.

MEASUREMENTS

Mini-Mental State Exam (MMSE), Clinical Dementia Rating sum-of-boxes (CDR-sb), and Neuropsychiatric Inventory (NPI).

RESULTS

Over a mean follow-up of 3.80 (range: 0.07-12.90) years, the mean (SD) annual rates of change were -1.53 (2.69) scale points on the MMSE, 1.44 (1.82) on the CDR-sb, and 2.55 (5.37) on the NPI. Among surviving participants, 30% to 58% progressed less than 1 point per year on these measures, even 5 to 7 years after dementia onset. Rates of change were correlated between MMSE and CDR-sb (r = -0.62, df = 201, p < 0.001) and between the CDR-sb and NPI (r = 0.20, df = 206, p < 0.004). Female subjects (LR χ = 8.7, df = 2, p = 0.013) and those with younger onset (likelihood ratio [LR] χ = 5.7, df = 2, p = 0.058) declined faster on the MMSE. Although one or more apolipoprotein E ε 4 alleles and ever use of FDA-approved antidementia medications were associated with initial MMSE scores, neither was related to the rate of progression in any domain.

CONCLUSIONS

A significant proportion of persons with AD progresses slowly. The results underscore differences between population-based versus clinic-based samples and suggest ongoing need to identify factors that may slow the progression of AD.

Operationalizing diagnostic criteria for Alzheimer's disease and other age-related cognitive impairment-Part 2

This article focuses on the effects of operational differences in case ascertainment on estimates of prevalence and incidence of cognitive impairment and/or dementia of the Alzheimer type. Experience and insights are discussed by investigators from the Framingham Heart Study, the East Boston Senior Health Project, the Chicago Health and Aging Project, the Mayo Clinic Study of Aging, the Baltimore Longitudinal Study of Aging, and the Aging, Demographics, and Memory Study. There is a general consensus that the single most important factor determining prevalence estimates of Alzheimer's disease (AD) is the severity of cognitive impairment used as a threshold to define cases. Studies that require a level of cognitive impairment in which persons are unable to provide self-care will have much lower estimates than the studies aimed at identifying persons in the earliest stages of AD. There are limited autopsy data from the aforementioned epidemiological studies to address accuracy in the diagnosis of etiological subtype, namely the specification of AD alone or in combination with other types of pathology. However, other community-based cohort studies show that many persons with mild cognitive impairment and also some persons without dementia or mild cognitive impairment meet pathological criteria for AD, thereby suggesting that the number of persons who would benefit from an effective secondary prevention intervention is probably higher than the published prevalence estimates. Improved accuracy in the clinical diagnosis of AD is anticipated with the addition of molecular and structural biomarkers in the next generation of epidemiological studies.

Almitrine-Raubasine combination for dementia

BACKGROUND

Almitrine-raubasine combination (brand name Duxil), has been considered as an alternative treatment for dementia.

OBJECTIVES

To determine the clinical efficacy and safety of Duxil in the treatment of patients with dementia.

SEARCH STRATEGY

We searched the Cochrane Dementia and Cognitive Improvement Group Specialised Register (now known as ALOIS) (September 2009), the China Biological Medicine Database (CBM-disc 1979 to December 2009), the Chinese National Knowledge Infrastructure (www.cnki.net 1979 to December 2009), the Stroke Trials Registry at www.strokecentre.org/trials/index.aspx. We searched identified citations for additional trials, contacted the first author of identified trials for additional references and unpublished data. We also contacted the pharmaceutical company manufacturing Duxil (Servier Pharmaceutical Co Ltd) for additional unpublished data.

SELECTION CRITERIA

Randomised controlled trials studying the efficacy and safety of Duxil for dementia were included, irrespective of blinding, publication status, or language. If the trial was cross-over in nature, only data from the first period were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality and extracted the data.

