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Biomedical subjects

C MacKnight

Publications and source records attributed to C MacKnight.

At least 19 recordsLinked to original sources
PubMed2002

The effect of the living situation on the severity of dementia at diagnosis.

INTRODUCTION: Previous studies have shown that social determinants not directly involved in the disease process may be implicated in the timing of dementia diagnosis. This study explores the relationship between a patient's living situation and the severity of dementia at diagnosis. METHODS: Data were collected from the baseline interviews of 1,325 patients with cognitive decline enrolled in the Consortium for the Investigation of Vascular Impairment of Cognition study. Data collected included: age, sex, living situation and scores on the Mini-Mental State Examination (MMSE), Global Deterioration Scale (GDS), the Functional Rating Scale (FRS), the Disability Assessment for Dementia (DAD) scale and the Cumulative Illness Rating Scale (CIRS). Living situation was grouped as: (1) lives alone, (2) lives with spouse, (3) lives with child, relative or other and (4) lives in a nursing home. A general linear model univariate analysis was used to compare patients by their respective living situations for differences in mean scores on each of the 4 measures of dementia severity. RESULTS: Statistical analysis of both unadjusted data and data adjusted for age, sex and CIRS scores showed significant differences among the groups. Those who lived alone were diagnosed at an earlier stage (mean scores: MMSE 21.4, GDS 3.6, FRS 20.0, DAD 29.8) followed by those who lived with a spouse (mean scores: MMSE 20.5, GDS 3.7, FRS 20.4, DAD 28.0), those who lived with a child or other (mean scores: MMSE 19.3, GDS 3.9, FRS 22.5, DAD 24.9) and finally those who lived in a nursing home (mean scores: MMSE 15.2, GDS 4.8, FRS 27.5, DAD 16.9). CONCLUSION: Living situation is related to the severity of dementia at diagnosis. Primary care providers should have a low threshold for case-finding in older adults who live with family or friends.

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PubMed2001

Progression of impairment in patients with vascular cognitive impairment without dementia.

Little is known about progression, short of dementia, in vascular cognitive impairment. In the Canadian Study of Health and Aging, 149 participants (79.3 +/- 6.7 years; 61% women) were found to have vascular cognitive impairment, no dementia (CIND). After 5 years, 77 participants (52%) had died and 58 (46%) had developed dementia. Women were at greater risk of dementia (OR 2.1, 1.0 to 4.5). Of 32 participants alive without dementia, cognition had deteriorated in seven and improved in four. Half of those with vascular CIND developed dementia within 5 years, suggesting a target for preventive interventions.

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PubMed2001

Clinical implications of bovine spongiform encephalopathy.

Bovine spongiform encephalopathy (BSE) is a new prion disease that was first identified in the United Kingdom in 1987. Its appearance was likely caused by changes in the rendering process used to produce a meat and bone supplement for cattle, changes that allowed this prion to enter the bovine food supply. Despite measures that were made to reduce the risk to humans, a new variant of Creutzfeldt-Jakob disease appeared in the mid-1990s and has been linked to BSE. Although the extent of the disease's impact on humans is not yet known, current estimates predict that there will be 136,000 cases of this fatal disease by the year 2040. The risk to humans of medications produced with bovine materials, gelatin, and blood transfusion is unknown.

Animals↗
PubMed2001

Butyrylcholinesterase and cognitive function.

Butyrylcholinesterase (BuChE) is expressed in brain structures involved in cognition, but the effect of selective BuChE inhibitors on human cognitive function is unknown. We report a patient whose cognitive function deteriorated following a reduction and improved following reinstitution of ethopropazine, a selective BuChE inhibitor. We suggest that, because neurons expressing BuChE may be involved in cognition, there is merit to further evaluation of selective BuChE inhibitors in treating cognitive dysfunction.

Adult↗
PubMed2001

Assessing hypertension in the Canadian Study of Health and Aging.

