Research evaluation and diagnosis of probable Alzheimer's disease over the last two decades: I

Effect of blood collection tube containing protease inhibitors on the pre-analytical stability of Alzheimer's disease plasma biomarkers

The reliability of plasma biomarkers of Alzheimer's disease (AD) can be compromised by protease-induced degradation. This can limit the feasibility of conducting plasma biomarker studies in environments that lack the capacity for immediate processing and appropriate storage of blood samples. We hypothesized that blood collection tube supplementation with protease inhibitors can improve the stability of plasma biomarkers at room temperatures (RT). In this study, we conducted a comparative analysis of blood biomarker stability in traditional ethylenediaminetetraacetic acid (EDTA) tubes versus BD™ P100 collection tubes, the latter being coated with a protease inhibitor cocktail. The stability of six plasma AD biomarkers was evaluated over time under RT conditions. We evaluated three experimental approaches. In Approach 1, pooled plasma samples underwent storage at RT for up to 96 h. In Approach 2, plasma samples isolated upfront from whole blood collected into EDTA or P100 tubes were stored at RT for 0 h or 24 h before biomarker measurements. In Approach 3, whole blood samples were collected into paired EDTA and P100 tubes, followed by storage at RT for 0 h or 24 h before isolating the plasma for analyses. Biomarkers were measured with Single Molecule Array (Simoa) and immunoprecipitation-mass spectrometry (IP-MS) assays. Both the IP-MS and Simoa methods revealed that the use of P100 tubes significantly improves the stability of Aβ42 and Aβ40 across all approaches. However, the Aβ42/Aβ40 ratio levels were significantly stabilized only in the IP-MS assay in Approach 3. No significant differences were observed in the levels of plasma p-tau181, GFAP, and NfL for samples collected using either tube type in any of the approaches. Supplementation of blood collection tubes with protease inhibitors could reduce the protease-induced degradation of plasma Aβ42 and Aβ40, and the Aβ42/40 ratio for the IP-MS assay. These findings have crucial implications for preanalytical procedures, particularly in resource-limited settings.

Effect of blood collection tube containing protease inhibitors on the pre-analytical stability of Alzheimer's disease plasma biomarkers

INTRODUCTION

The reliability of plasma Alzheimer's disease (AD) biomarkers can be compromised by protease-induced degradation. This limits the feasibility of conducting plasma biomarker studies in environments that lack the capacity for immediate processing and appropriate storage of blood samples. We hypothesized that blood collection tube supplementation with protease inhibitors can improve the stability of plasma biomarkers at room temperatures (RT). This study conducted a comparative analysis of blood biomarker stability in traditional ethylenediaminetetraacetic acid (EDTA) tubes versus BD™ P100 collection tubes, the latter being coated with a protease inhibitor cocktail. The stability of six plasma AD biomarkers was evaluated over time under RT conditions.

METHODS

We evaluated three experimental approaches. In Approach 1, pooled plasma samples underwent storage at RT for up to 96 hours. In Approach 2, plasma samples isolated upfront from whole blood collected into EDTA or P100 tubes were stored at RT for 0h or 24h before biomarker measurements. In Approach 3, whole blood samples were collected into paired EDTA or P100 tubes, followed by storage at RT for 0h or 24h before isolating the plasma for analyses. Biomarkers were measured with Single Molecule Array (Simoa) and immunoprecipitation-mass spectrometry (IP-MS) assays.

RESULTS

Both the IP-MS and Simoa methods revealed that the use of P100 tubes significantly improved the stability of Aβ42 and Aβ40 across all approaches. Additionally, the Aβ42/Aβ40 ratio levels were significantly stabilized only in the IP-MS assay in Approach 3. No significant differences were observed in the levels of plasma p-tau181, GFAP, and NfL for samples collected using either tube type in any of the approaches.

CONCLUSION

Supplementation of blood collection tubes with protease inhibitors could reduce the protease-induced degradation of plasma Aβ42 and Aβ40, and the Aβ ratio for IP-MS assay. This has crucial implications for preanalytical procedures, particularly in resource-limited settings.

Vesicular Glutamate Transporter Changes in the Cortical Default Mode Network During the Clinical and Pathological Progression of Alzheimer's Disease

BACKGROUND

Altered glutamatergic neurotransmission may contribute to impaired default mode network (DMN) function in Alzheimer's disease (AD). Among the DMN hub regions, frontal cortex (FC) was suggested to undergo a glutamatergic plasticity response in prodromal AD, while the status of glutamatergic synapses in the precuneus (PreC) during clinical-neuropathological AD progression is not known.

OBJECTIVE

To quantify vesicular glutamate transporter VGluT1- and VGluT2-containing synaptic terminals in PreC and FC across clinical stages of AD.

METHODS

Unbiased sampling and quantitative confocal immunofluorescence of cortical VGluT1- and VGluT2-immunoreactive profiles and spinophilin-labeled dendritic spines were performed in cases with no cognitive impairment (NCI), mild cognitive impairment (MCI), mild-moderate AD (mAD), or moderate-severe AD (sAD).

RESULTS

In both regions, loss of VGluT1-positive profile density was seen in sAD compared to NCI, MCI, and mAD. VGluT1-positive profile intensity in PreC did not differ across groups, while in FC it was greater in MCI, mAD, and sAD compared to NCI. VGluT2 measures were stable in PreC while FC had greater VGluT2-positive profile density in MCI compared to sAD, but not NCI or mAD. Spinophilin measures in PreC were lower in mAD and sAD compared to NCI, while in FC they were stable across groups. Lower VGluT1 and spinophilin measures in PreC, but not FC, correlated with greater neuropathology.

CONCLUSION

Frank loss of VGluT1 in advanced AD relative to NCI occurs in both DMN regions. In FC, an upregulation of VGluT1 protein content in remaining glutamatergic terminals may contribute to this region's plasticity response in AD.

Clinical Effectiveness of Muscarinic Receptor-Targeted Interventions in Neuropsychiatric Disorders: A Systematic Review

BACKGROUND

For decades, treatment of mood disorders, psychoses, anxiety and dementia have been confounded by limited efficacy and high rates of treatment resistance. Preclinical and clinical evidence have highlighted disruption of cholinergic signalling in several neuropsychiatric conditions and examined intervention strategies including acetylcholinesterase inhibitors and nicotinic receptor-targeted intervention. However, the effectiveness of these approaches is often curtailed by on-target side effects. Post mortem studies implicate muscarinic receptor dysregulation in neuropsychiatric pathophysiology; therefore, we conducted a systematic review and meta-analysis to investigate the therapeutic efficacy and safety of muscarinic receptor-targeted interventions in adults with neuropsychiatric disorders.

METHODS

PubMed, EMBASE, PsycINFO, EBSCO and Web of Science were searched using relevant keywords from database inception to 7 August 2022. Randomised, double-blind, placebo-controlled studies were included if they investigated the effect of muscarinic receptor-targeted intervention in adults with a diagnosis of a neuropsychiatric disorder and were published in English. A narrative synthesis approach was adopted to describe the findings. Wherever three or more studies with a similar intervention were available, effect sizes were calculated, and a meta-analysis was performed. Cochrane risk-of-bias-2 tool was utilised to assess the risk of bias, and sensitivity analyses were performed to identify publication bias. Certainty analysis (high, moderate, low and/or very low) was conducted using GRADE criteria.

RESULTS

Overall, 33 studies met the inclusion criteria and 5 were included in the meta-analysis. Despite a limited pool with several different interventions, we found therapeutic efficacy of xanomeline (M₁/M₄ agonist) in primary psychotic disorders plus behavioural and psychological symptoms of dementia. Scopolamine showed a significant antidepressant effect in a combined cohort of major depressive and bipolar disorders in the short-term outcome measure, but no effect following cessation of treatment. Results from bias assessments suggest "very low" certainty in the antidepressant effect of scopolamine. Critical limitations of the current literature included low power, high heterogeneity in the patient population and a lack of active comparators.

