Executive Function Test Norms in the Ecuadorian Population: A Generalized Additive Mixed Model Approach.

OBJECTIVE:This study aimed to develop demographically adjusted normative data for executive function tests in the Ecuadorian population, aiming to capture variability across the main regions of Ecuador across the Coast, Highlands, and Amazon regions. METHOD:A total of 1,084 healthy participants aged 6-82 years were recruited through a stratified sampling procedure. Participants completed the Stroop Color-Word Test, Symbol Digit Modalities Test, Trail Making Tests A and B, and Modified Wisconsin Card Sorting Test. Generalized additive mixed models were applied to examine nonlinear effects of age, education, and sex, with region included as a random effect. Normative percentiles were derived using the estimated probability distributions, and an interactive calculator was developed to facilitate clinical use. RESULTS:Age and education exerted significant nonlinear effects on performance across tests, with education moderating age-related decline especially in Trail Making Test B and Modified Wisconsin Card Sorting Test perseverative errors. Women with higher education outperformed men on tasks requiring cognitive flexibility. Negative binomial models effectively reduced overdispersion for count data, while gamma models provided optimal fits for time-based measures. Model fit indices (D² = 14.7%-62.6%) indicated robust predictive capacity and low overfitting rates (<10%). CONCLUSIONS:The study provides the first large-scale, demographically diverse normative data set for executive function in Ecuador, capturing complex demographic and regional effects through advanced modeling. These norms, integrated into an open-access calculator, enhance diagnostic accuracy and cross-cultural validity in neuropsychological assessment, supporting more equitable clinical practice in Latin America. (PsycInfo Database Record (c) 2026 APA, all rights reserved).