Biological risk factors Prevention of dementia Age is the most
important known risk factor for AD. The risk of developing the
disease doubles every five years over age 65. Dementia may occur
at any age, although rarely below the age of 60. Although age is
the most significant risk factor that we know about, dementia is
not an inevitable part of ageing. Family history of dementia
Some genetic risk factors have been identified so far, but only
a small proportion of AD cases can be explained by specific gene
mutations. The risk of dementia and AD has been shown to be
increased among people with a family history of dementia, but
contradictory results exist as well.Life table analyses have
shown a cumulative risk of dementia to first-degree relatives of
AD cases of approximately 50% by age 90, while relatives of
purported control subjects had a much lower cumulative risk.
Studies of AD among twin pairs over age 70 provide the strongest
support for genetic causation. Monozygotic twin pairs show
higher concordance r