CONCLUSION

While the results are not definitive, findings on muscarinic receptor-targeted interventions in several mental disorders are promising in terms of efficacy and safety, specifically in treating schizophrenia, mood disorders, and behavioural and psychiatric symptoms of Alzheimer's disease. However, orthosteric muscarinic receptor-targeted interventions are associated with a range of peripheral adverse effects that are thought to be mediated via M₂/M₃ receptors. The orthosteric binding site of muscarinic acetylcholine receptors is remarkably conserved, posing a challenge for subtype-selective interventions; nonetheless allosteric ligands with biased signalling pathways are now in development. We conclude that adequately powered prospective studies with subtype-selective interventions are required to determine the clinical effectiveness of muscarinic-receptor targeted interventions for the treatment of neuropsychiatric disorders.

Sleep Disturbances, Changes in Sleep, and Cognitive Function in Low-Income African Americans

BACKGROUND

Sleep problems may contribute to the disproportionate burden of Alzheimer's disease and related dementias (ADRD) among African Americans (AAs).

OBJECTIVE

To examine the role of sleep problems in contributing to cognitive function and clinically adjudicated cognitive impairment in a predominantly AA sample.

METHODS

This study (n = 216, 78.8% female; mean age = 67.7 years) examined associations between 1) the level (i.e., measured in 2018) and 2) change over time (from 2013 to 2018; n = 168) in actigraphy-assessed sleep with domain-specific cognitive function and clinically adjudicated cognitive impairment (2018) in a community-dwelling, predominantly AA (96.9%) sample. A comprehensive cognitive battery assessed global cognitive function (3MS) and domain-specific cognitive function (attention, visuo-spatial ability, language, delayed recall, immediate recall, and executive function) in 2018. Sleep was measured in 2013 and 2018 via actigraphy.

RESULTS

Higher sleep efficiency and less wakefulness after sleep onset (WASO; measured in 2018) were associated with greater attention, executive function, and visuospatial ability. Increases in sleep efficiency between 2013 and 2018 were associated with better executive function, language, immediate recall, and visuospatial ability, whereas increases in WASO (2013-2018) were associated with poorer attention, executive function, and visuospatial ability. Level or change in sleep duration were not associated with domain-specific cognitive function, nor were any sleep measures associated with clinically adjudicated cognitive impairment.

CONCLUSION

In a predominantly AA sample of older adults, both the level and change (i.e., worsening) of sleep efficiency and WASO were associated with poorer cognitive function. Improving sleep health may support ADRD prevention and reduce health disparities.

Small nucleolar RNAs in plasma extracellular vesicles and their discriminatory power as diagnostic biomarkers of Alzheimer's disease

The clinical diagnosis of Alzheimer's disease, at its early stage, remains a difficult task. Advanced imaging technologies and laboratory assays to detect Aβ peptides Aβ42 and Aβ40, total and phosphorylated tau in CSF provide a set of biomarkers of developing AD brain pathology and facilitate the diagnostic process. The search for biofluid biomarkers, other than in CSF, and the development of biomarker assays have accelerated significantly and now represent the fastest-growing field in AD research. The goal of this study was to determine the differential enrichment of noncoding RNAs (ncRNAs) in plasma-derived extracellular vesicles (EV) of AD patients and Cognitively Normal controls (NC). Using RNA-seq, we profiled four significant classes of ncRNAs: miRNAs, snoRNAs, tRNAs, and piRNAs. We report a significant enrichment of SNORDs - a group of snoRNAs, in AD samples compared to NC. To verify the differential enrichment of two clusters of SNORDs - SNORD115 and SNORD116, localized on human chromosome 15q11-q13, we used plasma samples of an independent group of AD patients and NC. We applied ddPCR technique and identified SNORD115 and SNORD116 with a high discriminatory power to differentiate AD samples from NC. The results of our study present evidence that AD is associated with changes in the enrichment of SNORDs, transcribed from imprinted genomic loci, in plasma EV and provide a rationale to further explore the validity of those SNORDs as plasma biomarkers of AD.

From Cerebrospinal Fluid Neurochemistry to Clinical Diagnosis of Alzheimer's Disease in the Era of Anti-Amyloid Treatments. Report of Four Patients

Analysis of classical cerebrospinal fluid biomarkers, especially when incorporated in a classification/diagnostic system such as the AT(N), may offer a significant diagnostic tool allowing correct identification of Alzheimer’s disease during life. We describe four patients with more or less atypical or mixed clinical presentation, in which the classical cerebrospinal fluid biomarkers amyloid peptide with 42 and 40 amino acids (Aβ₄₂ and Aβ₄₀, respectively), phospho-tau (τ_P-181) and total tau (τ_Τ) were measured. Despite the unusual clinical presentation, the biomarker profile was compatible with Alzheimer’s disease in all four patients. The measurement of classical biomarkers in the cerebrospinal fluid may be a useful tool in identifying the biochemical fingerprints of Alzheimer’s disease, especially currently, due to the recent approval of the first disease-modifying treatment, allowing not only typical but also atypical cases to be enrolled in trials of such treatments.

Cerebrospinal Fluid Biomarkers for Alzheimer's Disease in the Era of Disease-Modifying Treatments

Correct in vivo diagnosis of Alzheimer’s disease (AD) helps to avoid administration of disease-modifying treatments in non-AD patients, and allows the possible use of such treatments in clinically atypical AD patients. Cerebrospinal fluid (CSF) biomarkers offer a tool for AD diagnosis. A reduction in CSF β-amyloid (marker of amyloid plaque burden), although compatible with Alzheimer’s pathological change, may also be observed in other dementing disorders, including vascular cognitive disorders due to subcortical small-vessel disease, dementia with Lewy bodies and normal-pressure hydrocephalus. Thus, for the diagnosis of AD, an abnormal result of CSF β-amyloid may not be sufficient, and an increase in phospho-tau (marker of tangle pathology) is also required in order to confirm AD diagnosis in patients with a typical amnestic presentation and reveal underlying AD in patients with atypical or mixed and diagnostically confusing clinical presentations.

Diagnostic Accuracy of 10/66 Dementia Protocol in Fijian-Indian Elders Living in New Zealand

The 10/66 dementia protocol was developed as a language and culture-fair instrument to estimate the prevalence of dementia in non-English speaking communities. The aim of this study was to validate the 10/66 dementia protocol in elders of Indian ethnicity born in the Fiji Islands (Fijian-Indian) living in New Zealand. To our knowledge, this is the first time a dementia diagnostic tool has been evaluated in the Fijian-Indian population in New Zealand. We translated and adapted the 10/66 dementia protocol for use in in Fijian-Indian people. Individuals (age ≥ 65) who self-identified as Fijian-Indian and had either been assessed for dementia at a local memory service (13 cases, eight controls) or had participated in a concurrent dementia prevalence feasibility study (eight controls) participated. The sensitivity, specificity, positive predictive value, and Youden’s index were obtained by comparing the 10/66 diagnosis and its sub-components against the clinical diagnosis (reference standard). The 10/66 diagnosis had a sensitivity of 92.3% (95% CI 70.3–99.5), specificity of 93.8% (95% CI 75.3–99.6), positive predictive value of 92.3% (95% CI 70.3–99.5), and negative predictive value of 93.8% (95% CI 75.3–99.6). The study results show that the Fijian-Indian 10/66 dementia protocol has adequate discriminatory abilities to diagnose dementia in our sample. This instrument would be suitable for future dementia population-based studies in the Fijian-Indian population living in Aotearoa/New Zealand or the Fiji-Islands.

Hippocampal sclerosis, TDP-43, and the duration of the symptoms of dementia of AD patients

OBJECTIVES

To examine the relationship between duration of the cognitive symptoms, from the earliest reported symptom to death, and hippocampal sclerosis (HS) and TAR-DNA binding protein of 43kDA (TDP-43) in Alzheimer's disease (AD) patients.

METHODS

The study was conducted in 359 cognitively impaired patients who met the pathological criteria for AD (NIA-Reagan intermediate or high). The mean age at onset was 69.5 ± 8.8 years (range 37-95) and the mean duration of the symptoms was 10.5 ± 4.2 years. The association between symptoms duration and HS and TDP-43 was examined with logistic regression analyses controlling for age at death, atherosclerosis in the Circle of Willis (CW), cerebral infarcts, gender, baseline Mini Mental State Examination scores, APOE-4 allele, and presence of Lewy bodies (LB).

