We enrolled 50 cognitively normal subjects (26 ET and 24 age-, sex-, and education-matched healthy subjects), which scored within normal ranges individually in all tests of a comprehensive neuropsychological battery covering memory, executive function, attention, visuospatial abilities, and language. Unsupervised clustering was applied separately within each group. Cluster membership was validated by post-hoc comparisons using ANOVA and Bonferroni-corrected pairwise tests to compare the variables among the clusters.

This study demonstrates a cognitive heterogeneity in ET and reveals a memory-impaired subgroup absent among HC. The ET cluster with lower memory performance likely reflects a pattern of vulnerability for longitudinal decline or progression to mild cognitive impairment. The identification of this profile has relevant translational implications for prognosis and identification of early intervention strategies.