Hermann et al1 recently identified the neuropsychological features of the syndrome of mesial temporal lobe epilepsy (MTLE). Although their neuropsychological battery was comprehensive, they neglected to adequately define certain constructs of cognition; most notably, executive function (EF). To assess EF they used the Wisconsin Card Sorting Test, which is a widely recognized measure of shift of set and perseveration. However, these 2 constructs are subunits of the overall neuropsychological construct of EF, and the use of this test alone is not an adequate measure.2 The authors state that there are no differences, either main or interaction effects, thereby concluding that those patients (with and without MTLE) do not perform differentially, and thus there is no difference in EF between the 2 groups. We cannot agree with this conclusion because performance on a single measure is not an adequate indicator,3 especially with regards to EF. Furthermore, their battery contained other tests that are recognized as tests that assess specific aspects of EF, namely the Comprehension and Similarities test (part of the Wechsler Adult Intelligence Scale–Revised). From their own results there is a differential performance between those patients with MTLE and those without (P<.001) on these measures, indicating that there may be a difference in EF between these 2 groups. This study illustrates the current ambiguity that exists in neuropsychology with regards to the definitions of the constructs of EF, abstract thought, concept formation, reasoning, and shift of set. Many clinicians and researchers believe that executive function is an all encompassing term that includes the other higher functions mentioned. Currently, EF is a poorly defined neuropsychological construct and its definition needs to be rectified to prevent further ambiguity arising in both research work and clinical practice.
Schofield GM, Nielsen SMJ. Mesial Temporal Lobe Epilepsy. Arch Neurol. 1998;55(5):754. doi:
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