RESULTS

HS was present in 18% (n = 64) and TDP-43 in 51.5% (n = 185) of the patients. HS and TDP-43 were more frequent in patients whose symptoms lasted more than 10 years. LBs were present in 72% of the patients with HS and in 64% of the patients with TDP-43. Age at onset was not associated with TDP-43 or HS. HS was associated with duration of symptoms and LB, TDP-43, and atherosclerosis in the CW. TDP-43 was associated with duration of symptoms, LB, and HS.

INTERPRETATION

HS and TDP-43 are present in early and late onset AD. However, their presence is mainly driven by the duration of symptoms and the presence of LB. This suggests that HS and TDP-43 are part of the later neuropathological changes in AD.

Effects of Vitamin D Use on Outcomes of Psychotic Symptoms in Alzheimer Disease Patients

OBJECTIVE

To identify medications that may prevent psychosis in patients with Alzheimer disease (AD).

METHODS

The authors compared the frequency of medication usage among patients with AD with or without psychosis symptoms (AD + P versus AD - P). The authors also conducted survival analysis on time to psychosis for patients with AD to identify drugs with beneficial effects. The authors further explored the potential molecular mechanisms of identified drugs by gene-signature analysis. Specifically, the gene expression profiles induced by the identified drug(s) were collected to derive a list of most perturbed genes. These genes were further analyzed by the associations of their genetic variations with AD or psychosis-related phenotypes.

RESULTS

Vitamin D was used more often in AD - P patients than in AD + P patients. Vitamin D was also significantly associated with delayed time to psychosis. AD and/or psychosis-related genes were enriched in the list of genes most perturbed by vitamin D, specifically genes involved in the regulation of calcium signaling downstream of the vitamin D receptor.

CONCLUSION

Vitamin D was associated with delayed onset of psychotic symptoms in patients with AD. Its mechanisms of action provide a novel direction for development of drugs to prevent or treat psychosis in AD. In addition, genetic variations in vitamin D-regulated genes may provide a biomarker signature to identify a subpopulation of patients who can benefit from vitamin D treatment.

Comparison of longitudinal Aβ in nondemented elderly and Down syndrome

Down syndrome (DS) predisposes individuals to early Alzheimer's disease (AD). Using Pittsburgh Compound B ([11C]PiB), a pattern of striatal amyloid beta (Aβ) that is elevated relative to neocortical binding has been reported, similar to that of nondemented autosomal dominant AD mutation carriers. However, it is not known whether changes in striatal and neocortical [11C]PiB retention differ over time in a nondemented DS population when compared to changes in a nondemented elderly (NDE) population. The purpose of this work was to assess longitudinal changes in trajectories of Aβ in a nondemented DS compared to an NDE cohort. The regional trajectories for anterior ventral striatum (AVS), frontal cortex, and precuneus [11C]PiB retention were explored over time using linear mixed effects models with fixed effects of time, cohort, and time-by-cohort interactions and subject as random effects. Significant differences between DS and NDE cohort trajectories for all 3 region of interests were observed (p < 0.05), with the DS cohort showing a faster accumulation in the AVS and slower accumulation in the frontal cortex and precuneus compared to the NDE cohort. These data add to the previously reported distinct pattern of early striatal deposition not commonly seen in sporadic AD by demonstrating that individuals with DS may also accumulate Aβ at a rate faster in the AVS when compared to NDE subjects.

The Relationship of Current Cognitive Activity to Brain Amyloid Burden and Glucose Metabolism

Several studies have investigated how lifetime cognitive engagement affects levels of amyloid-beta (Aβ) deposition in the brain. However, there has been some disagreement, leaving the relationship of cognitive activity (CA) to Aβ a largely open question. The present study investigated the relationship between CA, Aβ deposition, and glucose metabolism. One hundred nine cognitively normal participants underwent Pittsburgh Compound-B (PiB) and [¹⁸F]fluorodeoxyglucose-positron emission tomography and completed a questionnaire designed to measure current CA. Statistical analyses revealed significant differences in PiB retention between those in the high and low CA groups. Linear regression models revealed a significant negative relationship between PiB retention and CA and a significant positive relationship between glucose metabolism and CA. These data suggest that CA may have a direct beneficial effect on the pathophysiology of AD or reflect another underlying process that results in both higher CA and lower AD pathophysiology.

Sleep moderates the relationship between amyloid beta and memory recall

Amyloid-β (Aβ) accumulation is a hallmark of Alzheimer's disease, although Aβ alone may be insufficient to cause impairments. Modifiable health factors, including sleep, may mitigate functional symptoms of neurodegeneration. We assessed whether sleep moderated the relationship between Aβ and cognitive performance in 41 older adults, mean age 83 years. Sleep measures included actigraphy-assessed wake after sleep onset and total sleep time. Cognitive performance was assessed with memory recall, cognitive flexibility, and verbal fluency. Memory recall was assessed with the Rey-Osterrieth Complex Figure task, cognitive flexibility with the Trail Making test, and verbal fluency with FAS word generation. Aβ was assessed with a global measure of Pittsburgh Compound B. Wake after sleep onset moderated the relationship between Aβ and memory, with a stronger positive association for Aβ and forgetting in those with poorer sleep. These results suggest a possible protective role of sleep in preclinical Alzheimer's disease.

Amyloid deposition and brain structure as long-term predictors of MCI, dementia, and mortality

OBJECTIVES

To test the hypothesis that brain structural integrity (i.e., hippocampal [HIP] volume), white matter lesions (WMLs), and β-amyloid deposition are associated with long-term increased risk of incident dementia and mortality in 183 cognitively normal individuals and patients with mild cognitive impairment (MCI) aged 80 years and older.

METHODS

All participants had a brain structural MRI scan and PET scan with ¹¹C-labeled Pittsburgh compound B in 2009 and were reexamined yearly through 2015 (mean follow-up time 5.2 ± 1.3 years).

RESULTS

In the last evaluation through 2010-2015, 56 (31%) participants were cognitively normal, 67 (37%) had MCI, and 60 (33%) had dementia. Fifty-seven (31%) died during follow-up, and 20 (35%) developed dementia before their death. All 3 biomarkers were independent predictors of incident dementia in all participants. After adjusting for the risk of dying, amyloid deposition and WMLs remained strong predictors. Of the 60 participants with incident dementia, 54 (90%) had at least one imaging abnormality. Participants with no biomarker positivity had a very low risk of dementia (16%), while 75% of the participants with the 3 biomarkers progressed to dementia. HIP volume and β-amyloid deposition were associated with death only in participants with MCI.

CONCLUSIONS

This study showed the presence of more than one biomarker was a stronger long-term predictor of incident dementia than any biomarker alone. After adjusting for the risk of dying, amyloid deposition and WMLs were stronger predictors of dementia than HIP volume. The risk of dying during follow-up was associated with both neurodegeneration and amyloid deposition, especially in individuals with MCI.

Factors influencing accuracy of cortical thickness in the diagnosis of Alzheimer's disease

There is great value to use of structural neuroimaging in the assessment of Alzheimer's disease (AD). However, to date, predictive value of structural imaging tend to range between 80% and 90% in accuracy and it is unclear why this is the case given that structural imaging should parallel the pathologic processes of AD. There is a possibility that clinical misdiagnosis relative to the gold standard pathologic diagnosis and/or additional brain pathologies are confounding factors contributing to reduced structural imaging classification accuracy. We examined potential factors contributing to misclassification of individuals with clinically diagnosed AD purely from cortical thickness measures. Correctly classified and incorrectly classified groups were compared across a range of demographic, biological, and neuropsychological data including cerebrospinal fluid biomarkers, amyloid imaging, white matter hyperintensity (WMH) volume, cognitive, and genetic factors. Individual subject analyses suggested that at least a portion of the control individuals misclassified as AD from structural imaging additionally harbor substantial AD biomarker pathology and risk, yet are relatively resistant to cognitive symptoms, likely due to "cognitive reserve," and therefore clinically unimpaired. In contrast, certain clinical control individuals misclassified as AD from cortical thickness had increased WMH volume relative to other controls in the sample, suggesting that vascular conditions may contribute to classification accuracy from cortical thickness measures. These results provide examples of factors that contribute to the accuracy of structural imaging in predicting a clinical diagnosis of AD, and provide important information about considerations for future work aimed at optimizing structural based diagnostic classifiers for AD.

