Aim: Higher order language skills, for example, non-literal language, humour, prosody deal with 'what is meant' and they are necessary for communicative exchange and relationships; No study has investigated their link with conversion to psychosis. The purpose of this study was to determine whether such skills could act as predictors of the onset of psychosis, and compare those of individuals converting and non-converting to psychosis with control of cognitive functions.
Methods: Seventy-three patients, aged 15 to 32 years, fulfilling ultrahigh risk criteria took part: 14% of whom were receiving antipsychotic drugs. The study was observational, prospective and longitudinal in nature, and scheduled for 60 months. Pragmatic language skills were evaluated using the Polish version of the right hemisphere language battery. The ultrahigh risk (UHR) criteria were evaluated with Comprehensive Assessment of At-Risk Mental States; attention, intelligence and verbal fluency were controlled.
Results: The conversion rate was 25%; converters demonstrated impaired humour comprehension and metaphor explanation abilities; composite score of pragmatic language was associated with a hazard ratio of 6.0 (95% CI 1.8-20.5) and AUC of .73. Verbal fluency was an independent predictor of conversion, but attention and intelligence were not; pragmatic language skills were associated with social function but not with prodromal symptoms.
Conclusions: The results suggest that deficits in humour comprehension and metaphor explanation could predict conversion to psychosis. These findings could improve diagnosis and create implications for speech and language therapy in UHR groups. Further studies on the mechanisms of pragmatic skills should analyze their relationship with abstract measures and semantic coherence.
Keywords: communication; conversion to schizophrenia; pragmatic language; transition to psychosis; ultrahigh risk state.
© 2020 John Wiley & Sons Australia, Ltd.