[A version of this item appears in: Dementia: the Latest Evidence Newsletter (RWHT), Volume 2 Issue 2, September 2011].
Approximately 820,000 people in Britain suffer from dementia, half of these having Alzheimer’s Disease (and half of the latter group of cases may have been preventable), said The Daily Mail.
A large systematic review of how strongly seven lifestyle-related risk factors are associated with Alzheimer’s Disease estimates that half of Alzheimer’s Disease cases could be prevented by lifestyle changes such as exercise, eating healthily and not smoking.
The proportion of people worldwide, and in the US, whose condition could be attributed to known risk factors was assessed by this thorough review of published research. Approximately half of all cases of Alzheimer’s Disease are associated with one or more key modifiable risk factors, namely (a) diabetes, (b) midlife high blood pressure, (c) midlife obesity, (d) depression, (e) physical inactivity, (f) smoking and (g) poor education / mental inactivity.
Note: While this research reinforces knowledge on potential risk factors for Alzheimer’s Disease, these statistical associations do not necessarily prove that each of these lifestyle factors actually causes Alzheimer’s Disease.
Across the worldwide population, 33.9 million people are estimated to have Alzheimer’s Disease. The researchers estimate that if the prevalence of all seven risk factors were 10% lower, there would be 1.1 million fewer Alzheimer’s Disease cases worldwide. If risk factor prevalence were 25% lower, Alzheimer’s Disease might be reduced by over 3.0 million cases worldwide. They expect these findings will be similar for all-cause dementia, too, because the risk factors for all-cause dementia are generally similar to those for Alzheimer’s Disease.
Note: The studies included in this systematic review varied in their design and study populations, so there could be a large degree of variation between the findings of individual studies; a phenomenon termed heterogeneity. This systematic review’s estimates of disease incidence and risk factors are based on global and US rates of risk factors, so they may not be specifically applicable to the UK population.
Study of seven Alzheimer’s risk factors. London: NHS Choices, July 19th 2011.
Full Text Link (b). (Access requires an Athens password or journal subscription).
Barnes, DE. Yaffe, K. (2011). The projected effect of risk factor reduction on Alzheimer’s disease prevalence. Lancet Neurology, July 18th 2011. [Epub ahead of print]. (Click here to view the PubMed abstract).