Dans le contexte du diagnostic précoce de la maladie d’Alzheimer, une direction de la recherche émerge autour de l’informatisation de tests cognitifs. Nous avons conçu un test de barrage informatisé sur tablette (test e-CT), développé à partir d’un test de barrage papier-crayon. Nous avons étudié les variables influençant les performances au test e-CT et ses propriétés psychométriques. Nous avons observé que chez les sujets âgés sains, la seule variable influençant était l’âge. Les performances au test e-CT n’étaient pas influencées par l’expérience avec un appareil informatique. Cependant, chez les patients présentant des troubles cognitifs, ceux qui utilisaient quotidiennement un appareil informatique avaient une meilleure performance que ceux qui n’avaient pas un usage quotidien. En effet, les patients utilisant quotidiennement un appareil informatique présentaient de meilleures capacités cognitives. Le test e-CT était corrélé avec plusieurs tests des fonctions exécutives (validité convergente), mais pas avec le test de la mémoire épisodique (validité divergente). Il présente aussi une bonne fidélité test-retest. Le test e-CT présente des bonnes performances diagnostiques, permettant de différencier les personnes âgées saines des patients présentant des troubles cognitifs. En conclusion, le test e-CT présente des propriétés psychométriques satisfaisantes et peut être utilisé pour l’évaluation cognitive chez le sujet âgé. / In the context of early detection of cognitive impairment associated with dementia, an area of research focus concerns development and validation of computerized tests. We have developed a tablet-based cancellation test (e-CT), based on an existing paper-and-pencil cancellation test (K-T test). We studied the variables influencing performance on the e-CT and its psychometric properties. Among healthy older adults, only age was found to be an influencing variable. The performance on the e-CT was not influenced by experience with a computer-based device. However, for patients suffering from cognitive impairment, those using a computer-based device daily outperformed those who were not daily users. Further analyses showed that daily users conserved better cognitive capacities than non-daily users. The e-CT showed significant correlations with several measures of executive functions (convergent validity), but there was no relationship between the e-CT and the episodic memory test (divergent validity). It showed good test-retest reliability. The e-CT had good diagnostic accuracy in differentiating between healthy elderly subjects and patients with cognitive impairment. In conclusion, the e-CT test shows satisfying psychometric properties and is a promising tool for neuropsychological assessment in older adults

Les hypersignaux de la substance blanche (HSB) ont été associés à des déficits exécutifs et mnésiques et à une atteinte des circuits corticaux et sous-corticaux frontaux. Leur présence, en plus du dépôt ß-amyloïde chez de nombreux patients avec un MCI (Mild Cognitive Impairment ou trouble cognitif léger) augmenterait le risque de conversion vers une maladie d'Alzheimer (MA). Un des enjeux importants dans la phase préclinique de la maladie est d'explorer le potentiel des interventions cognitives pour prévenir le déclin cognitif et la progression vers une MA. Alors que les HSB sont de plus en plus considérés comme un des facteurs déterminant l'hétérogénéité des patients MCI, peu d'étude ont pris en compte leur présence dans les interventions cognitives. L'hypothèse qu'une intervention pourrait induire des effets différentiels selon l'existence ou non d'hypersignaux dans le MCI reste inexplorée à notre connaissance, et est au cœur de ce travail de thèse. / White matter hyper signals (WMH) were associated with executive and memory deficits and impairment of the cortical and subcortical frontal circuits. Their presence, in addition to amyloid deposition in many patients with Mild Cognitive Impairment (MCI), would increase the risk of conversion to Alzheimer's disease (AD). An important issues in the preclinical phase of MCI is to explore the potential of cognitive interventions to prevent cognitive decline and progression to AD. While WMH are increasingly considered as one of factors determining the heterogeneity of MCI patients, few studies have take into account their presence in cognitive interventions. The hypothesis that an intervention could induce differential effects according to the existence or not of WMH in MCI remains unexplored to our knowledge, and is at the heart of this work of thesis.

