Cognitive Test Performance in a Community-Based Nondemented Elderly Sample in Rural India: The Indo-U.S. Cross-National Dementia Epidemiology Study

Abstract

Interpretation of cognitive test performance among individuals from a given population requires an understanding of cognitive norms in that population. Little is known about normative test performance among elderly illiterate non-English-speaking individuals. An age-straMied random sample of men and women, aged 55 years and older, was drawn from a community-based population in the rural area of Ballabgarh in northern India. These Hindispeaking individuals had little or no education and were largely illiterate. A battery of neuropsychological tests, specially adapted from the CERAD neuropsychological battery, which was administered to this sample, is described. Subjects also underwent a protocol diagnostic examination for dementia. Norms for test performance of 374 nondemented subjects on these tests are reported across the sample and also by age, gender, and literacy. Cognitive impairment, the hallmark of dementia, is detected subjectively from historical information offered by patients and other informants, and from the clinician's observations of general mental status. Objective assessment requires 507 508 M. Ganguli et al.the clinician to measure the individual's performance on one or more cognitive (neuropsychological) tests on one or more occasions. Interpretation of these measurements as being within or outside the normal range requires prior knowledge of the normal range for the population to which the individual belongs. Normative values on standardized cognitive tests are becoming increasingly available for westernized, predominantly Anglophone populations in industrialized countries. Norms are much less readily available for the populations of non-English-speaking developing societies, particularly where those populations have little education. Indeed, standardized cognitive tests barely exist for such populations.The need for tests appropriate to the culture and educational level of the population to be tested has been discussed previously Escobaret al., 1986;Ganguli et al., 1995;Graves et al., 1994;Hall et al., 1993). If neuropsychological test scores are to be used to detect the presence of dementia, and to measure its severity, it is essential to distinguish the effects of dementia on test performance from the preexisting and independent effects of culture, language, and education (White, 1989). No test is completely "culturefree"; at best, it can be relatively "culture-fair" and it can avoid penalizing members of one culture for poor performance on tests designed for, and standardized on, members of another. Culturally relevant factors can include comprehensibility, acceptability, perceived relevance of test content, fluency in the language, and familiarity with testing situations, concepts, procedures, and materials.In preparation for an epidemiological study of dementia in a rural community in northern India, we developed a battery of cognitive tests to screen for and characterize dementing illness among the elderly in that community. In this article, we describe the test battery and report nor...

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