A neuropsychological investigation of the Delis-Kaplan Executive Function System

Despite a strong historical association between frontal lobe lesions and executive dysfunction, questions remain regarding the neuropsychological characterization of specific regions within the prefrontal cortex, as well as the utility of some executive function measures. The Delis-Kaplan Executive Function System (D-KEFS; Delis, Kaplan, & Kramer, 2001) has gained popularity as a collection of executive function tests, but its sensitivity and specificity for detecting focal frontal lobe dysfunction remain uncertain. The current study investigated performances of patients with focal ventromedial prefrontal cortex (vmPFC, n = 13), dorsolateral prefrontal cortex (dlPFC, n = 14), and nonfrontal (NF, n = 18) lesions on the entire D-KEFS battery. We also obtained IQ data from conventional measures (the Wechsler Adult Intelligence Scale-Third Edition and Fourth Edition, WAIS-III/IV). On six D-KEFS indices, patients with dlPFC lesions performed lower than patients with vmPFC and NF lesions. On three other indices, the performances of the dlPFC group were lower than those of the NF group, but did not differ from those of the vmPFC group. However, none of these between-group differences were statistically significant after full-scale IQ and processing speed were controlled for, suggesting that the observed weaknesses in patients with dlPFC lesions were not specific to executive functions. Patients with vmPFC and NF lesions could not be differentiated based on their performances on any D-KEFS measures. While some D-KEFS measures show promise in differentiating patients with dlPFC lesions, the clinical advantage of using the D-KEFS over more traditional measures is not empirically compelling.