Cherie McCracken

Dramatic global increases in future numbers of people with dementia have been predicted. No multicentre population-based study powered to detect changes over time has reported dementia incidence. MRC Cognitive Function and Ageing Study (CFAS) undertook baseline interviews in populations aged 65+ years in England and Wales (1989-1994). Three areas (CFAS I) were selected for new sampling two decades later (2008-2011) with same geographical boundaries, sampling and approach methods (CFAS II). At 2 years CFAS I interviewed 5,156 (76% response) with 5,288 interviewed in CFAS II (74% response). Here we report a 20% drop in incidence (95% CI: 0-40%), driven by a reduction in men across all ages above 65. In the UK we estimate 209,600 new dementia cases per year. This study was uniquely designed to test for differences across geography and time. A reduction of age-specific incidence means that the numbers of people estimated to develop dementia in any year has remained relatively stable.

BACKGROUND: Substantial variation in the prevalence of Dementia with Lewy Bodies (DLB) has been reported with estimates ranging from 0 to 26.3% of all dementia cases, potentially making it the second most common dementia subtype. OBJECTIVES: The aim of this study was to review systematically and critically for the first time previous studies of the clinical prevalence and incidence of DLB in the population. METHODS: A systematic literature search was performed using PubMed. Selected articles had to describe an original study that provided a prevalence and/or incidence number for the whole population for DLB as defined by pre-set clinical criteria and findings. RESULTS: Six studies reporting the prevalence of DLB and one study reporting the incidence of DLB met the inclusion criteria. Prevalence estimates, depending on case criteria, range from 0 to 5% with regard to the general population, and from 0 to 30.5% of all dementia cases. The only estimate for DLB incidence is 0.1% a year for the general population and 3.2% a year for all new dementia cases. The number of available studies was too small to hypothesise on the potential effect of age, sex and genetic background on the results. CONCLUSIONS: Although the literature on the prevalence and incidence of DLB is limited, there is a general consensus that DLB must be considered in the range of neurodegenerative conditions in the elderly. The move towards use of consensus criteria facilitates comparison and is welcome. Their application in a more routine way towards rigorously defined and selected study populations will lead to more comparable and generalisable studies in the future.

BACKGROUND: Any hypothesis in longitudinal studies may be affected by attrition and poor response rates. The MRC Cognitive Function and Ageing study (MRC CFAS) is a population based longitudinal study in five centres with identical methodology in England and Wales each recruiting approximately 2,500 individuals. This paper aims to identify potential biases in the two-year follow-up interviews. METHODS: Initial non-response: Those not in the baseline interviews were compared in terms of mortality to those who were in the baseline interviews at the time of the second wave interviews (1993-1996). Longitudinal attrition: Logistic regression analysis was used to examine baseline differences between individuals who took part in the two-year longitudinal wave compared with those who did not. RESULTS: Initial non-response: Individuals who moved away after sampling but before baseline interview were 1.8 times more likely to die by two years (95% Confidence interval(CI) 1.3-2.4) compared to respondents, after adjusting for age. The refusers had a slightly higher, but similar mortality pattern to responders (Odds ratio 1.2, 95%CI 1.1-1.4). Longitudinal attrition: Predictors for drop out due to death were being older, male, having impaired activities of daily living, poor self-perceived health, poor cognitive ability and smoking. Similarly individuals who refused were more likely to have poor cognitive ability, but had less years of full-time education and were more often living in their own home though less likely to be living alone. There was a higher refusal rate in the rural centres. Individuals who moved away or were uncontactable were more likely to be single, smokers, demented or depressed and were less likely to have moved if in warden-controlled accommodation at baseline. CONCLUSIONS: Longitudinal estimation of factors mentioned above could be biased, particularly cognitive ability and estimates of movements from own home to residential homes. However, these differences could also affect other investigations, particularly the estimates of incidence and longitudinal effects of health and psychiatric diseases, where the factors shown here to be associated with attrition are risk factors for the diseases. All longitudinal studies should investigate attrition and this may help with aspects of design and with the analysis of specific hypotheses.

BACKGROUND: Depression and dementia often exist concurrently. The associations of depressive syndromes and severity of depression with incident dementia have been little studied. AIMS: To determine the effects of depressive syndromes and cases of depression on the risk of incident dementia. METHOD: Participants in China and the UK aged > or =65 years without dementia were interviewed using the Geriatric Mental State interview and re-interviewed 1 year later in 1254 Chinese, and 2 and 4 years later in 3341 and 2157 British participants respectively (Ageing in Liverpool Project Health Aspects: part of the Medical Research Council - Cognitive Function and Ageing study). RESULTS: Incident dementia was associated with only the most severe depressive syndromes in both Chinese and British participants. The risk of dementia increased, not in the less severe cases of depression but in the most severe cases. The multiple adjusted hazard ratio (HR)=5.44 (95% CI 1.67-17.8) for Chinese participants at 1-year follow-up, and HR=2.47 (95% CI 1.25-4.89) and HR=2.62 (95% CI 1.18-5.80) for British participants at 2- and 4-year follow-up respectively. The effect was greater in younger participants. CONCLUSIONS: Only the most severe syndromes and cases of depression are a risk factor for dementia.

BACKGROUND: This study was designed to identify all elderly people of ethnic minorities living in a defined geographical area in inner-city Liverpool and to identify psychiatric morbidity and barriers to use of services. This paper reports the prevalence of dementia and depression. METHOD: A survey of the community was carried out using the Geriatric Mental State Examination, AGECAT and ethnically matched interviewers. The sampling frame consisted of Family Health Services Authority lists as a basis, with additional information from community lists, 'snow-balling' and a door-to-door survey. RESULTS: 418 people were interviewed, with a high percentage (55%) of young elderly (65-74) men. The prevalence of dementia ranged from 2 to 9% and of depression from 5 to 19%, and there were no significant differences in levels between English-speaking ethnic groups and the indigenous population. Higher levels of dementia were found among non-English-speaking groups. CONCLUSIONS: A complete enumeration of the elderly in ethnic minority groups is best achieved by using several different methods. Diagnosis of dementia may be misleading among those who do not speak the dominant language.