Prevalence of dementia in an urban area in Taiwan

This two-stage epidemiologic study was to investigate the prevalence and types of dementia among elderly people in the San-Min district of Kaohsiung City in Taiwan. In stage one, the Chinese Mini-Mental Status Examination (CMMSE) and Blessed Dementia Rating Scale were employed. In stage two, a comprehensive neurobehavioral examination and neuropsychologic tests were administered by neurologists and neuropsychologists. Dementia was defined by DSM-III-R criteria. The National Institute of Neurological and Communication Disorders and Stroke-Alzheimer's Disease and Related Disorders Association guidelines for Alzheimer's disease (AD) and the National Institute of Neurological Disorder and Stroke-Association international pour la Recherche et l'Enseignement en Neurosciences criteria for vascular dementia (VaD) were applied. A total of 1,016 randomly selected elderly people participated in phase one; 131 people with CMMSE below cutoff values participated in phase two, Of whom 45 were confirmed to have a form of dementia. The prevalence of dementia in this sample was 4.4% (3.2% in men and 5.8% in women); 2.0% for those 65 to 74 years old, 8.3% for those 75 to 84 and 24.4% for those greater than or equal to 85 years old; 6.0% for those who were illiterate, 3.3% for those who attended grade-school; and 2.8% for those who finished junior-high-school. XD (22 cases, 48.9%) was the most common cause of dementia, followed by VaD (11 cases, 24.4%) and mixed dementia (MIX; 5 cases, 11.1%). Old age and being female were significant high risk factors for AD. Medical history indicated that stroke and hypertension were significant risk factors for VaD. A relatively high prevalence of dementia was observed in this study, probably because we assessed neurobehavior in great detail. Although AD was the leading cause of dementia in the present population sample, VaD and MIX also comprised an important proportion, reflecting the high prevalence of stroke in Taiwan. Older women had high risk for AD, not for VaD; and those with a history of stroke and hypertension had high risk for VaD, not for AD.