Dementia is not inevitable: A population-based study of Danish centenarians

The authors evaluated the prevalence of dementia in centenarians. In this p opulation-based survey, persons living in Denmark who turned 100 during the period April 1, 1995-May 31, 1996 (N = 276) were interviewed and examined at their residences. Additional health information was retrieved from medic al files, including the National Discharge Registry. A participation rate w as 75%, and no differences were found between participants and nonparticipa nts regarding sex and type of housing. The prevalence of mild to severe dem entia in centenarians was 51%; 37% had no signs of dementia. Among the 105 demented centenarians. 13 (12%) had diseases (vitamin B12 and folic acid de ficiencies, hypothyroidism, Parkinson's disease) that could contribute to a dementia diagnosis. Of the remaining 92 demented participants, 46 (50%) ha d 1 one or more cerebro- or cardiovascular diseases known to be risk factor s in the development of dementia. The prevalence of these risk factors was the same in demented and nondemented participants, whereas hypertension was significantly more frequent in nondemented than demented participants. Dem entia is common but not inevitable in centenarians. Cerebro- and cardiovasc ular diseases are equally common in demented and nondemented persons.