Neuropsychological study of familial Alzheimer's disease caused by mutation E280A in the presenilin 1 gene

The NeuroBel: A Screening Test for Verbal Language Impairment in Spanish-Speaking Elderly People With Cognitive Decline

PURPOSE

The NeuroBel is a short test that can detect cognitive decline using language tasks. This study replicated previous research using larger clinical samples from three Spanish-speaking countries.

METHOD

Eight tasks were used to analyze verbal language functioning using a psycholinguistic approach. A total of 232 elderly, monolingual Spanish speakers from Spain, Cuba, and Colombia participated in this study. Of these, 76 had Alzheimer's disease (AD) in the initial phase, 75 had mild cognitive impairment (MCI), and 81 did not exhibit cognitive impairment (healthy controls).

RESULTS

Significant differences were observed among the three clinical groups. The participants with AD and the participants with MCI had significantly lower NeuroBel scores than the control group on most of the tasks. However, repetition (in AD vs. MCI) and auditory lexical decision (in MCI vs. control) tasks were not significant in Tukey's post hoc tests. Discriminant analysis showed that 80.6% of the participants were correctly classified into the original groups and revealed the tasks that were the best and worst for differentiating among groups. The receiver-operating characteristic curves showed high sensitivity for AD and MCI. The area under the curve was .97 in the contrast of AD versus MCI + controls, .96 in the determination of overall cognitive decline (AD + MCI vs. controls), and .93 in the contrast of MCI and control groups.

CONCLUSION

This study confirmed that the NeuroBel is a suitable test for detecting cognitive decline based on language impairment in Spanish-speaking elderly people.

Cholinergic-like neurons and cerebral spheroids bearing the PSEN1 p.Ile416Thr variant mirror Alzheimer's disease neuropathology

Familial Alzheimer's disease (FAD) is a complex neurodegenerative disorder for which there are no therapeutics to date. Several mutations in presenilin 1 (PSEN 1), which is the catalytic component of γ-secretase complex, are causal of FAD. Recently, the p.Ile416Thr (I416T) PSEN 1 mutation has been reported in large kindred in Colombia. However, cell and molecular information from I416T mutation is scarce. Here, we demonstrate that menstrual stromal cells (MenSCs)-derived planar (2D) PSEN 1 I416T cholinergic-like cells (ChLNS) and (3D) cerebral spheroids (CSs) reproduce the typical neuropathological markers of FAD in 4 post-transdifferentiating or 11 days of transdifferentiating, respectively. The models produce intracellular aggregation of APPβ fragments (at day 4 and 11) and phosphorylated protein TAU at residue Ser202/Thr205 (at day 11) suggesting that iAPPβ fragments precede p-TAU. Mutant ChLNs and CSs displayed DJ-1 Cys106-SO3 (sulfonic acid), failure of mitochondria membrane potential (ΔΨm), and activation of transcription factor c-JUN and p53, expression of pro-apoptotic protein PUMA, and activation of executer protein caspase 3 (CASP3), all markers of cell death by apoptosis. Moreover, we found that both mutant ChLNs and CSs produced high amounts of extracellular eAβ42. The I416T ChLNs and CSs were irresponsive to acetylcholine induced Ca2+ influx compared to WT. The I416T PSEN 1 mutation might work as dominant-negative PSEN1 mutation. These findings might help to understanding the recurring failures of clinical trials of anti-eAβ42, and support the view that FAD is triggered by the accumulation of other intracellular AβPP metabolites, rather than eAβ42.

