Validation, Deployment, and Real-World Implementation of a Modular Toolbox for Alzheimer's Disease Detection and Dementia Risk Reduction: The AD-RIDDLE Project

The Real-World Implementation, Deployment, and Validation of Early Detection Tools and Lifestyle Enhancement (AD-RIDDLE) project, recently launched with the support of the EU Innovative Health Initiative (IHI) public-private partnership and UK Research and Innovation (UKRI), aims to develop, test, and deploy a modular toolbox platform that can reduce existing barriers to the timely detection, and therapeutic approaches in Alzheimer's disease (AD), thus accelerating AD innovation. By focusing on health system and health worker practices, AD-RIDDLE seeks to improve and smooth AD management at and between each key step of the clinical pathway and across the disease continuum, from at-risk asymptomatic stages to early symptomatic ones. This includes innovation and improvement in AD awareness, risk reduction and prevention, detection, diagnosis, and intervention. The 24 partners in the AD-RIDDLE interdisciplinary consortium will develop and test the AD-RIDDLE toolbox platform and its components individually and in combination in six European countries. Expected results from this cross-sectoral research collaboration include tools for earlier detection and accurate diagnosis; validated, novel digital cognitive and blood-based biomarkers; and improved access to individualized preventative interventions (including multimodal interventions and symptomatic/disease-modifying therapies) across diverse populations, within the framework of precision medicine. Overall, AD-RIDDLE toolbox platform will advance management of AD, improving outcomes for patients and their families, and reducing costs.

Longitudinal cerebrospinal fluid measurements show glial hypo- and hyperactivation in predementia Alzheimer's disease

BACKGROUND

Brain innate immune activation is associated with Alzheimer's disease (AD), but degrees of activation may vary between disease stages. Thus, brain innate immune activation must be assessed in longitudinal clinical studies that include biomarker negative healthy controls and cases with established AD pathology. Here, we employ longitudinally sampled cerebrospinal fluid (CSF) core AD, immune activation and glial biomarkers to investigate early (predementia stage) innate immune activation levels and biomarker profiles.

METHODS

We included non-demented cases from a longitudinal observational cohort study, with CSF samples available at baseline (n = 535) and follow-up (n = 213), between 1 and 6 years from baseline (mean 2.8 years). We measured Aβ42/40 ratio, p-tau181, and total-tau to determine Ab (A+), tau-tangle pathology (T+), and neurodegeneration (N+), respectively. We classified individuals into these groups: A-/T-/N-, A+/T-/N-, A+/T+ or N+, or A-/T+ or N+. Using linear and mixed linear regression, we compared levels of CSF sTREM2, YKL-40, clusterin, fractalkine, MCP-1, IL-6, IL-1, IL-18, and IFN-γ both cross-sectionally and longitudinally between groups. A post hoc analysis was also performed to assess biomarker differences between cognitively healthy and impaired individuals in the A+/T+ or N+ group.

RESULTS

Cross-sectionally, CSF sTREM2, YKL-40, clusterin and fractalkine were higher only in groups with tau pathology, independent of amyloidosis (p < 0.001, A+/T+ or N+ and A-/T+ or N+, compared to A-/T-/N-). No significant group differences were observed for the cytokines CSF MCP-1, IL-6, IL-10, IL18 or IFN-γ. Longitudinally, CSF YKL-40, fractalkine and IFN-γ were all significantly lower in stable A+/T-/N- cases (all p < 0.05). CSF sTREM2, YKL-40, clusterin, fractalkine (p < 0.001) and MCP-1 (p < 0.05) were all higher in T or N+, with or without amyloidosis at baseline, but remained stable over time. High CSF sTREM2 was associated with preserved cognitive function within the A+/T+ or N+ group, relative to the cognitively impaired with the same A/T/N biomarker profile (p < 0.01).

CONCLUSIONS

Immune hypoactivation and reduced neuron-microglia communication are observed in isolated amyloidosis while activation and increased fractalkine accompanies tau pathology in predementia AD. Glial hypo- and hyperactivation through the predementia AD continuum suggests altered glial interaction with Ab and tau pathology, and may necessitate differential treatments, depending on the stage and patient-specific activation patterns.

Axonal damage and astrocytosis are biological correlates of grey matter network integrity loss: a cohort study in autosomal dominant Alzheimer disease

Brain development and maturation leads to grey matter networks that can be measured using magnetic resonance imaging. Network integrity is an indicator of information processing capacity which declines in neurodegenerative disorders such as Alzheimer disease (AD). The biological mechanisms causing this loss of network integrity remain unknown. Cerebrospinal fluid (CSF) protein biomarkers are available for studying diverse pathological mechanisms in humans and can provide insight into decline. We investigated the relationships between 10 CSF proteins and network integrity in mutation carriers (N=219) and noncarriers (N=136) of the Dominantly Inherited Alzheimer Network Observational study. Abnormalities in Aβ, Tau, synaptic (SNAP-25, neurogranin) and neuronal calcium-sensor protein (VILIP-1) preceded grey matter network disruptions by several years, while inflammation related (YKL-40) and axonal injury (NfL) abnormalities co-occurred and correlated with network integrity. This suggests that axonal loss and inflammation play a role in structural grey matter network changes.

Key points

Abnormal levels of fluid markers for neuronal damage and inflammatory processes in CSF are associated with grey matter network disruptions.The strongest association was with NfL, suggesting that axonal loss may contribute to disrupted network organization as observed in AD.Tracking biomarker trajectories over the disease course, changes in CSF biomarkers generally precede changes in brain networks by several years.

Predicting progression to Alzheimer's disease with human hippocampal progenitors exposed to serum

Adult hippocampal neurogenesis is important for learning and memory and is altered early in Alzheimer's disease. As hippocampal neurogenesis is modulated by the circulatory systemic environment, evaluating a proxy of how hippocampal neurogenesis is affected by the systemic milieu could serve as an early biomarker for Alzheimer's disease progression. Here, we used an in vitro assay to model the impact of systemic environment on hippocampal neurogenesis. A human hippocampal progenitor cell line was treated with longitudinal serum samples from individuals with mild cognitive impairment, who either progressed to Alzheimer's disease or remained cognitively stable. Mild cognitive impairment to Alzheimer's disease progression was characterized most prominently with decreased proliferation, increased cell death and increased neurogenesis. A subset of 'baseline' cellular readouts together with education level were able to predict Alzheimer's disease progression. The assay could provide a powerful platform for early prognosis, monitoring disease progression and further mechanistic studies.

CSF proteome profiling across the Alzheimer's disease spectrum reflects the multifactorial nature of the disease and identifies specific biomarker panels

Development of disease-modifying therapies against Alzheimer's disease (AD) requires biomarkers reflecting the diverse pathological pathways specific for AD. We measured 665 proteins in 797 cerebrospinal fluid (CSF) samples from patients with mild cognitive impairment with abnormal amyloid (MCI(Aβ+): n = 50), AD-dementia (n = 230), non-AD dementias (n = 322) and cognitively unimpaired controls (n = 195) using proximity ligation-based immunoassays. Here we identified >100 CSF proteins dysregulated in MCI(Aβ+) or AD compared to controls or non-AD dementias. Proteins dysregulated in MCI(Aβ+) were primarily related to protein catabolism, energy metabolism and oxidative stress, whereas those specifically dysregulated in AD dementia were related to cell remodeling, vascular function and immune system. Classification modeling unveiled biomarker panels discriminating clinical groups with high accuracies (area under the curve (AUC): 0.85-0.99), which were translated into custom multiplex assays and validated in external and independent cohorts (AUC: 0.8-0.99). Overall, this study provides novel pathophysiological leads delineating the multifactorial nature of AD and potential biomarker tools for diagnostic settings or clinical trials.

