[Estimated prevalence of presenile dementia in Tottori prefecture].
A questionnaire study of dementia in the age group of 40-64 years old was performed among all hospitals and clinics in Tottori prefecture. Response rate was 52.9% (hospitals 53.2%, clinics 52.4%). A total of 100 patients (from April 1992 to March 1993) were reported. The estimated prevalence rate of all dementia in the age group of 40-64 years old was 81.4 per 100,000 population. Cerebrovascular dementia accounted for half and Alzheimer's disease, intoxication and trauma accounted for 14.0%, 11.5%, and 10.8% of dementia in the age group of 40-64 years old, respectively. There were several other types of dementia but numbers were very few. The estimated prevalence rates of cerebrovascular dementia in the age groups of 40-49, 50-59, and 60-64 years old were 0, 47.9 (male 66.0, female 31.5) and 113.2 (male 184.5, female 51.5), respectively. Those of Alzheimer's disease in the age groups of 40-49, 50-59, and 60-64 years old were 0, 5.6 (male 4.2, female 6.9) and 47.5 (male 50.3, female 45.0), respectively.