Verbal fluency in schizophrenia: relationship with executive function, semantic memory and clinical alogia

Abstract

SYNOPSIS To examine whether poor verbal fluency in schizophrenia represents a degraded semantic store or inefficient access to a normal semantic store, 25 normal volunteers and 50 DSM-III-R schizophrenic patients, matched for age, sex and IQ, were recruited. Although schizophrenic patients were impaired on both letter and category fluency, they showed a normal pattern of output in that category was superior to letter fluency, and an improvement in category fluency when a cueing technique was employed (Randolph et al. 1993). These results resemble those found in disorders of frontostriatal systems (Parkinson's and Huntington's disease) and suggest that poor verbal fluency in schizophrenia is because of inefficient access to semantic store. A measure of improvement with cueing was directly related to performance on the Stroop executive task. Of all symptom measures derived from SANS and Manchester Scales, only alogia was related to verbal fluency in that superior improvement correlated inversely with the degree of alogia. It is suggested that both alogia and poor verbal fluency are mediated by the same underlying cognitive abnormality that reflects frontostriatal dysfunction.

Is semantic verbal fluency impairment explained by executive function deficits in schizophrenia?

“…We chose this procedure because we believed that additional semantic trials would increase the risk of eliminating or reducing the differences detected. However, considering that similar results have been extensively reported in the literature, 6,11,13,16 we feel that our results are reliable. Another limitation is that our study did not examine strategy implementation according to clustering and switching subtypes in more detail.…”

“…The disproportionate impairment in semantic fluency found in SZ may have been caused by insufficient access and retrieval capabilities (due to the difficulty in selecting words for clustering) and by inhibiting distractors (resulting from increased SNR) 36 rather than by reduced semantic function in SZ per se. 11,15,33 The weak correlation between the number of RW and the working memory-associated trend to increase switching is consistent with working memory models and represents a measure of the inability to focus and/or inhibit distracting information. Instead of being a reflection of insufficient semantic store or absence of search and retrieval strategies, these deficits are the consequence of the ways in which the impairment of the executive function manifests itself.…”

“…17 With this in mind, it is possible to speculate that both groups generated more words in the semantic fluency task because of the broader activation range (there is more to choose from), and that SZ patients were proportionally worse at semantic clustering due to their inability to distinguish between signals (more competition). Furthermore, this would explain why SZ performance improves with cuing, 11 task repetition, 15,33 or prior organization strategies. 29 More specifically, these tactics reduce ''executive'' demands, enabling Data presented as mean 6 standard deviation, unless otherwise specified.…”

“…Authors have interpreted this as evidence of structural semantic knowledge impairment in SZ. However, Joyce et al 11 and Elvavag et al 10 have suggested that patients with SZ have executive deficits rather than semantic knowledge deficits. Both studies describe an improvement in semantic verbal fluency in SZ when executive demands are reduced.…”

Study of Neurocognitive correlates of Schizotypy Personality Clusters in healthy individuals

“…These results are also in agreement with the consistent finding of impaired verbal fluency in the studies of cognition in schizophrenia 50,51 . Moreover, studies carried out in non-affected relatives of schizophrenia patients suggest verbal fluency as a vulnerability factor for schizophrenia [52][53][54][55] , as indeed has been confirmed in recent meta-analyses [56][57][58] .…”