Empirical evaluation of language disorder in schizophrenia

Language disorder in schizophrenia has been described since the early accounts of this illness. Further, it has been suggested that language and psychosis have a common evolutionary origin.

Although schizophrenic speech is easily recognizable, it is difficult to define.

Nonetheless, multiple studies have examined speech samples of schizophrenia patients and reported anomalies at multiple levels of language processing.

At the lexical level, anomalies such as pronounceable nonword and confusion of antonymswere noted. At the sentence level, Chaika described aberrations such as subject or verb incompatibilities with sound grammatical structure (e.g., "the house burnt the cow horrendously always"), failures to pronominalize or delete (e.g., "I gave my friend food so my friend would not go hungry"), errors in tense and article choice.

Many syntactic peculiarities were also reported at the sentence and discourse levels. For example, Pylyshyn found more use of passive voice, perfect tense and state verbs but less use of achievement verbs and qualifying subordinators (e.g., if, since). Additionally, patients with thought disorders exhibited less use of conjunction links (e.g., and, but), pronominalization, reduction in the syntactic complexity and syntactical deviance.

Objective: Studies of the content of speech and of verbal hallucinations in schizophrenia point to dysfunction at multiple levels of language. In this study, we empirically evaluated language processes.

Methods: We examined the performance of 22 schizophrenia patients and 11 healthy control subjects with procedures designed to explore the sublexical, lexical, semantic, syntactic and discourse levels of language processing.

Results: Schizophrenia patients exhibit impairment in the recognition of incorrect, but not correct, linguistic stimuli at all but the sublexical level of language processing. The patients were not impaired in the recognition of nonlinguistic stimuli.

Conclusion: This language-specific differential impairment could explain speech abnormalities in schizophrenia. The nonrecognition of incorrect linguistic information would prevent patients from correcting the abnormal speech they may occasionally produce. A model of decreased power of linguistic computations (reduced number of operations) adequately accounts for this differential impairment.

Massoud Stephane, MD; Giuseppe Pellizzer, PhD; Charles R. Fletcher, PhD; Kate McClannahan, BA

J Psychiatry Neurosci 2007;32(4):250-8.

Stephane and McClannahan — Psychiatry Service Line and the Domenici Research Center for Mental Illness, VA Medical
Center; Stephane and Pellizzer — Brain Sciences Center, VA Medical Center; Stephane — Department of Psychiatry, Univer-