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Biomedical subjects

C Brayne

Publications and source records attributed to C Brayne.

At least 55 records · Page 3Linked to original sources
PubMed1999

Cognitive function in the Caerphilly study: associations with age social class, education and mood.

Baseline cognitive function was established for a study of pre-symptomatic cognitive decline in 1870 men from the general population aged 55-69 years as part of the third examination of the Caerphilly Study. Cognitive assessment included the AH4, a four choice serial reaction time task, a modified CAMCOG, MMSE, NART and various memory tests. Distributions and relationships with age, social class, education and mood at time of testing are presented for a younger population than has previously been available. Multiple linear regression showed cognitive function to be independently associated with all four factors. The age effect was equivalent to one half of a standard deviation (SD) in CRT and AH4 scores. Only the NART score was not associated with age, supporting the use of NART score as an estimate of pre-morbid IQ. The largest age adjusted differences between men with low and normal mood were for the AH4 (3 points, t = 5.6, p < 0.0001) and the CAMCOG (2 points, t = 5.8, p < 0.0001). The smallest age adjusted effect of mood was for the CRT (33 ms, t = 2.14, p = 0.32) and the MMSE (0.4 points, t = 2.97, p = 0.003). Age, mood and education adjusted social class effects were very large ranging between around 0.5 SD for the CRT, and 1.0 SD for the AH4 and NART, respectively. For educational status age, mood and social class adjusted differences were also substantial with tests for trend showing the largest differences for the NART (t = 12, p < 0.0001) and modified CAMCOG (t = 10.6, p < 0.0001) with the smallest differences for the CRT (t = 2.73, p = 0.006).

Affect↗
PubMed1999

Estimating the true extent of cognitive decline in the old old.

OBJECTIVE: To measure cognitive change using a brief measure over a period of 9 years and to adjust for attrition in the sample. DESIGN: The Cambridge City over 75 Cohort (CC75C), a complete sample of the 75 years and older age group from five group general practices in the city of Cambridge with a systematic one-third of a further practice, all followed on four occasions. SETTING: Cambridge city, UK, the respondents' place of residence. PARTICIPANTS: A total of 2106 subjects were included at study entry. MEASUREMENTS: A brief interview, administered by a trained interviewer, containing a short cognitive scale and the Mini-Mental State Examination (MMSE) at baseline, 2.4 years, 6 years, and 9 years. RESULTS: Decline in MMSE scores occurred across the population and was greater in the oldest age groups. Attrition at later stages of the follow-up was associated with greater decline at earlier stages. Adjusting the results for loss to the sample leads to considerably higher estimates of decline, with the older age groups declining faster from lower levels. CONCLUSIONS: To date, cognitive decline in the very old has been considerably underestimated by longitudinal studies. If studies of population samples are to reflect the health and social needs of this frail group accurately, adjustments for the effect of attrition must be included before true decline can be estimated.

Age Factors↗
PubMed1999

Smoking, drinking, and other life style factors and cognitive function in men in the Caerphilly cohort.

STUDY OBJECTIVES: To examine the cognitive function in a large, ongoing cohort study of older men, and to identify associations with social and lifestyle factors. DESIGN: A cross sectional study of cognitive function was conducted within the Caerphilly Prospective Study of Heart Disease and stroke. SETTING: The Caerphilly Study was originally set up in 1979-83 when the men were 45-59 years of age. Extensive data are available on a wide range of lifestyle and other factors of possible relevance to cognitive decline. Associations between some of these and cognitive function are reported. PARTICIPANTS: A representative sample of 1870 men aged 55-69 years. MAIN RESULTS: Age, social class, medication, and mood were found to be powerful determinants of performance. Self report data on the involvement of the men in leisure pursuits were examined by factor analysis. This indicated that the more intellectual leisure pursuits are the most strongly linked with performance. A measure of social contact showed a weak positive association with the test scores. Current cigarette smokers gave lower test cognitive function scores than either men who had never smoked, or ex-smokers. There was however no evidence of any gradient in function with the total lifetime consumption of tobacco. The disparity between these two data sets suggests that there had been prior selection of men who had originally started to smoke, but more particularly selection of those who later quit smoking. There was no significant association between alcohol consumption and cognitive function, though ex-drinkers had markedly lower test scores than either current drinkers or men who had never drunk alcohol. This seemed probably to be a consequence of an high prevalence of illness among the ex-drinkers. CONCLUSIONS: Age and social class show strong associations with cognitive function. Leisure persuits and social contact are also both positively associated. Neither tobacco smoking nor the drinking of alcohol seem to be associated with cognitive function, though there is evidence suggestive of self selection of both men who had never smoked and ex-smokers.