Alzheimer's Disease Diagnosis Relies on a Twofold Clinical-Biological Algorithm: Three Memory Clinic Case Reports

The International Working Group recently provided revised criteria of Alzheimer's disease (AD) proposing that the diagnosis of typical amnesic AD should be established by a clinical-biological signature, defined by the phenotype of an "amnesic syndrome of the hippocampal type" (ASHT) combined with positive in vivo evidence of AD pathophysiology in the cerebrospinal fluid (CSF) or on amyloid PET imaging. The application and clinical value of this refined diagnostic algorithm, initially intended for research purposes, is explored in three memory clinic cases presenting with different cognitive profiles including an ASHT, hippocampal atrophy, and CSF AD-biomarker data. The case reports highlight that the isolated occurrence of one of the two proposed AD criteria, ASHT or positive pathophysiological markers, does not provide a reliable diagnosis of typical AD. It is proposed that the twofold diagnostic IWG algorithm can be applied and operationalized in memory clinic settings to improve the diagnostic accuracy of typical amnesic AD in clinical practice.

Development of a Standardized Approach to Disclosing Amyloid Imaging Research Results in Mild Cognitive Impairment

The increased use of PET amyloid imaging in clinical research has sparked numerous concerns about whether and how to return such research test results to study participants. Chief among these is the question of how best to disclose amyloid imaging research results to individuals who have cognitive symptoms that could impede comprehension of the information conveyed. We systematically developed and evaluated informational materials for use in pre-test counseling and post-test disclosures of amyloid imaging research results in mild cognitive impairment (MCI). Using simulated sessions, persons with MCI and their family care partners (N = 10 dyads) received fictitious but realistic information regarding brain amyloid status, followed by an explanation of how results impact Alzheimer's disease risk. Satisfaction surveys, comprehension assessments, and focus group data were analyzed to evaluate the materials developed. The majority of persons with MCI and their care partners comprehended and were highly satisfied with the information presented. Focus group data reinforced findings of high satisfaction and included 6 recommendations for practice: 1) offer pre-test counseling, 2) use clear graphics, 3) review participants' own brain images during disclosures, 4) offer take-home materials, 5) call participants post-disclosure to address emerging questions, and 6) communicate seamlessly with primary care providers. Further analysis of focus group data revealed that participants understood the limitations of amyloid imaging, but nevertheless viewed the prospect of learning one's amyloid status as valuable and empowering.

Incident Psychosis in Subjects With Mild Cognitive Impairment or Alzheimer's Disease

OBJECTIVE

To estimate the incidence of psychotic symptoms in Alzheimer's disease.

METHODS

The study consists of 776 elderly subjects presenting to the Alzheimer Disease Research Center at the University of Pittsburgh (Pittsburgh, Pennsylvania) between May 9, 2000, and August 19, 2014. All participants were diagnosed with mild cognitive impairment (National Institute on Aging-Alzheimer's Association workgroup criteria) or possible or probable Alzheimer's disease (National Institute of Neurologic and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria) and were without psychosis at entry. Psychotic symptoms were evaluated using the Consortium to Establish a Registry for Alzheimer's Disease Behavioral Rating Scale every 6 months. One-, 3- and 5-year cumulative incidences of psychosis were calculated.

RESULTS

The 1-year psychosis incidence was 10% (95% CI, 8%-12%), and this annual rate remained remarkably consistent at 3 and 5 years. Psychosis incidence was related to cognitive status at all time points. However, the incidence rate reached a plateau during the disease course. Cumulative psychosis incidence at 5 years was 61% (95% CI, 52%-69%) in individuals with moderate to severe Alzheimer's disease, not statistically significantly different from the cumulative incidence at 3 years in this group, which was 48% (95% CI, 40%-55%) or from the 5-year incidence in individuals who entered the study with mild Alzheimer's disease, which was 48% (95% CI, 41%-56%).

CONCLUSIONS

Psychosis in Alzheimer's disease has been associated with a number of adverse clinical outcomes. We provide estimates of the risk of psychosis onset within clinically defined subgroups of individuals, a tool clinicians can use in treatment planning. Anticipating which subjects are at high risk for psychosis and the poor outcomes associated with it can help with family education and support decisions to implement nonpharmacologic strategies that may reduce or prevent symptoms.

Integrated care pathways in dementia: a challenge to National Institute for Health and Clinical Excellence/Social Care Institute for Excellence guidance

An integrated care pathway (ICP) is proposed for the diagnosis of dementia syndromes, encompassing the various disciplines which may be involved (psychiatry, geriatrics, neurology, clinical genetics) due to the heterogeneity of presentation at the clinical and aetiological level. This proposed ICP challenges guidance recently issued by the National Institute for Health and Clinical Excellence (NICE) and the Social Care Institute for Excellence (SCIE), which requires a ‘single point of referral’ to access all dementia services. The proposal is prompted by the non-unitary nature of dementia, which may be envisaged as a ‘boundary’ condition transcending traditional professional categories and involving a wide array of professional groups in patient diagnosis in secondary care. Diversity rather than uniformity may best serve patient needs in such a heterogeneous syndrome.

Exploring the excess mortality due to depressive symptoms in a community-based sample: The role of Alzheimer's Disease

BACKGROUND

Depression has been associated with increased risk of death. However, there is lack of studies exploring such relationship in the context of dementia. Given the high prevalence of both depression and Alzheimer's Disease (AD), investigating their temporal association with mortality is of public health relevance.

METHODS

Longitudinal data from the WHICAP study were analyzed (1958 individuals aged ≥65 years). Depressive symptoms were assessed with the 10-item Center for Epidemiologic Studies Depression Scale (CES-D). Respondents were identified as having AD if they satisfied the criteria of the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease. Cox regressions analyses were performed to determine the association between depressive symptoms and risk of all-cause mortality using the overall sample, and by AD status.

RESULTS

Depressive symptoms were significantly associated with higher mortality risk after adjusting for all potential covariates in the overall sample (HR=1.22; 95% CI=1.02, 1.46) and in individuals with incident AD (HR=1.88; 95% CI=1.12, 3.18).

LIMITATIONS

The CES-D does not measure clinical depression but depressive symptomatology. Since those who were exposed to known risk factors for mortality are likely to die prematurely, our results may have been skewed to the individuals with longer survival.

CONCLUSIONS

Strategies focusing on prevention and early treatment of depression in the elderly may have a beneficial effect not only on patient quality of life and disability, but may also increase survival in the context of AD.

Amyloid-β Imaging in Older Adults Presenting to a Memory Clinic with Subjective Cognitive Decline: A Pilot Study

BACKGROUND

Subjective cognitive decline (SCD) in otherwise normal aging may be identified via symptom inventories in a research setting ('questionnaire-discovered complaints') or via patients seeking evaluation/services in a clinical setting ('presenting complainers'). Most studies of SCD and amyloid-β (Aβ) imaging to date have used the former approach, with inconsistent results.

OBJECTIVE

To test whether 'presenting SCD' participants in an academic memory clinic setting show increased brain Aβ deposition on imaging.

METHODS

Fourteen patients (mean age 68.1, SD 4.0 years) diagnosed with subjective cognitive complaints with normal neuropsychological testing were recruited into a Pittsburgh compound B (PiB)-PET study. Detailed self-report inventories and additional cognitive tests were administered. Results were compared to a reference cohort of cognitively normal volunteers (NC) from an independent neuroimaging study (mean age 73.6, SD 5.8 years).

RESULTS

57% (8/14) of SCD participants were PiB-positive by a sensitive, regionally-based definition, compared to 31% (26/84) of the NC cohort. SCD participants had significantly higher PiB retention (SUVR) than NC in three of six regions of interest: frontal cortex (p = 0.02), lateral temporal cortex (p = 0.02), and parietal cortex (p = 0.04). SCD participants showed measurable deviations on questionnaires reflecting high negative affect (i.e., depressive symptoms and neuroticism). Findings were suggestive that deficits on verbal associative binding may be specific to Aβ-positive versus Aβ-negative SCD.

