Abstract
We investigated the utility of traditional neuropsychological tests in older uneducated/illiterate individuals without dementia to determine the possibility that they are likely not appropriate for this group. We assessed the neuropsychological performance of 1122 older adults [≥65 years old; mean age: 74.03 (SD = 5.46); mean education: 4.76 (SD = 2.5) years; women: n = 714], in the context of the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD), a population-based study conducted in Greece. We based our analyses on three groups: high-functioning/cognitively healthy (i.e., without dementia) uneducated/illiterate individuals (n = 80), high-functioning/cognitively healthy educated/literate individuals (n = 932), and low-functioning/cognitively impaired educated/literate individuals (presumably with dementia; n = 110). We used binary regression analyses with Bonferroni correction to investigate whether test performance differentiated uneducated/illiterate from educated/literate individuals. Models were adjusted for age and sex; raw test scores were the predictor variables. The uneducated/illiterate cohort was at a disadvantage relative to the healthy educated/literate group on all variables but verbal memory recognition and consolidation, congruent motor responses, and phonological fluency clustering (p>.002). Moreover, only word list learning immediate and delayed free recall and delayed cued recall differentiated the high-functioning/cognitively healthy uneducated/illiterate from the low-functioning/cognitively impaired educated/literate group, favoring the former (p's<.002). Our findings suggest that only particular verbal memory test variables are fair in determining whether older uneducated/illiterate individuals have functional/cognitive impairment suggestive of a neurodegenerative process. On all other neuropsychological variables, this cohort was at a disadvantage. Therefore, we highlight the need for identifying appropriate methods of assessment for older uneducated/illiterate individuals.
Highlights
A notable proportion of the world’s population is illiterate and/or lacks formal education
We found that the high-functioning/cognitively healthy uneducated/illiterate group was indistinguishable from the low-functioning/cognitively impaired educated/ literate group on all test variables, except immediate and delayed free recall, and delayed cued recall on a verbal
Our data show that the potential effect of education/literacy on cognitive abilities and the nature of the tasks may lead to an underestimation of the cognitive functioning of healthy older uneducated/illiterate individuals
Summary
A notable proportion of the world’s population is illiterate and/or lacks formal education. Mainly in industrialized countries, uneducated/illiterate individuals are over-represented among the elderly (UIS, eAtlas of Literacy, 2020). Given the frequency of cognitive decline with age, many uneducated/illiterate older individuals may at some point require a neuropsychological assessment. As psychometric tests are typically developed for literate individuals with formal schooling experience, performance on them may be affected by factors such as culture, language, education, and literacy (Ardila et al, 2010; Nielsen & Waldemar, 2016). The use of such tests may lead to an underestimation of the cognitive abilities of uneducated/ illiterate individuals, potentially overestimating the probability of neuropathology. It is imperative that appropriate psychometric tools for these populations are identified
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