Genome-wide meta-analysis for Alzheimer's disease cerebrospinal fluid biomarkers

Amyloid-beta 42 (Aβ42) and phosphorylated tau (pTau) levels in cerebrospinal fluid (CSF) reflect core features of the pathogenesis of Alzheimer's disease (AD) more directly than clinical diagnosis. Initiated by the European Alzheimer & Dementia Biobank (EADB), the largest collaborative effort on genetics underlying CSF biomarkers was established, including 31 cohorts with a total of 13,116 individuals (discovery n = 8074; replication n = 5042 individuals). Besides the APOE locus, novel associations with two other well-established AD risk loci were observed; CR1 was shown a locus for Aβ42 and BIN1 for pTau. GMNC and C16orf95 were further identified as loci for pTau, of which the latter is novel. Clustering methods exploring the influence of all known AD risk loci on the CSF protein levels, revealed 4 biological categories suggesting multiple Aβ42 and pTau related biological pathways involved in the etiology of AD. In functional follow-up analyses, GMNC and C16orf95 both associated with lateral ventricular volume, implying an overlap in genetic etiology for tau levels and brain ventricular volume.

Differential insular cortex sub-regional atrophy in neurodegenerative diseases: a systematic review and meta-analysis

The insular cortex is proposed to function as a central brain hub characterized by wide-spread connections and diverse functional roles. As a result, its centrality in the brain confers high metabolic demands predisposing it to dysfunction in disease. However, the functional profile and vulnerability to degeneration varies across the insular sub-regions. The aim of this systematic review and meta-analysis is to summarize and quantitatively analyze the relationship between insular cortex sub-regional atrophy, studied by voxel based morphometry, with cognitive and neuropsychiatric deficits in frontotemporal dementia (FTD), Alzheimer’s disease (AD), Parkinson’s disease (PD), and dementia with Lewy bodies (DLB). We systematically searched through Pubmed and Embase and identified 519 studies that fit our criteria. A total of 41 studies (n = 2261 subjects) fulfilled the inclusion criteria for the meta-analysis. The peak insular coordinates were pooled and analyzed using Anatomic Likelihood Estimation. Our results showed greater left anterior insular cortex atrophy in FTD whereas the right anterior dorsal insular cortex showed larger clusters of atrophy in AD and PD/DLB. Yet contrast analyses did not reveal significant differences between disease groups. Functional analysis showed that left anterior insular cortex atrophy is associated with speech, emotion, and affective-cognitive deficits, and right dorsal atrophy with perception and cognitive deficits. In conclusion, insular sub-regional atrophy, particularly the anterior dorsal region, may contribute to cognitive and neuropsychiatric deficits in neurodegeneration. Our results support anterior insular cortex vulnerability and convey the differential involvement of the insular sub-regions in functional deficits in neurodegenerative diseases.

Alzheimer's Disease Composite Score: A Post-Hoc Analysis Using Data from the LipiDiDiet Trial in Prodromal Alzheimer's Disease

As research evolves in prodromal AD, the need to validate sufficiently sensitive outcome measures, e.g. the Alzheimer's Disease Composite Score (ADCOMS) is clear. In the LipiDiDiet randomized trial in prodromal AD, cognitive decline in the study population was much less than expected in the timeframe studied. While the primary composite endpoint was insufficiently sensitive to detect a difference in the modified intention to treat population, the per-protocol population showed less decline in the active than the control group, indicating better treatment effects with regular product intake. These results were further strengthened by significant benefits on secondary endpoints of cognition and function, and brain atrophy. The present post-hoc analysis investigated whether ADCOMS could detect a difference between groups in the LipiDiDiet population (138 active, 140 control). The estimated mean change in ADCOMS from baseline (standard error) was 0.085 (0.018) in the active and 0.133 (0.018) in the control group; estimated mean treatment difference -0.048 (95% confidence intervals -0.090, -0.007; p=0.023), or 36% less decline in the active group. This suggests ADCOMS identified the cognitive and functional benefits observed previously, confirming the sensitivity of this composite measure.

Amygdalar nuclei and hippocampal subfields on MRI: Test-retest reliability of automated volumetry across different MRI sites and vendors

BACKGROUND

The amygdala and the hippocampus are two limbic structures that play a critical role in cognition and behavior, however their manual segmentation and that of their smaller nuclei/subfields in multicenter datasets is time consuming and difficult due to the low contrast of standard MRI. Here, we assessed the reliability of the automated segmentation of amygdalar nuclei and hippocampal subfields across sites and vendors using FreeSurfer in two independent cohorts of older and younger healthy adults.

METHODS

Sixty-five healthy older (cohort 1) and 68 younger subjects (cohort 2), from the PharmaCog and CoRR consortia, underwent repeated 3D-T1 MRI (interval 1-90 days). Segmentation was performed using FreeSurfer v6.0. Reliability was assessed using volume reproducibility error (ε) and spatial overlapping coefficient (DICE) between test and retest session.

RESULTS

Significant MRI site and vendor effects (p ​< ​.05) were found in a few subfields/nuclei for the ε, while extensive effects were found for the DICE score of most subfields/nuclei. Reliability was strongly influenced by volume, as ε correlated negatively and DICE correlated positively with volume size of structures (absolute value of Spearman's r correlations >0.43, p ​< ​1.39E-36). In particular, volumes larger than 200 ​mm³ (for amygdalar nuclei) and 300 ​mm³ (for hippocampal subfields, except for molecular layer) had the best test-retest reproducibility (ε ​< ​5% and DICE ​> ​0.80).

CONCLUSION

Our results support the use of volumetric measures of larger amygdalar nuclei and hippocampal subfields in multisite MRI studies. These measures could be useful for disease tracking and assessment of efficacy in drug trials.

A metabolite-based machine learning approach to diagnose Alzheimer-type dementia in blood: Results from the European Medical Information Framework for Alzheimer disease biomarker discovery cohort

Introduction

Machine learning (ML) may harbor the potential to capture the metabolic complexity in Alzheimer Disease (AD). Here we set out to test the performance of metabolites in blood to categorize AD when compared to CSF biomarkers.

Methods

This study analyzed samples from 242 cognitively normal (CN) people and 115 with AD-type dementia utilizing plasma metabolites (n = 883). Deep Learning (DL), Extreme Gradient Boosting (XGBoost) and Random Forest (RF) were used to differentiate AD from CN. These models were internally validated using Nested Cross Validation (NCV).

Results

On the test data, DL produced the AUC of 0.85 (0.80–0.89), XGBoost produced 0.88 (0.86–0.89) and RF produced 0.85 (0.83–0.87). By comparison, CSF measures of amyloid, p-tau and t-tau (together with age and gender) produced with XGBoost the AUC values of 0.78, 0.83 and 0.87, respectively.

Discussion

This study showed that plasma metabolites have the potential to match the AUC of well-established AD CSF biomarkers in a relatively small cohort. Further studies in independent cohorts are needed to validate whether this specific panel of blood metabolites can separate AD from controls, and how specific it is for AD as compared with other neurodegenerative disorders.

Longitudinal cerebrospinal fluid biomarker trajectories along the Alzheimer's disease continuum in the BIOMARKAPD study

INTRODUCTION

Within-person trajectories of cerebrospinal fluid (CSF) biomarkers in Alzheimer's disease (AD) are not well defined.

METHODS

We included 467 subjects from the BIOMARKAPD study with at least two serial CSF samples. Diagnoses were subjective cognitive decline (n = 75), mild cognitive impairment (n = 128), and AD dementia (n = 110), and a group of cognitively unimpaired subjects (n = 154) were also included. We measured baseline and follow-up CSF levels of total tau (t-tau), phosphorylated tau (p-tau), YKL-40, and neurofilament light (NfL). Median CSF sampling interval was 2.1 years.