CONCLUSION

Older participants with SCD presenting to a memory clinic in this pilot study sample have higher brain Aβ deposition compared to normal aging study volunteers unselected on complaints. Further study of presenting SCD are warranted to determine the prognostic significance of Aβ deposition in this context.

Psychometric Properties of a Decisional Capacity Screening Tool for Individuals Contemplating Participation in Alzheimer's Disease Research

BACKGROUND

With the growing population of individuals affected by Alzheimer's disease (AD) and related disorders, there is a pressing demand for research on late-life cognitive disorders. However, this population's high risk for decisional incapacity necessitates evaluation of capacity to consent to research participation, adding cost and complexity to the research process. The University of California, San Diego Brief Assessment of Capacity to Consent (UBACC) was initially validated in a sample of persons with schizophrenia and healthy controls.

OBJECTIVE

To assess the psychometric properties of the UBACC when used in a sample of individuals contemplating participation in AD research.

METHODS

The UBACC was administered to a convenience sample (n = 132) consisting of individuals with mild to moderate cognitive impairment (n = 52), their study partners (n = 52), and healthy older adults control subjects (n = 30), as part of a broader study to evaluate perceived burden of research participation. Reliability tests, correlational analyses, and exploratory factor analytic methods were used to examine the psychometric properties of the instrument.

RESULTS

UBACC scores were significantly associated with both global cognition (rs= 0.564, p <  0.001) and verbal fluency (rs = 0.511, p <  0.001), indicating concurrent validity with related constructs. The resulting factor structure differed from that reported by the developers in their initial testing. Items clustered almost entirely on one factor; items reflecting the construct of understanding accounted for 32.12% of total variance, with no evidence for distinct reasoning or appreciation scales.

CONCLUSION

The UBACC shows promise when used to screen for decisional capacity among those considering participation in AD research.

A Bayesian model of psychosis symptom trajectory in Alzheimer's disease

OBJECTIVE

Psychosis, like other neuropsychiatric symptoms of dementia, has many features that make predictive modeling of its onset difficult. For example, psychosis onset is associated with both the absolute degree of cognitive impairment and the rate of cognitive decline. Moreover, psychotic symptoms, while more likely than not to persist over time within individuals, may remit and recur. To facilitate predictive modeling of psychosis for personalized clinical decision making, including evaluating the role of risk genes in its onset, we have developed a novel Bayesian model of the dual trajectories of cognition and psychosis symptoms.

METHODS

Cognition was modeled as a four-parameter logistic curve with random effects for all four parameters and possible covariates for the rate and time of fall. Psychosis was modeled as a continuous-time hidden Markov model with a latent never-psychotic class and states for pre-psychotic, actively psychotic and remitted psychosis. Covariates can affect the probability of being in the never-psychotic class. Covariates and the level of cognition can affect the transition rates for the hidden Markov model.

RESULTS

The model characteristics were confirmed using simulated data. Results from 434 AD patients show that a decline in cognition is associated with an increased rate of transition to the psychotic state.

CONCLUSIONS

The model allows declining cognition as an input for psychosis prediction, while incorporating the full uncertainty of the interpolated cognition values. The techniques used can be used in future genetic studies of AD and are generalizable to the study of other neuropsychiatric symptoms in dementia.

A New Measure of Research Participant Burden: Brief Report

Effective conceptualizations of research burden should address indirect burdens related to research duration, intensity, and invasiveness. Introducing the concept of perceived research burden, we developed, tested, and validated a new instrument, the Perceived Research Burden Assessment (PeRBA). Initial psychometric evaluation of PeRBA reveals good internal consistency, evidence of face validity, and acceptable convergent and discriminant validity.

Alzheimer's disease or Alzheimer's syndrome?: a longitudinal computed tomography neuroradiological follow-up study of 56 cases diagnosed clinically as Alzheimer's disease

BACKGROUND

Some 200 patients, including those with Alzheimer's disease and other types of dementia, stay year-round in Yokohama - Houyuu Hospital. They undergo computed tomography (CT) neuroradiological examination at least once or twice a year. For this study, the accumulative data, including clinical and neuroradiological, were analyzed.

METHODS

Differential diagnoses of Alzheimer's disease were performed in accordance with the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria. The 56 patients (15 men, 41 women) included in this study underwent in-hospital observation on average for 4.4 years (range: 1-10 years). The patients were classified into four groups according to the age of disease onset. The CT findings were summarized for each group and then compared among the groups to determine if there were any differences related to age of onset and, if so, to identify and analyze them.

RESULTS

(1) The duration of deceased cases' total clinical course (in years) compared among the four groups. In general, the degree of dementia was more severe among those with earlier disease onset. (2) In cases admitted within 2 years from onset (n =14), the suspected initiating focus of cortical atrophy occurred in the frontal lobe (n = 6), the temporal lobe (n = 6), or the fronto-temporal lobes (n = 2). (3) Although CT findings generally showed that the more severe cases had earlier onset, serial CT examinations in each case showed widely different pathologies in degree, nature and manner of progression, regardless of group classification. (4) The earliest sites of brain atrophy, sites of its severest involvement within the brain, and neuroradiological development of the cerebral cortex pathology in combination with hemispheric white matter, lateral ventricles, and third ventricles varied among the four groups and between case within each group. Alzheimer's disease could not be subclassified simply by the age of clinical onset.

CONCLUSION

Cases of so-called Alzheimer's disease, as observed through continued clinical follow-up and serial CT examinations, appear so diverse in symptomatology and radiological pathomorphology that it is difficult to consider them a single nosological entity. The pathology of Alzheimer's disease has to be reconsidered in accordance with the variety observed in the sequential development of neuroradiological findings. The pathology must be reconstructed in terms of topographical dimensions and chronological developments. The diagnosis of Alzheimer's disease appears to be not so simple based on any conventional diagnostic operational standards.

Cognitive testing in older primary care patients: A cluster-randomized trial

Introduction

This study investigated whether neuropsychological testing in primary care (PC) offices altered physician-initiated interventions related to cognitive impairment (CI) or slowed the rate of CI progression.

Methods

This 24-month, cluster-randomized study included 11 community-based PC practices randomized to either treatment as usual (5 practices) or cognitive report (CR; 6 practices) arms. From 2005 to 2008, 533 patients aged ≥65 years and without a diagnosis of CI were recruited; 423 were retested 24 months after baseline.

Results

CR physicians were significantly more likely to order cognitive-related interventions (P = .02), document discussions about cognition (P = .003), and order blood tests to rule out reversible CI (P = .002). At follow-up, significantly more CR patients had a medication for cognition listed in their chart (P = .02). There was no difference in the rate of cognitive decline between the groups.

Discussion

Providing cognitive information to physicians resulted in higher rates of physician-initiated interventions for patients with CI.

Longitudinal assessment of neuroimaging and clinical markers in autosomal dominant Alzheimer's disease: a prospective cohort study

BACKGROUND

The biomarker model of Alzheimer's disease postulates a dynamic sequence of amyloidosis, neurodegeneration, and cognitive decline as an individual progresses from preclinical Alzheimer's disease to dementia. Despite supportive evidence from cross-sectional studies, verification with long-term within-individual data is needed.

METHODS

For this prospective cohort study, carriers of autosomal dominant Alzheimer's disease mutations (aged ≥21 years) were recruited from across the USA through referrals by physicians or from affected families. People with mutations in PSEN1, PSEN2, or APP were assessed at the University of Pittsburgh Alzheimer's Disease Research Center every 1-2 years, between March 23, 2003, and Aug 1, 2014. We measured global cerebral amyloid β (Aβ) load using (11)C-Pittsburgh Compound-B PET, posterior cortical metabolism with (18)F-fluorodeoxyglucose PET, hippocampal volume (age and sex corrected) with T1-weighted MRI, verbal memory with the ten-item Consortium to Establish a Registry for Alzheimer's Disease Word List Learning Delayed Recall Test, and general cognition with the Mini Mental State Examination. We estimated overall biomarker trajectories across estimated years from symptom onset using linear mixed models, and compared these estimates with cross-sectional data from cognitively normal control individuals (age 65-89 years) who were negative for amyloidosis, hypometabolism, and hippocampal atrophy. In the mutation carriers who had the longest follow-up, we examined the within-individual progression of amyloidosis, metabolism, hippocampal volume, and cognition to identify progressive within-individual changes (a significant change was defined as an increase or decrease of more than two Z scores standardised to controls).