MAIN RESULTS

Three trials involving a total of 206 participants were included, all patients with vascular dementia. All three included studies were assessed as being at high risk of bias. When analysing these trials together, there was significant beneficial effect of Duxil on the improvement of cognitive function measured by MMSE (WMD 2.04, 95% CI 1.43 to 2.66). No data on behaviour and death at the end of treatment and follow-up were available from the included trials. Two trials failed to show an improvement of functional performance measured by ADL (WMD -1.68; 95% CI -3.70 to 0.35). Of the three included trials, all described the adverse events in detail, there were no statistically significant differences across the trials (OR 4.84, 95%CI 0.55 to 42.67). Behaviour disturbance, quality of life, caregiver burden were not undertaken in the included trials.

AUTHORS' CONCLUSIONS

Due to the low methodological quality of included trials, small number of trials and probable publication bias, this review did not provide sufficient evidence to support the routine use of Duxil for the treatment of patients with dementia. High-quality and large-scale randomised controlled trials are needed to confirm or refute these results.

The neuropathology of older persons with and without dementia from community versus clinic cohorts

Community-based cohorts of older persons may differ neuropathologically from clinic-based cohorts. This study investigated age-related pathologies in persons with and without dementia and included autopsied participants from two community-based cohorts, the Rush Religious Orders Study (n=386) and the Memory and Aging Project (n=195), and one clinic-based cohort, the Clinical Core of the Rush Alzheimer's Disease Center (n=392). Final clinical diagnoses included no cognitive impairment (n=202), mild cognitive impairment (MCI) (n=150), probable Alzheimer's disease (AD) (n=474), possible AD (n=88), and other dementias (n=59). Postmortem diagnoses included pathologic AD, cerebral infarcts, and Lewy body disease. Community-based persons with clinical AD had less severe AD pathology (p<0.001) and had more cerebral infarcts (p<0.001) compared to clinic-based persons. Additionally, community-based persons with MCI had more infarcts compared to clinic-based persons. Overall, there was a higher proportion of Lewy bodies and atypical pathologies in the clinic-based compared to the community-based cohorts (p<0.001). Community-based persons with probable AD show less severe AD pathology and more often have infarcts and mixed pathologies; those with MCI more often have infarcts and mixed pathologies. Overall, clinic-based persons have more Lewy bodies and atypical pathologies. The spectrum of pathologies underlying cognitive impairment in clinic-based cohorts differs from community-based cohorts.

Cerebral arachidonate cascade in dementia: Alzheimer's disease and vascular dementia

Phospholipase A(2) (PLA(2)), cyclooxygenase (COX) and prostaglandin (PG) synthase are enzymes involved in arachidonate cascade. PLA(2) liberates arachidonic acid (AA) from cell membrane lipids. COX oxidizes AA to PGG(2) followed by an endoperoxidase reaction that converts PGG(2) into PGH(2). PGs are generated from astrocytes, microglial cells and neurons in the central nervous system, and are altered in the brain of demented patients. Dementia is principally diagnosed into Alzheimer's disease (AD) and vascular dementia (VaD). In older patients, the brain lesions associated with each pathological process often occur together. Regional brain microvascular abnormalities appear before cognitive decline and neurodegeneration. The coexistence of AD and VaD pathology is often termed mixed dementia. AD and VaD brain lesions interact in important ways to decline cognition, suggesting common pathways of the two neurological diseases. Arachidonate cascade is one of the converged intracellular signal transductions between AD and VaD. PLA(2) from mammalian sources are classified as secreted (sPLA(2)), Ca(2+)-dependent, cytosolic (cPLA(2)) and Ca(2+)-independent cytosolic PLA(2) (iPLA(2)). PLA(2) activity can be regulated by calcium, by phosphorylation, and by agonists binding to G-protein-coupled receptors. cPLA(2) is upregulalted in AD, but iPLA(2) is downregulated. On the other hand, sPLA(2) is increased in animal models for VaD. COX-2 is induced and PGD(2) are elevated in both AD and VaD. This review presents evidences for central roles of PLA(2)s, COXs and PGs in the dementia.

Comparison of clinical and neuropathologic diagnoses of Alzheimer's disease in 3 epidemiologic samples

BACKGROUND

Studies of dementia in populations avoid many of the selection biases in clinical samples but require special evaluation and diagnostic methods to obtain high participation rates. To address this issue, we developed a unique in-home dementia assessment. We assessed validity of these assessments using neuropathologic confirmation of the clinical diagnosis in 3 epidemiologic samples.

