Trajectories of cognitive decline in different types of dementia

BACKGROUND

To investigate trajectories of cognitive decline in patients with different types of dementia compared to controls in a longitudinal study.

METHOD

In 199 patients with Alzheimer's disease (AD), 10 with vascular dementia (VaD), 26 with dementia with Lewy bodies (DLB), 20 with behavioural variant frontotemporal dementia (bvFTD), 15 with language variant frontotemporal dementia (lvFTD) and 112 controls we assessed five cognitive domains: memory, language, attention, executive and visuospatial functioning, and global cognition (Mini-Mental State Examination, MMSE). All subjects had at least two neuropsychological assessments (median 2, range 2-7). Neuropsychological data were standardized into z scores using baseline performance of controls as reference. Linear mixed models (LMMs) were used to estimate baseline cognitive functioning and cognitive decline over time for each group, adjusted for age, gender and education.

RESULTS

At baseline, patients with dementia performed worse than controls in all cognitive domains (p < 0.05) except visuospatial functioning, which was only impaired in patients with AD and DLB (p < 0.001). During follow-up, patients with AD declined in all cognitive domains (p < 0.001). DLB showed decline in every cognitive domain except language and global cognition. bvFTD showed rapid decline in memory, language, attention and executive functioning (all p < 0.01) whereas visuospatial functioning remained fairly stable. lvFTD declined mostly in attention and executive functioning (p < 0.01). VaD showed decline in attention and executive functioning.

CONCLUSIONS

We show cognitive trajectories of different types of dementia. These estimations of natural disease course have important value for the design of clinical trials as neuropsychological measures are increasingly being used as outcome measures.

The effect of galantamine on brain atrophy rate in subjects with mild cognitive impairment is modified by apolipoprotein E genotype: post-hoc analysis of data from a randomized controlled trial

INTRODUCTION

The aim of this investigation was to assess the effect of galantamine, an acetylcholinesterase inhibitor and allosteric modulator of nicotinic receptors, on brain atrophy in individuals with mild cognitive impairment (MCI), and to assess effect modification by apolipoprotein E (APOE) genotype.

METHODS

We used data from the Galantamine-International-11 (Gal-Int-11) trial, a 24-month, randomized, double blind, placebo-controlled, flexible-dose (16 to 24 mg daily) study in patients with MCI. Brain magnetic resonance imaging (MRI), including a 3-dimensional T1-weighted gradient echo volumetric sequence, was performed at screening and at 24 months. We recorded whole brain and hippocampal volumes, and calculated annual atrophy rates. Linear regression analysis was used to calculate adjusted mean differences in the rate of whole brain and hippocampal atrophy, between MCI patients treated with galantamine and with placebo. Additionally, we performed stratified analyses according to APOE genotype.

RESULTS

Data from 364 MCI patients with 24-month MRI data (galantamine, n = 176; placebo, n = 188) were included in the volumetric analysis. Subjects treated with galantamine demonstrated a lower rate of whole brain atrophy compared to those treated with placebo (adjusted mean difference 0.18% per year (95% confidence interval (CI) 0.04; 0.30)). Stratified analyses according to APOE genotype, showed that this effect was confined to patients who carried an APOE ϵ4 allele (adjusted mean difference 0.28% per year (95% CI 0.07; 0.50)). Rates of hippocampal atrophy did not differ significantly between study groups.

CONCLUSIONS

Patients with MCI who were treated with galantamine demonstrated a lower rate of whole brain atrophy, but not of hippocampal atrophy, over a 24-month treatment period, compared to those treated with placebo. This protective effect of galantamine on whole brain atrophy rate in MCI was only present in APOE ϵ4 carriers.

