Mean T scores over time for Trail Making Test Part B (Trails B) and Digit Symbol Substitution Test (Digit Symbol) with standard errors. Trails B measures divided attention, visual-motor integration, ability to inhibit competing stimuli, and psychomotor speed. Digit Symbol measures learning, sustained attention, visual-motor integration, and psychomotor speed. For T scores, the population norm is set at 50, with SD of 10, and adjusted for the age, sex, and education of the patient. Asterisks denote statistical difference from the norm (^*P < .05 and ^**P < .01).