Title: A meta-analysis of prospective studies on the role of physical activity and the prevention of Alzheimer’s disease in older adults
Authors: Beckett, M. Arden, C. Rotondi, M.
Journal: BMC Geriatrics
Date: 2015
Impact Factor: 2.3
Web-link: http://www.biomedcentral.com/1471-2318/15/9
Why they did it?
Alzheimer’s disease is a chronic condition that leads to a decline in cognitive function, resulting in a loss of personal identity and changes in behaviours, mood and the ability to perform basic daily living activities (see https://fightdementia.org.au for further details). The risk of being affected by Alzheimer’s disease increases with age, with the likelihood of getting this disease doubling every 5 years over the age of 65. Worldwide it is estimated that 35.6 million have Alzheimer’s disease, with a trend for adults to now live longer, this is expected to affect around 115.4 million by 2050. The causes of Alzheimer’s disease are complex, with the latest evidence suggesting that as we age, the cells of the brain lose their ability to repair and regenerate as a part of normal biological process. It has been suggested that the reason why Alzheimer’s disease has only become a recent public health issue is that previous human populations simply did not live long enough to be affected by it! Evidence from controlled laboratory experiences has shown that physical activity and exercise increases oxygen delivery to brain, which improves our brain tissues ability to repair and regenerate. In this study, the protective effects of exercise on Alzheimer’s disease were examined among adults who were 65 years and over.
How they did it?
This was study used a meta-analysis, which is a statistical technique were data is combined from previous studies and used to quantify the strength of a behaviour (e.g. exercise) on a health outcome. A systematic literature online search was conducted. Studies were only included if they were: longitudinal, with all participants being Alzheimer’s free at baseline; used a validated measure of physical activity and dementia; and had participants who were 65 years or older. A total of 10 studies meet the eligibility criteria. The sample sizes for included studies ranged between 716-4,166, and mean number of follow-up period was 5.5 years.
What they found?
A total of 1,358 participants out of 20,326 in all studies were diagnosed with Alzheimer’s disease. Overall, when compared to physically active adults aged 65 years and over, those that remained inactive were at a 49% higher risk of being diagnosed with Alzheimer’s disease.
Ok, what does this mean to me?
This study supports the evidence that regular physical activity is protective for offsetting Alzheimer’s disease. A limitation of the study was the use of a wide range of physical activity assessment tools. This makes it not possible to quantify the dose-response relationship between physical activity and a reduced Alzheimer’s disease risk. For example, was walking 30 minutes/day sufficient to protect against cognitive decline? Further studies are needed using standardised assessment instruments before such recommendations are devised. Nevertheless, older adults should be encouraged to maintain regular physical activity to delay the onset of Alzheimer’s.