METHODS

Subjects were 175 participants in 3 ongoing studies of dementia. Two were population based and identified dementia by cognitive screening. The third study sought volunteers via advertisements. Dementia evaluations were then conducted at the participants' residences by specially trained nurses and psychometricians. Evaluation results were interpreted, and preliminary diagnoses were assigned by a geropsychiatrist or neurologist and a psychologist. Final diagnoses were assigned by a consensus panel of neurologists, geropsychiatrists, and psychologists. We compared the clinical diagnoses with the gold-standard neuropathologic diagnoses for those participants who subsequently underwent autopsy.

RESULTS

Among the demented, the sensitivity of a clinical diagnosis of probable or possible Alzheimer's disease (AD) was 93% across the 3 studies. The rate of overall diagnostic agreement was 81%. Measures of agreement did not differ meaningfully across varying levels of dementia severity.

CONCLUSIONS

Rates of neuropathologic confirmation for clinical AD diagnoses in these studies were similar to those reported from clinic-based samples. These results support the validity of clinical diagnoses of AD from a structured in-home assessment of community dwelling and institutionalized individuals using relatively economical methods of dementia screening and assessment.

The neuropathology of probable Alzheimer disease and mild cognitive impairment

OBJECTIVE

Mixed pathologies are common in older persons with dementia. Little is known about mixed pathologies in probable Alzheimer disease (AD) and about the spectrum of neuropathology in mild cognitive impairment (MCI). The objective of this study was to investigate single and mixed common age-related neuropathologies in persons with probable AD and MCI.

METHODS

The study included 483 autopsied participants from the Religious Orders Study and the Rush Memory and Aging Project with probable AD (National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria), MCI (amnestic and nonamnestic), or no cognitive impairment. We excluded 41 persons with clinically possible AD and 14 with other dementias. We documented the neuropathology of AD (National Institute on Aging-Reagan criteria), macroscopic cerebral infarcts, and neocortical Lewy body (LB) disease.

RESULTS

Of 179 persons (average age, 86.9 years) with probable AD, 87.7% had pathologically confirmed AD, and 45.8% had mixed pathologies, most commonly AD with macroscopic infarcts (n = 54), followed by AD with neocortical LB disease (n = 19) and both (n = 8). Of the 134 persons with MCI, 54.4% had pathologically diagnosed AD (58.7% amnestic; 49.2% nonamnestic); 19.4% had mixed pathologies (22.7% amnestic; 15.3% nonamnestic). Macroscopic infarcts without pathologically diagnosed AD accounted for 4.5% of probable AD, 13.3% of amnestic MCI, and 18.6% of nonamnestic MCI. Pure neocortical LB disease was uncommon in all persons with cognitive impairment (<6%). Microscopic infarcts (without macroscopic infarcts) were common as a mixed pathology, but rarely accounted for a clinical diagnosis of probable AD (n = 4) or MCI (n = 3).

INTERPRETATION

Clinically diagnosed probable AD and MCI, even amnestic MCI, are pathologically heterogeneous disorders, with many persons exhibiting mixed pathologies.

Clinicopathological concordance in dementia diagnostics

OBJECTIVE

Accurate distinction between dementia subtypes is important for patient care and pharmacological treatment. Continuing systematic comparisons of clinical and neuropathological dementia diagnoses may provide a basis for further improvement of the diagnostic procedure. The purpose of this study was to investigate concordance between clinical dementia diagnosis and neuropathological findings in the specialized dementia care.

METHODS

Inclusion required 1) a clinical dementia disorder diagnosed at a hospital-based memory clinic and 2) a neuropathological examination within the Department of Pathology at the University Hospital in Lund, Sweden, during the years 1996-2006. A total of 176 consecutive patients fulfilled the criteria and were thus included. Clinical dementia diagnoses were obtained from the medical records and compared with the neuropathological findings.

