Executive function as predictors of persistent thought disorder in first-episode schizophrenia: A one-year follow-up study

Language disorganization is an important clinical indicator of acute psychosis, yet the longitudinal course and pathogenesis are not well understood. Executive dysfunction has been suggested as a vital contributor to formal thought disorder (FTD) and may serve as a stable predictor of symptomatic risk. The paper reports a one-year prospective study of language disorganization in sixty patients with first-episode schizophrenia-spectrum disorders and investigates executive function as a predictor of persistent FTD one year after illness onset. FTD was captured using the Clinical Language Disorder Rating Scale (CLANG), which segregates language abnormalities into three empirically validated levels: syntactic, semantic, and production. After one year, patients' syntactic and semantic deficits were substantially reduced, but production impairments persisted. Patients' improvement of semantic impairment was associated with reduced disorganized symptoms while production impairment was associated with negative symptoms. We further identified two different patterns of baseline executive function predictors for both residual semantic and production impairment. We found that sustained FTD at the semantic level was predicted by both sustained attention and planning at illness onset, while residual production failure was only predicted by sustained attention. In conclusion, the present paper documents the distinct characteristics of psycholinguistic levels in FTD and isolates two different patterns of executive function predictors for persistent semantic and production language disorganization at follow-up. The findings help to disentangle FTD dimensions at different levels of language production processes, which provide clinical implications for targeting patients at risk for prolonged FTD concordant upon executive dysfunction at illness onset. (C) 2014 Elsevier B. V. All rights reserved.