Frequency of Alzheimer's disease and other dementias in a community outreach sample of Hispanics.

OBJECTIVES: To determine the proportion of Alzheimer's disease (AD) and other dementia types in a community sample of Hispanics.
DESIGN: This is a descriptive diagnostic study of a nonrandom community outreach sample utilizing established criteria for the diagnosis of dementia type. Recruitment involved direct community outreach with diagnostic evaluations conducted at a university-affiliated outpatient clinic.
SETTING: Hispanic Neuropsychiatric and Memory Research Clinic at the Olive View-UCLA Medical Center in Sylmar, California. PARTICIPANTS: One hundred community-dwelling Hispanics age 55 and older without prior diagnosis or treatment of their cognitive symptoms. MEASUREMENTS: Each subject underwent a complete medical diagnostic evaluation, in Spanish, including neuropsychological tests, neurological examination, laboratory tests, and brain imaging (computed tomography or magnetic resonance imaging) to establish dementia type. Presence of dementia was established according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria. Diagnosis for probable or possible AD and vascular dementia (VascD) was established using criteria from the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association for probable AD and by research criteria from the National Institute of Neurological Disorders and Stroke and the Association Internationale pour la Recherche et l'Enseignement en Neurosciences for VascD, respectively. Frontotemporal dementia was diagnosed using recommendations set forth by the Lund and Manchester groups.
RESULTS: Subjects were poor, with low acculturation levels despite long years of U.S. residence. Forty percent of subjects had had undiagnosed cognitive symptoms for 3 or more years. Of those demented, 38.5% had AD and 38.5% met criteria for VascD. The best predictors of VascD were hypertension and cerebrovascular disease, whereas apolipoprotein E4 allele best predicted AD. Other forms of dementia were also present. Twenty percent of the sample was clinically depressed but not demented.
CONCLUSIONS: In comparison with data from predominantly white populations, our proportion of AD cases was lower and that of VascD cases was considerably higher than anticipated. The percentage of clinically depressed older individuals was also high. These findings could have implications for differential cultural and genetic risk factors for dementia among diverse ethnic/racial groups. Further studies are needed to obtain accurate prevalence estimates of dementing disorders among the different U.S. Hispanic populations.