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The overall aim was to improve knowledge of the consequences of cognitive dysfunction in everyday life and of instruments to make these assessments. The thesis contains four studies each of different design using different populations. In study I, the relationship between cognitive function, ability to perform activities of daily living and perceived health-related quality of life were investigated in a population of 85-year-old individuals in the community of Linköping (n = 373). The study was part of the Elderly in Linköping Screening Assessment 85 (ELSA 85). Even mild cognitive dysfunction correlated with impaired ability to perform activities of daily living and lower health-related quality of life. In study II, the diagnostic accuracy and clinical utility of Cognistat, a cognitive screening instrument, were evaluated for identifying individuals with cognitive impairment in a primary care population. Cognistat has relatively good diagnostic accuracy with a sensitivity of 0.85, a specificity of 0.79 and a Clinical Utility Index (CUI) of 0.72. The corresponding values were 0.59, 0.91 and 0.53 for the Mini Mental State Examination (MMSE), and 0.26, 0.88 and 0.20 for the Clock Drawing Test (CDT). In study III, the aim was to develop an instrument measuring self-perceived or caregiver reported ability to perform everyday life activities in persons with suspected cognitive impairment or dementia and to perform psychometric testing of this instrument, named the Cognitive Impairment in Daily Life (CID). The CID was found to have good content validity. In study IV, experiences of cognitive impairment, its consequences in everyday life and the need for support in persons with mild cognitive impairment (MCI) or mild dementia and their relatives were explored. Interviews were performed with five people with MCI, eight people with mild dementia and their relatives (n = 13). The main finding was that persons with MCI and dementia experienced cognitive changes that could be burdensome and result in changed activity patterns. In conclusion, the findings support earlier research and show that cognitive dysfunction even at mild stages has an impact on everyday life and reduces perceived quality of life. To improve interventions for persons with cognitive impairment, it is important to assess not only cognitive function but also its consequences in everyday life activities.

Introduction: Dementia is a syndrome due to disease of the brain, usually of a chronic nature, in which there is disturbance of multiple higher cortical functions including Memory, Comprehension, Thinking, Judgment, Orientation, language and communication skills and abstract thinking. It is one of the most challenging disorders both in terms of prevalence and economic burden. There are currently approximately 800,000 people with dementia in UK and national cost is 17 billion per year. It is estimated that in next thirty years, number of people with dementia will increase to 1.4 million and the national cost will be over 50 billion. The exceptional advances in modern medicine in terms of prolonging life expectancy do not necessarily improve the care delivered to people with dementia. Dementia is a progressive condition where clinical recovery is not possible despite the discovery of cognition enhancing drugs. This belief leads to low expectations that tend to erode hope and foster indignity. Advances in treatment of Alzheimer’s disease have, however, stimulated new thinking and methods of service delivery. At certain stage of their illness, if not from the very beginning, personal, and social recovery becomes more meaningful for service users than their clinical recovery. Objective: To investigate whether recovery-orientated psychiatric assessment and therapeutic intervention enhances the wellbeing of people with memory problems and their family carers. Method: This study was a preliminary randomised control study. Patients were randomly allocated to recovery focus group or treatment as usual group acting as the control. Participants in the recovery focus group received a recovery-focused pre-diagnostic wellbeing assessment and counselling, diagnostic consultation with written feedback and post-diagnostic support over a period of six months. Participants in both groups were assessed using the WHO Wellbeing Index (WHO-5) as the primary outcome measure. The Mini Mental State Examination, Cornell Scale for Depression in Dementia, EuroQol-5D and Zarit Burden Interview were used as secondary outcome measures. Written records of the narrative accounts of participants in the recovery focus group were also obtained. Results: 48 patients with early dementia were recruited and agreed to take part in the study. Out of these, 34 patients completed the study, of which 17 patients were in the recovery focus group and 17 patients were in the treatment as usual group (control).There was a significant difference between the groups in terms of greater improvement in wellbeing as rated by the WHO – 5 Wellbeing Index in the recovery focus group compared to the control group. The secondary outcome measures in the areas of cognition, quality of life and caregiver burden showed no differences between the groups. However, case histories from the recovery focus group identified the main areas of improvement in improved mood, increased social interaction, reduction in carer strain and/or burden and improved self-worth and/or confidence. Conclusions: This study shows that recovery focused care can enhance the wellbeing of people with mild to moderate dementia. The additional benefits perceived by the patients and their relatives /carers include improvement in mood symptoms, social interaction and confidence as well as reduction in carer burden and strain.

