Ethnic variability in dementia: results from Singapore.

The diversity of Singapore's population affords a unique opportunity to study ethnic variability in the dementias. We sought to explore the effects of ethnicity on the frequency of Alzheimer disease and vascular dementia in a large Singaporean sample. A total of 357 patients were studied: 190 with vascular dementia and 167 with Alzheimer disease. Vascular dementia was more common among Chinese and Malays, whereas Alzheimer disease was more common in Indians and Eurasians. Factors that may contribute to the observed ethnic variability in dementia etiologies include differential frequency of the ApoE-e4 allele, frequency of vascular risk factors, lifestyle choices, and cultural attitudes toward health care utilization.

Single stroke dementia: insights from 12 cases in Singapore.

BACKGROUND: Vascular dementia (VaD) is occasionally caused by a single, strategically located stroke. In this report, we describe the clinical and anatomical features of 12 cases of strategic single infarct dementia (SSID) from Singapore. METHODS: Each patient completed a standardized diagnostic evaluation including history, neurological and neuropsychological examination, laboratory testing, and brain imaging. Dementia was diagnosed using the Diagnostic and Statistical Manual, 3rd edition, revised (DSM-III-R) criteria, and VaD was diagnosed using the National Institute of Neurologic Disorders and Stroke and the Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) criteria. VaD patients whose brain imaging study revealed a single cerebrovascular event were diagnosed with SSID. RESULTS: We identified 12 cases of SSID among 125 VaD patients (9.6%). Stroke mechanism was lacunar infarction in five cases, embolism in four cases, large vessel thrombosis in two cases, and parenchymal hemorrhage in one case. The most commonly impaired cognitive domains on neuropsychological testing were visual memory, visuoconstruction, and language. In 11 of the 12 SSID cases, the stroke was located in the left hemisphere. The thalamus, either alone or as the proximal portion of a posterior cerebral artery infarction, was involved in 8 of the 12 cases. Stroke locations in the nonthalamic SSID cases included left angular gyrus, subcortical left frontal lobe including minor forceps, left basal forebrain and medial frontal lobe plus anterior corpus callosum (proximal anterior cerebral artery infarction), and anterior corpus callosum alone. CONCLUSIONS: Various stroke mechanisms may produce SSID. In our SSID cases, vascular damage almost always involved the left hemisphere and frequently involved the thalamus and major interhemispheric or intrahemispheric white matter pathways.