RESULTS

CSF levels of t-tau, p-tau, NfL, and YKL-40 were 2% higher per each year of baseline age in controls (P <.001). In AD, t-tau levels were 1% lower (P <.001) and p-tau levels did not change per each year of baseline age. Longitudinally, only NfL (P <.001) and YKL-40 (P <.02) increased during the study period.

DISCUSSION

All four CSF biomarkers increase with age, but this effect deviates in AD for t-tau and p-tau.

Functional and effective whole brain connectivity using magnetoencephalography to identify monozygotic twin pairs

Resting-state functional connectivity patterns are highly stable over time within subjects. This suggests that such 'functional fingerprints' may have strong genetic component. We investigated whether the functional (FC) or effective (EC) connectivity patterns of one monozygotic twin could be used to identify the co-twin among a larger sample and determined the overlap in functional fingerprints within monozygotic (MZ) twin pairs using resting state magnetoencephalography (MEG). We included 32 cognitively normal MZ twin pairs from the Netherlands Twin Register who participate in the EMIF-AD preclinAD study (average age 68 years). Combining EC information across multiple frequency bands we obtained an identification rate over 75%. Since MZ twin pairs are genetically identical these results suggest a high genetic contribution to MEG-based EC patterns, leading to large similarities in brain connectivity patterns between two individuals even after 60 years of life or more.

Dementia prevalence and incidence in a federation of European Electronic Health Record databases: The European Medical Informatics Framework resource

INTRODUCTION

The European Medical Information Framework consortium has assembled electronic health record (EHR) databases for dementia research. We calculated dementia prevalence and incidence in 25 million persons from 2004 to 2012.

METHODS

Six EHR databases (three primary care and three secondary care) from five countries were interrogated. Dementia was ascertained by consensus harmonization of clinical/diagnostic codes. Annual period prevalences and incidences by age and gender were calculated and meta-analyzed.

RESULTS

The six databases contained 138,625 dementia cases. Age-specific prevalences were around 30% of published estimates from community samples and incidences were around 50%. Pooled prevalences had increased from 2004 to 2012 in all age groups but pooled incidences only after age 75 years. Associations with age and gender were stable over time.

DISCUSSION

The European Medical Information Framework initiative supports EHR data on unprecedented number of people with dementia. Age-specific prevalences and incidences mirror estimates from community samples in pattern at levels that are lower but increasing over time.

Clinical and biomarker profiling of prodromal Alzheimer's disease in workpackage 5 of the Innovative Medicines Initiative PharmaCog project: a 'European ADNI study'

BACKGROUND

In the field of Alzheimer's disease (AD), the validation of biomarkers for early AD diagnosis and for use as a surrogate outcome in AD clinical trials is of considerable research interest.

OBJECTIVE

To characterize the clinical profile and genetic, neuroimaging and neurophysiological biomarkers of prodromal AD in amnestic mild cognitive impairment (aMCI) patients enrolled in the IMI WP5 PharmaCog (also referred to as the European ADNI study).

METHODS

A total of 147 aMCI patients were enrolled in 13 European memory clinics. Patients underwent clinical and neuropsychological evaluation, magnetic resonance imaging (MRI), electroencephalography (EEG) and lumbar puncture to assess the levels of amyloid β peptide 1-42 (Aβ42), tau and p-tau, and blood samples were collected. Genetic (APOE), neuroimaging (3T morphometry and diffusion MRI) and EEG (with resting-state and auditory oddball event-related potential (AO-ERP) paradigm) biomarkers were evaluated.

RESULTS

Prodromal AD was found in 55 aMCI patients defined by low Aβ42 in the cerebrospinal fluid (Aβ positive). Compared to the aMCI group with high Aβ42 levels (Aβ negative), Aβ positive patients showed poorer visual (P = 0.001), spatial recognition (P < 0.0005) and working (P = 0.024) memory, as well as a higher frequency of APOE4 (P < 0.0005), lower hippocampal volume (P = 0.04), reduced thickness of the parietal cortex (P < 0.009) and structural connectivity of the corpus callosum (P < 0.05), higher amplitude of delta rhythms at rest (P = 0.03) and lower amplitude of posterior cingulate sources of AO-ERP (P = 0.03).

CONCLUSION

These results suggest that, in aMCI patients, prodromal AD is characterized by a distinctive cognitive profile and genetic, neuroimaging and neurophysiological biomarkers. Longitudinal assessment will help to identify the role of these biomarkers in AD progression.

Suspected non-Alzheimer disease pathophysiology--concept and controversy

Suspected non-Alzheimer disease pathophysiology (SNAP) is a biomarker-based concept that applies to individuals with normal levels of amyloid-β biomarkers in the brain, but in whom biomarkers of neurodegeneration are abnormal. The term SNAP has been applied to clinically normal individuals (who do not meet criteria for either mild cognitive impairment or dementia) and to individuals with mild cognitive impairment, but is applicable to any amyloid-negative, neurodegeneration-positive individual regardless of clinical status, except when the pathology underlying neurodegeneration can be reliably inferred from the clinical presentation. SNAP is present in ∼23% of clinically normal individuals aged >65 years and in ∼25% of mildly cognitively impaired individuals. APOE*ε4 is underrepresented in individuals with SNAP compared with amyloid-positive individuals. Clinically normal and mildly impaired individuals with SNAP have worse clinical and/or cognitive outcomes than individuals with normal levels of neurodegeneration and amyloid-β biomarkers. In this Perspectives article, we describe the available data on SNAP and address topical controversies in the field.

[Are the prevalence and incidence of dementia declining?]

The Framingham Heart Study showed a 35 per cent drop in new dementia cases in 25 years from the late 1970s to the early 2010s. The question that has been asked is: can we stop worrying about the dementia pandemic? We argue that dementia will remain a major health problem. In the Framingham Heart Study the largest decrease in incidence occurred in the early nineties and levelled off in later years. Higher educational levels and improved cardiovascular risk management may explain part of the decreased incidence. The latter justifies intensive treatment of cardiovascular risk factors. This may have to start at an earlier age than is currently the case since hypertension, obesity and diabetes are now prevalent at younger ages. Despite the decrease in dementia incidence, the absolute numbers of people with dementia will increase due to the aging population. Research on early diagnosis and new treatments for dementia therefore remains crucial.

Use of amyloid-PET to determine cutpoints for CSF markers: A multicenter study

OBJECTIVES

To define CSF β-amyloid 1-42 (Aβ42) cutpoints to detect cortical amyloid deposition as assessed by 11C-Pittsburgh compound B ([11C]PiB)-PET and to compare these calculated cutpoints with cutpoints currently used in clinical practice.

METHODS

We included 433 participants (57 controls, 99 with mild cognitive impairment, 195 with Alzheimer disease [AD] dementia, and 82 with non-AD dementia) from 5 European centers. We calculated for each center and for the pooled cohort CSF Aβ42 and Aβ42/tau ratio cutpoints for cortical amyloid deposition based on visual interpretation of [11C]PiB-PET images.

RESULTS

Amyloid-PET-based calculated CSF Aβ42 cutpoints ranged from 521 to 616 pg/mL, whereas existing clinical-based cutpoints ranged from 400 to 550 pg/mL. Using the calculated cutpoint from the pooled sample (557 pg/mL), concordance between CSF Aβ42 and amyloid-PET was 84%. Similar concordance was found when using a dichotomized Aβ42/tau ratio. Exploratory analysis showed that participants with a positive amyloid-PET and normal CSF Aβ42 levels had higher CSF tau and phosphorylated tau levels and more often had mild cognitive impairment or AD dementia compared with participants who had negative amyloid-PET and abnormal CSF Aβ42 levels.

CONCLUSIONS

Amyloid-PET-based CSF Aβ42 cutpoints were higher and tended to reduce intercenter variability compared with clinical-based cutpoints. Discordant participants with normal CSF Aβ42 and a positive amyloid-PET may be more likely to have AD-related amyloid pathology than participants with abnormal CSF Aβ42 and a negative amyloid-PET.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that an amyloid-PET-based CSF Aβ42 cutpoint identifies individuals with amyloid deposition with a sensitivity of 87% and specificity of 80%.

