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1.
Age Ageing ; 51(3)2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-35174850

RESUMO

The COVID-19 pandemic resulted in catastrophic levels of morbidity and mortality for care home residents. Despite this, research platforms for COVID-19 in care homes arrived late in the pandemic compared with other care settings. The Prophylactic Therapy in Care Homes Trial (PROTECT-CH) was established to provide a platform to deliver multi-centre cluster-randomized clinical trials of investigational medicinal products for COVID-19 prophylaxis in UK care homes. Commencing set-up in January 2021, this involved the design and development of novel infrastructure for contracting and recruitment, remote consent, staff training, research insurance, eligibility screening, prescribing, dispensing and adverse event reporting; such infrastructure being previously absent. By the time this infrastructure was in place, the widespread uptake of vaccination in care homes had changed the epidemiology of COVID-19 rendering the trial unfeasible. While some of the resources developed through PROTECT-CH will enable the future establishment of care home platform research, the near absence of care home trial infrastructure and nationally linked databases involving the care home sector will continue to significantly hamper progress. These issues are replicated in most other countries. Beyond COVID-19, there are many other research questions that require addressing to provide better care to people living in care homes. PROTECT-CH has exposed a clear need for research funders to invest in, and legislate for, an effective care home research infrastructure as part of national pandemic preparedness planning. Doing so would also invigorate care home research in the interim, leading to improved healthcare delivery specific to those living in this sector.


Assuntos
COVID-19 , COVID-19/epidemiologia , Atenção à Saúde , Humanos , Pandemias/prevenção & controle
3.
BMJ Ment Health ; 27(1)2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38796179

RESUMO

QUESTION: Does neurodegenerative disease underlie the increased rate of dementia observed in older people with schizophrenia? Several studies have reported a higher prevalence of dementia in people with schizophrenia compared with the general population. This may reflect a higher risk of developing neurodegenerative diseases such as vascular dementia or Alzheimer's disease (AD). Alternatively, this may reflect non-pathological, age-related cognitive decline in a population with low cognitive reserve. STUDY SELECTION AND ANALYSIS: We reviewed papers that compared postmortem findings, hippocampal MRI volume or cerebrospinal fluid (CSF) markers of AD, between patients with schizophrenia with evidence of cognitive impairment (age ≥45 years) with controls. We subsequently performed a meta-analysis of postmortem studies that compared amyloid-ß plaques (APs) or neurofibrillary tangles (NFTs) in cognitively impaired patients with schizophrenia to normal controls or an AD group. FINDINGS: No studies found a significant increase of APs or NFTs in cognitively impaired patients with schizophrenia compared with controls. All postmortem studies that compared APs or NFTs in patients with schizophrenia to an AD group found significantly more APs or NFTs in AD. No studies found a significant differences in CSF total tau or phosphorylated tau between patients with schizophrenia and controls. The two studies which compared CSF Aß42 between patients with schizophrenia and controls found significantly decreased CSF Aß42 in schizophrenia compared with controls. Hippocampal volume findings were mixed. CONCLUSIONS: Studies have not found higher rates of AD-related pathology in cognitively impaired individuals with schizophrenia compared with controls. Higher rates of dementia identified in population studies may reflect a lack of specificity in clinical diagnostic tools used to diagnose dementia.


Assuntos
Biomarcadores , Esquizofrenia , Humanos , Esquizofrenia/líquido cefalorraquidiano , Esquizofrenia/patologia , Biomarcadores/líquido cefalorraquidiano , Doenças Neurodegenerativas/líquido cefalorraquidiano , Doenças Neurodegenerativas/patologia , Doenças Neurodegenerativas/diagnóstico por imagem , Doenças Neurodegenerativas/diagnóstico , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/patologia , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/diagnóstico , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Peptídeos beta-Amiloides/metabolismo , Emaranhados Neurofibrilares/patologia , Placa Amiloide/patologia , Placa Amiloide/diagnóstico por imagem
4.
Psychiatr Danub ; 24 Suppl 1: S185-90, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22945220

