Controversial claims about Alzheimer's risk factors
The causes of dementia and Alzheimer's disease are still not yet fully understood.
Understanding the causes can help with measures to help prevent dementia and for the development of treatments.
Over the years, various theories have been suggested and tested. What do we know?
Known risk factors
Age is one of the biggest risk factors in the development of Alzheimer's disease. The chances of developing Alzheimer's double every 5 years after the age of 65.
A family history of Alzheimer's may give a higher risk of developing the condition than in someone with no family history.
Having Down's syndrome increases a person's Alzheimer's risk, as does suffering a severe head injury or whiplash.
Vascular disease can also increase a person's risk of developing Alzheimer’s disease.
Other medical conditions and lifestyle factors may also be to blame. These include smoking, being obese, having diabetes, high blood pressure and high cholesterol.
Aluminium,became a suspected cause of Alzheimer's disease when researchers found traces of this metal in the brains of patients with Alzheimer's disease. Many studies since then have either not been able to confirm this finding or have had questionable results.
Aluminium is present in higher amounts than normal in some autopsy studies of Alzheimer's patients, but not in all. Further doubt about the importance of aluminium stems from the possibility that the aluminium found in some studies did not all come from the brain tissues being studied. Instead, some could have come from the special substances used in the laboratory to study brain tissue.
Aluminium is found in small amounts in numerous household products and in many foods. As a result, there have been fears that aluminium in the diet or absorbed in other ways could be a factor in Alzheimer's. One study found that people who used antiperspirants and antacids containing aluminium had a higher risk of developing Alzheimer's. Others have also reported an association between aluminium exposure and Alzheimer's disease.
On the other hand, various studies have found that groups of people exposed to high levels of aluminium do not have an increased risk. Moreover, aluminium in cooking utensils does not get into food in significant concentration, and the aluminium that does occur naturally in some foods, such as potatoes, is not absorbed well by the body.
In 2012, Keele University preliminary research suggested that drinking silicon-rich mineral water may improve cognitive decline by helping to clearing aluminium from the body.
However, Alzheimer's Research UK says there is still no firm evidence that aluminium exposure causes dementia.