Building a new paradigm for the early recognition of behavioral variant frontotemporal dementia: Late Onset Frontal Lobe Syndrome study

OBJECTIVE

To describe the aims and design of the ongoing Late Onset Frontal Lobe Syndrome study (LOF study), a study on the spectrum of neurodegenerative and psychiatric etiologies causing behavioral changes in later life, and on the role of magnetic resonance imaging (MRI), [(18)F]-fluorodeoxyglucose-positron emission tomography (FDG-PET), and cerebrospinal fluid (CSF) biomarkers in predicting and identifying the different underlying pathologies with a special focus on the behavioral variant of frontotemporal dementia.

METHODS

The LOF study is an observational cross-sectional and prospective follow-up study. Patients aged 45-75 years with a frontal behavioral change consisting of apathy, disinhibition, or compulsive/stereotypical behavior were included (April 2011-2013). Patients underwent a multidisciplinary assessment by a neurologist and psychiatrist and MRI, CSF, and PET measurements at inclusion and after 2 years of follow-up.

RESULTS

The diagnostic added value of MRI, PET, and CSF results and their predictive value will be measured after 2 years of follow-up.

CONCLUSION

This is the first large-scale prospective follow-up study of patients with late-onset behavioral disorders.

Prevalence of cortical superficial siderosis in a memory clinic population

OBJECTIVE

To determine prevalence, topography, and severity of cortical superficial siderosis (SS), a recently recognized manifestation of cerebral amyloid angiopathy, and its possible association with Alzheimer disease (AD) in a memory clinic patient cohort.

METHODS

We included 809 patients (56% men, aged 66 ± 10 years) from the Amsterdam Dementia Cohort between November 2010 and November 2012 scanned on a 3-tesla MRI system. We analyzed prevalence and topography of cortical SS according to demographic, clinical, and MRI data. Agreement for SS detection between 2 neuroradiologists was calculated by using Cohen κ.

RESULTS

Agreement for detection of SS was excellent (unweighted κ of 0.81). In 17 patients (2.1%), cortical SS was found without a known cause. The prevalence of idiopathic SS differed according to diagnostic groups (p < 0.001): nearly 5% (95% confidence interval [CI] 2.8%-8.2%) in patients with AD (n = 168) vs 2% (95% CI 0.7%-6.0%) in patients with mild cognitive impairment (n = 143) and 2.5% (95% CI 0.7%-8.7%) in other types of dementia (n = 80). By contrast, SS was not found in patients with subjective complaints (n = 168) or in those with other disorders (n = 157). Presence of SS was associated with APOE ε4, microbleeds, and white matter hyperintensities (all p < 0.05) independent of diagnosis.

CONCLUSION

The prevalence of cortical SS in a memory clinic setting is higher than reported in the general population but lower than reported in cerebral amyloid angiopathy. The relatively high prevalence of SS in AD suggests that SS is a relevant radiologic manifestation of amyloid pathology in AD. Presence of SS does not seem to predict severity of AD. Further longitudinal research is needed to investigate clinical relevance.

Associations between magnetic resonance imaging measures and neuropsychological impairment in early and late onset alzheimer's disease

AIM

To assess the associations of global atrophy and white matter hyperintensities (WMH) with neuropsychological function in early and late onset Alzheimer's disease (AD).

METHODS

We included 107 patients with sporadic AD (21 early onset and 86 late onset) from our memory clinic. Tests for (working) memory, language, executive function, mental speed, and attention were administered. Global atrophy and global and lobar WMH were measured using 1 Tesla MRI. Linear regression analyses with terms for MRI measures, neuropsychological test results, age, gender, education, and the interaction between separate brain measures and age of onset were performed.

RESULTS

Global atrophy was associated with more severely impaired global cognition, working memory, mental speed, and executive function (p < 0.05). Significant interactions between global atrophy and age at onset showed that these associations were mostly attributable to patients with early onset AD. By contrast, an association between global atrophy and memory was found, which was specifically attributable to late onset AD patients. No associations between global WMH and cognitive function were found. Subsequently we analyzed regional WMH and found that temporal WMH was associated with impaired memory, and frontal WMH was associated with slower mental speed.