RESUMO

BACKGROUND: There is a need to increase the recruitment to psychiatry in France. Our aim in this study was to compare factors influencing career choice between French medical students considering and not considering psychiatry as a specialty. SUBJECTS AND METHODS: Quantitative cross-sectional online survey on 145 French students in their last year of medical school. RESULTS: 22.7% of our sample considered choosing a career in psychiatry. A preference for a career in psychiatry was associated with more frequent history of personal/familial mental illness, higher ratings of psychiatric teaching, more weeks of compulsory psychiatry teaching and placement, during which students had more often met patients in recovery and been asked their opinion on patients. Students considering psychiatry as a career also emphasized more the need for a good work-life balance, and presented better attitudes toward psychiatry. CONCLUSIONS: Improving opportunities of interactions between students and psychiatrists or psychiatric patients might help to improve recruitment in psychiatry.


Assuntos
Escolha da Profissão , Educação de Pós-Graduação em Medicina , Psiquiatria/educação , Estudantes de Medicina/psicologia , Adulto , Coleta de Dados , Feminino , França , Humanos , Masculino , Motivação , Inquéritos e Questionários
5.
J Alzheimers Dis ; 87(3): 1003-1007, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35404287

RESUMO

The controversial approval in June 2021 by the Food and Drug Administration (FDA) of aducanumab (marketed as Aduhelm), Biogen's monoclonal antibody for patients with Alzheimer's disease, raises significant concerns for the dementia field and drug approval process, considering its lack of adequate evidence for clinical efficacy, safety issues, and cost. On 15 December 2021, an international group of clinicians, basic science experts, psychological and social science researchers, lay people with lived experience of dementia, and advocates for public health met to discuss making a recommendation for whether aducanumab's approval should be withdrawn. Attendees considered arguments both in favor of and in opposition to withdrawal and voted unanimously to recommend that the FDA withdraw its approval for aducanumab and to support the Right Care Alliance's filing of a formal Citizen Petition to this effect.


Assuntos
Doença de Alzheimer , Anticorpos Monoclonais Humanizados , Doença de Alzheimer/tratamento farmacológico , Anticorpos Monoclonais Humanizados/uso terapêutico , Aprovação de Drogas , Humanos , Estados Unidos , United States Food and Drug Administration
6.
Artigo em Inglês | MEDLINE | ID: mdl-35082975

RESUMO

BACKGROUND: The initial limited supply of COVID-19 vaccine in the U.S. presented significant allocation, distribution, and delivery challenges. Information that can assist health officials, hospital administrators and other decision makers with readily identifying who and where to target vaccine resources and efforts can improve public health response. OBJECTIVE: The objective of this project was to develop a publicly available geographical information system (GIS) web mapping tool that would assist North Carolina health officials readily identify high-risk, high priority population groups and facilities in the immunization decision making process. METHODS: Publicly available data were used to identify 14 key health and socio-demographic variables and 5 differing themes (social and economic status; minority status and language; housing situation; at risk population; and health status). Vaccine priority population index (VPI) scores were created by calculating a percentile rank for each variable over each N.C. Census tract. All Census tracts (N = 2,195) values were ranked from lowest to highest (0.0 to 1.0) with a non-zero population and mapped using ArcGIS. RESULTS: The VPI tool was made publicly available (https://enchealth.org/) during the pandemic to readily assist with identifying high risk population priority areas in N.C. for the planning, distribution, and delivery of COVID-19 vaccine. DISCUSSION: While health officials may have benefitted by using the VPI tool during the pandemic, a more formal evaluation process is needed to fully assess its usefulness, functionality, and limitations. CONCLUSION: When considering COVID-19 immunization efforts, the VPI tool can serve as an added component in the decision-making process.