Biological and Cognitive Markers of Presenilin1 E280A Autosomal Dominant Alzheimer's Disease: A Comprehensive Review of the Colombian Kindred

The study of individuals with autosomal dominant Alzheimer's disease affords one of the best opportunities to characterize the biological and cognitive changes of Alzheimer's disease that occur over the course of the preclinical and symptomatic stages. Unifying the knowledge gained from the past three decades of research in the world's largest single-mutation autosomal dominant Alzheimer's disease kindred - a family in Antioquia, Colombia with the E280A mutation in the Presenilin1 gene - will provide new directions for Alzheimer's research and a framework for generalizing the findings from this cohort to the more common sporadic form of Alzheimer's disease. As this specific mutation is virtually 100% penetrant for the development of the disease by midlife, we use a previously defined median age of onset for mild cognitive impairment for this cohort to examine the trajectory of the biological and cognitive markers of the disease as a function of the carriers' estimated years to clinical onset. Studies from this cohort suggest that structural and functional brain abnormalities - such as cortical thinning and hyperactivation in memory networks - as well as differences in biofluid and in vivo measurements of Alzheimer's-related pathological proteins distinguish Presenilin1 E280A mutation carriers from non-carriers as early as childhood, or approximately three decades before the median age of onset of clinical symptoms. We conclude our review with discussion on future directions for Alzheimer's disease research, with specific emphasis on ways to design studies that compare the generalizability of research in autosomal dominant Alzheimer's disease to the larger sporadic Alzheimer's disease population.

NeuroBel: Spanish screening test for oral psycholinguistics disabilities in elderly people with mild cognitive impairment and early-stage Alzheimer's disease

INTRODUCTION

The NeuroBel is a short test that allows for psycholinguistic assessment of basic processes of oral comprehension and language production deterioration in the elderly. The objective is to carry out a pilot study of the initial reference values and cut-off points of this battery using a sample of Spanish elderly adults, with and without cognitive impairment, and detecting performance differences among them.

METHOD

NeuroBel consists of 8 tasks that analyze oral language functioning from the theoretical model proposed by the Psycholinguistic approach. Seventy-five Spanish monolingual adult-elderly participants of both genders. Of those, 25 with Alzheimer's disease (AD) in the initial phase, 25 with mild cognitive impairment (MCI) and 25 participants without cognitive impairment (Controls). All subjects were evaluated using NeuroBel.

RESULTS

There are significant differences between the three groups. The participants with AD are significantly worse in the total score of NeuroBel. A discriminant analysis shows that 86.7% of the cases appear correctly classified in the groups originally selected. Likewise, participants with MCI obtained results that are statistically significantly worse than the control group. NeuroBel shows a high correlation with the MMSE (.89) and Sensitivity (.96) in the determination of AD and cognitive deterioration (AD + MCI vs. Controls). The area under the ROC curve is .97 in the contrast of AD vs. Controls and .98 in the determination of cognitive deterioration (AD + MCI vs. Controls). The canonical discriminant functions and the precision cut-offs from the ROC analyses are also shown in the results.

CONCLUSIONS

NeuroBel is shown as a "very good" test in the detection of cognitive-linguistic impairment in elderly-adults.

Phenotypic Variability in Autosomal Dominant Familial Alzheimer Disease due to the S170F Mutation of Presenilin-1

BACKGROUND

In rare cases, patients with Alzheimer disease (AD) present at an early age and with a family history suggestive of an autosomal dominant mode of inheritance. Mutations of the presenilin-1 (PSEN1) gene are the most common causes of dementia in these patients. Early-onset and particularly familial AD patients frequently present with variable non-amnestic cognitive symptoms such as visual, language or behavioural changes as well as non-cognitive, e.g. motor, symptoms.

OBJECTIVE

To investigate the phenotypic variability in carriers of the PSEN1 S170F mutation.

METHODS

We report a family with 4 patients carrying the S170F mutation of whom 2 underwent detailed clinical examinations. We discuss our current findings in the context of previously reported S170F cases.

RESULTS

The clinical phenotype was consistent regarding initial memory impairment and early onset in the late twenties found in all S170F patients. There were frequent non-amnestic cognitive changes and, at early stages of the disease, indications of a more pronounced disturbance of visuospatial abilities as compared to face and object recognition. Non-cognitive symptoms most often included myoclonus and cerebellar ataxia. A review of the available case reports indicates some phenotypic variability associated with the S170F mutation including different constellations of symptoms such as parkinsonism and delusions.

