Alzheimer’s disease (AD) is the most common form of dementia. It affects the hippocampus, a region of the brain that plays an important role in memory and learning. As the hippocampus is damaged by AD, symptoms of memory loss occur – typically starting mildly and gradually worsening as the disease progresses. One person is diagnosed with AD every 60 seconds and the worldwide prevalence of AD is expected to increase dramatically from today’s 36 million to 108 million by the year 2050. Currently, patients live on average 8 years after AD diagnosis. AD is fatal 100% of the time and, as of yet, there is no successful cure.
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Advancing age is the greatest known risk factor for AD. Only a few cases (less than 5%) have a clear genetic cause. For the rest of the patients the cause is not yet fully understood and is described as multifactorial – meaning that there is not one single cause, but a complex interaction among different risk factors resulting in the development of the disease.
As pharmacological trials fail in treating the disease, much recent research has shifted focus towards prevention. Although we cannot change our family history or age, more and more research is revealing clues about modifiable risk factors – meaning risk factors we may be able to influence via lifestyle choices. For example, mounting evidence suggests that the health of the brain is closely linked to the health of the heart and cardiovascular system. Cardiovascular diseases such as stroke and heart attacks increase the risk of AD and other dementias, while the risk factors for cardiovascular disease, such as high blood pressure, diabetes, smoking and physical inactivity have also been identified as risk factors for AD.
A recent review paper published in the Lancet Neurology calculated that about 19% (nearly 6,5 million) of AD cases are attributable to low education, and about 13% (nearly 4,3 million) are attributable to physical inactivity. Importantly, they calculated that as many as 3 million cases of AD worldwide could be prevented by reducing the exposure to modifiable risk factors by 25%.
Therefore, reducing your risk of cardiovascular disease may also help you reduce your risk of developing AD later in life. Of all the modifiable risk factors, physical activity has been shown to be the most effective for AD prevention, with studies showing a 50% reduction in risk of developing AD in those physically active and fit. However, there is a lack of consistent evidence and more studies is needed in order to better understand the potential of lifestyle interventions.
While we all are at risk of developing AD, some of us are more at risk than others. A person who has some of the risk factors will not necessarily develop AD; likewise, reducing exposure to risk factors does not necessarily guarantee remaining healthy – but it does not hurt to try.
Atefe Tari, PhD Candidate at CERG