RESULTS

The clinical and pathological dementia diagnoses were in full accordance in 86 (49%) of the patients (kappa 0.37). In an additional 24 (14%) cases, the clinical diagnosis corresponded with some but not all pathological components judged to contribute to the dementia disorder. Of the patients with clinical Alzheimer disease, 84% (46/55) had a significant Alzheimer component with or without other significant pathology at neuropathological examination. The corresponding figure for vascular dementia (VaD) was 59% (24/41), for frontotemporal dementia 74% (20/27), for combined Alzheimer and VaD 25% (4/16), and for dementia with Lewy bodies 67% (6/9).

CONCLUSIONS

This study shows that clinical dementia diagnoses do not always correspond with neuropathological changes. It stresses the importance of neuropathological examination in research and in daily clinical practice.

Magnetic resonance spectroscopy performance for detection of dementia, Alzheimer's disease and mild cognitive impairment in a community-based survey

BACKGROUND/AIMS

To evaluate (1)H-labelled magnetic resonance spectroscopy (MRS) in patients with a low Mini Mental State Examination (MMSE) score identified during a dementia community-based survey.

METHODS

A population sample of 1,500 individuals (>64 years old) was randomly selected. Two hundred and fifteen individuals (MMSE < or =24) were sorted into clinical groups: dementia, Alzheimer's disease, mild cognitive impairment (MCI), normal. Up to 56 of these individuals attended the MRS appointment. Two single-voxel sequences (TR 1,500, TE 35/144 ms) were carried out in the posterior cingulate gyrus of each individual, and the ratios N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (mI)/Cr, NAA/mI and NAA/Cho were compared statistically. The ability of MRS to distinguish clinical groups was assessed by receiver-operating characteristics analysis. Cognition effects on metabolite ratios were estimated, with gender and cognition as categorical variables and age as a continuous covariate.

RESULTS

NAA/Cr and NAA/Cho ratios were lower in dementia or Alzheimer's disease than in MCI and normal groups. The NAA/Cr ratio at TE 35 ms performed best when distinguishing dementia or Alzheimer's disease from non-demented subjects (cut-off point 1.40). MRS could not distinguish between MCI patients and normal subjects. Dementia was an independent predictor of metabolite values.

CONCLUSION

In a population sample, conventional MRS still proved to be a useful tool for dementia discrimination, but it is potentially far less useful as a surrogate marker for MCI.

Prognosis of Alzheimer's disease today: a two-year prospective study in 686 patients from the REAL-FR Study

BACKGROUND

The aim of the present study was to describe the long-term evolution of Alzheimer's disease (AD) in a prospective cohort of patients under treatment with a close follow-up.

METHODS

Six hundred eighty-six AD patients from the French Network on AD (REAL-FR) were followed up and assessed every 6 months for 2 years. Cognitive, functional, behavioral, nutritional, and global status were evaluated by using Mini-Mental State Examination (MMSE), cognitive subscale of AD Assessment Scale (ADAS-cog), Activities of Daily Living scale (ADL), Neuropsychiatric Inventory (NPI), Mini-Nutritional Assessment (MNA), and Clinical Dementia Rating (CDR).

RESULTS

There were 85.13% of patients who were specifically treated for AD during their participation in the study. We observed significant changes (P < .0001) on MMSE, -4.57 +/- 0.23; ADAS-cog, 7.11 +/- 0.41; ADL, -1.32 +/- 0.07; NPI, 2.94 +/- 0.77; MNA, -0.81 +/- 0.17; and sum of boxes of the CDR (CDR-SB), 4.17 +/- 0.17. After 2 years, 10.79% (95% confidence interval [CI], 8.47 to 13.11) of the patients evolved twice as rapidly as the mean of the whole cohort on MMSE (loss, > or =9 points), 65.89% (95% CI, 62.34 to 69.44) reported a loss of 3 to 9 points, and 23.32% (95% CI, 20.16 to 26.46) were stable or improved (loss of -2 points maximum). Annual incidences for institutionalization, hospitalization, and death were 11.84% (95% CI, 9.76 to 13.92), 26.13% (95% CI, 22.52 to 29.74), and 5.95% (95% CI, 4.56 to 7.34), respectively.