CONCLUSION

Cortical atrophy, a key feature of AD, is linked to a wide range of cognitive functions, specifically in early onset AD patients. For WMH, there were no interactions with age at onset, but we found specific associations between temporal WMH and memory and frontal WMH and mental speed.

Predictors of progression from mild cognitive impairment to dementia in the placebo-arm of a clinical trial population

We studied the predictive value of cognitive performance, vascular risk factors, apolipoprotein E (APOE) genotype, and structural brain changes on MRI, on progression to dementia in post hoc analyses of 426 placebo patients (mean age 71 years; 55% women) with mild cognitive impairment (MCI) who participated in a previously published large multi-center clinical trial (Gal-Int-11). The ADAS-cog/MCI test, the New York University Paragraph Recall Test, and the Digit Symbol Coding Test were available at baseline, as were vascular risk factors and APOE genotype. Medial temporal lobe atrophy (MTA), white matter hyperintensities (WMH) and lacunes were assessed on MRI. Over two years of follow-up, 81 patients (19%) converted to dementia, while 345 patients (81%) remained stable. Results of Cox proportional-hazards regression analysis showed that higher age, worse cognitive test performance, presence of an APOE ε4 allele, and higher MTA scores on MRI increased the risk of progression to dementia in univariate analyses. Vascular risk factors, and WMH and lacunes on MRI, were not associated with progression to dementia. Lower performance on the ADAS-cog/MCI test (HR 1.08 per point increase; 95% CI 1.06-1.10) and Delayed recall test (HR 0.76 per point increase; 95% CI 0.68-0.85), as well as higher MTA scores on MRI (HR 1.33 per point increase; 95% CI 1.00-1.77) were independent predictors of progression to dementia in a step-wise Cox proportional-hazards model with age and gender forced into the model. We conclude that global cognitive function, episodic memory performance, and MTA on MRI independently predict progression to dementia in patients with MCI.

Treating Alzheimer's disease with monoclonal antibodies: current status and outlook for the future

In the past decade, Alzheimer's disease drug discovery has been directed at 'disease modifying drugs' that are able to counteract the progression of Alzheimer's disease by intervening in specific parts of its neuropathological process. Passive immunization with monoclonal antibodies (mAbs) may be able to clear toxic amyloid-β species either directly or through microglia or complement activation, thereby halting the amyloid cascade and preventing neurodegeneration and cognitive and functional decline. Thus far, results from two large phase 3 trial programs with bapineuzumab and solaneuzumab, respectively, have brought rather disappointing results. Possible explanations could be that these compounds were either targeting the wrong amyloid-β species, or were given too late in the disease process. Several new mAbs targeting various amyloid-β epitopes are now being tested in ongoing phase 2 and 3 clinical trials. The present review discusses the various mAbs aimed at amyloid-β, summarizes trial results and provides an outlook for the future.

Episodic memory impairment in frontotemporal dementia; a ⁹⁹mTc- HMPAO SPECT study

Alzheimer's disease (AD) and frontotemporal dementia (FTD) are the most common types of dementia in the presenile population. Episodic memory impairment, the clinical hallmark of AD, can also be encountered in patients with FTD, complicating accurate diagnosis. Several studies in FTD have correlated memory deficits with neuroimaging findings, but lacked to compare neuroimaging results in FTD patients with and without memory impairment, while this latter analysis may give us insight into the underlying mechanisms of memory impairment in FTD. The aim of the present study was to compare (99m)Tc-HMPAO SPECT hypoperfusion patterns between FTD with episodic memory impairment (n = 13), FTD patients without episodic memory impairment (n = 10) as well as early onset (< 70 yrs) AD patients (n = 13), and controls (n = 15). We performed our analyses by means of Statistical Parametric Mapping software (SPM5), and showed that FTD patients with episodic memory impairment had lower perfusion in the right temporal lobe compared with FTD patients without memory impairment. Lower perfusion in this region correlated with worse memory performance on the Clinical Dementia Rating scale in FTD patients. With equal performances on memory tests, patients with early onset AD showed posterior temporal and parietal lobe hypoperfusion in comparison with patients with FTD and memory impairment, while vice versa hypoperfusion in the anterior frontotemporal regions was found in FTD patients with memory impairment in comparison with AD.

