Effects of disinhibition on performance of the Word Fluency Test in patients with frontal lesions.

Abstract

The Modified Stroop Test (MST) and Word Fluency Test (WFT) using initial letters and categories were administered to 21 patients with frontal lesions, 32 patients with non-frontal lesions and 24 normal controls. Patients with aphasia were excluded. In the WFT using initial letters, the frontal group showed significantly lower results than the non-frontal group. In order to assess the degree of aspontaneity, we adopted the time which is required for MST ( Part I ) as used to evaluate simple reading fluency. Using the median time of Part I , frontally damaged patients were classified into one group with severe aspontaneity and another with mild aspontaneity. In the latter group, we found a significant negative correlation between performance on WFT using initial letters and disinhibition of stereotypes in the MST, corresponding to the time lag between Part III and Part I . These results suggest that disinhibition of stereotypes plays an important role in the poor performance on the WFT in the frontal group with mild aspontaneity.