The trajectory of cognitive decline in the pre-dementia phase in memory clinic visitors: findings from the 4C-MCI study

BACKGROUND

We investigated the course of decline in multiple cognitive domains in non-demented subjects from a memory clinic setting, and compared pattern, onset and magnitude of decline between subjects who progressed to Alzheimer's disease (AD) dementia at follow-up and subjects who did not progress.

METHOD

In this retrospective cohort study 819 consecutive non-demented patients who visited the memory clinics in Maastricht or Amsterdam between 1987 and 2010 were followed until they became demented or for a maximum of 10 years (range 0.5-10 years). Differences in trajectories of episodic memory, executive functioning, verbal fluency, and information processing speed/attention between converters to AD dementia and subjects remaining non-demented were compared by means of random effects modelling.

RESULTS

The cognitive performance of converters and non-converters could already be differentiated seven (episodic memory) to three (verbal fluency and executive functioning) years prior to dementia diagnosis. Converters declined in these three domains, while non-converters remained stable on episodic memory and executive functioning and showed modest decline in verbal fluency. There was no evidence of decline in information processing speed/attention in either group.

CONCLUSIONS

Differences in cognitive performance between converters to AD dementia and subjects remaining non-demented could be established 7 years prior to diagnosis for episodic memory, with verbal fluency and executive functioning following several years later. Therefore, in addition to early episodic memory decline, decline in executive functions may also flag incident AD dementia. By contrast, change in information processing speed/attention seems less informative.

Advancing research diagnostic criteria for Alzheimer's disease: the IWG-2 criteria

In the past 8 years, both the International Working Group (IWG) and the US National Institute on Aging-Alzheimer's Association have contributed criteria for the diagnosis of Alzheimer's disease (AD) that better define clinical phenotypes and integrate biomarkers into the diagnostic process, covering the full staging of the disease. This Position Paper considers the strengths and limitations of the IWG research diagnostic criteria and proposes advances to improve the diagnostic framework. On the basis of these refinements, the diagnosis of AD can be simplified, requiring the presence of an appropriate clinical AD phenotype (typical or atypical) and a pathophysiological biomarker consistent with the presence of Alzheimer's pathology. We propose that downstream topographical biomarkers of the disease, such as volumetric MRI and fluorodeoxyglucose PET, might better serve in the measurement and monitoring of the course of disease. This paper also elaborates on the specific diagnostic criteria for atypical forms of AD, for mixed AD, and for the preclinical states of AD.

Hippocampal volume change measurement: quantitative assessment of the reproducibility of expert manual outlining and the automated methods FreeSurfer and FIRST

BACKGROUND

To measure hippocampal volume change in Alzheimer's disease (AD) or mild cognitive impairment (MCI), expert manual delineation is often used because of its supposed accuracy. It has been suggested that expert outlining yields poorer reproducibility as compared to automated methods, but this has not been investigated.

AIM

To determine the reproducibilities of expert manual outlining and two common automated methods for measuring hippocampal atrophy rates in healthy aging, MCI and AD.

METHODS

From the Alzheimer's Disease Neuroimaging Initiative (ADNI), 80 subjects were selected: 20 patients with AD, 40 patients with mild cognitive impairment (MCI) and 20 healthy controls (HCs). Left and right hippocampal volume change between baseline and month-12 visit was assessed by using expert manual delineation, and by the automated software packages FreeSurfer (longitudinal processing stream) and FIRST. To assess reproducibility of the measured hippocampal volume change, both back-to-back (BTB) MPRAGE scans available for each visit were analyzed. Hippocampal volume change was expressed in μL, and as a percentage of baseline volume. Reproducibility of the 1-year hippocampal volume change was estimated from the BTB measurements by using linear mixed model to calculate the limits of agreement (LoA) of each method, reflecting its measurement uncertainty. Using the delta method, approximate p-values were calculated for the pairwise comparisons between methods. Statistical analyses were performed both with inclusion and exclusion of visibly incorrect segmentations.

RESULTS

Visibly incorrect automated segmentation in either one or both scans of a longitudinal scan pair occurred in 7.5% of the hippocampi for FreeSurfer and in 6.9% of the hippocampi for FIRST. After excluding these failed cases, reproducibility analysis for 1-year percentage volume change yielded LoA of ±7.2% for FreeSurfer, ±9.7% for expert manual delineation, and ±10.0% for FIRST. Methods ranked the same for reproducibility of 1-year μL volume change, with LoA of ±218 μL for FreeSurfer, ±319 μL for expert manual delineation, and ±333 μL for FIRST. Approximate p-values indicated that reproducibility was better for FreeSurfer than for manual or FIRST, and that manual and FIRST did not differ. Inclusion of failed automated segmentations led to worsening of reproducibility of both automated methods for 1-year raw and percentage volume change.

CONCLUSION

Quantitative reproducibility values of 1-year microliter and percentage hippocampal volume change were roughly similar between expert manual outlining, FIRST and FreeSurfer, but FreeSurfer reproducibility was statistically significantly superior to both manual outlining and FIRST after exclusion of failed segmentations.

Preclinical AD predicts decline in memory and executive functions in subjective complaints

OBJECTIVE

We assessed whether preclinical Alzheimer disease (AD) based on CSF biomarkers at baseline predicts decline in cognitive functioning as measured by repeated neuropsychological tests for 4 cognitive domains in patients with subjective complaints.

METHODS

We included 132 patients with subjective complaints from our memory clinic-based Amsterdam Dementia Cohort, who underwent lumbar puncture and had repeated (range 2-7) neuropsychological evaluations. Follow-up was 2 ± 1 years. CSF biomarkers amyloid-β (Aβ42), total tau (Tau), and hyperphosphorylated tau-181 were used to define National Institute on Aging-Alzheimer's Association (NIA-AA) preclinical AD stages. Predictive value of preclinical AD stages as defined by CSF biomarkers, individual biomarkers, and Aβ42/tau ratio was assessed using linear mixed models. Outcome measures were compound z scores for memory, attention, executive functioning, language, and global cognition. Analyses were adjusted for age, sex, and education.

RESULTS

Patients were 61 ± 8 years old; 56 (42%) were women. Average baseline Mini-Mental State Examination score was 28.3 ± 1.5. Patients who fulfilled criteria for preclinical AD (stage 1: n = 11 + stage 2: n = 10) showed decline over time in memory (β ± SE -0.41 ± 0.14, p < 0.01), executive functions (-0.21 ± 0.08, p < 0.01), and global cognition (-0.29 ± 0.10, p < 0.01). There were no differences in cognitive decline between NIA-AA preclinical AD stages 1 and 2. In patients with normal CSF biomarkers, we observed memory improvement (0.19 ± 0.07, p < 0.01) and stable performance in all other domains.

CONCLUSIONS

CSF evidence of preclinical AD in patients with subjective complaints predicted cognitive decline over time, encompassing more than memory alone. Executive functioning and global cognitive functioning also deteriorated. On the other hand, 2-year prognosis for patients without evidence of AD pathophysiology was good.

Anxiety is related to Alzheimer cerebrospinal fluid markers in subjects with mild cognitive impairment

BACKGROUND

Anxiety, apathy and depression are common in subjects with mild cognitive impairment (MCI) and may herald Alzheimer's disease (AD). We investigated whether these symptoms correlated with cerebrospinal fluid (CSF) markers for AD in subjects with MCI. Method Subjects with MCI (n=268) were selected from the 'Development of screening guidelines and criteria for pre-dementia Alzheimer's disease' (DESCRIPA) and Alzheimer's Disease Neuroimaging Initiative (ADNI) studies. We measured amyloid β(1-42) protein (Aβ42) and total tau (t-tau) in CSF. Neuropsychiatric symptoms were measured with the Neuropsychiatric Inventory.