FINDINGS

16 people with mutations in PSEN1, PSEN2, or APP, aged 28-56 years, completed between two and eight assessments (a total of 83 assessments) over 2-11 years. Significant differences in mutation carriers compared with controls (p<0·01) were detected in the following order: increased amyloidosis (7·5 years before expected onset), decreased metabolism (at time of expected onset), decreased hippocampal volume and verbal memory (7·5 years after expected onset), and decreased general cognition (10 years after expected onset). Among the seven participants with longest follow-up (seven or eight assessments spanning 6-11 years), three individuals had active amyloidosis without progressive neurodegeneration or cognitive decline, two amyloid-positive individuals showed progressive neurodegeneration and cognitive decline without further progressive amyloidosis, and two amyloid-positive individuals showed neither active amyloidosis nor progressive neurodegeneration or cognitive decline.

INTERPRETATION

Our results support amyloidosis as the earliest component of the biomarker model in autosomal dominant Alzheimer's disease. Our within-individual examination suggests three sequential phases in the development of autosomal dominant Alzheimer's disease-active amyloidosis, a stable amyloid-positive period, and progressive neurodegeneration and cognitive decline-indicating that Aβ accumulation is largely complete before progressive neurodegeneration and cognitive decline occur. These findings offer supportive evidence for efforts to target early Aβ deposition for secondary prevention in individuals with autosomal dominant Alzheimer's disease.

FUNDING

National Institutes of Health and Howard Hughes Medical Institute.

Genome-wide copy-number variation study of psychosis in Alzheimer's disease

About 40-60% of patients with late-onset Alzheimer's disease (AD) develop psychosis, which represents a distinct phenotype of more severe cognitive and functional deficits. The estimated heritability of AD+P is ~61%, which makes it a good target for genetic mapping. We performed a genome-wide copy-number variation (CNV) study on 496 AD cases with psychosis (AD+P), 639 AD subjects with intermediate psychosis (AD intermediate P) and 156 AD subjects without psychosis (AD-P) who were recruited at the University of Pittsburgh Alzheimer's Disease Research Center using over 1 million single-nucleotide polymorphisms (SNPs) and CNV markers. CNV load analysis found no significant difference in total and average CNV length and CNV number in the AD+P or AD intermediate P groups compared with the AD-P group. Our analysis revealed a marginally significant lower number of duplication events in AD+P cases compared with AD-P controls (P=0.059) using multivariable regression model. The most interesting finding was the presence of a genome-wide significant duplication in the APC2 gene on chromosome 19, which was protective against developing AD+P (odds ratio=0.42; P=7.2E-10). We also observed suggestive associations of duplications with AD+P in the SET (P=1.95E-06), JAG2 (P=5.01E-07) and ZFPM1 (P=2.13E-07) genes and marginal association of a deletion in CNTLN (P=8.87E-04). We have identified potential novel loci for psychosis in Alzheimer's disease that warrant follow-up in large-scale independent studies.

Dyadic Analysis of Illness Perceptions Among Persons with Mild Cognitive Impairment and Their Family Members

PURPOSE OF THIS STUDY

To characterize illness perceptions among persons with mild cognitive impairment (PWMCI) and their family care partners, and to examine whether PWMCI's and their family care partners' illness perceptions were associated with their own, as well as the other member of the dyad's, emotional reactions to MCI.

DESIGN AND METHODS

This cross-sectional study of PWMCI and their family care partners (n = 60 dyads) used patient and relative versions of the Revised Illness Perception Questionnaire (IPQ-R) to assess metacognitive and emotional features of illness perception in MCI along 5 dimensions of perceived: seriousness of potential consequences, personal controllability, timeline, fluctuation (cycling) of symptoms, and illness coherence (clear vs. confusing).

RESULTS

As compared to family members, PWMCI perceived MCI to be less potentially serious and to be more within their personal control, but dyads otherwise shared similar perceptions of MCI. Among PWMCI, perceived seriousness of the potential consequences of MCI was the only dimension to be significantly correlated with emotional distress. For family members, increased MCI-related emotional distress was significantly associated with perceptions of MCI as potentially serious, permanent, or confusing. A dyadic analysis using APIM showed that MCI-related emotional distress, in both PWMCI and family members, was linked to the PWMCI's perception of the seriousness of MCI.

IMPLICATIONS

MCI-related education and support should be tailored for both the PWMCI and family member audiences, while acknowledging interdependence of illness perceptions within family units. Tailored information and support will be critical in managing MCI going forward, as illness perceptions are likely key factors on which individuals will plan for the future or base medical decisions.

Amyloid imaging in atypical presentations of Alzheimer's disease

Alzheimer's disease (AD) is thought to progress in a fairly stereotyped manner, with episodic memory loss being the first and most salient domain of impairment, reflecting the early disease in structures supporting this function. However, there is considerable heterogeneity in the relative involvement of different cognitive domains, and at the extreme are three syndromes associated with AD: (1) logopenic progressive aphasia, (2) posterior cortical atrophy, and (3) frontal variant of AD. As each of these syndromes is variably associated with non-AD dementia and clinically overlaps with other presentations more commonly associated with different causes of neurodegeneration (e.g., progressive nonfluent aphasia), the use of amyloid imaging for detection of the molecular pathologic features of AD is of significant clinical value. This article reviews several amyloid imaging studies of these populations which support autopsy case series and reveal a dissociation between the spatial distribution of amyloid plaques and clinical phenotype.

Infection hospitalization increases risk of dementia in the elderly

OBJECTIVES

Severe infections, often requiring ICU admission, have been associated with persistent cognitive dysfunction. Less severe infections are more common and whether they are associated with an increased risk of dementia is unclear. We determined the association of pneumonia hospitalization with risk of dementia in well-functioning older adults.

DESIGN

Secondary analysis of a randomized multicenter trial to determine the effect of Gingko biloba on incident dementia.

SETTING

Five academic medical centers in the United States.

SUBJECTS

Healthy community volunteers (n = 3,069) with a median follow-up of 6.1 years.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

We identified pneumonia hospitalizations using International Classification of Diseases, 9th Edition-Coding Manual codes and validated them in a subset. Less than 3% of pneumonia cases necessitated ICU admission, mechanical ventilation, or vasopressor support. Dementia was adjudicated based on neuropsychological evaluation, neurological examination, and MRI. Two hundred twenty-one participants (7.2%) incurred at least one hospitalization with pneumonia (mean time to pneumonia = 3.5 yr). Of these, dementia was developed in 38 (17%) after pneumonia, with half of these cases occurring 2 years after the pneumonia hospitalization. Hospitalization with pneumonia was associated with increased risk of time to dementia diagnosis (unadjusted hazard ratio = 2.3; CI, 1.6-3.2; p < 0.0001). The association remained significant when adjusted for age, sex, race, study site, education, and baseline mini-mental status examination (hazard ratio = 1.9; CI, 1.4-2.8; p < 0.0001). Results were unchanged when additionally adjusted for smoking, hypertension, diabetes, heart disease, and preinfection functional status. Results were similar using propensity analysis where participants with pneumonia were matched to those without pneumonia based on age, probability of developing pneumonia, and similar trajectories of cognitive and physical function prior to pneumonia (adjusted prevalence rates, 91.7 vs 65 cases per 1,000 person-years; adjusted prevalence rate ratio = 1.6; CI, 1.06-2.7; p = 0.03). Sensitivity analyses showed that the higher risk also occurred among those hospitalized with other infections.

CONCLUSION

Hospitalization with pneumonia is associated with increased risk of dementia.