Cerebral small vessel disease affects white matter microstructure in mild cognitive impairment

Microstructural white matter deterioration is a frequent finding in mild cognitive impairment (MCI), potentially underlying default mode network (DMN) dysfunctioning. Thus far, microstructural damage in MCI has been attributed to Alzheimer's disease pathophysiology. A cerebrovascular role, in particular the role of cerebral small vessel disease (CSVD), received less interest. Here, we used diffusion tensor imaging (DTI) to examine the role of CSVD in microstructural deterioration within the normal appearing white matter (NAWM) in MCI. MCI patients were subdivided into those with (n = 20) and without (n = 31) macrostructural CSVD evidence on MRI. Using TBSS we performed microstructural integrity comparisons within the whole brain NAWM. Secondly, we segmented white matter tracts interconnecting DMN brain regions by means of automated tractography segmentation. We used NAWM DTI measures from these tracts as dependent variables in a stepwise-linear regression analysis, with structural and demographical predictors. Our results indicated microstructural deterioration within the anterior corpus callosum, internal and external capsule and periventricular white matter in MCI patients with CSVD, while in MCI patients without CSVD, deterioration was restricted to the right perforant path, a tract along the hippocampus. Within the full cohort of MCI patients, microstructure within the NAWM of the DMN fiber tracts was affected by the presence of CSVD. Within the cingulum along the hippocampal cortex we found a relationship between microstructural integrity and ipsilateral hippocampal volume and the extent of white matter hyperintensity. In conclusion, we found evidence of CSVD-related microstructural damage in fiber tracts subserving the DMN in MCI.

Amyloid imaging in clinical trials

The possibility to map amyloid-beta, the Alzheimer's disease hallmark protein, in vivo opens the application for amyloid imaging in clinical trials with disease-modifying agents. Monitoring change in amyloid burden, particularly when potential amyloid-lowering drugs are at play, requires accurate analytical methods. Studies to date have used suboptimal methods that do not account for heterogeneous changes in flow associated with disease progression and potentially with anti-amyloid drugs. In this commentary, we discuss practical and methodological issues regarding longitudinal amyloid imaging and propose several quantitative, yet feasible, alternatives for reliable assessment of changes over time in amyloid burden.

Specific risk factors for microbleeds and white matter hyperintensities in Alzheimer's disease

We investigated whether microbleeds and white matter hyperintensities (WMH) in Alzheimer's disease (AD) associate more with conventional vascular risk factors or with risk factors that reflect amyloid burden. A total of 371 patients with probable AD were included. WMH (Fazekas 2 or 3) were present in 107 (29%) patients and microbleeds were seen in 98 (26%). Patients with both microbleeds and WMH were older and presented more frequently with lacunes and multiple microbleeds than patients with microbleeds in isolation (all p < 0.05). Using multivariate regression models, we found that WMH presence showed independent associations with age, hypertension, current smoking, and lacune presence. Microbleeds were independently associated with male gender, higher blood pressure, lower cerebrospinal fluid Aβ42, and apolipoprotein E ε4 homozygosity. Separate analyses for microbleeds according to their location showed that these associations were driven by microbleeds in lobar locations. Our results suggest that, unlike WMH, microbleeds in AD are particularly associated with additional amyloid burden, and as such, may relate to cerebral amyloid angiopathy.

The influence of cerebral small vessel disease on default mode network deactivation in mild cognitive impairment

Introduction

Cerebral small vessel disease (CSVD) is thought to contribute to cognitive dysfunction in patients with mild cognitive impairment (MCI). The underlying mechanisms, and more specifically, the effects of CSVD on brain functioning in MCI are incompletely understood. The objective of the present study was to examine the effects of CSVD on brain functioning, activation and deactivation, in patients with MCI using task-related functional MRI (fMRI).

