The cause of Alzhemer's has not yet been identified, current thinking would suggest that it may be due to a combination of different factors-
Genetics
A family history of late onset Alzheimer's is associated with an increased risk of developing the condition but no single genetic abnormality has been found to account for this.
People with Down's Syndrome are much more likely than the general population to develop Alzheimer's. Down's Syndrome is a genetic disorder and the result of a chromosonal abnormality.
A gene (Apoe e 4) has been identified as a risk factor for Alzheimers although the causal link between someone possessing this substance and then going on to develop Alzheimer's is currently unclear.
Age
It is known that the risk of developing Alzheimer's increases with age. There are however a number of exceptions to this-
Young onset Alzheimers Disease affects adults much earlier in life although this condition is relatively rare.
Adults who have Down's Syndrome are likely to start developing Alzheimer's between 30 and 40 years earlier than the general population.
All of this would seem to suggest that ageing does not of itself cause Alzheimer's but may be a contributory factor along with others.
Heart Problems
Atherosclerosis or the presence of fatty deposits inside large and middle sized arteries are said to be associated with the development of Alzheimer's and all other dementia types.
High blood pressure is also a known risk factor for Alzheimer's
Other Factors
The NICE guidance on dementia also lists smoking and diabetes mellitus as independent risk factors for the development of Alzheimer's.
Toxins
The geographical "clustering" of Alzheimer's in industrial areas could point to the role of toxins in the environment but as yet none have been identified. There is currently no evidence of a link with occupational exposure to lead or to solvents. Ingestion of aluminium is known to be harmful to the brain but it is not known if it can be responsible for the extensive damage seen in dementia.
It is important to recognise that we know very little about the causes of Alzheimer's and that all of the above is really little better than informed speculation. What is clear is that we won't be able to begin tackling this condition until we have a much clearer idea of its cause.