CONCLUSIONS

In a recent large AD cohort mostly under treatment, AD evolution appeared to be variable, with high incidences for death or institutionalization and with 11.84% of the patients exhibiting a rapid cognitive decline, whereas one fourth of the cohort appeared in relatively stable condition, and two thirds had a moderate but significant evolution of the disease. More studies are needed to better understand these variations in patients' evolution.

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

OBJECTIVE

We tested the hypothesis that a higher education level is associated with faster cognitive decline and lower survival in a cohort of 670 Alzheimer's disease patients, followed for 3.5 years at the Lille-Bailleul memory centre.

METHODS

The patients were categorized in 3 groups according to educational levels: low (<or=8 years), intermediate (9-12 years) and high (>12 years). Cognitive function was measured with the Mini Mental State Examination (MMSE) and the Mattis Dementia Rating Scale (DRS). Survival was analyzed with a Cox model. Analyses were adjusted for age, sex, cholinesterase inhibitor treatment, diabetes, hypertension, visible vascular lesions on MRI, baseline DRS and MMSE.

RESULTS

The adjusted mixed random model showed that MMSE declined faster for patients with high and intermediate educational levels compared with those with a low educational level (p < 0.0001). The mean annually adjusted DRS decline was highest for the groups with the most education (p = 0.05). The mortality risk was not higher in the better-educated groups (high vs. low: RR = 0.84; 95% CI = 0.35-1.99, intermediate vs. low: RR = 0.82; 95% CI = 0.41-1.63).

CONCLUSION

In our cohort, highly educated patients had a faster cognitive decline than less educated patients but similar mortality rates. Our findings support the cognitive reserve hypothesis.

Diagnosing Alzheimer's disease--non-clinicians and computerised algorithms together are as accurate as the best clinical practice

BACKGROUND

An accurate diagnosis of Alzheimer's disease and an exclusion of other dementias is important in many clinical studies. Obtaining such a clinical diagnosis in epidemiological studies and clinical trials that recruit large numbers of patients is time consuming.

OBJECTIVES

To construct an algorithm using a limited number of data points to generate a diagnosis of the commonest forms of dementia using information collected by non clinicians.

METHODS

We constructed a computer algorithm to generate a diagnosis of Alzheimer's disease (AD), Dementia with Lewy Bodies (DLB), frontotemporal dementia (FTD), vascular dementia or to flag the case as needing a clinical review based on a limited number of data points taken from a largely structured interview using widely used scales. The diagnosis generated in life by the algorithm in a prospective, longitudinal study was compared to definitive diagnosis at post mortem.

RESULTS

Post mortem diagnosis was available for 43 cases. The positive predictive value of the algorithm was greater than 95%. AD was diagnosed by the algorithm and at post mortem in 36 of the cases. Two cases with FTD were wrongly diagnosed as having AD by the algorithm, five cases were flagged as needing a clinical review due to concomitant medical conditions of whom four had AD and one, who had been diagnosed clinically as having AD, was diagnosed on post mortem with corticobasal degeneration.

CONCLUSIONS

A combination of non-clinical researchers, a structured interview and a computerised algorithm is as effective at identifying AD as highly trained and skilled clinicians.

Dementia syndromes: evaluation and treatment

As our population ages, diseases affecting memory and daily functioning will affect an increasing number of individuals, their families and the healthcare system. The social, financial and economic impacts will be profound. This article provides an overview of current dementia syndromes to assist clinicians in evaluating, educating and treating these patients.

Decision rules guiding the clinical diagnosis of Alzheimer's disease in two community-based cohort studies compared to standard practice in a clinic-based cohort study

We developed prediction rules to guide the clinical diagnosis of Alzheimer's disease (AD) in two community-based cohort studies (the Religious Orders Study and the Rush Memory and Aging Project). The rules were implemented without informant interviews, neuroimaging, blood work or routine case conferencing. Autopsies were performed at death and the pathologic diagnosis of AD made with a modified version of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) criteria. We compared the positive predictive value of the clinical diagnosis in the two community-based studies to the positive predictive value of the clinical diagnosis of AD made by standard clinical practice in a clinic-based cohort study using AD pathology as the gold standard. Of 306 clinic cases with probable AD, 286 (93.5%) met CERAD neuropathologic criteria for AD; the results were comparable for those with possible AD (51 of 54, 94.4%). Of 141 study subjects with probable AD, 130 (92.2%) met CERAD neuropathologic criteria for AD; the results were lower but acceptable for those with possible AD (26 of 37, 70.3%). The results were similar in secondary analyses using alternate neuropathologic criteria for AD. The clinical diagnosis of AD can be made in community-based studies without the use of informant interviews, neuroimaging, blood work or routine case conferencing. This approach holds promise for reducing the operational costs of epidemiologic studies of aging and AD.

