The letter digit substitution test: demographic influences and regression-based normative data for school-aged children.

The Letter Digit Substitution Test (LDST) was administered to a sample of N=296 healthy children (aged between 8.03 and 15.87). The aim of the present study was to evaluate the impact of age, gender, and parental educational level on LDST performance and to establish demographically corrected normative data. The results showed that the relationship between age and LDST performance was curvilinear (i.e., improvements in test performance were more pronounced for younger children than for older children) and was moderated by gender (i.e., the gender differences were small at younger ages but increased as a function of age, with girls outperforming boys). Moreover, children who had parents with a higher level of education outperformed their counterparts who had parents with a lower level of education. Regression-based normative LDST data were established, and an automatic scoring program was provided.