title: Flexibility and variability in lexicon usage among Yoruba-speaking Nigerian outpatients with schizophrenia: a controlled study.
abstract: BACKGROUND
  The studies on language dysfunction in schizophrenia are few, inconclusive and have all been done in the western culture. There may be cross-cultural and cross-lingual differences in problems with speeches of patients with schizophrenia. This study aims to examine the flexibility or variability in the use of words among a group of Nigerian patients with schizophrenia compared with healthy controls.
  
  
  METHODS
  The spoken samples of 48 outpatients with schizophrenia and 48 matched controls were assessed using the mean segmental type-token ratio (MSTTR). The sociodemographic and clinical variables of the patients with schizophrenia were also compared with their MSTTR scores.
  
  
  RESULTS
  The MSTTR score for the patients with schizophrenia was significantly lower compared with that of healthy controls (p < 0.001). The factors independently associated with a lower MSTTR in patients with schizophrenia include younger age at onset of illness, presence of negative formal thought disorder and simple or hebephrenic subtype of schizophrenia.
  
  
  CONCLUSIONS
  The problem with flexibility and variability in lexicon usage among patients with schizophrenia is a cross-cultural phenomenon. The MSTTR may have value in predicting clinical judgements of thought disorder or in identifying deviant language. These may have broad potentials for application in longitudinal and pathogenetic studies of schizophrenia.
authors.affiliation: Department of Linguistics and African Languages, Faculty of Arts, University of Ibadan, Ibadan, Nigeria.
authors.forename: Abiola O
authors.initials: AO
authors.lastname: Adewuya
authors.forename: Abiodun O
authors.initials: AO
authors.lastname: Adewuya
mesh_terms: D000328:Adult; D000553:Ambulatory Care; D003431:Cross-Cultural Comparison; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005006:Ethnicity / Q000208:ethnology*; D005260:Female; D006801:Humans; D007806:Language Disorders / Q000175:diagnosis / Q000208:ethnology; D008297:Male; D009549:Nigeria; D012559:Schizophrenia / Q000175:diagnosis / Q000208:ethnology* / Q000628:therapy*; D012720:Severity of Illness Index; D014705:Verbal Behavior; D014825:Vocabulary