7.
J Neurotrauma ; 37(24): 2624-2631, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-32821007

RESUMO

The objective of this study was to determine if initial or repeat measurements of serum concentrations of glial fibrillary acidic protein (GFAP) or ubiquitin C-terminal hydrolase L1 (UCH-L1) are predictive of an acute unfavorable neurological outcome in patients who present to the emergency department (ED) with brain injury and an initial Glasgow Coma Scale Score (GCS) of 14-15. This multi-center observational trial included brain-injured adults presenting to the ED, receiving a head computed tomography (CT) and venipuncture for biomarker concentration measurements within 6 h of injury. Subjects had repeat serum sampling and GCS scores every 4 h for the first 24 h, if available for assessment. We analyzed blood samples using an enzyme-linked immunosorbent assay approved by the Food and Drug Administration (FDA). Wilcoxin two-sample test was used to compare initial and repeat serum concentrations for both biomarkers between CT-positive patients who did not have an acute unfavorable neurological outcome and those patients who did. A total of 145 enrolled subjects had adequate data for analysis; 69 were CT-positive, 74 were CT-negative, and 2 were CT-inconclusive. Five subjects developed an acute unfavorable neurological outcome, defined as need for intracranial pressure monitoring, craniotomy, persistent neurological deficits, or death resulting from brain injury. Initial median serum concentrations of GFAP and UCH-L1 (obtained <6 h from injury) were significantly greater in CT-positive patients who had an acute unfavorable neurological outcome than in CT-positive patients who did not (GFAP: 5237 pg/mL [IQR 4511, 8180] versus 283.5 pg/mL [IQR 107, 1123]; p = 0.026; UCH-L1: 3329 pg/mL [QR 1423, 5010] versus 679.5 pg/mL [IQR 363, 1100] p = 0.014). Repeat serum testing (6- < 12 h from injury) showed that UCH-L1 serum concentration, but not GFAP, was also significantly greater in the acute unfavorable neurological outcome group than in those without an unfavorable outcome: 1088 pg/mL versus 374 pg/mL; p = 0.041.


Assuntos
Biomarcadores/sangue , Concussão Encefálica/sangue , Proteína Glial Fibrilar Ácida/sangue , Recuperação de Função Fisiológica , Ubiquitina Tiolesterase/sangue , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
8.
J Alzheimers Dis ; 75(2): 607-615, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32310163

RESUMO

BACKGROUND: Few studies have shown that an increased risk of dementia is associated with diabetes mellitus. OBJECTIVE: To estimate the prevalence and incidence of dementia in people with diabetes in primary care in the UK. METHODS: We conducted a descriptive study using the UK The Health Improvement Network (THIN) database. People diagnosed with diabetes from 2000 to 2016 were included in the study. Prevalence and incidence rates of dementia were calculated annually, stratified by age and gender. RESULTS: The prevalence of dementia was 0.424% [95% CI (0.420%-0.427%)] in 2000 and 2.508% [95% CI (2.501%-2.515%)] in 2016. The highest prevalence was in those aged 85+ from 2.9% [95% CI (2.890%-2.974%)] in 2000 to 11.3% [95% CI (11.285%-11.384%)] in 2016. The incidence of dementia increased 3.7 times, from 0.181 cases per 100 persons [95% CI (0.179-0.183)] in 2000 to 0.683 cases per 100 persons [95% CI (0.679-0.686)] in 2016, respectively. Women had a higher prevalence and incidence of dementia than men 3.138% [95% CI (3.127%-3.150%)] versus 2.014% [95% CI (2.006%-2.022%)] and 0.820 [95% CI (0.814-0.826)] versus 0.576 cases per 100 persons [95% CI (0.571-0.580)] in 2016, respectively. CONCLUSION: There was a trend of increasing prevalence and incidence of dementia in people with diabetes over the period of 2000 to 2016. This study adds to the evidence on dementia prevalence and incidence, particularly in the diabetic population.


