The effect of illiteracy on performance in screening tools for dementia: A meta-analysis

Research indicates that many tools designed for screening dementia are affected by literacy level. The objective of this study was to estimate the overall effects of this confounding factor. A meta-analysis was conducted to evaluate differences in performance in dementia screening tools between literate and illiterate individuals.

Electronic databases were searched from 1975 to June 2021 to identify empirical studies examining performance in dementia screening tools in literate and illiterate individuals over 50 years old. Data for effect sizes, participant demographic information, and study information were extracted.

We identified 27 studies methodologically suitable for meta-analysis. Multi-level random-effects modeling demonstrated a significant overall effect, with literate participants scoring significantly higher than illiterate participants (g = -1.2, 95% CI = -1.47, -0.95, p < .001). Moderator analyses indicated significant effects of test type and the presence of cognitive impairment on the extent of the difference in performance between literate and illiterate participants. The difference in performance between groups was smaller in screening tests modified for illiterate individuals (p < .01), and in individuals with cognitive impairment (p < .001).

Our findings substantiate the unsuitability of many dementia screening tools for individuals who are illiterate. The results of this systematic review and meta-analysis emphasize the need for the development and validation of tools that are suitable for individuals of all abilities.