RESULTS

Depressive symptoms were reported by 55 subjects (21%), anxiety by 35 subjects (13%) and apathy by 49 subjects (18%). The presence of anxiety was associated with abnormal CSF Aβ42 [odds ratio (OR) 2.3, 95% confidence interval (CI) 1.6-3.3] and t-tau (OR 2.6, 95% CI 1.9-3.6) concentrations and with the combination of abnormal concentrations of both Aβ42 and t-tau (OR 3.1, 95% CI 2.0-4.7). The presence of agitation and irritability was associated with abnormal concentrations of Aβ42 (agitation: OR 1.6, 95% CI 1.1-2.3; irritability: OR 2.2, 95% CI 1.5-3.3). Symptoms of depression and apathy were not related to any of the CSF markers.

CONCLUSIONS

In subjects with MCI, symptoms of anxiety, agitation and irritability may reflect underlying AD pathology, whereas symptoms of depression and apathy do not.

[Use of cerebrospinal fluid (CSF) biomarkers for Alzheimer's type dementia: diagnosis in mild cognitive impairment]

An increasing number of people with mild cognitive impairment (MCI) visits a memory clinic to find out whether their symptoms indicate Alzheimer's disease (AD). Markers in cerebrospinal fluid are increasingly used for the diagnosis of Alzheimer's disease. In the short term, CSF biomarkers are more accurate in ruling out progression to AD-type dementia than demonstrating progression. The predictive value of the CSF biomarkers increases with longer-duration follow-up and declines with age. The added value of CSF biomarkers is not yet clear in MCI patients in whom extensive clinical, neuropsychological examination or imaging have already been performed.

Increased risk of mortality associated with social isolation in older men: only when feeling lonely? Results from the Amsterdam Study of the Elderly (AMSTEL)

BACKGROUND

Loneliness has a significant influence on both physical and mental health. Few studies have investigated the possible associations of loneliness with mortality risk, impact on men and women and whether this impact concerns the situation of being alone (social isolation), experiencing loneliness (feeling lonely) or both. The current study investigated whether social isolation and feelings of loneliness in older men and women were associated with increased mortality risk, controlling for depression and other potentially confounding factors.

METHOD

In our prospective cohort study of 4004 older persons aged 65-84 years with a 10-year follow-up of mortality data a Cox proportional hazard regression analysis was used to test whether social isolation factors and feelings of loneliness predicted an increased risk of mortality, controlling for psychiatric disorders and medical conditions, cognitive functioning, functional status and sociodemographic factors.

RESULTS

At 10 years follow-up, significantly more men than women with feelings of loneliness at baseline had died. After adjustment for explanatory variables including social isolation, the mortality hazard ratio for feelings of loneliness was 1.30 [95% confidence interval (CI) 1.04-1.63] in men and 1.04 (95% CI 0.90-1.24) in women. No higher risk of mortality was found for social isolation.

CONCLUSIONS

Feelings of loneliness rather than social isolation factors were found to be a major risk factor for increasing mortality in older men. Developing a better understanding of the nature of this association may help us to improve quality of life and longevity, especially in older men.

Regional differences in effects of APOE ε4 on cognitive impairment in non-demented subjects

BACKGROUND

The APOE ε4 allele is a risk factor for Alzheimer's disease (AD). APOE ε4 is common in non-demented subjects with cognitive impairment. In both healthy people and people with AD, its prevalence has a north-south gradient across Europe. In the present study, we investigated whether the relation between the APOE ε4 allele and cognitive impairment varied across Northern, Middle and Southern Europe. We also investigated whether a north-south gradient existed in subjects with subjective cognitive impairment (SCI), amnestic mild cognitive impairment (MCI) and non-amnestic MCI.

METHODS

Data from 16 centers across Europe were analyzed.

RESULTS

A north-south gradient in APOE ε4 prevalence existed in the total sample (62.7% for APOE ε4 carriers in the northern region, 42.1% in the middle region, and 31.5% in the southern region) and in subjects with SCI and amnestic MCI separately. Only in Middle Europe was the APOE ε4 allele significantly associated with poor performance on tests of delayed recall and learning, as well as with the amnestic subtype of MCI.

CONCLUSION

The APOE ε4 allele frequencies in subjects with SCI and amnestic MCI have a north-south gradient. The relation between the APOE ε4 allele and cognition is region dependent.

Age and diagnostic performance of Alzheimer disease CSF biomarkers

OBJECTIVES

Core CSF changes in Alzheimer disease (AD) are decreased amyloid β(1-42), increased total tau, and increased phospho-tau, probably indicating amyloid plaque accumulation, axonal degeneration, and tangle pathology, respectively. These biomarkers identify AD already at the predementia stage, but their diagnostic performance might be affected by age-dependent increase of AD-type brain pathology in cognitively unaffected elderly.

METHODS

We investigated effects of age on the diagnostic performance of CSF biomarkers in a uniquely large multicenter study population, including a cross-sectional cohort of 529 patients with AD dementia (median age 71, range 43-89 years) and 304 controls (67, 44-91 years), and a longitudinal cohort of 750 subjects without dementia with mild cognitive impairment (69, 43-89 years) followed for at least 2 years, or until dementia diagnosis.

RESULTS

The specificities for subjects without AD and the areas under the receiver operating characteristics curves decreased with age. However, the positive predictive value for a combination of biomarkers remained stable, while the negative predictive value decreased only slightly in old subjects, as an effect of the high AD prevalence in older ages.

CONCLUSION

Although the diagnostic accuracies for AD decreased with age, the predictive values for a combination of biomarkers remained essentially stable. The findings highlight biomarker variability across ages, but support the use of CSF biomarkers for AD even in older populations.

[The role of CSF markers in the early diagnosis of Alzheimer's disease]

BACKGROUND

Biomarkers in cerebrospinal fluid (CSF) are being used increasingly to diagnose early Alzheimer's disease (AD). A CSF profile that is suggestive of ad is an abnormal ratio of the proteins Ab1-42 to total tau.

AIM

To describe the prevalence and prognosis of a CSF profile in patients without dementia but with subjective memory problems and mild cognitive impairments (MCI) at a memory clinic.

METHOD

A multi-centre study.

RESULTS

A European multi-centre study showed that a CSF AD profile was often present in patients with subjective complaints and patients with MCI . The CSF AD profile predicted a decline in cognition and daily functioning over a period of 3 years in patients with MCI. Patients with amnestic MCI and a CSF AD profile developed AD more often within this period than patients without this profile.

CONCLUSION

CSF markers suggestive of ad are common in persons without dementia. It may be possible to use these markers for the prognosis of patients who have MCI .

The effect of the APOE-epsilon4 allele and ACE-I/D polymorphism on cognition during a two-year follow-up in first-ever stroke patients

BACKGROUND

Cognitive impairment is commonly observed after stroke and has a negative impact on survival and rehabilitation. Some stroke patients deteriorate in cognitive functioning whereas others do not. Environmental and demographic risk factors cannot fully explain this. There is growing evidence that a genetic predisposition plays a role in the pathogenesis of post-stroke cognitive decline.

OBJECTIVE

To study the influence of the APOE-epsilon4 allele and the ACE-I/D polymorphism on cognitive functioning after stroke.

METHODS

We included 194 first-ever stroke patients of whom information about APOE genotyping and ACE-I/D polymorphism was available in 92 and 129 patients, respectively. Patients were cognitively assessed at 1, 6, 12 and 24 months after the event. Linear mixed models with slope estimates were used to study the influence of the APOE-epsilon4 allele and the ACE-I/D polymorphism on the MMSE score, CAMCOG, executive functioning, psychomotor speed, and verbal memory function during follow-up.