Assuntos
Demência/epidemiologia , Diabetes Mellitus/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Bases de Dados Factuais , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Prevalência , Reino Unido/epidemiologia
9.
J Nerv Ment Dis ; 196(5): 375-83, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18477879

RESUMO

We aimed to identify transdiagnostic psychological processes associated with persecutory delusions. Sixty-eight schizophrenia patients, 47 depressed patients, and 33 controls were assessed for paranoia, positive and negative self-esteem, estimations of the frequency of negative, neutral, and positive events occurring to the self in the past and in the future and similar estimates for events affecting others in the future. Negative self-esteem and expectations of negative events were strongly associated with paranoia in all groups. Currently deluded patients were asked to rate whether their persecution was deserved on an analogue scale. Mean deservedness scores were higher in deluded-depressed patients than deluded-schizophrenia patients, but patients in both groups used the full range of scores. The findings indicate that negative self-esteem and negative expectations independently contribute to paranoia, but do not support a simple categorical distinction between poor-me (persecution undeserved) and bad-me (persecution deserved) patients.


Assuntos
Delusões/psicologia , Transtorno Depressivo Maior/psicologia , Acontecimentos que Mudam a Vida , Transtornos Paranoides/psicologia , Transtornos Psicóticos/psicologia , Esquizofrenia/diagnóstico , Psicologia do Esquizofrênico , Autoimagem , Adulto , Cultura , Delusões/diagnóstico , Transtorno Depressivo Maior/diagnóstico , Feminino , Culpa , Humanos , Controle Interno-Externo , Masculino , Pessoa de Meia-Idade , Transtornos Paranoides/diagnóstico , Inventário de Personalidade/estatística & dados numéricos , Escalas de Graduação Psiquiátrica/estatística & dados numéricos , Psicometria , Transtornos Psicóticos/diagnóstico , Esquizofrenia Paranoide/diagnóstico , Esquizofrenia Paranoide/psicologia
10.
Health Technol Assess ; 21(26): 1-192, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28625273

RESUMO

BACKGROUND: There is currently no disease-modifying treatment available to halt or delay the progression of the disease pathology in dementia. An agreed core set of the best-available and most appropriate outcomes for disease modification would facilitate the design of trials and ensure consistency across disease modification trials, as well as making results comparable and meta-analysable in future trials. OBJECTIVES: To agree a set of core outcomes for disease modification trials for mild to moderate dementia with the UK dementia research community and patient and public involvement (PPI). DATA SOURCES: We included disease modification trials with quantitative outcomes of efficacy from (1) references from related systematic reviews in workstream 1; (2) searches of the Cochrane Dementia and Cognitive Improvement Group study register, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, EMBASE, Latin American and Caribbean Health Sciences Literature and PsycINFO on 11 December 2015, and clinical trial registries [International Standard Randomised Controlled Trial Number (ISRCTN) and clinicaltrials.gov] on 22 and 29 January 2016; and (3) hand-searches of reference lists of relevant systematic reviews from database searches. REVIEW METHODS: The project consisted of four workstreams. (1) We obtained related core outcome sets and work from co-applicants. (2) We systematically reviewed published and ongoing disease modification trials to identify the outcomes used in different domains. We extracted outcomes used in each trial, recording how many used each outcome and with how many participants. We divided outcomes into the domains measured and searched for validation data. (3) We consulted with PPI participants about recommended outcomes. (4) We presented all the synthesised information at a conference attended by the wider body of National Institute for Health Research (NIHR) dementia researchers to reach consensus on a core set of outcomes. RESULTS: We included 149 papers from the 22,918 papers screened, referring to 125 individual trials. Eighty-one outcomes were used across trials, including 72 scales [31 cognitive, 12 activities of daily living (ADLs), 10 global, 16 neuropsychiatric and three quality of life] and nine biological techniques. We consulted with 18 people for PPI. The conference decided that only cognition and biological markers are core measures of disease modification. Cognition should be measured by the Mini Mental State Examination (MMSE) or the Alzheimer's Disease Assessment Scale - Cognitive subscale (ADAS-Cog), and brain changes through structural magnetic resonance imaging (MRI) in a subset of participants. All other domains are important but not core. We recommend using the Neuropsychiatric Inventory for neuropsychiatric symptoms: the Disability Assessment for Dementia for ADLs, the Dementia Quality of Life Measure for quality of life and the Clinical Dementia Rating scale to measure dementia globally. LIMITATIONS: Most of the trials included participants with Alzheimer's disease, so recommendations may not apply to other types of dementia. We did not conduct economic analyses. The PPI consultation was limited to members of the Alzheimer's Society Research Network. CONCLUSIONS: Cognitive outcomes and biological markers form the core outcome set for future disease modification trials, measured by the MMSE or ADAS-Cog, and structural MRI in a subset of participants. FUTURE WORK: We envisage that the core set may be superseded in the future, particularly for other types of dementia. There is a need to develop an algorithm to compare scores on the MMSE and ADAS-Cog. STUDY REGISTRATION: The project was registered with Core Outcome Measures in Effectiveness Trials [ www.comet-initiative.org/studies/details/819?result=true (accessed 7 April 2016)]. The systematic review protocol is registered as PROSPERO CRD42015027346. FUNDING: The National Institute for Health Research Health Technology Assessment programme.