Age Factors↗
PubMed1998

Incidence of dementia and cognitive decline in over-75s in Cambridge: overview of cohort study.

This paper summarises the methods and some of the findings of a large cohort study of dementia and cognitive decline in subjects aged over 75 years in Cambridge, particularly regarding the incidence wave. From a sample of 1968 subjects previously studied in a prevalence study in 1985-1987, survivors were restudied at 2.4 years, in a two-stage design employing the Mini; Mental State Examination (MMSE) and the Cambridge Examination for Mental Disorders of the Elderly (CAMDEX). High incidence rates of dementia were found, which rose steeply with age, particularly for Alzheimer's disease. New minimal dementia and milder cognitive impairment were also common. Cognitive decline on the MMSE showed a near normal, non-bimodal distribution. The sample has since been restudied at intervals for a total of up to 9 years to document longitudinal cognitive change. Brains have been obtained for post mortem neuropathological and molecular biological study, particularly of the early sequential changes associated with cognitive decline and dementia.

Age Distribution↗
PubMed1998

Examination of the validity of the hierarchical model of neuropathological staging in normal aging and Alzheimer's disease.

The neuropathological staging model of Alzheimer's disease proposed by Braak and Braak [Acta Neuropathol (1991) 82:259] requires that the evolution of neurofibrillary pathology follows a predictable pattern that can be ordered in a regular regional hierarchy. We have operationalized the neuropathological staging system to permit testing of its validity. Forty-two cases were derived from an epidemiological study of cognitive function in an elderly population for which post-mortem brain tissue was collected. Cases with neuropathological diagnoses other than Alzheimer's disease and normal aging were excluded. Neurofibrillary tangle counts were determined in all cortical laminae and regions used for staging. There was a significant correlation between the overall extent of neurofibrillary pathology and the number of regions affected. There were frequent order violations in the proposed hierarchy: 19 instances (45%) involving entorhinal and transentorhinal cortices, and 16 instances (38%) involving CA1 of hippocampus and entorhinal cortex. Only 6 out of 42 cases conformed in all regions to the expected hierarchy. Nevertheless, 90% of the cases had 2 order violations or less, supporting the approximate validity of the hierarchy.

Aging↗
PubMed1998

Aging and lymphocyte subpopulations: whole-blood analysis of immune markers in a large population sample of healthy elderly individuals.

Immune status was determined in a representative sample of elderly people by measuring lymphocyte subsets in whole-blood samples as part of an epidemiological study of the population aged 65 and over. Venepuncture was undertaken in more than 500 individuals who took part in an extensive interview that focused on the lifestyle and psychosocial determinants of healthy aging. The results show that median levels of all lymphocyte subsets tend to decline as the age of the sample increases. In the total sample there were significant age effects (p < 0.05) on total lymphocytes, CD3, CD4, and CD19 (B cells); age differences did not reach significance for CD8 and CD57. There were also significant sex differences (p < 0.05) on CD3, CD4, and CD19, and in all cases women had higher values than men. When we selected a particularly healthy subsample who did not report any illness and took no medication, the findings were unchanged. We conclude that the peripheral expression of lymphocytes appears little affected by aging-related illnesses in the general population, but is affected by aging itself. The study provides reference values for the lymphocyte measures, which can be regarded as having greater validity than the values usually cited.

Aged↗
PubMed1998

Changes in self-rated health, disability and contact with services in a very elderly cohort: a 6-year follow-up study.