RESULTS

Patients carrying the APOE-epsilon4 allele more often suffered a lacunar infarction than non-carriers. The APOE-epsilon4 allele had no effect on cognitive functioning during the follow-up. ACE-DD homozygosity was associated with a worse performance in executive functioning compared to patients with neither an APOE-epsilon4 allele nor the ACE-DD genotype. There was no interaction between the APOE-epsilon4 allele and the ACE-DD phenotype in the prediction of cognitive decline.

CONCLUSION

The ACE-DD genotype may be associated with post-stroke cognitive decline while the APOE-epsilon4 allele is not. Further research is needed to examine the role of genetic risk factors for post-stroke cognitive decline and to determine why some patients deteriorate cognitively after stroke but others do not.

Atrophy in the parahippocampal gyrus as an early biomarker of Alzheimer's disease

The main aim of the present study was to compare volume differences in the hippocampus and parahippocampal gyrus as biomarkers of Alzheimer's disease (AD). Based on the previous findings, we hypothesized that there would be significant volume differences between cases of healthy aging, amnestic mild cognitive impairment (aMCI), and mild AD. Furthermore, we hypothesized that there would be larger volume differences in the parahippocampal gyrus than in the hippocampus. In addition, we investigated differences between the anterior, middle, and posterior parts of both structures. We studied three groups of participants: 18 healthy participants without memory decline, 18 patients with aMCI, and 18 patients with mild AD. 3 T T1-weighted MRI scans were acquired and gray matter volumes of the anterior, middle, and posterior parts of both the hippocampus and parahippocampal gyrus were measured using a manual tracing approach. Volumes of both the hippocampus and parahippocampal gyrus were significantly different between the groups in the following order: healthy>aMCI>AD. Volume differences between the groups were relatively larger in the parahippocampal gyrus than in the hippocampus, in particular, when we compared healthy with aMCI. No substantial differences were found between the anterior, middle, and posterior parts of both structures. Our results suggest that parahippocampal volume discriminates better than hippocampal volume between cases of healthy aging, aMCI, and mild AD, in particular, in the early phase of the disease. The present results stress the importance of parahippocampal atrophy as an early biomarker of AD.

Affective symptoms as predictors of Alzheimer's disease in subjects with mild cognitive impairment: a 10-year follow-up study

BACKGROUND

Affective symptoms are common in subjects with mild cognitive impairment (MCI), but there is disagreement whether these symptoms are predictive for Alzheimer's disease (AD). We investigated the predictive accuracy of affective symptoms for AD during a follow-up study in subjects with MCI, and whether the predictive accuracy was modified by age, the presence of amnestic MCI or the length of follow-up.

METHOD

Newly referred subjects (n=263) with MCI older than 55 years were selected from a memory clinic and followed up after 2, 5 and 10 years. Predictors investigated were: symptoms of depression, anxiety, apathy and sleeping problems.

RESULTS

Affective symptoms were present in 50-70% of the subjects. The average follow-up period was 5.4 years and 79 subjects (29%) developed AD. Sleeping problems were associated with a decreased risk for AD [odds ratio (OR) 0.35, p<0.001]. Symptoms of depression (OR 0.61, p=0.059) and anxiety (OR 0.58, p=0.051) showed a trend in the same direction. The OR of apathy for AD was 0.67 (p=0.14). Depression was associated with a decreased risk for AD only in subjects without amnestic MCI, but not in subjects with amnestic MCI. Moreover, anxiety was related to the risk for AD differently between subjects diagnosed with AD at the 5-year follow-up (OR 0.23) and subjects diagnosed with AD at the 10-year follow-up (OR 1.7).

CONCLUSIONS

Affective symptoms are associated with a decreased risk for AD. The risk may be dependent on MCI subtype or length of follow-up, but it does not depend on age.

Consensus statement on dementia education and training in Europe

OBJECTIVES

The aim of the current statement is to agree on: (1) what is the current situation with education and training on dementia in Europe; (2) what are the minimum educational requirements for professionals (neurologists, psychiatrists, primary care providers, nurses, biologists, neuroradiologists, etc.) regarding Alzheimer's disease and dementia, and (3) how to start a course of action for the future.

DESIGN

In 2005, a simple questionnaire was sent to members of the European Alzheimer's Disease Consortium (EADC) concerning the education and training on dementia in their countries. Fourteen universities of the respective countries responded to this simple questionnaire. The answers varied, and the conclusion of this effort was that little was done concerning the training of students and health professionals on dementia. In 2008, another more structured and specified questionnaire was sent to professors in different universities of the same countries.

RESULTS

The answers obtained were different from those of the previous questionnaire and demonstrated that it is very difficult to know about training and education in the field of dementia in every European country.

CONCLUSION

From the data collected, it seems that although in the recent past little had been done concerning training on dementia, nowadays training has been developed in most European countries, and relevant educational projects exist both for medical students and doctors during their specialty training. Our main purpose is to develop training material or develop specific courses to improve the professional knowledge about dementia so that best medical and non-medical practice is implemented.

White matter hyperintensities and medial temporal lobe atrophy in clinical subtypes of mild cognitive impairment: the DESCRIPA study

BACKGROUND

Clinical subtypes of mild cognitive impairment (MCI) may represent different underlying aetiologies.

METHODS

This European, multicentre, memory clinic based study (DESCRIPA) of non-demented subjects investigated whether MCI subtypes have different brain correlates on MRI and whether the relation between subtypes and brain pathology is modified by age. Using visual rating scales, medial temporal lobe atrophy (MTA) (0-4) and white matter hyperintensities (WMH) (0-30) were assessed.

RESULTS

Severity of MTA differed between MCI subtypes (p<0.001), increasing from a mean of 0.8 (SD 0.7) in subjective complaints (n = 77) to 1.3 (0.8) in non-amnestic MCI (n = 93), and from 1.4 (0.9) in single domain amnestic MCI (n = 70) to 1.7 (0.9) in multiple domain amnestic MCI (n = 89). The association between MCI subtype and MTA was modified by age and mainly present in subjects >70 years of age. Severity of WMH did not differ between MCI subtypes (p = 0.21). However, the combination of MTA and WMH differed between MCI subtypes (p = 0.02)

CONCLUSION

We conclude that MCI subtypes may have different brain substrates, especially in older subjects. Isolated MTA was mainly associated with amnestic MCI subtypes, suggesting AD as the underlying cause. In non-amnestic MCI, the relatively higher prevalence of MTA in combination with WMH may suggest a different pathophysiological origin.

Predictive value of mild cognitive impairment for dementia. The influence of case definition and age

BACKGROUND/AIMS

In population studies, different mild cognitive impairment (MCI) definitions have been used to predict dementia at a later stage. This study compared predictive values of different MCI definitions for dementia, and the effect of age on the predictive values was investigated.

METHODS

This study was conducted as part of an ongoing longitudinal study into the determinants of cognitive aging, the Maastricht Aging Study.

RESULTS

MCI best predicted dementia when multiple cognitive domains were considered and subjective complaints were not (sensitivity: 0.66, specificity: 0.78). Age had a strong influence on the sensitivity of MCI for dementia (age 60-70 years: sensitivity = 0.56; age 70-85 years: sensitivity = 0.70).

CONCLUSION

The inclusion of multiple cognitive domains and participants aged 70 years and older leads to the best prediction of dementia, regardless of subjective complaints.

The association between APOE genotype and memory dysfunction in subjects with mild cognitive impairment is related to age and Alzheimer pathology

BACKGROUND

Memory problems are a main feature of mild cognitive impairment (MCI) and may be related to the apolipoprotein E (APOE) epsilon4 allele. We investigated whether the effect of the APOE genotype on memory in subjects with MCI was dependent on age and underlying Alzheimer disease (AD) pathology.

METHODS

Subjects with MCI (n = 180) were selected from a memory clinic setting. Subjects with at least one APOE epsilon4 allele (n = 83) were compared to non-carriers on several memory measures. Subjects were reassessed 5-10 years later in order to identify those who developed AD.