Measuring hope among families impacted by cognitive impairment

The current exploratory investigation aims to establish the reliability and validity of a hope measure, the Herth Hope Index, among families impacted by early cognitive impairment (N = 96). Exploratory factor analysis was used to examine the dimensionality of the measure. Bivariate analyses were used to examine construct validity. The sample had moderately high hope scores. A two-factor structure emerged from the factor analysis, explaining 51.44% of the variance. Both factors exhibited strong internal consistency (Cronbach's alphas ranged from .83 to .86). Satisfaction with social support was positively associated with hope, supporting convergent validity. Neurocognitive status, illness insight, and depression were not associated with hope, indicating discriminant validity. Families impacted by cognitive impairment may maintain hope in the face of a potentially progressive illness, regardless of cognitive status. The Herth Hope Index can be utilized as a reliable and valid measure of hope by practitioners providing support to families impacted by cognitive impairment.

Spousal loss and cognitive function in later life: a 25-year follow-up in the AGES-Reykjavik study

The aim of this study was to investigate the associations between loss of a life partner and the development of dementia and decline in cognitive function in later life. We used an Icelandic cohort of 4,370 participants in the Age, Gene/Environment Susceptibility-Reykjavik Study who were living as married in 1978 (born in 1907-1935) and were either still married (unexposed cohort) or widowed (exposed cohort) at follow-up (in 2002-2006). We ascertained history of marital status and spouse's death by record linkage to the Registry of the Total Population, Statistics Iceland. The outcome measures were as follows: 1) dementia and mild cognitive impairment; and 2) memory, speed of processing, and executive function. During the observation period, 3,007 individuals remained married and 1,363 lost a spouse through death. We did not find any significant associations between loss of a spouse and our outcome variables, except that widowed women had poorer executive function (mean = -0.08) during the first 2 years after their husbands' deaths compared with still-married women (mean = 0.09). Our findings do not support the notion that the risk of dementia is increased following the loss of a spouse, yet women demonstrate a seemingly temporary decline in executive function following the death of a partner.

Investigation of an amyloid precursor protein protective mutation (A673T) in a North American case-control sample of late-onset Alzheimer's disease

A rare amyloid precursor protein gene variant, A673T (rs63750847) was recently reported to protect against Alzheimer's disease and age-related cognitive decline among Icelanders and the same rare variant was observed also in Finnish, Norwegian, and Swedish populations. We investigated this variant in 1674 late-onset Alzheimer's disease cases and 2644 elderly control subjects, all North American Whites (US Whites). We did not observe any example of the A673T variant in our large sample. Our findings suggest that this rare variant could be specific to the individuals of the origin from the Nordic countries.

[An autopsy case of Alzheimer's disease presenting with corticobasal syndrome]

A right-handed Japanese man developed memory loss at 51 years of age. The right side clumsiness developed from 52 years of age and then progressively worsened. Temporal/parietal lobe atrophy was observed predominantly on the left side upon MR imaging. Subsequently, limb-kinetic apraxia and parkinsonism became apparent predominantly on the right side. These symptoms became aggravated along with dementia, ultimately leading to an apallic state. The patient eventually died at the age of 59 due to aspiration pneumonia. An autopsy was carried out and cerebral atrophy was observed predominantly on the left side. Senile plaques were observed on the entire cerebral cortex at a high frequency, along with many cotton wool plaques. Anti-phosphorylated tau-positive neurofibrillary tangles and several neuropil threads were observed upon immunostaining. The tau-positive structures were also positive for both RD3 and RD4 antibodies. The findings of tauopathy of the glia were poor, and the tau lesion of the brainstem was milder than that of the cerebral cortex. These results suggest the possibility that the corticobasal syndrome clinically developed in some type of Alzheimer's disease and a definite diagnosis was made only by pathological examination.

The long-term effects of conventional and atypical antipsychotics in patients with probable Alzheimer's disease

OBJECTIVE

The authors sought to determine the effects of conventional and atypical antipsychotic use on time to nursing home admission and time to death in a group of outpatients with mild to moderate probable Alzheimer's disease.

METHOD

The authors examined time to nursing home admission and time to death in 957 patients with the diagnosis of probable Alzheimer's disease who had at least one follow-up evaluation (mean follow-up time, 4.3 years [SD=2.7]; range, 0.78-18.0 years) using Cox proportional hazard models adjusted for age, gender, education level, dementia severity, hypertension, diabetes mellitus, heart disease, extrapyramidal signs, depression, psychosis, aggression, agitation, and dementia medication use.

RESULTS

A total of 241 patients (25%) were exposed to antipsychotics at some time during follow-up (conventional, N=138; atypical, N=95; both, N=8). Nursing home admission (63% compared with 23%) and death (69% compared with 34%) were more frequent in individuals taking conventional than atypical antipsychotics. In a model that included demographic and cognitive variables, hypertension, diabetes mellitus, heart disease, incident strokes, and extrapyramidal signs, only conventional antipsychotic use was associated with time to nursing home admission. However, the association was no longer significant after adjustment for psychiatric symptoms. Psychosis was strongly associated with nursing home admission and time to death, but neither conventional nor atypical antipsychotics were associated with time to death.

CONCLUSIONS

The use of antipsychotic medications, both conventional and atypical, was not associated with either time to nursing home admission or time to death after adjustment for relevant covariates. Rather, it was the presence of psychiatric symptoms, including psychosis and agitation, that was linked to increased risk of institutionalization and death after adjustment for exposure to antipsychotics.

Gray matter atrophy associated with extrapyramidal signs in the Lewy body variant of Alzheimer's disease

Up to 60% of the patients with Alzheimer's disease (AD) can have cortical or brainstem Lewy bodies (LB), and extrapyramidal signs (EPS) have been found to be associated with LB in AD patients. However, the relationship between EPS and brain volumes has not been studied in the LB variant of AD using structural magnetic resonance imaging (MRI). The purpose of this study was to determine the relationship between patterns of brain atrophy and clinical EPS in patients with pathologically confirmed AD. We compared gray matter structure using voxel-based morphometry in 29 Definite AD cases, 16 (55%) of whom also had LBs identified with α-synuclein immunohistochemistry. Multivariate models analyzed brain volume at a voxel level accounting for subject group, Mini-Mental State Examination (MMSE), EPS, total brain volume, and the time from MRI scan to death. There was no significant difference in gray matter volume in the Definite AD patients as a function of LB. There was a significant association between gray matter volumes and the MMSE in AD patients, both with and without LBs. There was a significant correlation between gray matter volume and EPS only in the group of AD patients with LBs, and not in those with pure AD. These findings suggest that that the etiology of EPS in patients with the LB variant of AD is associated with neuronal loss in the nigrostriatal tracts. By contrast, the source of the EPS in AD alone appears to be less well localized.

The impact of alcohol on Alzheimer's disease: a systematic review

Currently, there is discrepancy regarding alcohol's impact on Alzheimer's disease (AD). Consequently, the purpose of this systematic review was to determine whether alcohol serves as a protective agent against the development of AD, as well as whether protective effects are influenced by quantity and/or frequency of drinking. Adapted versions of the Matrix Method and PRISMA guidelines were used in order to identify, organize, and synthesize relevant research. Overall, there is no consensus regarding alcohol's impact on AD. Specifically, seven articles suggested drinking alcohol decreases the risk of AD, three studies found drinking led to an increased risk of AD, and yet another nine reported alcohol had no impact on AD. Validity and consistency of both alcohol and AD measures across studies represents a severe limitation. Prior to the development of standards and/or clinical recommendations, more investigations into the association between alcohol and AD are necessary. Considering the current evidence base, alcohol should not be used as a means to decrease risk of developing AD.

Definitions of dementia and predementia states in Alzheimer's disease and vascular cognitive impairment: consensus from the Canadian conference on diagnosis of dementia

There have been several newly proposed sets of diagnostic criteria for Alzheimer's disease/mild cognitive impairment, advanced by the National Institute of Aging/Alzheimer's Association working groups in 2011 and by the International Working Group in 2007 and 2010. These sets each aim to provide broader disease stage coverage with incorporation of disease biomarkers into the diagnostic process. They have focused particular attention on the earlier identification of disease with focus on the preclinical and predementia stages. This paper reviews these diagnostic criteria and provides 2012 consensus recommendations from the Canadian Consensus Conference on the Diagnosis and Treatment of Dementia on their applications in both clinical and research settings.