Methods

We included 16 MCI patients with CSVD, 26 MCI patients without CSVD and 25 controls. All participants underwent a physical and neurological examination, neuropsychological testing, structural MRI, and fMRI during a graded working memory paradigm.

Results

MCI patients with and without CSVD had a similar neuropsychological profile and task performance during fMRI, but differed with respect to underlying (de)activation patterns. MCI patients with CSVD showed impaired deactivation in the precuneus/posterior cingulate cortex, a region known to be involved in the default mode network. In MCI patients without CSVD, brain activation depended on working memory load, as they showed relative ‘hyperactivation’ during vigilance, and ‘hypoactivation’ at a high working memory load condition in working memory related brain regions.

Conclusions

We present evidence that the potential underlying mechanism of CSVD affecting cognition in MCI is through network interference. The observed differences in brain activation and deactivation between MCI patients with and without CSVD, who had a similar ‘clinical phenotype’, support the view that, in patients with MCI, different types of pathology can contribute to cognitive impairment through different pathways.

Amyloid imaging in prodromal Alzheimer's disease

Patients with mild cognitive impairment are at an increased risk of progression to Alzheimer's disease. However, not all patients with mild cognitive impairment progress, and it is difficult to accurately identify those patients who are in the prodromal stage of Alzheimer's disease. In a recent paper, Koivunen and colleagues report that Pittsburgh compound-B, an amyloid-beta positron emission tomography ligand, predicts the progression of patients with mild cognitive impairment to Alzheimer's disease. Of 29 subjects with mild cognitive impairment, 21 (72%) had a positive Pittsburgh compound-B positron emission tomography baseline scan. In their study, 15 of these 21 (71%) patients progressed to Alzheimer's disease, whilst only 1 out of 8 (12.5%) Pittsburgh compound-B-negative patients with mild cognitive impairment did so. Moreover, in these mild cognitive impairment patients, the overall amyloid burden increased approximately 2.5% during the follow-up period. This is consistent with other longitudinal amyloid imaging studies that found a similar increase in amyloid deposition over time in patients with mild cognitive impairment. These studies together challenge current theories that propose a flattening of the increase of brain amyloid deposition already in the preclinical stage of Alzheimer's disease. These findings may have important implications for the design of future clinical trials aimed at preventing progression to Alzheimer's disease by lowering the brain amyloid-beta burden in patients with mild cognitive impairment.

Efficacy of early cognitive-linguistic treatment and communicative treatment in aphasia after stroke: a randomised controlled trial (RATS-2)

BACKGROUND

The two main approaches in aphasia treatment are cognitive-linguistic treatment (CLT), aimed at restoring the linguistic levels affected, semantics, phonology or syntax, and communicative treatment, aimed at optimising information transfer by training compensatory strategies and use of residual language skills. The hypothesis that CLT is more effective than communicative treatment in the early stages after stroke was tested in this study.

METHODS

In this multicentre, randomised, parallel group trial with blinded outcome assessment, 80 patients with aphasia after stroke were included within 3 weeks post-stroke. Patients received 6 months of CLT, comprising semantic and/or phonological training, or communicative treatment for at least 2 h per week. They were assessed before treatment and at 3 and 6 months with the Amsterdam-Nijmegen Everyday Language Test (ANELT-A, primary outcome) and semantic and phonological tests (secondary outcomes). The intervention effect was evaluated by means of analysis of covariance, with adjustment for baseline scores.

RESULTS

There was no difference between the mean ANELT-A score of the CLT group (n=38) and the communicative treatment group (n=42), at 3 months (adjusted difference 1.5, 95% CI -2.6 to 5.6) or at 6 months (adjusted difference 1.6, 95% CI -2.3 to 5.6) post-stroke. On two of six specific semantic and phonological tests, the mean scores differed significantly, both in favour of CLT.

