25% drop in Dementia provides a new optimism

Aug 18, 2014 | | Say something

25% drop in Dementia provides a new optimism ;


Good news from England: “dementia rates fall as improving public health.” More information about the authoritative study of the University of Cambridge based on 20 years of British research.

Researchers at the Institute of Public Health in Cambridge showed that the number of people with dementia in the UK was much lower than expected, based on trends in past two decades.


using the types of dementia by age and gender specific collected from interviews in 1991, researchers estimated at about 884,000 people over 65 years (8.3%) have dementia in 2011. However, fresh interviews in 2011 is indicated only about 670,000 (6.5%) had dementia. This was 214,000 fewer people aging population alone would have predicted and represents an overall reduction of 24%.

Almost half of the people who asked for the second survey did not participate for one reason or another, it may have been a source of error in the estimates. However, the effect of this is likely to be small, and the overall conclusions seem reliable.

The study authors suggest that the reduction in prevalence since 1991 may be linked to improved public health messages encouraging people to eat a healthy diet and exercise more. However, they advised not to rest on their laurels, because increasing levels of obesity and poor diet could reverse the trend over the next 20 years.

What is good for the heart is good for the brain

One issue discussed by the researchers is that the fall in rates of dementia may be due to improvements in the ‘heart health’. That is, risk factors that can reduce blood flow to the heart, such as a high cholesterol diet and smoking can also reduce blood flow to the brain. This can cause a type of dementia known as vascular dementia .

Therefore take steps to improve your heart health is largely a win-win option, as it will also reduce your risk of vascular dementia.

How the story came from?

The study was conducted by researchers Cambridge Institute of Public Health at the University of Cambridge and was funded by the Medical Research Council UK with support from other funding agencies, including the Institute national for Health Research.

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The study was published in peer-reviewed medical journal The Lancet.

story was widely reported by the media in the UK and reporting was generally accurate. There was much discussion about whether the prevalence of dementia could continue to decline in the future, especially given the increasing levels of obesity, which has emerged as a important risk factor for dementia .

What kind of research was this?

This was an analysis of two cross-sectional studies in order to ascertain whether the prevalence of dementia had changed in the last two decades.

The prevalence of dementia is a major public health problem and estimates of future plan for the provision of care are needed. However, many of the estimates are outdated and objective of the study was to update the estimates made in 1991 using methods identical topography for a new estimate for 2011.

What research did include

Between 1989 and 1994, the Medical Research Council cognitive function and Ageing study (MRC CFA) interviewed 7,635 people aged 65 and over (9,602 approached, the response rate 80%) from three areas in the UK – Cambridgeshire, Newcastle and Nottingham. This was done to produce an estimate of the prevalence of dementia in the UK. This is known as the estimated ACF, which is for 1991 (the midpoint between 1989 and 1994).

Between 2008 and 2011, new interviews were conducted in the same three areas for CFAS II study. In total, 7,769 people completed interviews with a total 14,242 they approached, a response rate of 56%. Both I and II CFAS CFAS use the same methods of sampling and survey, and the same criteria for the diagnosis of dementia are used. This ensured that the results were directly comparable, despite being two decades apart.

The analysis compared the prevalence of dementia in 7,635 people interviewed in CFAS I with 7,796 people interviewed for CFAS II. They also used the ACF I data to predict the number of people with dementia would have expected to see in 2011, and whether it was higher or lower than what they really found the use of ACF most up-to-date II 2011 data .

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prevalence is estimated between men and women separately and in different age groups.

prevalence estimates were modified to take into account the way the information (known as the design of the sample) and the impact of people who were asked to participate in the study was collected, but they did not choose (no answer). Both of which can potentially biasing the results. This approach was appropriate. ¿

What were the basic results?

In 1991, the use of CFAS I data, the researchers estimated 664,000 people over 65 have dementia in the UK. Given the effect of the aging population, they predicted that number would have increased to 884,000 people (8.3%) in 2011.

However, the use of identical methods, CFAS II estimated the number of people with dementia in the UK in 2011 was 670 000 (6.5%). This was 214,000 fewer people than the elderly population alone would have predicted, representing an overall reduction of 24%.

While the actual number of people with dementia in 1991 (664.000) and 2011 (670.000) increased due to a higher proportion of the total population in the groups of older (aging population) the proportion of over 65 years with dementia was not nearly as much as expected.

These estimates did not change when changes in the response rate were taken into consideration, suggesting that they were not affected significantly by the low response rate in ACF II.

How do researchers interpret the results?

The authors concluded that “this study provides compelling evidence of a reduction in the prevalence of dementia in the elderly population over two decades.”


This study suggests that the prevalence of dementia in people over 65 years in 2011 is lower than would have been expected.

The study had many strengths, including the large number of people interviewed from different areas and techniques of coherent research adopted in 1991 and again in 2011, especially with the same criteria for the diagnosis of dementia in both time points. This means we can be relatively sure that their conclusions are reliable.

said, it has some limitations to consider. The response rate in 2011 (56%) was much lower than in 1991 (80%). The study authors offer a number of explanations for this, including historical trends that show people are less likely to respond to polls today. However, they take this “lack of response” into account in its analysis, and did not alter the results.

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However, this accounting uses assumptions about the prevalence of dementia in people who did not take part that is less robust than has a high response rate to begin with. Therefore, the results still may have been influenced by response bias.

The authors acknowledged that the procedure for diagnosis of dementia is used in both studies has passed and is no longer the norm.

There has been a large clinical debate and change around the best way to diagnose dementia since 1991 and using different methods can produce different estimates of prevalence in different age groups. With this in mind, it is difficult to know to what extent the diagnostic method would have influenced the estimates of the actual numbers of people expected to have dementia.

However, because they used the same method in both periods, the relative comparison (the change between 1991 and 2011) should be broadly accurate.

Discussion in the Lancet highlighted that the results “suggest that changes in lifestyle – for example, in diet, exercise and smoking -. They may reduce the risk of dementia and promote the general health and welfare “This is interesting because if positive changes in health behavior can decrease the prevalence of dementia, then the negative lifestyles could increase dementia.

It is possible that current levels of obesity and related cardiovascular disorders, stroke and diabetes may mean that future rates of dementia actually “rebound” and could be higher than in the past.

This point is summarized in a quote from Professor Hugh Perry at the Telegraph said: “We can not assume that this reduction will in future studies, therefore, the need for us to find ways to prevent and treatment of dementia is more urgent than ever. “

analysis Bazian . Edited by NHS Choices . Follow Behind the headlines on Twitter .

This article was originally published on alzheimersweekly, Read the original article here

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Posted in: Alzheimer's & Dementia, Prevention, Statistics, Understanding Dementia

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