New analysis says Alzheimer's preventable in a third, not half of cases

Date: Jul-15-2014 In a new analysis, researchers suggest around a third of Alzheimer's disease cases

worldwide are attributable to modifiable risk factors - by which they mean there is a chance of

preventing them through improving access to education and making lifestyle changes, such as giving

up smoking, doing more exercise, as well as tackling depression, diabetes, mid-life high blood

pressure and obesity.

The team, from Cambridge University in the UK, points out the new estimate is lower than that

made in a previous analysis that suggested over half of Alzheimer's cases were

preventable. The researchers say the earlier study - which involved some of the same authors

- overestimated the number of preventable Alzheimer's cases because it treated the risk factors

independently, whereas the new analysis takes interactions into account.

For instance, the team explains that three of the risk factors that the previous study treated

as independent of each other - diabetes, high blood pressure and obesity - are all linked to

physical inactivity, and all four are also linked to educational level.

According to the World Health Organization (WHO), globally there are around 35 million people with dementia - a syndrome that affects memory, thinking, behavior and

autonomy. This number is expected to almost double by 2030 to nearly 66 million, and triple by

2050 to 115 million.

About 70% of dementia cases are Alzheimer's disease, where brain cells die after faulty

proteins accumulate inside and around them.

Study examined the effect of seven key lifestyle risk factors

While we do not know exactly what triggers the process of Alzheimer's, we know a complex

interplay of genes and lifestyle is involved, says the team, which was led by Carol Brayne, a

professor in the Cambridge Institute of Public Health at Cambridge University.

The researchers estimate that reducing the risk posed by seven lifestyle factors by only 10% would be enough to reduce the rate of Alzheimer's in 2050 by 8.5% - meaning that 9 million fewer people would develop the disease.

For the study, the team reviewed existing studies that had already pooled and analyzed the

effect of seven key lifestyle risk factors for which there is consistent evidence of a link with

Alzheimer's disease.

These were:

Diabetes
High blood pressure (hypertension) in midlife
Obesity in midlife
Lack of physical activity
Smoking
Depression
Poor educational attainment.

The researchers estimate that reducing the risk posed by each of these factors by only 10%

would be enough to reduce the rate of Alzheimer's in 2050 by 8.5% - meaning that 9 million fewer

people would develop the disease.

Poor education highest risk factor for Alzheimer's worldwide

For example, they found that overall, the risk factor with the highest impact on Alzheimer's worldwide was

poor education, while in the US, Europe and the UK it was physical inactivity.

They also found that when they treated the seven risk factors as independent from each other,

their combined worldwide effect brought the estimated percentage of preventable Alzheimer's cases

to 49.9%, which equates to 16.8 million attributable cases. This is more or less what the 2011

study found.

However, after adjusting for the fact the risk factors are not independent - they overlap

somewhat - the team found the estimated percentage of Alzheimer's cases that are preventable

reduces to 28.2%, which equates to 9.6 million attributable cases.

For the US, Europe and the UK, the combined percentage was found to be a little higher, at

about 30%, note the authors.

Physical activity reduces obesity, hypertension, diabetes and risk of dementia

Prof. Brayne says while there is no single way to prevent dementia, we can reduce our risk of

developing it in old age - we know what many of the factors are and that they are often

linked:

"Simply tackling physical inactivity, for example, will reduce levels of obesity, hypertension

and diabetes, and prevent some people from developing dementia as well as allowing a healthier

old age in general - it's a win-win situation."

Co-author Deborah Barnes, associate professor in the department of psychiatry at the School of

Medicine in the University of California, San Francisco, led the 2011 study. She explains it is

important to get these projections right, and also to accurately assess the impact that lifestyle

changes can make:

"Alzheimer's disease is placing an ever increasing burden on health services worldwide as well

as on both patients and their carers. Our hope is that these estimates will help public health

professionals and health policy makers design effective strategies to prevent and manage this

disease."

Funds from the National Institute for Health Research Collaboration for Leadership in Applied

Health Research and Care (NIHR CLAHRC) for Cambridgeshire and Peterborough helped finance the

study.

Written by Catharine Paddock PhD

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Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.