Neuropsychological correlates underlying verbal fluency deficits in schizophrenia: The role of attention and executive function

Abstract

Verbal fluency deficits are commonly observed in patients with schizophrenia. The role of executive functions is still a topic of critical debate, although other neuropsychological domains, e.g. attention, working memory and verbal intelligence, may also influence verbal fluency task performance. Furthermore, some studies report semantic fluency dysfunctions suggesting particular semantic access deficits, while others report regular patterns of verbal fluency task performance, with better performance in semantic fluency as compared to lexical fluency, suggesting general retrieval difficulties. In addition, formal thought disorder symptomatology is often associated with reduced verbal fluency performance. To further address these issues of verbal fluency deficits in schizophrenia, patients with schizophrenia (n=50) as well as a healthy control group (n=36) were recruited and tested according to the aforementioned neuropsychological parameters and both semantic and lexical fluency. Results indicate that executive dysfunctions are associated with verbal fluency performance particularly in the lexical fluency domain. Furthermore, a strong relationship was found between sustained-attention deficits and both semantic and lexical fluency, indicating that verbal fluency deficits in general are mainly driven by attention dysfunctions rather than aberrations in the executive domain. Results showed that patients with schizophrenia did not perform differently for letter vs. semantic fluency. Furthermore, controlling for attention, the results suggest that formal thought disorder symptomatology is unrelated to performance on verbal fluency. Taken together, impaired attention drives the decreased performance in verbal fluency tasks in patients with schizophrenia.