CONCLUSION

The variable clinical findings associated with the S170F mutation highlight the relevance of atypical phenotypes in the context of research and under a clinical perspective. CSF sampling and detection of Aβ species may be essential to indicate AD pathology in unclear cases presenting with cognitive and motor symptoms at a younger age.

Precuneus Failures in Subjects of the PSEN1 E280A Family at Risk of Developing Alzheimer's Disease Detected Using Quantitative Electroencephalography

BACKGROUND

Presenilin-1 (PSEN1) mutations are the most common cause of familial early onset Alzheimer's disease (AD). The PSEN1 E280A (E280A) mutation has an autosomal dominant inheritance and is involved in the production of amyloid-β. The largest family group of carriers with E280A mutation is found in Antioquia, Colombia. The study of mutation carriers provides a unique opportunity to identify brain changes in stages previous to AD. Electroencephalography (EEG) is a low cost and minimally invasiveness technique that enables the following of brain changes in AD.

OBJECTIVE

To examine how previous reported differences in EEG for Theta and Alpha-2 rhythms in E280A subjects are related to specific regions in cortex and could be tracked across different ages.

METHODS

EEG signals were acquired during resting state from non-carriers and carriers, asymptomatic and symptomatic subjects from E280A kindred from Antioquia, Colombia. Independent component analysis (ICA) and inverse solution methods were used to locate brain regions related to differences in Theta and Alpha-2 bands.

RESULTS

ICA identified two components, mainly related to the Precuneus, where the differences in Theta and Alpha-2 exist simultaneously at asymptomatic and symptomatic stages. When the ratio between Theta and Alpha-2 is used, significant correlations exist with age and a composite cognitive scale.

CONCLUSION

Theta and Alpha-2 rhythms are altered in E280A subjects. The alterations are possible to track at Precuneus regions using EEG, ICA, and inverse solution methods.

Linear Combinations of Multiple Outcome Measures to Improve the Power of Efficacy Analysis ---Application to Clinical Trials on Early Stage Alzheimer Disease

Modern clinical trials on Alzheimer disease (AD) focus on the early symptomatic stage or even the preclinical stage. Subtle disease progression at the early stages, however, poses a major challenge in designing such clinical trials. We propose a multivariate mixed model on repeated measures to model the disease progression over time on multiple efficacy outcomes, and derive the optimum weights to combine multiple outcome measures by minimizing the sample sizes to adequately power the clinical trials. A cross-validation simulation study is conducted to assess the accuracy for the estimated weights as well as the improvement in reducing the sample sizes for such trials. The proposed methodology is applied to the multiple cognitive tests from the ongoing observational study of the Dominantly Inherited Alzheimer Network (DIAN) to power future clinical trials in the DIAN with a cognitive endpoint. Our results show that the optimum weights to combine multiple outcome measures can be accurately estimated, and that compared to the individual outcomes, the combined efficacy outcome with these weights significantly reduces the sample size required to adequately power clinical trials. When applied to the clinical trial in the DIAN, the estimated linear combination of six cognitive tests can adequately power the clinical trial.

The Alzheimer's prevention initiative composite cognitive test score: sample size estimates for the evaluation of preclinical Alzheimer's disease treatments in presenilin 1 E280A mutation carriers

OBJECTIVE

To identify a cognitive composite that is sensitive to tracking preclinical Alzheimer's disease decline to be used as a primary end point in treatment trials.

METHOD

We capitalized on longitudinal data collected from 1995 to 2010 from cognitively unimpaired presenilin 1 (PSEN1) E280A mutation carriers from the world's largest known early-onset autosomal dominant Alzheimer's disease kindred to identify a composite cognitive test with the greatest statistical power to track preclinical Alzheimer's disease decline and estimate the number of carriers age 30 years and older needed to detect a treatment effect in the Alzheimer's Prevention Initiative's (API) preclinical Alzheimer's disease treatment trial. The mean-to-standard-deviation ratios (MSDRs) of change over time were calculated in a search for the optimal combination of 1 to 7 cognitive tests/subtests drawn from the neuropsychological test battery in cognitively unimpaired mutation carriers during a 2- and 5-year follow-up period (n = 78 and 57), using data from noncarriers (n = 31 and 56) during the same time period to correct for aging and practice effects. Combinations that performed well were then evaluated for robustness across follow-up years, occurrence of selected items within top-performing combinations, and representation of relevant cognitive domains.