We investigated the self-report hypertension variables in the CSHA, recorded in the screening questionnaire and the Self-Administered Risk Factor (SARF) questionnaire. The two questions showed high agreement (phi coefficient 0.83). Each was modestly but significantly associated with other simultaneous reports of heart disease and stroke, and with subsequent mortality. Only the SARF asked questions about treatment; controlling for treatment effects, five-year survival was longest among those with no hypertension and no treatment (mean survival time 1,645 days; 95% CI 1,632 to 1,658), and shortest for those with no reported hypertension who were receiving "antihypertensive" medications presumably prescribed for other cardiovascular disease (mean survival time 1,496 days; 95% CI 1,457 to 1,535). The SARF questions incorporating high blood pressure and treatment appear preferable to assess the risks associated with hypertension.

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PubMed2001

Use of the chronic disease score to measure comorbidity in the Canadian Study of Health and Aging.

Most older adults have multiple chronic diseases. Consideration of these conditions can improve the performance of statistical models in epidemiological analyses. The Chronic Disease Score (CDS) is a measure of comorbidity derived from medication usage, which may have some advantages over measures derived from other sources. The calculation of the CDS from data contained in the Canadian Study of Health and Aging (CSHA) is described. This measure can be used to estimate comorbidity within the CSHA database.

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PubMed2001

Estimating the prevalence of dementia in elderly people: a comparison of the Canadian Study of Health and Aging and National Population Health Survey approaches.

The Canadian Study of Health and Aging (CSHA) and the National Population Health Survey (NPHS) collected data on the prevalence of dementia in differing fashions. The CSHA used a two-stage method with objective testing and expert judgment, and the NPHS used self-report and proxy data. The present report compares estimates of prevalence and the methodology for ascertainment in the two surveys. The more detailed approach of the CSHA offers the more valid means of estimating prevalence and providing data on subtypes, and can be used in naturalhistory studies. TheNPHSmeasures, including a self/proxy report of diagnosed dementia and a derived cognitive measure, are not sufficiently valid for useful inferences to be made. However, the NPHS method can be improved through supplementation with data on functional disability, providing age group-specific point estimates closer to the CSHA's estimates of cognitive impairment and dementia from the community sample. Future waves of the NPHS may wish to include objective cognitive function measures as a cost-efficient and more accurate method of estimating the prevalence of the dementia syndrome without attempting to estimate the prevalence of particular causes of that syndrome.

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PubMed2001

Sleep disturbances and mortality: results from the Canadian Study of Health and Aging.

OBJECTIVES: To cross-validate, in a secondary analysis, the observation that daytime sleepiness is associated with an increased risk of death. DESIGN: Prospective cohort study. SETTING: Canada, a nationally representative sample of people age 65 and older. PARTICIPANTS: Nine thousand and eight community-dwelling participants in the Canadian Study of Health and Aging. MEASUREMENTS EXPOSURES: self-reported sleep disturbances. OUTCOMES: Cox hazard ratios (HRs) for death. RESULTS: The unadjusted analysis showed a small increased risk of death from daytime sleepiness (HR = 1.89; 95% confidence interval (CI) = 1.44-2.46), but this finding did not persist in a multivariate model adjusted for age, depression, cognition, comorbid illness, and function. CONCLUSION: Daytime sleepiness itself is not associated with an increased risk of death when other factors are taken into account. Daytime sleepiness may be a proxy for other morbid conditions and therefore for overall tiredness.

Activities of Daily Living↗
PubMed2001

Assessing the clinical importance of statistically significant improvement in anti-dementia drug trials.

A strategy for assessing the clinical importance of statistically significant treatment benefits in recent dementia drug trials is proposed. Traditional criteria for the assessment of valid inferences are helpful: the more likely the treatment effects are valid, the greater the chance that they will be clinically important. The role of the Clinician's Interview-Based Impression of Change is also of some importance. Progress in this area faces the special challenge that the 'new' disease entity of partial treatment of Alzheimer's disease has not been well described. Large, systematic clinical studies of treated patients remain necessary to define reliable guides to successful treatment.