OBJECTIVES: To study the relationships between global self-rated health, reported physical symptoms and depressive symptoms and the receipt of community services by very elderly people, and to examine changes in these variables over time. DESIGN: Three-wave study with follow-up at 2.4 and 6 years after first interview. Structured interview, incorporating cognitive examination (Mini-Mental State Examination) and enquiring specifically about overall self-rated health, physical symptoms and depressive symptoms. SETTING: Community setting in city of Cambridge, UK. PARTICIPANTS: 2609 were initially recruited: all patients aged 75 years and over from lists of six general practices (and one in three from a seventh practice). At 2.4 years, 1173 individuals re-examined and at 6 years 628 individuals. MEASUREMENTS: General health self-rated in comparison to others of similar age and individual physical and depressive symptoms self-rated as present or absent. Symptoms were added to produce physical health and depressive symptom scores. Data presented from cross-sectional analysis of 6-year sample; also examined longitudinal data from all three waves of study for ageing and cohort effects. Finally the effect of health variables on the receipt of services was examined. Statistics used included chi(2) and non-parametric statistics for continuous data, also odds ratios for likelihood of receiving services. RESULTS: At 6 years, 70% rated their overall health as good or very good. Overall self-rated health showed both ageing and cohort effects, improving with increasing age and especially with more recent cohort. Reported physical symptoms increased with ageing. Depression scores also increased with ageing but the relationship between depressive symptoms and ageing was less clear-cut. Receipt of services was associated with poor self-rated health and reported physical symptoms as well as with ageing. Higher depression scores at 2.4 years were associated with increased service receipt at 6 years, indicating a lag between the symptoms and the service response. Individuals in the more recent cohort were less likely to receive services, but those who did so received more frequent contact. CONCLUSIONS: Although very elderly people have a high prevalence of reported physical symptoms, they often rate their overall health as good. There was a stronger relationship between ageing and physical symptoms than with depressive symptoms. Symptoms of both kinds influenced the likelihood of receiving services, although there was a lag between depressive symptoms and service response. Cohort effects on service receipt may reflect changes in public service policy.

Aged↗
PubMed1998

The impact on prevalence of dementia in the oldest age groups of differential mortality patterns: a deterministic approach.

BACKGROUND: Until recently relatively little data have been available on the prevalence of dementia in the oldest age groups, and yet it is these age groups which are expanding fastest. It is therefore important to understand whether the prevalence of dementia rises inexorably with age ('age-dependent'), or, as some suggest, levels off or even declines in the very oldest age groups ('age-related'). Combined analysis of the many prevalence studies now available has led to modelled curves which do suggest a slowing of rise in prevalence at these great ages, and has been interpreted as meaning that dementia is age-related. This interpretation does not take into account the differential survival of individuals with cognitive impairment compared with normals of the same age. METHOD: Flexible prevalence-incidence-duration models were generated using a deterministic approach applied to published combined analyses of prevalence rates, population death rates and mortality odds ratios. RESULTS: The variation in observed prevalence patterns with age is explained to a great extent by the mortality observed in the cognitively impaired. Simple examination of age patterns in prevalence does not answer the fundamental question surrounding the age-dependence of cognitive impairment. CONCLUSION: Inferring biological meaning from these observed curves is not valid without examining the mathematical phenomena of the relationship of incidence, mortality and prevalence. This approach allows an examination of the impact of varying mortality and incidence on the prevalence of dementia and cognitive impairment and will be useful in determining the potential impact of preventive strategies on the population.

Age Distribution↗
PubMed1998

The epidemiology of Parkinson's disease in an Australian population.

A prevalence study of Parkinson's disease (PD) was conducted in the rural town of Nambour, Australia. There were 5 cases of PD in a study population of 1207, yielding a crude prevalence ratio of 414 per 100,000 (95% confidence interval; 53-775). We performed a separate case-control study involving 224 patients with PD and 310 controls from South East Queensland and Central West New South Wales, to determine which factors increase the risk for PD in Australia. A positive family history of PD was the strongest risk factor for the development of the disease (odds ratio = 3.4; p < 0.001). In addition, rural residency was a significant risk factor for PD (odds ratio = 1.8, p < 0.001). Hypertension, stroke and well water ingestion were inversely correlated with the development of PD. There was no significant difference between patients and controls for exposure to herbicides and pesticides, head injury, smoking or depression. The high prevalence of PD in Nambour may be explained by rural residency. However, the most significant risk factor for PD was a positive family hisotry. This demonstrates the need for improved understanding of the genetic nature of the disease.

