Abstract

Objective: To systematically generate the first and most comprehensive demographic-adjusted norms for the Symbol Digit Modalities Test (SDMT) in Latin America. Method: The sample consisted of 3, 279 healthy subjects from 10 countries in Latin America that approximated the demographic distribution of the countries' populations. The majority of participants were women (61.3%), and the average age was 50.1 ± 20.0 years. The average length of education was 10.2 ± 5.6 years. Participants completed the SDMT. Results: Two analyses of variance (ANOVAs) showed significant differences in age and education among countries (p's < .001). An ANOVA adjusted by age and education was then run that showed significant differences among countries in SDMT scores, F(9, 3247) = 56.50, p < .001, suggesting the development of differential norms by country. A linear regression yielded main effects for age (β = −.468; p < .001) and education (β = .453; p < .001) on the SDMT (R2 = .547). As a result, age and education corrections were created, and a table of percentiles by country was calculated based on the distribution of corrected scores. In the table, percentiles for individual raw scores are generated by adding the corrections and looking up the resulting corrected score for patients in a particular country. Conclusion(s): This study was the first to create norms for the SDMT across Latin America and include appropriate adjustments for age and education. These data represent a critical advance in the assessment of cognitive deficits among individuals with and without neurological conditions in Latin America.