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PubMed2001

Pharmacotherapy of behavioral and psychological symptoms of dementia: time for a different paradigm?

Behavioral and psychological symptoms of dementia can occur in 60-80% of patients with Alzheimer's disease or other dementing illnesses, and are important in that they are a source of significant caregiver stress and often precipitate nursing home placement. These symptoms, namely, aggression, delusions, hallucinations, apathy, anxiety, and depression, are clinically managed with a variety of psychotropic drugs such as antipsychotics, antidepressants, antiepileptic drugs, and benzodiazepines. Various advances in the neuropathophysiology and pharmacotherapy must be considered in the optimal design of regimens for patients with these symptoms.

Alzheimer Disease↗
PubMed2000

Incidence and outcomes of diabetes mellitus in elderly people: report from the Canadian Study of Health and Aging.

BACKGROUND: The epidemiology of diabetes in elderly people is not well understood. The purpose of this study was to estimate the incidence of diabetes mellitus among elderly people in Canada and the relative risks of death and admission to an institution among elderly diabetic patients. METHODS: The study was a secondary analysis of data for a community-dwelling sample from the Canadian Study of Health and Aging, a nationwide representative cohort study of 9008 elderly people (65 years of age or older at baseline) in Canada. Diabetes was identified primarily by self-reporting, and a clinician's diagnosis and the presence of treatments for diabetes were used to identify diabetic patients who did not report that they had the condition. RESULTS: The reliability of self-reported diabetes (the kappa statistic) was 0.85. The estimated annual incidence of diabetes was 8.6 cases per thousand for elderly Canadians. Incidence decreased with age, from 9.5 for subjects 65-74 years of age, to 7.9 for those 75-84 years of age and then to 3.1 for those 85 years of age and older. Diabetes was associated with death (relative risk 1.87, 95% confidence interval 1.59-2.19) and admission to an institution (relative risk 1.58, 95% confidence interval 1.28-1.94). INTERPRETATION: Diabetes mellitus is common among elderly people, but the incidence declines among the very old.

Aged↗
PubMed2000

Prevalence and outcomes of vascular cognitive impairment. Vascular Cognitive Impairment Investigators of the Canadian Study of Health and Aging.

OBJECTIVE: To assess the importance of vascular cognitive impairment and its three subgroups (cognitive impairment, no dementia; vascular dementia; and AD with a vascular component) to the prevalence and burden of cognitive impairment in elderly people. BACKGROUND: Vascular lesions may produce a spectrum of cognitive changes. Omitting elderly patients whose cognitive impairment falls short of dementia (vascular cognitive impairment, no dementia) may give a falsely low indication of the prevalence and burden of disease. To test this proposition, we compared the rates of adverse outcomes for patients with no cognitive impairment, vascular cognitive impairment (and its subgroups), and probable AD. METHODS: The Canadian Study of Health and Aging is a prospective cohort study of 10,253 randomly selected community-dwelling and institution-dwelling respondents aged 65 years or older. In the community, all participants (n = 9,008) were screened for cognitive impairment; those who screened positive and a sample of those who screened negative received a clinical assessment (n = 1,659). All patients living in institutions received a clinical assessment (n = 1,255). Participants were reassessed 5 years after the original survey. RESULTS: Vascular cognitive impairment without dementia was the most prevalent form of vascular cognitive impairment among those aged 65 to 84 years. Rates of institutionalization and mortality for those with vascular cognitive impairment were significantly higher than those of people who had no cognitive impairment, and the mortality rate for patients with vascular cognitive impairment was similar to that of patients with AD. CONCLUSIONS: Failure to consider vascular cognitive impairment without dementia underestimates the prevalence of impairment and the risk for adverse outcomes associated with vascular cognitive impairment.

Age Distribution↗
PubMed2000

Rasch analysis of the hierarchical assessment of balance and mobility (HABAM).

