Perseveration during verbal fluency in traumatic brain injury reflects impairments in working memory.

OBJECTIVE: Previous studies of verbal fluency have reported higher rates of perseverative responses in both Alzheimer's disease (AD) and traumatic brain injury (TBI) relative to control groups. These perseverations could arise from a number of impairments-for example, failures in working memory, inhibitory control, or word retrieval-and different clinical populations may show an increase in perseveration because of different underlying deficits. The objective of the current report is to investigate the cause of perseveration in verbal fluency in individuals with TBI and compare those results to a recent study of individuals with AD.

METHOD: In a previous study, conducted by Miozzo, Fischer-Baum, and Caccappolo-van Vliet (2013), perseveration errors produced by individuals with AD were shown to have long lags between the 1st occurrence of a word and its repetition in verbal fluency, suggesting that perseverations were caused by a failure of the working memory mechanisms that control response monitoring. In the present investigation, we applied the same analysis to the perseveration errors produced during 197 administrations of the verbal fluency task with 143 individuals with TBI.

RESULTS: The perseverations of individuals with TBI showed a lag distribution similar to that of the AD population, with the lag between the 1st occurrence of a word and its repetition systematically longer than would be expected by chance.

CONCLUSIONS: These results suggest that the perseverations produced during verbal fluency in individuals with TBI stem from the same working memory mechanism proposed in AD, rather than inhibitory control or word retrieval deficits. (PsycINFO Database Record