Semantic Fluency in Schizophrenia

Article excerpt

Abstract

Background: Patients with schizophrenia exhibit various cognitive dysfunctions, most of them rendered evident by language.

Objectives: The aims of the current study are: to compare the global semantic performance of schizophrenics with those of normal controls and to explore the schizophrenics' semantic network.

Method: 62 schizophrenic patients, admitted to the Second Psychiatric Clinic, diagnosed according to ICD-10 criteria and 158 healthy controls were evaluated with tasks for semantic fluency (animals, fruits, and body parts).

Statistical analysis: The correlation between clinical symptoms, demographic data and the verbal fluency variables has been determined using Pearson's correlations. Data were analysed using ANOVA and for semantic fluency this was followed by multidimensional scaling (MDS).

Results: Patients with schizophrenia generated fewer words than healthy controls on semantic fluency tasks. The MDS analysis showed that the semantic structure for schizophrenics with hallucinations was more disorganized than that for schizophrenics without hallucinations. The study emphasized in the later subgroup a lack of any organisation or logical associations within their semantic network of animals, fruits or body parts.

Conclusions: The comparison between schizophrenia patients and normal controls indicated impaired semantic structure in the patient group, in addition to decreased word production.

Key words: verbal fluency, schizophrenia, semantic store

INTRODUCTION

Schizophrenic patients show impaired functioning in multiple cognitive domains such as memory, attention and cognitive function (van Beilen et al, 2004).

The verbal fluency tasks are useful to assess cognitive dysfunctions in schizophrenia as they evaluate both executive and semantic memory function requiring language skills such as quick and spontaneous word productions (Sumiyoshi et al., 2005).

DSM-IV-TR (APA, 2000) requires among A diagnostic criteria the disorganized speech (such as frequent derailment or incoherence) while ICD-10 (WHO, 1996) mentions language disturbance at the end of the list among negative symptoms (paucity of speech), letting the diagnostician to deduce them from the frontline thought disorders (thought echo, thought insertion and broadcasting).

Formal thought disorders are intrinsic connected to the semantic verbal relaxation. The semantic and syntactic tools are less put into practice, leading to a broadening of the sense of speech.

In verbal fluency tasks, formal thought disorder was associated with producing fewer contextually related words, and hallucinations were associated with producing more related words (Kerns et al., 1999).

Both semantic verbal fluency and phonological fluency are good cognitive markers in schizophrenia. According to Stolar et al. (1994) phonological deficits are related to alogia in schizophrenia being a potential marker for psychosis. Semantic fluency has been more related to delusion (Rossell et al., 1999).

Verbal fluency and differences between language productions of schizophrenics compared with normal population have been extensively studied by international literature (see also Paulsen et al., 1996). However, this is the first study on the topic of verbal fluency in schizophrenia conducted on a group of patients who are native Romanian language speakers. This study is important in order to see if the established pattern of the verbal fluency in schizophrenia, mainly on English-speaking populations, can be generalized to Romanian language too.

OBJECTIVES

The aims of the current study are:

* to compare the global semantic performance of schizophrenics with those of normal controls;

* to analyse the type of association of the produced words during the semantic verbal fluency tasks;

* to investigate if schizophrenic patients' performance on semantic fluency tasks could be explained by different impairments in cognitive strategies as switches or clusters;

* to emphasize the relation between psychotic symptoms and the deterioration of the semantic memory in schizophrenics patients;

* to explore the schizophrenics' semantic network. …