Measuring changes in mobility and balance offers a means of responding to the clinically important challenge of tracking progression and recovery in frail elderly patients who become ill. This article uses Rasch analysis to construct an interval scale from ordinal observations of such changes, using the Hierarchical Assessment of Balance and Mobility (HABAM) on 204 frail elderly inpatients. Principal components analysis confirmed the unidimensionality of the scale. The Rasch analysis confirmed the hierarchy of the HABAM, and pointed to gaps and redundant items. On this basis, an improved version of the HABAM was developed, suitable in its graphical form for everyday clinical use and for research, using the interval numbers that were generated.

Aged↗
PubMed2000

Feasibility and measurement properties of the functional reach and the timed up and go tests in the Canadian study of health and aging.

BACKGROUND: Physical performance measures may offer advantages over self-report in the functional assessment of older people. Estimates of the feasibility, reliability, and construct validity of these measures in large, heterogeneous samples are necessary to establish their importance relative to traditional measures of function. METHODS: Analysis of clinical data from Phase 2 of the Canadian Study of Health and Aging, a nation-wide representative survey of elderly people in Canada (N = 2,305). RESULTS: Both physical performance measures proved infeasible in many subjects (29.3% for the Timed Up and Go [TUG], 35.9% for the Functional Reach [FR]). Cognitive impairment was the most important determinant of inability to complete the tests. For those able to complete the tests, cognitively unimpaired subjects could reach farther (median 29 cm) and complete the TUG in less time (median 12 seconds) than those cognitively impaired (25 cm for FR, 15 seconds for the TUG). Test-retest reliability between the screening and clinical administrations of the TUG was .56 for all participants (intra-class correlations), .50 for the cognitively unimpaired, and .56 for the cognitively impaired. Construct validity was substantial, and correlations between performance measures and self-report activities of daily living (ADL) measures ranged from .40 to .70. Compared with a global clinical measure of frailty, correlations were more modest (.38 to .60). CONCLUSIONS: The FR and the TUG were not feasible tools in this study. The TUG showed poor test-retest reliability. Our data support the observation that subsequent studies of measurement instruments typically reveal lower performance than the original reports.

Activities of Daily Living↗
PubMed2000

Interrater reliability of the Clinical Dementia Rating in a multicenter trial.

OBJECTIVE: To test the interrater reliability of the Clinical Dementia Rating (CDR) in a multicenter clinical trial. DESIGN: Observational study. SETTING: Training session for a multicenter trial of milameline, a direct muscarinic agonist, in the treatment of Alzheimer's disease. PARTICIPANTS: Twenty-four raters (physicians and nurses) familiar with drug trials and expert in the care of patients with Alzheimer's disease. METHODS: Independent scoring of the CDR using four videotaped CDR interviews. OUTCOME MEASURE: Interrater reliability, as tested by the Kappa statistic RESULTS: The overall interrater reliability was 0.62. Within the CDR domains, the global kappas ranged from 0.33 +/- 0.06 to 0.88 +/- 0.06. CONCLUSIONS: The data support moderate to high overall interrater reliability but show important difficulties in the reliable assessment of early dementia.

Dementia↗
PubMed2000

Conceptualisation and measurement of frailty in elderly people.

The use of the term 'frailty' has shown tremendous growth in the last 15 years, but this has not been accompanied by a widely accepted definition, let alone agreed-upon measures. In this paper, we review approaches to the definition and measurement of frailty and discuss the relationship between frailty, aging and disability. Two trends are evident in definitions, which often trade off comprehensiveness for precision: frailty can be seen as being synonymous with a single-system problem or as a multisystem problem. The essential feature of frailty is the notion of risk due to instability (itself suggesting a balance of many factors), and has been only poorly measured to date. Future models of frailty should incorporate more precise operationalisation of the probability of frailty and better explain the relationship between disease, disability and frailty.

Aged↗