RESULTS

In the middle-aged subgroup, the APOE epsilon4 allele was most strongly related to decreased subjective organization and in the old subgroup to a decreased delayed recall. After excluding subjects with incipient AD (n = 33), results remained similar in the middle-aged subgroup, but in the old subgroup the APOE genotype was no longer associated with memory dysfunction.

CONCLUSION

The presence of the APOE epsilon4 allele is associated with impaired memory functioning in both middle-aged and old subjects with MCI, although the memory function affected varies with age. Its effect on memory function may be dependent on underlying AD pathology in elderly subjects, but not in middle-aged subjects.

Development of screening guidelines and clinical criteria for predementia Alzheimer's disease. The DESCRIPA Study

BACKGROUND

There is an urgent need to identify subjects with Alzheimer's disease (AD) in the predementia phase, but validated diagnostic approaches are currently lacking. In this paper, we present the background, design and methods of a study, which aims to develop clinical criteria for predementia AD. We also present baseline characteristics of the subjects included. The study was part of the multicentre DESCRIPA project, which is being conducted within the network of the European Alzheimer's Disease Consortium.

METHODS

Clinical criteria will be based on a prospective cohort study of non-demented subjects older than 55 years and referred to a memory clinic. At baseline, a number of markers and risk factors for AD were collected, including demographic variables, measures of performance in activities of daily living, cognitive, neuroimaging and genetic markers, and serum and cerebrospinal fluid markers. Subjects will be reassessed annually for 2-3 years, and we will evaluate which combination of variables best predicts AD-type dementia at follow-up.

RESULTS

Between 2003 and 2005, 881 subjects were included from 20 memory clinics. Subjects were on average 70.3 years old, and had 10.4 years of education. The average score on the Mini-Mental State Examination was 27.4.

Mild cognitive impairment as predictor for Alzheimer's disease in clinical practice: effect of age and diagnostic criteria

BACKGROUND

We investigated whether the predictive accuracy of mild cognitive impairment (MCI) for Alzheimer-type dementia (AD) in a clinical setting is dependent on age and the definition of MCI used.

METHOD

Non-demented subjects older than 40 (n=320) who attended a memory clinic of a university hospital were reassessed 5 years later for the presence of AD. MCI was diagnosed according to the criteria of amnestic MCI, mild functional impairment (MFI), ageing-associated cognitive decline (AACD), and age-associated memory impairment (AAMI). The main outcome measure was the area under the curve (AUC) of a receiver operating characteristic (ROC) curve. Analyses were conducted on the entire sample and on subgroups of subjects aged 40-54, 55-69 and 70-85 years.

RESULTS

A diagnosis of AD at follow-up was made in 58 subjects. Four of them were in the 40-54 age group, 29 in the 55-69 age group and 25 in the 70-85 age group. The diagnostic accuracy in the entire sample was low to moderately high with AUCs ranging from 0.56 (AACD) to 0.75 (amnestic MCI). A good predictive accuracy with an AUC >0.80 was only observed in subjects aged 70-85 using the criteria of amnestic MCI (AUC=0.84).

CONCLUSIONS

The predictive accuracy of MCI for AD is dependent on age and the definition of MCI used. The predictive accuracy is good only for amnestic MCI in subjects 70-85 years. As subjects with prodromal AD are often younger than 70, the usefulness of MCI as predictor of AD in clinical practice is limited.

The ICTUS Study: A Prospective Longitudinal Observational Study of 1,380 AD Patients in Europe

The long-term objective of the ICTUS study is to identify milestones in Alzheimer's disease (AD) progression and to develop a model to predict disease course in individual AD patients in Europe. The secondary objectives are to describe the patterns of prescribing, and the socioeconomic impact of AD in Europe. Between 2003 and 2005 1,380 patients with probable AD were recruited in specialised (secondary care) clinics in 12 European countries. Their mean age was 76 years and they had a mean of 8.0 +/- (SD) 4.6 years of education. Thirty-five percent were male. The mean MMSE score was 20.4 +/- (SD) 4.0. Forty-three percent had very mild dementia (CDR 0.5) and 44% had mild dementia (CDR 1). All patients completed baseline evaluation and biannual follow-up is ongoing. The goals of the current study are to describe the specific methods for recruitment in this crosscultural setting and the characteristics of the inception ICTUS cohort, including clinical features, co-morbidity, neuropsychological performance, neuropsychiatric symptoms, functional impairment and social burden.

Research criteria for the diagnosis of Alzheimer's disease: revising the NINCDS-ADRDA criteria

The NINCDS-ADRDA and the DSM-IV-TR criteria for Alzheimer's disease (AD) are the prevailing diagnostic standards in research; however, they have now fallen behind the unprecedented growth of scientific knowledge. Distinctive and reliable biomarkers of AD are now available through structural MRI, molecular neuroimaging with PET, and cerebrospinal fluid analyses. This progress provides the impetus for our proposal of revised diagnostic criteria for AD. Our framework was developed to capture both the earliest stages, before full-blown dementia, as well as the full spectrum of the illness. These new criteria are centred on a clinical core of early and significant episodic memory impairment. They stipulate that there must also be at least one or more abnormal biomarkers among structural neuroimaging with MRI, molecular neuroimaging with PET, and cerebrospinal fluid analysis of amyloid beta or tau proteins. The timeliness of these criteria is highlighted by the many drugs in development that are directed at changing pathogenesis, particularly at the production and clearance of amyloid beta as well as at the hyperphosphorylation state of tau. Validation studies in existing and prospective cohorts are needed to advance these criteria and optimise their sensitivity, specificity, and accuracy.

Mild cognitive impairment (MCI) in medical practice: a critical review of the concept and new diagnostic procedure. Report of the MCI Working Group of the European Consortium on Alzheimer's Disease

Mild cognitive impairment (MCI) was proposed as a nosological entity referring to elderly people with mild cognitive deficit but no dementia. MCI is a heterogeneous clinical entity with multiple sources of heterogeneity. The concept of MCI was reviewed and a diagnostic procedure with three different stages was proposed by the European Consortium on Alzheimer's Disease Working Group on MCI. Firstly, MCI should correspond to cognitive complaints coming from the patients or their families; the reporting of a relative decline in cognitive functioning during the past year by a patient or informant; cognitive disorders as evidenced by clinical evaluation; absence of major repercussions on daily life; and absence of dementia. These criteria, similar to those defined during an international workshop in Stockholm, make it possible to identify an MCI syndrome, which is the first stage of the diagnostic procedure. Secondly, subtypes of MCI had to be recognised. Finally, the aetiopathogenic subtype could be identified. Identifying patients at a high risk for progression to dementia and establishing more specific and adapted therapeutic strategies at an early stage, together with more structured overall management, is made possible by the diagnostic procedure proposed.

Role of cognitive testing in disease modifying AD trials

Cognitive impairment is a key feature of Alzheimer's disease (AD). Cognitive performance will therefore be an important outcome measure in disease modifying drug trials. However, cognitive assessment also has several limitations such as a large inter and intra individual variability and floor and ceiling effects. To reduce the effect of these limitations on the accuracy with which drug-related changes can be detected, it is proposed to analyse cognitive change using a slope analysis. In addition, it is suggested to use as the main outcome measure for cognitive impairment a neuropsychological compound score that is based on a z-score transformation of a number of well-validated tests. The selection of these tests would depend on a number of study characteristics such as the inclusion criteria and the length of follow-up.

Do MCI criteria in drug trials accurately identify subjects with predementia Alzheimer's disease?

BACKGROUND

Drugs effective in Alzheimer-type dementia have been tested in subjects with mild cognitive impairment (MCI) because these are supposed to have Alzheimer's disease in the predementia stage.

OBJECTIVES

To investigate whether MCI criteria used in these drug trials can accurately diagnose subjects with predementia Alzheimer's disease.