CONCLUSION

This study does not confirm the hypothesis that patients with aphasia after stroke benefit more from CLT, aimed at activation of the underlying semantic and phonologic processes, than from general, non-specific communicative treatment (ISRCTN67723958 Current Controlled Trials).

Can novel therapeutics halt the amyloid cascade?

The amyloid hypothesis provides a basis for the development of new therapeutic strategies in Alzheimer's disease. Two large trials have recently been published. The first is a phase 2 study of passive immunotherapy with bapineuzumab, a humanized anti-Aβ monoclonal antibody directed against the N-terminus of Aβ. This trial showed no differences within dose cohorts on the primary efficacy analysis. Exploratory analyses showed potential treatment differences on cognitive and functional endpoints in study completers and apolipoprotein E ε4 noncarriers. A safety concern was the occurrence of reversible vasogenic edema. The second study is a phase 3 trial of tarenflurbil, a modulator of the activity of γ-secretase. Tarenflurbil had no beneficial effect on the primary or secondary outcomes. The tarenflurbil group had a small increase in frequency of dizziness, anemia, and infections. Possible explanations for the negative results of these trials may be related to the study design or the choice of dosage. However, it may also be that these negative findings reflect our still incomplete understanding of, at least part of, the pathogenesis of Alzheimer's disease.

Progression of cerebral small vessel disease in relation to risk factors and cognitive consequences: Rotterdam Scan study

BACKGROUND AND PURPOSE

Cerebral white matter lesions and lacunar infarcts are small vessel disease-related lesions, which are associated with cognitive decline and dementia. We aimed to assess the relationship between risk factors, effect modifiers, and progression of these lesions. Furthermore, we studied the cognitive consequences of lesion progression.

METHODS

Six hundred sixty-eight people, aged 60 to 90 years, underwent repeated MRI scanning and neuropsychological testing within 3-year follow-up. We rated incident lacunar infarcts and change in periventricular and subcortical white matter lesion severity with a semiquantitative scale. We assessed the relationships between age, sex, baseline lesion load, risk factors, lesion progression, and change in cognitive function by multivariate regression analyses and additional stratified analyses.

RESULTS

Baseline lesion load, higher age, high blood pressure, and current smoking were independently associated with progression of white matter lesions. Women had more marked progression of subcortical white matter lesions and incident lacunar infarcts compared with men. Carotid atherosclerosis was associated with incident lacunar infarcts. Higher blood pressure did not contribute to lesion progression in people with already severe lesions at baseline nor in the very old. Lesion progression was associated with a paralleled decline in general cognitive function and in particular with a decreased information processing speed.

CONCLUSIONS

Higher age, female sex, cigarette smoking, elevated blood pressure, and baseline lesion load were associated with small vessel disease progression. Age and baseline lesion load influenced the risk relations with blood pressure. Progression of small vessel disease was related to a paralleled decline in cognitive function.

Glucocorticoid receptor variant and risk of dementia and white matter lesions

OBJECTIVE

Elevated glucocorticoid levels are associated with dementia. A glucocorticoid receptor gene variant (ER22/23EK) is related to relative glucocorticoid resistance. We investigated whether the ER22/23EK allele is associated with dementia and structural brain abnormalities.

METHODS

This study was performed in two prospective population-based cohort studies among elderly. The first study included 6034 participants who were screened for dementia (mean follow-up 5.8 years). The second study included 1011 elderly subjects with an MRI at baseline and follow-up. The ER22/23EK allele was assessed for association with dementia, cognitive function and white matter lesions.

RESULTS

The ER22/23EK allele was associated with a decreased risk of dementia. Among non-demented participants, ER22/23EK-carriers had a better performance on psychomotor speed tests than non-carriers. No differences were found in memory function between genotypes. In addition, both presence and progression of white matter lesions was lower in ER22/23EK-carriers. No association was found with brain atrophy on MRI.

CONCLUSIONS

Our findings suggest a protective effect of the ER22/23EK allele on the risk of dementia and white matter lesions.