One-third of Alzheimer's cases worldwide could potentially be prevented, new research suggests.

Alzheimer's disease affects an estimated 44 million people worldwide and some 35,000 people in Ireland. As the world's population ages, prevalence of the disease is increasing and according to UK and US researchers, by 2050, an estimated 106 million people will have the disease.

It is caused by a range of different genetic and lifestyle factors. Lifestyle factors can include smoking, a lack of exercise, a poor education and depression.

The researchers studied each of these lifestyle risk factors separately and found that one in three cases of Alzheimer's disease could be attributed to them.

Since these risk factors are modifiable, this means that one in three cases of Alzheimer's could potentially be prevented.

The researchers found seven key lifestyle risk factors associated with Alzheimer's - physical inactivity, smoking, depression, midlife obesity, midlife hypertension (high blood pressure), diabetes and a poor education.

They estimated that by reducing the relative risk from each of these seven factors by 10%, it would be possible to cut the prevalence of Alzheimer's in 2050 by at least 8% - this is equivalent to nine million cases of the disease.

According to the study's co-author, Dr Deborah Barnes, of the University of California, San Francisco, 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," she said.

Dr Barnes had led a study in 2011 which suggested that as many as half of Alzheimer's cases could potentially be prevented by the modification of lifestyle factors. However, because this study looked at the risk factors as being independent of each other, this estimate was lowered to one-third.

According to lead researcher, Prof Carol Brayne of the University of Cambridge, while there is ‘no single way to prevent dementia', people may be able to take steps to reduce their risk.

"We know what many of these 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," she insisted.

Details of these findings are published in the journal, The Lancet Neurology.

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