METHODS

MCI criteria of the Gal-Int 11 study, InDDEx study, ADCS memory impairment study, ampakine CX 516 study, piracetam study, and Merck rofecoxib study were applied retrospectively in a cohort of 150 non-demented subjects from a memory clinic. Forty two had progressed to Alzheimer type dementia during a five year follow up period and were considered to have predementia Alzheimer's disease at baseline. Outcome measures were the odds ratio, sensitivity, specificity, and positive and negative predictive value.

RESULTS

The odds ratio of the MCI criteria for predementia Alzheimer's disease varied between 0.84 and 11. Sensitivity varied between 0.46 and 0.83 and positive predictive value between 0.43 and 0.76. None of the criteria combined a high sensitivity with a high positive predictive value. Exclusion criteria for depression led to an increase in positive predictive value and specificity at the cost of sensitivity. In subjects older than 65 years the positive predictive value was higher than in younger subjects.

CONCLUSIONS

The diagnostic accuracy of MCI criteria used in trials for predementia Alzheimer's disease is low to moderate. Their use may lead to inclusion of many patients who do not have predementia Alzheimer's disease or to exclusion of many who do. Subjects with moderately severe depression should not be excluded from trials in order not to reduce the sensitivity.

Predictive accuracy of MCI subtypes for Alzheimer's disease and vascular dementia in subjects with mild cognitive impairment: a 2-year follow-up study

AIM

The aim of this study was to investigate the prognostic accuracy of different subtypes of mild cognitive impairment (MCI): amnestic MCI, multiple domain MCI, and single non-memory domain MCI, for the development of Alzheimer's dementia (AD) and vascular dementia (VaD).

PATIENTS

Nondemented patients from a memory clinic cohort (n = 118), and a stroke cohort (n = 80, older than 55 years and with a cognitive impairment).

RESULTS

'Multiple domain MCI' had the highest sensitivity for both AD (80.8%) and VaD (100%), and 'amnestic MCI' had the highest specificity (85.9% for AD, 100% for VaD). The positive predictive value was low for all subtypes (0.0-32.7%), whereas the negative predictive value was high (72.8-100%).

DISCUSSION

The subtype 'multiple domain MCI' has high sensitivity in identifying people at risk for developing AD or VaD. The predictive accuracy of the MCI subtypes was similar for both AD and VaD.

Biomarker profiles and their relation to clinical variables in mild cognitive impairment

The aim of the study was to compare clinical variables between MCI patients at different risk for Alzheimer's disease (AD) according to their biomarker profile. Fifty-four percent out of 39 MCI patients had a low Abeta42 and high tau in cerebrospinal fluid (CSF) (high-risk), 26% either a low CSF Abeta32 or high CSF tau (intermediate-risk) and 20% a normal CSF Abeta42 and tau (low-risk). Both high-and intermediate-risk subjects differed from the low-risk group in episodic memory, executive functions and the preclinical AD scale (PAS),which combines a set of clinical parameters. Subjects at high risk did not differ from subjects with an intermediate risk. Abeta42 levels correlated with the MTA and PAS scores, tau levels with episodic memory. These correlations suggest that the biomarkers are not independent when compared to the other AD markers. Longitudinal studies are necessary to interpret the correlations between biomarkers, imaging, and neuropsychological markers.

Global and local gray matter loss in mild cognitive impairment and Alzheimer's disease

PURPOSE

Mild cognitive impairment (MCI) is thought to be the prodromal phase to Alzheimer's disease (AD). We analyzed patterns of gray matter (GM) loss to examine what characterizes MCI and what determines the difference with AD.

MATERIALS AND METHODS

Thirty-three subjects with AD, 14 normal elderly controls (NCLR), and 22 amnestic MCI subjects were included and underwent brain MR imaging. Global GM volume was assessed using segmentation and local GM volume was assessed using voxel-based morphometry (VBM); VBM was optimized for template mismatch and statistical mass.

RESULTS

AD subjects had significantly (12.3%) lower mean global GM volume when compared to controls (517 +/- 58 vs. 590 +/- 52 ml; P < 0.001). Global GM volume in the MCI group (552 +/- 52) was intermediate between these two: 6.2% lower than AD and 6.5% higher than the controls but not significantly different from either group. VBM showed that subjects with MCI had significant local reductions in gray matter in the medial temporal lobe (MTL), the insula, and thalamus compared to NCLR subjects. By contrast, when compared to subjects with AD, MCI subjects had more GM in the parietal association areas and the anterior and the posterior cingulate.

CONCLUSION

GM loss in the MTL characterizes MCI, while GM loss in the parietal and cingulate cortices might be a feature of AD.

Medial temporal lobe atrophy predicts Alzheimer's disease in patients with minor cognitive impairment

OBJECTIVES

To investigate whether medial temporal lobe atrophy predicted outcome in patients with minor cognitive impairment and whether assessment of the medial temporal lobe could increase the predictive accuracy of age and delayed recall for outcome. Quantitative and qualitative methods of assessing the medial temporal lobe were also compared.

METHODS

Patients with minor cognitive impairment older than 50 years (n=31) were selected from a memory clinic and were followed up for on average 1.9 years. The medial temporal lobe was assessed in three different ways: volumetry of the hippocampus, volumetry of the parahippocampal gyrus, and qualitative rating of medial temporal lobe atrophy (MTA). Outcome measures were Alzheimer type dementia or cognitive decline at follow up. Delayed recall was tested with a verbal learning test.

RESULTS

Ten patients had experienced cognitive decline at follow up, of whom seven had probable Alzheimer type dementia. All medial temporal lobe measurements were associated with cognitive decline at follow up (p trend analysis between 0.001 (hippocampus) and 0.05 (parahippocampal gyrus)). Only the hippocampal volume and MTA score were associated with Alzheimer type dementia at follow up (p trend analysis respectively 0.003 and 0.01). All medial temporal lobe measurements increased the predictive accuracy of age and the delayed recall score for cognitive decline (p increase in predictive accuracy varied between <0.001 (hippocampus) and 0.02 (parahippocampal gyrus and MTA score)) and the hippocampal volume and the MTA score increased the predictive accuracy of age and the delayed recall score for Alzheimer type dementia (p= 0.02).

CONCLUSIONS

The ability to detect patients at high risk for Alzheimer type dementia among those with minor cognitive impairment increases when data on age and memory function are combined with measures of medial temporal lobe atrophy. Volumetry of the hippocampus is preferred, but qualitative rating of medial temporal lobe atrophy is a good alternative.

Diagnosis of preclinical Alzheimer's disease in a clinical setting

INTRODUCTION

The aim of the study was to investigate whether the preclinical stage of Alzheimer's disease (AD) can be diagnosed in a clinical setting. To this end we investigated whether subjects with preclinical AD could be differentiated from subjects with nonprogressive mild cognitive impairment and from subjects with very mild AD-type dementia.

METHODS

Twenty-three subjects with preclinical AD, 44 subjects with nonprogressive mild cognitive impairment, and 25 subjects with very mild AD-type dementia were selected from a memory clinic population. Variables that were used to differentiate the groups were demographic variables, the Mini-Mental State Examination score, performance on cognitive tests, measures of functional impairment, and measures of noncognitive symptomatology.

RESULTS

Age and the scores for the delayed recall task could best discriminate between subjects with preclinical AD and subjects with nonprogressive mild cognitive impairment. The overall accuracy was 87%. The score on the Global Deterioration Scale and a measure of intelligence could best discriminate between subjects with preclinical AD and subjects with very mild AD-type dementia. The overall accuracy was 85%.

CONCLUSIONS

Subjects with preclinical AD can be distinguished from subjects with nonprogressive mild cognitive impairment and from subjects with very mild AD-type dementia. This means that preclinical AD is a diagnostic entity for which clinical criteria should be developed.