Alzheimer's disease (AD) is a progressive, irreversible, neurodegenerative disease. The key to understanding AD is to elucidate the pathogenesis of neuron degeneration in specific brain regions.We hypothesize that there is increased DNA oxidation in AD brain compared to age-matched control subjects, especially in mitochondrial DNA (mtDNA), and that the changes in DNA bases will affect protein expression in mitochondria and contribute to neurodegeneration in AD. To test this hypothesis:1) We quantified multiple oxidized bases in nuclear DNA (nDNA) and mtDNA of frontal, parietal, and temporal lobes and cerebellum from late-stage AD (LAD), mild cognitive impairment (MCI), and age-matched control subjects using gas chromatography/mass spectrometry with selective ion monitoring (GC/MS-SIM). Also, we quantified oxidized DNA bases in cortex of APP/PS1 transgenic mice. (a) nDNA and mtDNA were extracted from eight LAD and eight control subjects. We found levels of multiple oxidized bases were significantly higher in frontal, parietal, and temporal lobes and that mtDNA had approximately 10-fold higher levels of oxidized bases than nDNA. Eight-hydroxyguanine was approximately 10-fold higher than other oxidized base adducts in both LAD and control subjects. These results suggest that oxidative damage to mtDNA may contribute to the neurodegeneration of AD. (b) Mild Cognitive Impairment (MCI), the phase between normal aging and early dementia, is a common problem in the elderly with many subjects going on to develop AD. Results from eight amnestic MCI and six control subjects suggest oxidative damage to DNA occurs in the earliest detectable phase of AD. (c) Analysis of nDNA from the cortex of four groups (3m, 6m, 9m, 12m) of APP/PS1 and wild type mice showed elevations of 8-hydroxyguanine in 12 month old APP/PS1 mice.2) To analyze mitochondrial protein changes in LAD, 2D gels were run to separate proteins and MALDI-TOF mass spectrometry was used to identify proteins.Five mitochondrial proteins were significantly decreased in LAD. This proteomic study provides a proteome map of mitochondria in LAD brain and an insight into the pathogenesis of neuron degeneration in Alzheimer's disease.

Dementia is increasingly recognized as a major and growing threat to public health worldwide, and there is a critical need for prevention and treatment strategies. However, it is necessary that appropriate methodologies are used in the identification of risk factors. The purpose of this dissertation research was to develop further the body of literature featuring Markov chains as an analytic tool for data derived from longitudinal studies of aging and dementia. Data drawn from 649 participants in the University of Kentucky’s Alzheimer’s Disease Center’s (UK ADC) Biologically Resilient Adults in Neurological Studies (BRAiNS) cohort, which was established in 1989 and follows adults age 60 years and older who are cognitively normal at baseline to death, were used to conduct three studies. The first study, “Mild cognitive impairment: Statistical models of transition using longitudinal clinical data,” shows that mild cognitive impairment is a stable clinical entity when a rigorous definition is applied. The second study, “Self-reported head injury and risk of cognitive impairment and Alzheimer’s-type pathology in a longitudinal study of aging and dementia,” shows that when the competing risk of death is properly accounted for, self-reported head injury is a clear risk factor for late-life dementia and is associated with increased beta-amyloid deposition in the brain. The third study, “Incorporating prior-state dependence among random effects and beta coefficients improves multistate Markov chain model fit,” shows that the effect of risk factors, like age, may not be constant over time and may be altered based on the subject’s cognitive state and that model fit is significantly improved when this is taken into account.

