Lexical cohesion and LSA coherence in schizophrenic patients with and without thought disorder

Abstract

Language abnormalities called Formal Thought Disorder may be present in patients with schizophrenia. Disorganized speech is one of these abnormalities, and it may be studied by examining the semantic relationships between parts of the text. Two such approaches are lexical cohesion and LSA coherence. Previous studies have found apparently contradictory evidence, with lexical cohesion being increased in the discourse of patients with Formal Thought Disorder and LSA coherence being decreased. In this study, we tested the idea that these findings are not contradictory, and that one may find both these disturbances in the same sample of patients, with both explaining relevant clinical variables independently of each other. Results didn’t provide strong support for our hypotheses. We attempt to provide explanations for this failure to find the expected results. Methodological differences with previous literature, low subject number and lack of control of certain symptomatology variables may explain our null findings.