The actual cause of Alzheimer's isn't fully understood, but there are several working theories and risk factors that have been discovered. According to most experts, the first and foremost risk factor is age. Scientists are unsure of exactly why age is a cause of Alzheimer’s, but the chances for developing the disease increase significantly with each year as a person gets older. Other things that have been linked as possible causes of Alzheimer’s include injuries to the brain, heart problems, and genetics. Many experts think that the cause of Alzheimer’s may vary in different cases, and sometimes it may be a mix of different factors.
According to some experts, by the time a person reaches 85 years of age, there is almost a 50% chance that they will have developed Alzheimer's disease. Most people who get the disease are generally under 65, but not always. For example, there are cases of people developing Alzheimer’s disease in their 40s. Once the disease develops, it is progressive, and people will gradually worsen until they become unable to function normally.
In terms of the actual mechanics of the disorder, the cause of Alzheimer's disease is an accumulation of certain proteins in a person’s brain. Most doctors suggest that these proteins eventually lead to cell death. For the most part, the brain never replaces cells that die, so with Alzheimer’s disease, the accumulated cell death eventually leads to total dysfunction in the brain.
One of the more common things associated with a cause of Alzheimer's is a lack of normal blood circulation to the brain. This can happen for many different reasons, including several heart conditions and problems with the circulatory system. The reasons for this association are unproven, but some experts think it may lead to the protein accumulation mentioned above.
If people have family members who suffered with Alzheimer's, their chances of getting the disease are greatly increased. Two of the genes that lead to this inheritance have been identified, but scientists think that there are probably other genes that may be discovered eventually. One of the genes that has been uncovered increases a person’s chances, but doesn’t guarantee a case of Alzheimer’s. The other gene, which is generally very rare, creates a 100% chance that the individual will develop Alzheimer's at some point, assuming he or she lives long enough. For most cases, scientists think that genetic factors may simply increase a person’s susceptibility to other causes.