Quantification of Alzheimer pathology in ageing and dementia: age-related accumulation of amyloid-beta(42) peptide in vascular dementia

Clinicopathological observations suggest there is considerable overlap between vascular dementia (VaD) and Alzheimer's disease (AD). We used immunochemical methods to compare quantities of amyloid-beta (Abeta) peptides in post mortem brain samples from VaD, AD subjects and nondemented ageing controls. Total Abeta peptides extracted from temporal and frontal cortices were quantified using a previously characterized sensitive homogenous time-resolved fluorescence (HTRF) assay. The HTRF assays and immunocapture mass spectrometric analyses revealed that the Abeta(42) species were by far the predominant form of extractable peptide compared with Abeta(40) peptide in VaD brains. The strong signal intensity for the peak representing Abeta(4-42) peptide confirmed that these N-terminally truncated species are relatively abundant. Absolute quantification by HTRF assay showed that the mean amount of total Abeta(42) recovered from VaD samples was approximately 50% of that in AD, and twice that in the age-matched controls. Linear correlation analysis further revealed an increased accumulation with age of both Abeta peptides in brains of VaD subjects and controls. Interestingly, VaD patients surviving beyond 80 years of age exhibited comparable Abeta(42) concentrations with those in AD in the temporal cortex. Our findings suggest that brain Abeta accumulates increasingly with age in VaD subjects more so than in elderly without cerebrovascular disease and support the notion that they acquire Alzheimer-like pathology in older age.

Cognitive impairment in preclinical Alzheimer's disease: a meta-analysis

To determine the size of the impairment across different cognitive domains in preclinical Alzheimer's disease (AD), a meta-analysis based on 47 studies involving 9,097 controls and 1,207 preclinical AD cases was conducted. There were marked preclinical deficits in global cognitive ability, episodic memory, perceptual speed, and executive functioning; somewhat smaller deficits in verbal ability, visuospatial skill, and attention; and no preclinical impairment in primary memory. Younger age (< 75 years) and shorter follow-up intervals (< 3 years) were associated with larger effect sizes for both global cognitive ability and episodic memory. For global cognitive ability, studies that used population-based sampling yielded larger effect sizes; for episodic memory, larger differences were seen in studies that preidentified groups in terms of baseline cognitive impairment. Within episodic memory, delayed testing and recall-based assessment resulted in the largest effect sizes. The authors conclude that deficits in multiple cognitive domains are characteristic of AD several years before clinical diagnosis. The generalized nature of the deficit is consistent with recent observations that multiple brain structures and functions are affected long before the AD diagnosis.

Genetic association between the APOE*4 allele and Lewy bodies in Alzheimer disease

OBJECTIVE

To explore the association between APOE*4 and pathologically confirmed cases of the Lewy body (LB) variant of Alzheimer disease (AD).

METHODS

With use of alpha-synuclein (AS) immunohistochemistry, LBs were detected in 74 of 131 (56.5%) of the AD + LB cases; the remaining 57 cases (43.5%) did not have LBs.

RESULTS

There were no differences in gender or age between Caucasian subjects with AD + LB or AD alone or control subjects. The APOE*4 allele frequency was highest in the AD + LB group (47.3%; 95% CI = 37.8 to 57.0%), intermediate in the AD-alone group (35.1%; 95% CI = 25.3 to 46.3%), and lowest in the control group (14.2%; 95% CI = 10.5 to 18.9%). With use of logistic regression analysis, the odds of having AD + LB vs AD alone were 2.1-fold (95% CI = 1.0 to 4.5, p = 0.055) greater in persons with an APOE*4 allele than in those without an APOE*4 allele.