RESULTS

The optimal test combination included Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word List Recall, CERAD Boston Naming Test (high frequency items), Mini-Mental State Examination (MMSE) Orientation to Time, CERAD Constructional Praxis, and Raven's Progressive Matrices (Set A), with an MSDR of 1.62. This composite is more sensitive than using either the CERAD Word List Recall (MSDR = 0.38) or the entire CERAD-Col battery (MSDR = 0.76). A sample size of 75 cognitively normal PSEN1 E280A mutation carriers aged 30 years and older per treatment arm allows for a detectable treatment effect of 29% in a 60-month trial (80% power, P = .05).

CONCLUSIONS

We have identified a composite cognitive test score representing multiple cognitive domains that, compared to the most sensitive single test item, has improved power to track preclinical Alzheimer's disease decline in autosomal dominant Alzheimer's disease mutation carriers and to evaluate preclinical Alzheimer's disease treatments. This API composite cognitive test score will be used as the primary end point in the first API trial in cognitively unimpaired autosomal dominant Alzheimer's disease carriers within 15 years of their estimated age at clinical onset. We have independently confirmed our findings in a separate cohort of cognitively healthy older adults who progressed to the clinical stages of late-onset Alzheimer's disease, described in a separate report, and continue to refine the composite in independent cohorts and compared with other analytic approaches.

Alzheimer's Prevention Initiative: a plan to accelerate the evaluation of presymptomatic treatments

There is an urgent need to find effective presymptomatic Alzheimer's disease (AD) treatments that reduce the risk of AD symptoms or prevent them completely. It currently takes too many healthy people, too much money and too many years to evaluate the range of promising presymptomatic treatments using clinical endpoints. We have used brain imaging and other measurements to track some of the earliest changes associated with the predisposition to AD. We have proposed the Alzheimer's Prevention Initiative (API) to evaluate investigational amyloid-modifying treatments in healthy people who, based on their age and genetic background, are at the highest imminent risk of developing symptomatic AD using brain imaging, cerebrospinal fluid (CSF), and cognitive endpoints. In one trial, we propose to study AD-causing presenilin 1 [PS1] mutation carriers from the world's largest early-onset AD kindred in Antioquia, Colombia, close to their estimated average age at clinical onset. In another trial, we propose to study apolipoprotein E (APOE) ε4 homozygotes (and possibly heterozygotes) close to their estimated average age at clinical onset. The API has several goals: 1) to evaluate investigational AD-modifying treatments sooner than otherwise possible; 2) to determine the extent to which the treatment's brain imaging and other biomarker effects predict a clinical benefit-information needed to help qualify biomarker endpoints for use in pivotal prevention trials; 3) to provide a better test of the amyloid hypothesis than clinical trials in symptomatic patients, when these treatments may be too little too late to exert their most profound effect; 4) to establish AD prevention registries needed to support these and other presymptomatic AD trials; and 5) to give those individuals at highest imminent risk of AD symptoms access to the most promising investigational treatments in clinical trials.

Hippocampal hyperactivation in presymptomatic familial Alzheimer's disease

OBJECTIVE

The examination of individuals who carry fully penetrant genetic alterations that result in familial Alzheimer's disease (FAD) provides a unique model for studying the early presymptomatic disease stages. In AD, deficits in episodic and associative memory have been linked to structural and functional changes within the hippocampal system. This study used functional MRI (fMRI) to examine hippocampal function in a group of healthy, young, cognitively-intact presymptomatic individuals (average age 33.7 years) who carry the E280A presenilin-1 (PS1) genetic mutation for FAD. These PS1 subjects will go on to develop the first symptoms of the disease around the age of 45 years. Our objective was to examine hippocampal function years before the onset of clinical symptoms.