Incidence of mild cognitive impairment in the Pittsburgh Cardiovascular Health Study-Cognition Study

OBJECTIVES AND METHODS

The purpose of this study was to examine the incidence of mild cognitive impairment (MCI) and patterns of progression from incident MCI to dementia in 285 cognitively normal subjects (mean age, 78.9 years) in the Cardiovascular Health Study-Cognition Study from 1998-1999 to 2010-2011.

RESULTS

Two hundred (70%) of the participants progressed to MCI; the age-adjusted incidence of MCI was 111.09 (95% confidence interval, 88.13-142.95) per 1,000 person-years. A total of 107 (53.5%) of the incident MCI subjects progressed to dementia. The mean time from MCI to dementia was 2.8 ± 1.8 years. Forty (20%) of the incident MCI cases had an "unstable" course: 19 (9.5%) converted to MCI and later returned to normal; 10 (5%) converted to MCI, to normal, and later back to MCI; 7 (3.5%) converted to MCI, to normal, to MCI, and later to dementia; and 4 (2%) converted to MCI, to normal, and later to dementia. There was an increased mortality rate among the cognitively normal group (110.10 per 1,000 person-years) compared to those with incident MCI who converted to dementia (41.32 per 1,000 person-years).

CONCLUSIONS

The majority of the subjects aged >80 years developed an MCI syndrome, and half of them progressed to dementia. Once the MCI syndrome was present, the symptoms of dementia appeared within 2 to 3 years. Progression from normal to MCI or from normal to MCI to dementia is not always linear; subjects who developed MCI and later returned to normal can subsequently progress to dementia. Competing mortality and morbidity influence the study of incident MCI and dementia in population cohorts.

Temporal stability of receptiveness to clinical research on Alzheimer disease

Research advance directives are a proposed mechanism for ensuring that decisions with regard to research participation adhere to preferences voiced by persons with Alzheimer disease (AD) before losing decisional capacity. Although this approach rests on the assumption that preferences with regard to research participation are consistent over time, little is known about the stability of such preferences. The purpose of this study was to evaluate the temporal stability of older adults' receptiveness to participation in clinical trials, neuroimaging studies, and psychosocial investigations on AD. One hundred and four participants in the University of Pittsburgh Alzheimer Disease Research Center were annually surveyed with regard to their willingness to be contacted with regard to clinical drug trials, neuroimaging studies, and psychosocial research for which they might be eligible. Receptiveness to contact with regard to AD research was compared at 2 time points, 1 year apart. At baseline, most respondents were willing to be contacted with regard to their eligibility for drug trials, imaging studies, and psychosocial research. Thirty-seven percent of respondents voiced a different set of preferences at year 2 as compared with year 1. Differences included both increased and decreased willingness to be contacted. Neither stability of preferences nor direction of change (more vs. less willing) varied by diagnostic group. Bivariate analyses revealed that participation in at least 1 ancillary research study was associated with an overall increase in willingness to be contacted. We conclude that a significant proportion of research-friendly individuals voice different sets of preferences with regard to the possibility of research participation when queried at different points in time. Amenability to participating in clinical research on AD is a relatively dynamic personal attribute that may be influenced by personal experience with research participation. This finding has relevance for the policy debate around research advance directives, an approach which assumes that preferences with regard to research participation are consistent over time.

Accuracy of the clinical diagnosis of Alzheimer disease at National Institute on Aging Alzheimer Disease Centers, 2005-2010

The neuropathologic examination is considered to provide the gold standard for Alzheimer disease (AD). To determine the accuracy of currently used clinical diagnostic methods, clinical and neuropathologic data from the National Alzheimer's Coordinating Center, which gathers information from the network of National Institute on Aging (NIA)-sponsored Alzheimer Disease Centers (ADCs), were collected as part of the National Alzheimer's Coordinating Center Uniform Data Set (UDS) between 2005 and 2010. A database search initially included all 1198 subjects with at least one UDS clinical assessment and who had died and been autopsied; 279 were excluded as being not demented or because critical data fields were missing. The final subject number was 919. Sensitivity and specificity were determined based on "probable" and "possible" AD levels of clinical confidence and 4 levels of neuropathologic confidence based on varying neuritic plaque densities and Braak neurofibrillary stages. Sensitivity ranged from 70.9% to 87.3%; specificity ranged from 44.3% to 70.8%. Sensitivity was generally increased with more permissive clinical criteria and specificity was increased with more restrictive criteria, whereas the opposite was true for neuropathologic criteria. When a clinical diagnosis was not confirmed by minimum levels of AD histopathology, the most frequent primary neuropathologic diagnoses were tangle-only dementia or argyrophilic grain disease, frontotemporal lobar degeneration, cerebrovascular disease, Lewy body disease and hippocampal sclerosis. When dementia was not clinically diagnosed as AD, 39% of these cases met or exceeded minimum threshold levels of AD histopathology. Neurologists of the NIA-ADCs had higher predictive accuracy when they diagnosed AD in subjects with dementia than when they diagnosed dementing diseases other than AD. The misdiagnosis rate should be considered when estimating subject numbers for AD studies, including clinical trials and epidemiologic studies.

A medial temporal lobe division of labor: insights from memory in aging and early Alzheimer disease

Dual process theories of recognition memory posit that recollection and familiarity represent dissociable processes. Animal studies and human functional imaging experiments support an anatomic dissociation of these processes in the medial temporal lobes (MTL). By this hypothesis, recollection may be dependent on the hippocampus, while familiarity appears to rely on extrahippocampal MTL (ehMTL) structures, particularly perirhinal and lateral entorhinal cortices. Despite these findings, the dual process model and these anatomic mappings remain controversial, in part because the study of patients with lesions to the MTL has been limited and has revealed predominantly single dissociations. We examined measures of recollection and familiarity in three groups (normal older adults, amnesic-mild cognitive impairment, Alzheimer's disease) in which these memory measures and the relative integrity of MTL structures are variable, thus enhancing our power to detect MTL-memory relationships. Recollection and familiarity and volumes of hippocampus and ehMTL, defined as a region including entorhinal/perirhinal cortices and parahippocampus, were measured. Regression analyses revealed a stronger relationship of recollection with the hippocampus compared to ehMTL, while familiarity was more highly related to ehMTL compared to hippocampus. These results are consistent with a division of labor in the MTL and the dual process model.

Amyloid imaging in dementias with atypical presentation

BACKGROUND

With the potential emergence of disease specific therapies, an accurate biomarker of Alzheimer's Disease pathology is needed in cases in which the underlying etiology is uncertain. We explored the potential value of amyloid imaging in patients with atypical presentations of dementia.

METHODS

Twenty-eight patients with atypical dementia underwent positron emission tomography imaging with the amyloid imaging tracer Pittsburgh compound B (PiB). Twenty-six had [18F]fluoro-2-deoxy-D-glucose positron emission tomography scans. After extensive clinical evaluation, this group of patients generated considerable diagnostic uncertainty and received working diagnoses that included possible Alzheimer's disease (AD), focal dementias (e.g., posterior cortical atrophy [PCA]), or cases in which no clear diagnostic category could be determined (dementia of uncertain etiology). Patients were classified as PiB-positive, PiB-negative, or PiB-intermediate, based on objective criteria. Anterior-posterior and left-right indices of PiB and [18F]fluoro-2-deoxy-D-glucose uptake were calculated to examine differences in distribution of amyloid pathology and metabolic changes associated with clinical phenotype.

RESULTS

Eleven patients (39%) were PiB positive, 16 were PiB negative (57%), and one (4%) was PiB intermediate. By diagnostic category, three of 10 patients (30%) with dementia of uncertain etiology, one of five (20%) with primary progressive aphasia, three of five (60%) with PCA, and four of seven (57%) with possible AD were PiB positive. Brain metabolism of both PiB-positive and PiB-negative patients was generally similar by phenotype, but appeared to differ from typical AD. PCA patients also appeared to differ in their relative distribution of PiB compared with typical AD, consistent with their atypical phenotype.

CONCLUSIONS

AD pathology is frequently present in atypical presentations of dementia and can be identified by amyloid imaging. Clinical phenotype is more related to the pattern of cerebral hypometabolism than the presence/absence of amyloid pathology. These findings have diagnostic, prognostic, and therapeutic implications.