D-KEFS Trail Making Test performance in patients with lateral prefrontal cortex lesions.

This study evaluated cognitive set-shifting in 12 patients with focal lesions in the lateral prefrontal cortex (LPC) by examining their performance on the Trail Making Test from the Delis-Kaplan Executive Function System (D-KEFS). Patients with LPC lesions performed significantly worse than controls on the D-KEFS Trail Making Test on the Letter Sequencing, Number-Letter Switching (set-shifting), and Motor Speed conditions. Patients with LPC lesions performed significantly more slowly on the Number-Letter Switching condition even after controlling for performance on the four baseline conditions of the test. In addition, patients with LPC lesions exhibited significantly elevated error rates on the Number-Letter Switching condition. Results suggest that LPC lesions can lead to impaired cognitive set-shifting on a visual-motor sequencing task.