Assuntos
Demência , Testes de Estado Mental e Demência , Ensaios Clínicos Controlados Aleatórios como Assunto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Atividades Cotidianas , Doença de Alzheimer/terapia , Biomarcadores , Cuidadores , Conferências de Consenso como Assunto , Demência/terapia , Progressão da Doença , Grupos Focais , Testes de Estado Mental e Demência/normas , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto/normas , Resultado do Tratamento
11.
PLoS One ; 12(6): e0179521, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28662127

RESUMO

BACKGROUND: There are no disease-modifying treatments for dementia. There is also no consensus on disease modifying outcomes. We aimed to produce the first evidence-based consensus on core outcome measures for trials of disease modification in mild-to-moderate dementia. METHODS AND FINDINGS: We defined disease-modification interventions as those aiming to change the underlying pathology. We systematically searched electronic databases and previous systematic reviews for published and ongoing trials of disease-modifying treatments in mild-to-moderate dementia. We included 149/22,918 of the references found; with 81 outcome measures from 125 trials. Trials involved participants with Alzheimer's disease (AD) alone (n = 111), or AD and mild cognitive impairment (n = 8) and three vascular dementia. We divided outcomes by the domain measured (cognition, activities of daily living, biological markers, neuropsychiatric symptoms, quality of life, global). We calculated the number of trials and of participants using each outcome. We detailed psychometric properties of each outcome. We sought the views of people living with dementia and family carers in three cities through Alzheimer's society focus groups. Attendees at a consensus conference (experts in dementia research, disease-modification and harmonisation measures) decided on the core set of outcomes using these results. Recommended core outcomes were cognition as the fundamental deficit in dementia and to indicate disease modification, serial structural MRIs. Cognition should be measured by Mini Mental State Examination or Alzheimer's Disease Assessment Scale-Cognitive Subscale. MRIs would be optional for patients. We also made recommendations for measuring important, but non-core domains which may not change despite disease modification. LIMITATIONS: Most trials were about AD. Specific instruments may be superseded. We searched one database for psychometric properties. INTERPRETATION: This is the first review to identify the 81 outcome measures the research community uses for disease-modifying trials in mild-to-moderate dementia. Our recommendations will facilitate designing, comparing and meta-analysing disease modification trials in mild-to-moderate dementia, increasing their value. TRIAL REGISTRATION: PROSPERO no. CRD42015027346.


Assuntos
Demência/patologia , Progressão da Doença , Grupos Focais , Humanos , Avaliação de Resultados em Cuidados de Saúde
13.
Trials ; 10: 57, 2009 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-19630974

