As found in Alzheimer's patients, these levels increase in the normal aging brain. It seems that the Alzheimer's pathology is not just the simple consequence of an acceleration of a normal aging process. Plaques and tangles are also found in the brains of people with Down's Syndrome who live to be forty or fifty years old. People with this syndrome have a characteristic appearance and a special form of mental retardation and are born with three and not the normal two copies of chromosome twenty-one in their cells. In times past they only used to live to age thirty or so, but nowadays many live longer and almost all of this group develop Alzheimer's Disease.
Boxers can suffer irreversible brain damage due to blows to the head.
Last year it was also reported that autopsies of two young boxers who died in the ring revealed tangles, but not plaques, in their brains. Other forms of head injury have been shown to lead to plaque formation within days. It is not known whether the effects of such traumas would have led to Alzheimer's Disease. It is evident however that, in some instances, there can be a rapid development of plaques and tangles in the brain, in contrast to the very slow buildup in Alzheimer's Disease. A second risk factor is being female, although this factor could well become less important in the future with the increasing use of post-menopausal estrogen replacement therapy since there is some evidence that estrogen may delay the onset of the disease.