Semantic hyperpriming in thought-disordered patients with schizophrenia: state or trait?--a longitudinal investigation.

Enhanced semantic priming (SP) has been reported in individuals with schizophrenia who exhibit positive formal thought disorder (TD) and it has been linked to heightened automatic spreading activation in semantic networks of these patients. However, the state or trait nature of semantic hyperpriming in schizophrenia and its relation to clinical features (e.g., length of illness, symptom shifts) is not clear. To explore these issues, we administered a lexical decision task with semantically related, indirectly related or unrelated prime-target pairs to acutely ill inpatients with schizophrenia shortly after admission and again after 12-16 weeks, while most patients were already in (partial) remission (n=33). In addition, we examined 20 healthy control subjects twice (2 weeks apart). Relative to control subjects, TD patients with schizophrenia exhibited hyperpriming only in the acute psychotic state, but not during the follow-up examination, when TD and other positive symptoms had resolved. There were no associations between priming effects and length of illness or number of previous psychotic episodes. In conclusion, semantic hyperpriming in TD patients with schizophrenia appears to be clearly state-dependent and might be viewed as an episode marker of psychosis with TD.