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

Area of Science:

• Cognitive Neuroscience
• Psychiatry

Background:

• Verbal fluency impairment is a common symptom in schizophrenia.
• The underlying mechanisms, whether executive function deficits or semantic memory issues, remain debated.

Purpose of the Study:

• To differentiate between executive function deficits and semantic store/retrieval problems in schizophrenia-related verbal fluency impairment.
• To investigate the specific nature of verbal fluency deficits in individuals with schizophrenia.

Main Methods:

• Compared 141 individuals with schizophrenia (SZ) and 119 healthy controls on semantic and phonetic verbal fluency tasks.
• Assessed performance using word generation count, clustered/related word count, and switching scores.
• Analyzed the relationship between working memory, cluster production, and switching.

Main Results:

• SZ individuals produced fewer words overall and showed disproportionate impairment in semantic fluency.
• After controlling for total words, semantic tasks revealed group differences in cluster-related word generation.
• Working memory positively correlated with cluster production and inversely with switching.

Conclusions:

• Semantic fluency impairment in schizophrenia may stem from reduced cognitive control, hindering signal differentiation and cue maintenance for memory retrieval.
• Deficits in executive functions, specifically cognitive control, are implicated in the observed verbal fluency impairments in schizophrenia.