CONCLUSION

The APOE*4 allele is associated with the presence of concomitant Lewy bodies in Alzheimer disease.

The Rush Memory and Aging Project: study design and baseline characteristics of the study cohort

The long-term objective of the Rush Memory and Aging Project is to identify the postmortem indices linking genetic and environmental risk factors to the development of Alzheimer's disease (AD). The overall study design involves a detailed assessment of risk factors for AD in older persons without known dementia who agree to annual clinical evaluation and organ donation at the time of death. In contrast to other clinical-pathologic studies which are conducted on special populations, the Rush Memory and Aging Project enrolled a cohort with much greater diversity in terms of educational attainment, in addition to gender, race, and ethnicity. From September of 1997 through April of 2005, more than 1,000 older persons without known dementia from more than 30 residential facilities across the Chicago metropolitan area agreed to participate. Their mean age was 81 years, about a third had 12 or fewer years of education, a third were men, and about 10% were members of a racial or ethnic minority group. More than 950 already have completed their baseline clinical evaluation.

Tc-99m HMPAO brain SPECT findings in mild and moderate Alzheimer's disease: Correlation with event related potentials

We investigated whether brain SPECT findings show any differences between patients with mild and moderate Alzheimer's disease (AD) and to compare results with event related potentials (ERPs). Twenty-two patients with mild to moderate AD diagnosed according to NINCDS-ADRDA criteria and 10 age-matched control subjects were included in this prospective study. All subjects underwent ERP recordings and Tc-99m HMPAO brain SPECT study. Cortical perfusion index (CPI) was calculated as the ratio of cortical activity to the cerebellum activity. CPI was found to be statistically lower in bilaterally posterolateral temporal cortex and precuneus in the moderate AD compared to the control group. There was no statistically significant difference between the mild AD and control groups for CPI in any cortical areas. The mean P300 latency was statistically prolonged in the mild and moderate AD compared to the control group. In addition, in moderate AD P300 latency was longer than in mild AD. While the mean P300 amplitude was statistically reduced in moderate AD compared to the control and mild AD, there was no statistically significant difference between the mild AD and control groups. There was a strong negative correlation between P300 latency and CPI in the right and left precuneus in the moderate AD group. The present study suggested that Tc-99m HMPAO SPECT study is the more appropriate technique for patients with moderate AD rather than mild AD. Our results indicated that alterations in ERPs, especially prolongation of P300 latency could be a finding that occurred earlier than the deterioration in cerebral blood flow. We thought that precuneus is closely related to cognitive function and may have an important role in the pathophysiology of AD.

Imaging is superior to cognitive testing for early diagnosis of Alzheimer’s disease

Alzheimer's disease (AD) starts at a molecular level possibly decades earlier than could be detected by neuropsychological tests (NPTs). Neuropathological and neuroimaging data suggest that amyloid accumulation precedes the clinical onset of AD. Disease-modifying agents would have to be used early to alter the course of AD. Therefore, preclinical diagnosis is necessary. Structural and functional neuroimaging are superior for detection of the earliest stages of AD. Magnetic resonance imaging (MRI) and positron emission tomography (PET) techniques, including amyloid visualization, will have therapeutic importance for prevention as well as intervention as further refinements of current imaging techniques and biochemical markers occur. Neuropsychological tests measure the effect of pathology for an individual based upon norms obtained from an artificial population-often white and relatively highly educated. Unless serial NPTs are performed, the individual is compared to a population to which they may not conform. Neuroimaging can provide objective measures of preclinical disease state and, when measured serially, rate of change. Such information can be used in prevention trials.

Molecular genetics of Alzheimer's disease

Alzheimer disease (AD) is the most common cause of dementia. In the past decade, many advances in the understanding of the etiology of AD have been reported. Familial early onset AD is a heterogeneous disorder that can be caused by mutations in at least three different genes. Current studies are focused on identifying genetic risk factors for late onset AD. In this article, the authors will review the progress in understanding the pathogenic implications of the genes mutated in familial early onset AD and the mapping studies to identify additional genes involved in late-onset AD.