RESUMO

BACKGROUND: Alzheimer's disease (AD) is the commonest cause of dementia. Cholinesterase inhibitors, such as donepezil, are the drug class with the best evidence of efficacy, licensed for mild to moderate AD, while the glutamate antagonist memantine has been widely prescribed, often in the later stages of AD. Memantine is licensed for moderate to severe dementia in AD but is not recommended by the England and Wales National Institute for Health and Clinical Excellence. However, there is little evidence to guide clinicians as to what to prescribe as AD advances; in particular, what to do as the condition progresses from moderate to severe. Options include continuing cholinesterase inhibitors irrespective of decline, adding memantine to cholinesterase inhibitors, or prescribing memantine instead of cholinesterase inhibitors. The aim of this trial is to establish the most effective drug option for people with AD who are progressing from moderate to severe dementia despite treatment with donepezil. METHOD: DOMINO-AD is a pragmatic, 15 centre, double-blind, randomized, placebo controlled trial. Patients with AD, currently living at home, receiving donepezil 10 mg daily, and with Standardized Mini-Mental State Examination (SMMSE) scores between 5 and 13 are being recruited. Each is randomized to one of four treatment options: continuation of donepezil with memantine placebo added; switch to memantine with donepezil placebo added; donepezil and memantine together; or donepezil placebo with memantine placebo. 800 participants are being recruited and treatment continues for one year. Primary outcome measures are cognition (SMMSE) and activities of daily living (Bristol Activities of Daily Living Scale). Secondary outcomes are non-cognitive dementia symptoms (Neuropsychiatric Inventory), health related quality of life (EQ-5D and DEMQOL-proxy), carer burden (General Health Questionnaire-12), cost effectiveness (using Client Service Receipt Inventory) and institutionalization. These outcomes are assessed at baseline, 6, 18, 30 and 52 weeks. All participants will be subsequently followed for 3 years by telephone interview to record institutionalization. DISCUSSION: There is considerable debate about the clinical and cost effectiveness of anti-dementia drugs. DOMINO-AD seeks to provide clear evidence on the best treatment strategies for those managing patients at a particularly important clinical transition point. TRIAL REGISTRATION: Current controlled trials ISRCTN49545035.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Dopaminérgicos/uso terapêutico , Indanos/uso terapêutico , Memantina/uso terapêutico , Nootrópicos/uso terapêutico , Piperidinas/uso terapêutico , Donepezila , Medicina Baseada em Evidências , Humanos , Projetos de Pesquisa , Índice de Gravidade de Doença
14.
Int J Geriatr Psychiatry ; 21(8): 768-77, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16906623

RESUMO

BACKGROUND AND AIMS: It has been suggested that delusions may serve as a defence against negative self-representations. The present study investigated general psychological well-being and evidence for defensive emotional processes among people with late-onset psychosis. METHOD: The performance and responses of older people with late-onset psychosis (n = 13), older people with depression (n = 15), and age-matched healthy controls (n = 15) were compared in a cross-sectional design. Participants rated their own levels of depression and self-esteem, and completed an emotional Stroop task to establish whether there was evidence of implicit depression in the absence of explicit acknowledgement. Participants rated themselves on a number of personal attributes in relation to two life stages to generate discrepancies in 'actual', 'ideal' and 'other' self-concepts, and completed measures of their perceptions of current and past psychological well-being. RESULTS: People with late-onset psychosis showed no evidence of overt depression or low-self esteem. All three groups showed an attentional bias to depression-related and age-related words, although response times overall were faster for controls. The psychosis group showed no discrepancies between either their past or their current 'actual' and 'other' self-concepts, suggesting that they do not have more negative views about how others see them. CONCLUSIONS: Evidence from this study does not support the application of the 'delusion-as-defence' model to late-onset psychosis, but methodological constraints must be borne in mind when interpreting the findings.


Assuntos
Mecanismos de Defesa , Delusões/psicologia , Transtornos Psicóticos/psicologia , Autoimagem , Idoso , Estudos Transversais , Transtorno Depressivo/psicologia , Feminino , Humanos , Masculino
15.
Neuroimage ; 25(1): 141-58, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15734351

