Possible Causes of
Many clues to Alzheimer's disease have been identified but have yet to converge on a single causal explanation. There is growing evidence that Alzheimer's is a complex disease caused by multiple factors, and these factors must act in some sequence or combination for the disease to be expressed. The abnormal protein, beta-amyloid, provides a good example. It is associated with at least one genetic cause of the disease and is implicated in causing the death of neurons. Some believe it has a very central and precipitating role in the development of the disease. Despite evidence of its many associations with different aspects of the disease, the role of beta-amyloid remains a topic of intense scientific investigation.
Of the causes being considered, genetic factors are the only ones that definitely cause the disease in a small percentage of cases. Genetic factors and theories concerning slow viruses, the immune system, and brain inflammation are discussed in this chapter. Excess aluminum intake is also discussed.
It also appears highly likely that certain psychosocial factors can influence the development of Alzheimer's disease and the severity of its symptoms. We therefore look at environment, psychiatric history, social and sensory deprivation, and one's sense of support and control.
A word also seems in order about what does not cause Alzheimer's disease. It is not caused by simple old age, hardening of the arteries, or stroke. Most importantly, it is not caused by the person's character or behavior. “Bad” or “lazy” people do not develop Alzheimer's disease any more often than “good”