9 Risk Factors Contribute Most to Alzheimer's Disease
Currently, Alzheimer’s disease has no cure, but in a new study researchers have identified 9 risk factors that contribute to the majority of Alzheimer’s disease cases. The fact that these risk factors can be modified to some degree offers the possibility that individuals can help ward off development of this devastating condition.
In addition to the 9 risk factors that contribute to the development of the majority of Alzheimer’s disease cases, the authors of the study also identified others that can play a significant role in the neurodegenerative disease. Overall, most of the risk factors are ones over which individuals can have some control.
What the study reveals
The investigators focused on 323 studies out of nearly 17,000 that involved more than 5,000 individuals. They looked at 93 different potential risk factors and graded them based on their relevance.
The nine risk factors found to contribute to about two-thirds of Alzheimer’s disease cases are:
- Current smoking (among Asians)
- Type 2 diabetes (among Asians)
- Low educational status
- High homocysteine levels
- High blood pressure
- Narrowing of the carotid artery
Most of these risk factors can be acted upon, suggesting individuals can have an active role in helping to prevent the disease. However, it should be noted that this was an observational study, so no conclusive statements can be made about cause and effect.
In addition, the authors noted that the following factors can provide a protective effect against Alzheimer’s disease:
- Use of cholesterol-lowering drugs (statins)
- Drugs to lower high blood pressure
- Use of anti-inflammatory drugs
- Vitamins E, C, and folate
- Coffee consumption
It should be noted that previous research has also shown that dietary factors beyond those noted in this study (e.g., vitamins C, E, and folate) are associated with a reduced risk of Alzheimer’s disease. Notable in this area is following a Mediterranean-style diet, which includes lots of fruits and vegetables, fish, olive oil, whole grains, and legumes, while limiting the amount of red meat, dairy, and sugar.
Among the studies linking a Mediterranean diet to a lower risk of dementia and Alzheimer’s disease is one from the University of Exeter Medical School. According to the study’s lead author, Iliana Lourida, “our systematic review shows it [Mediterranean diet] may help to protect the ageing brain by reducing the risk of dementia.”
Another lifestyle feature associated with a reduced risk of dementia and Alzheimer’s disease is exercise. The authors of a recent review (July 2015) in the Journal of Clinical Neurology noted that “the current knowledge supports PA [physical activity] as an important preventive factor against the onset of both AD and PD [Alzheimer’s disease and Parkinson’s disease]”and that physical exercise “is crucial for the maintenance or slow decline of optimal functional ability levels” in both of these diseases.
The bottom line is that although Alzheimer’s disease has no cure, many of the risk factors associated with the disease are modifiable. Therefore everyone has an opportunity to take steps to help prevent the disease.
Paillard T et al. Protective effects of physical exercise in Alzheimer’s disease and Parkinson’s disease: a narrative review. Journal of Clinical Neurology 2015 Jul; 11(3): 212-19
Xu W et al. Meta-analysis of modifiable risk factors for Alzheimer’s disease. Journal of Neurology, Neurosurgery & Psychiatry 2015. Published online August 20