RESUMO

Fractional Gaussian noise (fGn) provides a parsimonious model for stationary increments of a self-similar process parameterised by the Hurst exponent, H, and variance, sigma2. Fractional Gaussian noise with H < 0.5 demonstrates negatively autocorrelated or antipersistent behaviour; fGn with H > 0.5 demonstrates 1/f, long memory or persistent behaviour; and the special case of fGn with H = 0.5 corresponds to classical Gaussian white noise. We comparatively evaluate four possible estimators of fGn parameters, one method implemented in the time domain and three in the wavelet domain. We show that a wavelet-based maximum likelihood (ML) estimator yields the most efficient estimates of H and sigma2 in simulated fGn with 0 < H < 1. Applying this estimator to fMRI data acquired in the "resting" state from healthy young and older volunteers, we show empirically that fGn provides an accommodating model for diverse species of fMRI noise, assuming adequate preprocessing to correct effects of head movement, and that voxels with H > 0.5 tend to be concentrated in cortex whereas voxels with H < 0.5 are more frequently located in ventricles and sulcal CSF. The wavelet-ML estimator can be generalised to estimate the parameter vector beta for general linear modelling (GLM) of a physiological response to experimental stimulation and we demonstrate nominal type I error control in multiple testing of beta, divided by its standard error, in simulated and biological data under the null hypothesis beta = 0. We illustrate these methods principally by showing that there are significant differences between patients with early Alzheimer's disease (AD) and age-matched comparison subjects in the persistence of fGn in the medial and lateral temporal lobes, insula, dorsal cingulate/medial premotor cortex, and left pre- and postcentral gyrus: patients with AD had greater persistence of resting fMRI noise (larger H) in these regions. Comparable abnormalities in the AD patients were also identified by a permutation test of local differences in the first-order autoregression AR(1) coefficient, which was significantly more positive in patients. However, we found that the Hurst exponent provided a more sensitive metric than the AR(1) coefficient to detect these differences, perhaps because neurophysiological changes in early AD are naturally better described in terms of abnormal salience of long memory dynamics than a change in the strength of association between immediately consecutive time points. We conclude that parsimonious mapping of fMRI noise properties in terms of fGn parameters efficiently estimated in the wavelet domain is feasible and can enhance insight into the pathophysiology of Alzheimer's disease.


Assuntos
Doença de Alzheimer/diagnóstico , Artefatos , Encéfalo/fisiopatologia , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética/estatística & dados numéricos , Distribuição Normal , Idoso , Idoso de 80 Anos ou mais , Encéfalo/patologia , Feminino , Análise de Fourier , Fractais , Humanos , Funções Verossimilhança , Masculino , Valores de Referência , Estatística como Assunto
16.
Int J Geriatr Psychiatry ; 19(7): 611-23, 2004 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15254917

RESUMO

BACKGROUND: Psychosis with first onset after the age of 60, and arising in the absence of dementia or primary affective disorder, is thought to affect 2-4% of older people, and as many as half will not respond fully to medication. AIMS: This study represents a preliminary attempt to explore a number of possible psychosocial correlates of late-onset psychosis with potential relevance for a cognitive-behavioural formulation and for the development of psychosocial interventions for this group. METHODS: The nature and extent of adverse early life experiences, presence of maladaptive cognitive schemas, and morale in relation to ageing were compared for older people with a diagnosis of late-onset psychosis (LOP; n = 14) or late-onset depression (DEP; n = 13) and healthy older volunteers (HEV; n = 18) in a cross-sectional design. RESULTS: Both LOP and DEP groups reported significantly higher levels of adverse life experiences than the HEV group, with between-group differences in the types of experiences described. The LOP group scored significantly higher than the HEV group on four out of five schema domains, and significantly higher than the DEP group on two domains, other-directedness and over-vigilance/inhibition. The LOP group had significantly lower overall morale in relation to ageing than the HEV group, reflecting significantly higher levels of lonely-dissatisfaction. CONCLUSIONS: Life experiences, cognitive schemas and attitudes to ageing are important psychosocial correlates of LOP. These findings contribute to an understanding of the emotional world of individuals who develop psychosis in later life and may have implications for developing more effective intervention approaches.


Assuntos
Atitude , Transtornos Psicóticos/etiologia , Idade de Início , Idoso , Envelhecimento , Estudos de Casos e Controles , Estudos Transversais , Depressão , Feminino , Humanos , Acontecimentos que Mudam a Vida , Masculino , Moral , Transtornos Psicóticos/psicologia
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