Semantic memory deficits based on category fluency performance in schizophrenia: Similar impairment patterns of semantic organization across Turkish and Japanese patients

Patients with schizophrenia exhibit a wide range of cognitive dysfunction, including impairments in semantic memory and verbal fluency. Previous studies report that semantic memory, i.e. associated meaning of words or knowledge, is specifically disorganized in patients who use the English or Japanese language. The purpose of the present study was to determine if semantic memory, as evaluated by verbal fluency data, shows similar patterns of semantic disorganization in non-English-speaking patients who do (Turkish) or do not (Japanese) use an alphabetical language. Turkish (N=20) and Japanese (N=22) patients with schizophrenia, as well as Japanese normal controls (N=22), entered the study. As a measure of semantic memory organization, two types of cluster analyses, i.e. ADDTREE and hierarchical cluster analysis, were performed on category fluency task data. The cluster analyses revealed a greater similarity between the Turkish patients vs. Japanese patients comparison than the Japanese patients vs. Japanese controls comparison. The results provide further support to the concept that impaired semantic memory organization is one of the core features of schizophrenia, and is independent of the language system or cultural backgrounds.

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