Dementia in subjects over 65 years of age in the Republic of San Marino.

A study on neurological conditions was performed in the Republic of San Marino, which is the smallest independent state in the world (60 km2, 21,792 people). We personally examined or collected information on all people born in 1898, 1903, 1908, 1913 and 1918 and living in the Republic of San Marino on 31 July 1985. We found 29 people out of 488 with mild to severe dementia. Frequency of dementia increased progressively with age, from 1.8% among 67-year-olds to 25% among 87-year-olds. In women the increase was due mainly to primary degenerative dementia, whereas in men other types of dementia were involved. Our study shows a female/male ratio of more than 2:1 for primary degenerative dementia even considering mild dementia, and this form of dementia represents about 50% of all types of dementia. We found an association between severe auditory loss and primary degenerative dementia.