Impairment in event sequencing in disorganised and non-disorganised patients with schizophrenia

It has been suggested that thought disorder in schizophrenia is associated with impaired executive functions and with a defective understanding of others' behaviour. Action sequence knowledge processing and goal detection are considered as crucial components of executive functioning. Here, we used a picture-sequencing task to assess the ability of schizophrenic patients (n = 40) with and without disorganisation symptoms to arrange different types of action sequence representations. Disorganisation symptoms appear to be associated with a general sequencing impairment, while patients without disorganisation symptoms displayed difficulties in ordering sequences requiring subjects to infer mental states in story characters along with a relatively preserved performance in correctly arranging mechanical or behavioural event sequences. These results reveal that only schizophrenic patients without disorganisation symptoms show a selective deficit in mentalising abilities whereas disorganisation symptoms are associated with a more severe event sequencing impairment probably reflecting basic failures of inferential reasoning.