Cognitive and behavioural predictors of survival in Alzheimer disease: results from a sample of treated patients in a tertiary‐referral memory clinic

“…Identification of dementia by means of death certification is thought to identify only ~70% of cases. 7 Although the authors state that this is unlikely to change any associations, this is unproven, and for future research there is an urgent need to improve the recording of dementia in electronic health records.…”

Section: Clinical Opinionmentioning

confidence: 99%

Body mass index and the risk of dementia – what do we know and what should we do?

Harrison

Shenkin²

2015

J R Coll Physicians Edin

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Summary'Being overweight can cut risk of dementia'. The news that a health status usually associated with poor outcomes and stigma may actually be protective for one of the most feared diseases of our time was enthusiastically greeted by the media and many individuals. The reports focused on this aspect -that risk of dementia fell with increasing body mass index (BMI) -although the authors of the study focused on the findings that being underweight in middle and old age carries an increased risk of dementia. Previous findings in this area have been contradictory, and appropriate interpretation is vital in view of the public health implications if the message that obesity is protective against dementia were to be accepted.The study was a large retrospective cohort study using routinely collected UK primary care data, from the Clinical Practice Research Datalink (CPRD) database. Individuals' records were accessed if they were aged >=40 years between 1992 and 2007. Data from 1,958,191 participants were used, comprising just 32% of those in the CPRD database of the appropriate age group. The population characteristics are not presented in the paper. BMI and incident dementia data were collected between January 1992 and December 2013. First recorded BMI was used and no subsequent changes in BMI were included. Median follow-up time was 9.1 years, although the conclusions are presented as data over two decades.During the period of follow-up 45,507 people (2% of total sample) developed incident dementia. Coding of dementia was based on the use of the terms dementia, Alzheimer, Lewy body disease, Pick's disease, being used in the individual record or on death certificate.The underweight group (BMI < 20kg/m 2 ) n = 101,754, 5% of the total sample, had a 34% excess risk of dementia compared to those of a healthy weight. Incidence of dementia fell as BMI category increased adjustment for potential confounders -smoking status, alcohol use, statin use, antihypertensive use, diabetes and previous myocardial infarction -did not affect the association. CliniCal OpiniOnThe paper is interesting in its use of a large sample, and routinely collected data, to investigate an important health topic, but some methodological issues, in particular the incomplete data availability, merit caution in the interpretation of the findings.As an observational study, the results can only describe an association; causation cannot be attributed. The authors acknowledge that the association between weight and risk is complex. Flegal et al., 1 in a systematic review and meta-analysis, also identified that being overweight is associated with lower mortality than being of normal weight; however the relationship was not seen in those who were obese. On the other hand, other studies report that overweight is not associated with lower dementia risk. Kivipelto et al.2 focused on the impact of vascular risk factors in middle age and were able to adjust for sociodemographic variables not included in the current study. They found increased odds (odds ratio 2.4...

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“…Death certification is widely used in epidemiological studies to identify cases of dementia, though any mention of dementia on the death certificate is considered a better dependent variable than instances when dementia is recorded as the underlying cause of death, since many people with dementia die from something else [20,21]. Although this methodology has previously been criticised [22], more recent studies suggest that dementia reporting on death certificates is improving and seems to be sufficiently robust for epidemiological purposes, see for example a false-negative rate of 18% in a memory clinic population [12,20]. However, death certification probably remains less reliable in identifying dementia subtype; for example, while Alzheimer's disease is by far the commonest cause of dementia, in Italy the proportion of cases denoted as Alzheimer's disease ranged from 23 to 67% (median 45%), the figures in New Zealand were 0-71% (median 32%) and in Chile 11-59% (median 42%).…”

Section: Discussionmentioning

confidence: 99%

Geographical Variation in Dementia Mortality in Italy, New Zealand, and Chile: The Impact of Latitude, Vitamin D, and Air Pollution

Russ¹,

Murianni

Icaza

et al. 2016

Dement Geriatr Cogn Disord

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Background: Dementia risk is reported as being higher in the north compared to the south, which may be related to vitamin D deficiency. If this were the case, an opposite gradient of risk would be observed in the southern hemisphere, but this has not been investigated previously. Methods: We calculated standardised mortality ratios (SMRs) for deaths in 2012 where dementia (Alzheimer's disease, vascular or unspecified dementia) was recorded as the underlying cause for 20 regions in Italy, 20 District Health Board areas in New Zealand and 29 Health Service areas in Chile. Results: Dementia SMRs were higher in northern than central or southern Italy. The inverse pattern was seen in women in New Zealand, with rates higher on South Island than North Island. However, dementia risk was raised in eight regions in the north and centre of Chile in both men and women. Conclusions: Geographical variation plays a key role in dementia risk, but patterns vary in men and women. In the northern hemisphere, dementia mortality is higher in the north, but the pattern in the southern hemisphere is more complex.

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Cognitive and behavioural predictors of survival in Alzheimer disease: results from a sample of treated patients in a tertiary‐referral memory clinic

Abstract: At diagnosis, in addition to the anticipated impact of age and gender, the presence of psychotic symptoms and poor performance on paired-associate learning are also indicators of poor prognosis.

Cited by 56 publications

References 62 publications

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Association Between Psychological Distress and Liver Disease Mortality: A Meta-analysis of Individual Study Participants

Body mass index and the risk of dementia – what do we know and what should we do?

Geographical Variation in Dementia Mortality in Italy, New Zealand, and Chile: The Impact of Latitude, Vitamin D, and Air Pollution

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