The aim of the research presented in this thesis was to improve the characterisation of the changes in brain structure and function that occur at different stages of Alzheimer’s disease (AD) progression, from pre-symptomatic AD, to mild cognitive impairment (MCI), to clinically evident dementia, using magnetic resonance imaging (MRI) techniques. Baseline structural MRI data from a cohort of healthy older adults who were followed prospectively for ten years, during which time some developed MCI and some AD, were analysed. It was found that structural MRI could detect volume loss in medial-temporal lobes up to 7-10 years before clinical symptoms of AD appear. In addition, volumetric variability of medial-temporal regions detected by structural MRI across cognitively healthy older adults correlated with their performance on a task of visuospatial associative memory, and functional activation of the same regions occurred during successful performance of the same task on functional MRI (fMRI). Three groups of participants - cognitively healthy controls, people with MCI, and patients with probable AD - were then recruited and underwent a multimodal MRI protocol, which included functional sequences acquired at rest and during the execution of two different cognitive tasks (visuospatial associative memory and self-appraisal). Cross-sectional comparisons showed: (i) that successful visuospatial associative memory performance was associated with increased functional activity (measured with task fMRI) in lateral prefrontal regions in AD patients relative to controls and (ii) that increased functional activity overlapped with frontal brain networks showing increased functional connectivity (measured with resting fMRI) in the same AD patients. Further, by demonstrating group- and condition-specific decreased frontal activity in AD patients relative to controls during a self-appraisal fMRI task, it was shown the specific utility of fMRI to unravel cognitive mechanisms underlying specific neuropsychological symptoms such as unawareness of cognitive impairment (anosognosia) in MCI and AD. In conclusion, structural MRI can detect morphological changes in the preclinical stage of AD, possibly earlier than previously described, and these reliably match cognitive functioning in older adults. In the MCI and AD stages, once symptoms of cognitive impairment are clinically evident and measurable, task-related and resting functional MRI can inform on residual brain function detectable over and above the known changes in brain morphology and cognitive performance that have already occurred at these stages, emerging as a sensitive marker of residual ability that could potentially be used to measure the effect of new treatments.

Depressive symptoms are very common among people with neurocognitive disorder. The comorbidity of both diseases and the overlap of their symptoms complicates correct diagnosis and thus also the initiation of a correct treatment. The instruments of depression measuring in seniors with a severe cognitive deficit are also a discussed issue. The subject of the theoretical part is to describe the issue of depression and cognitive disorders in the old age with a focus on Alzheimer's disease, which is the most common mental disorder in the elderly together with depression. The goal of the empirical part of the thesis is to research based on the interviews with seniors if the most frequently used method of depression measuring in the elderly, Geriatric Depression Scale (GDS), is a suitable measuring instrument also in seniors with a cognitive deficit and further examine how these seniors actually experience the individual mood qualities which are the subjects of items in GDS. Forty seniors with a various degree of cognitive deficit participated in the research. The study results showed that the questionnaire is usable for seniors with a mild cognitive impairment and mild dementia. To detect the border of the cognitive deficit, below which it is not suitable to use the depression measuring method GDS, a...

Alzheimer's disease (AD) is neurodegenerative disorder that causes memory loss and cognitive dysfunction. It affects one in five people over the age of 80 and is distressing for both sufferers and their families. A transitional stage between normal ageing and dementia including AD is termed a mild cognitive impairment (MCI). Recent studies have shown that people with MCI may convert to AD over time although not all MCI cases progress to AD. Much research is now focussing on early detection of AD and diagnosing an MCI that will progress to AD to allow prompt treatment and disease management before the neurons degenerate to a stage beyond repair. Hence, the ability to obtain a method of identifying MCI is of great importance. Virtual reality plays an important role in healthcare and offers opportunities for detection of MCI. There are various studies that have focused on detection of early AD using virtual environments, although results remain limited. One significant drawback of these studies has been their limited capacity to incorporate levels of difficulty to challenge users' capability. Furthermore, at best, these studies have only been able to discriminate between early AD and healthy elderly with about 80% of overall accuracy. As a result, a novel virtual simulation called Virtual Reality for Early Detection of Alzheimer's Disease (VREAD) was developed. VREAD is a quick, easy and friendly tool that aims to investigate cognitive functioning in a group of healthy elderly participants and those with MCI. It focuses on the task of following a route, since Topographical Disorientation (TD) is common in AD. An investigation was set up with two cohorts: non-elderly and elderly participants. The findings with regard to the non-elderly are important as they represent a first step towards implementation with elderly people. The results with elderly participants indicate that this simulation based assessment could provide a method for the detection of MCI since significant correlations between the virtual simulation and existing neuropsychological tests were found. In addition, the results proved that VREAD is comparable with well-known neuropsychological tests, such as Cambridge Neuropsychological Automated Test Battery, Paired Associate Learning (CANTAB PAL) and Graded Naming Test (GNT). Furthermore, analysis through the use of machine learning techniques with regard to the prediction of MCI also obtained encouraging results. This novel simulation was able to predict with about 90% overall accuracy using weighting function proposed to discriminate between MCI and healthy elderly.