Age of Onset↗
PubMed1997

Incidence of functional decline and improvement in a community-dwelling, very elderly population.

With the aging of the population, functional decline is one of the major challenges to health care systems. The objective of this study was to estimate the incidence of functional decline and improvement in a community-dwelling population of people aged 75 years and above. A representative sample of elderly people living at home in the city of Sherbrooke (Québec, Canada) was assessed yearly on three occasions (1991-1993) by a nurse. Disabilities were measured by the Functional Autonomy Measurement System, a 29-item rating scale developed according to the World Health Organization classification of disabilities. From the 655 subjects who agreed to participate, a total of 572 subjects completed the study, including 68 who subsequently died. The probability of declining was 20.1% for the first year and 12.4% for the second year. The incidence of functional decline among previously stable subjects was 11.9% (95% confidence interval (CI) 8.9-15.9). Age was strongly related to decline (relative risk (RR) = 1.15/year, 95% CI 1.09-1.21), but there was no significant sex effect (RRmale = 0.88, 95% CI 0.55-1.39). The incidence of improvement among previously disabled subjects was estimated at 7.5% (95% CI 5.1-10.9) for the first year and 17.9% (95% CI 14.0-23.0) for the second year. Neither age (RR = 1.07, 95% CI 0.99-1.15) nor sex (RRmale = 1.70, 95% CI 0.90-3.18) was significantly associated with the probability of improving. This study stresses the importance of precise measurement of disabilities and the complex and dynamic process of functional transitions.

Activities of Daily Living↗
PubMed1997

Five-year incidence and prediction of dementia and cognitive decline in a population sample of women aged 70-79 at baseline.

OBJECTIVE: To determine the incidence of dementia and cognitive decline and their predictors in a population sample. SETTINGS: A rural geographically defined population served by a single health centre. SAMPLE: 75% of the 70-74-year-old, 100% of the 75-79-year-old women registered with the practice. METHOD: Interview the total sample using an augmented version of CAMDEX, including informant interview, and reaction times at baseline and 5 years later. IQ was estimated at baseline only. RESULTS: 365 women were interviewed at baseline, 237 at follow-up. Incidence of dementia of all severities was 3.1% per annum (95% CI, 2.2-4.3). CAMCOG declined by 12.6 points in those who became demented, MMSE by 3 points. Observed, self-reported and informant-reported cognitive difficulty at baseline all predicted later incidence of dementia. The additional use of estimated IQ and reaction times did not increase the efficiency of either cross-sectional detection of dementia or prediction of dementia at 5 years. CONCLUSIONS: The incidence of dementia was in the range reported by other studies; slight cognitive decline was noted in the total population, increasing with age and marked in incident dementia. Of clinical importance was the finding that both the individuals and the informants of those who subsequently demented were aware of decline 5 years earlier. Simple and relatively easily administered cognitive tests were found to be the most efficient method of detection of dementia.

Aged↗
PubMed1997

Setting the minimal metrically detectable change on disability rating scales.

OBJECTIVE: To determine the minimal metrically detectable change (MMDC) on rating scales by comparing two methods: (1) using the reliability coefficient derived from an external study in the calculation of the standard error of measurement (psychometric method); and (2) examining the variability of scores in a stable subsample from a longitudinal study (empirical method). DESIGN: Longitudinal survey. SETTING: General community. PARTICIPANTS: Population-based representative sample of community-dwelling people older than 75 (n = 572). MAIN OUTCOME MEASURE: Disability as measured by the Functional Autonomy Measuring System (SMAF). RESULTS: Using the psychometric method, a change in score of 3.7 on the SMAF was obtained using a reliability coefficient derived from an external test-retest study, and 5.2 using the reliability coefficient measured in a stable subsample of the longitudinal study. With the empirical method, a change of 5 points was established as the MMDC. CONCLUSION: The setting of the MMDC on a disability scale could be useful for calculating sample size or interpreting results from clinical trials because it helps to establish the minimal clinically important difference, which should be equal to or larger than the MMDC.

Aged↗