METHODS

Twenty carriers of the Alzheimer's-associated E280A PS1 mutation and 19 PS1-negative control subjects participated. Both groups were matched for age, sex, education level, and neuropsychological test performance. All participants performed a face-name associative encoding task while in a Phillips 1.5T fMRI scanner. Analysis focused on the hippocampal system.

RESULTS

Despite identical behavioral performance, presymptomatic PS1 mutation carriers exhibited increased activation of the right anterior hippocampus during encoding of novel face-name associations compared to matched controls.

INTERPRETATION

Our results demonstrate that functional changes within the hippocampal memory system occur years before cognitive decline in FAD. These presymptomatic changes in hippocampal physiology in FAD suggest that hippocampal fMRI patterns during associative encoding may also provide a preclinical biomarker in sporadic AD.

ERP generator anomalies in presymptomatic carriers of the Alzheimer's disease E280A PS-1 mutation

Although subtle anatomical anomalies long precede the onset of clinical symptoms in Alzheimer's disease, their impact on the reorganization of brain networks underlying cognitive functions has not been fully explored. A unique window into this reorganization is provided by presymptomatic cases of familial Alzheimer's disease (FAD). Here we studied neural circuitry related to semantic processing in presymptomatic FAD cases by estimating the intracranial sources of the N400 event-related potential (ERP). ERPs were obtained during a semantic-matching task from 24 presymptomatic carriers and 25 symptomatic carriers of the E280A presenilin-1 (PS-1) mutation, as well as 27 noncarriers (from the same families). As expected, the symptomatic-carrier group performed worse in the matching task and had lower N400 amplitudes than both asymptomatic groups, which did not differ from each other on these variables. However, N400 topography differed in mutation carrier groups with respect to the noncarriers. Intracranial source analysis evinced that the presymptomatic-carriers presented a decrease of N400 generator strength in right inferior-temporal and medial cingulate areas and increased generator strength in the left hippocampus and parahippocampus compared to the controls. This represents alterations in neural function without translation into behavioral impairments. Compared to controls, the symptomatic-carriers presented a similar anatomical shift in the distribution of N400 generators to that found in presymptomatic-carriers, albeit with a larger reduction in generator strength. The redistribution of N400 generators in presymptomatic-carriers indicates that early focal degeneration associated with the mutation induces neural reorganization, possibly contributing to a functional compensation that enables normal performance in the semantic task.

Consortium to Establish a Registry for Alzheimer's Disease (CERAD): the first twenty years

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) was funded by the National Institute on Aging in 1986 to develop standardized, validated measures for the assessment of Alzheimer's disease (AD). The present report describes the measures that CERAD developed during its first decade and their continued use in their original and translated forms. These measures include clinical, neuropsychological, neuropathologic, and behavioral assessments of AD and also assessment of family history and parkinsonism in AD. An approach to evaluating neuroimages did not meet the standards desired. Further evaluations that could not be completed because of lack of funding (but where some materials are available) include evaluation of very severe AD and of service use and need by patient and caregiver. The information that was developed in the U.S. and abroad permits standardized assessment of AD in clinical practice, facilitates epidemiologic studies, and provides information valuable for individual and public health planning. CERAD materials and data remain available for those wishing to use them.

Cognitive changes in the preclinical phase of familial Alzheimer's disease

Few studies have examined the presence of linguistic deficits in the preclinical phase of Alzheimer's disease (AD). A total of 19 healthy carriers of the E280A presenilin-1 gene mutation in chromosome 14 and 21 noncarrier family members from Antioquia, Colombia, were administered a neurolinguistic evaluation of lexical-semantic processes. Both groups were similar in age, educational level, and gender. Carriers scored significantly lower than noncarriers on naming of famous faces. Cognitive changes in lexical-semantic tasks can be detected before the clinical diagnosis of probable familial AD, and a neurolinguistic evaluation may be a useful tool in the early clinical diagnosis of sporadic AD as well.