Drury V M, Robinson E J, Birchwood M
Department of Psychology, University of Birmingham.
Psychol Med. 1998 Sep;28(5):1101-12. doi: 10.1017/s0033291798006850.
A neuropsychological formulation of schizophrenia has suggested that problems with meta-representation underpin both positive and negative symptoms. This study tested Frith's account by asking patients experiencing an acute episode of psychosis to complete a set of tasks that involved Theory of Mind (ToM) skills.
Fourteen patients who fulfilled criteria for schizophrenia, 10 deluded patients who were suffering from psychotic disorders other than schizophrenia and 12 depressed patients completed second-order false belief tasks, a test which involved substitution of a co-referential term in a linguistic description of an event, and metaphor and irony tasks. The battery of tests was completed during the acute phase and following recovery. Selection of these patient groups allowed comparisons to be made between schizophrenia patients and non-schizophrenia patients and between patients with and without persecutory delusions.
Schizophrenia patients, who had a multiplicity of positive and negative symptoms, performed significantly worse than non-schizophrenia patients on some of the ToM tasks during an acute episode. Patients with delusions of persecution and reference did not perform significantly worse than non-deluded patients on ToM tasks. There was no significant difference between groups in performance on any of the tasks at recovery.
The results provide at best weak support for Frith's account and it remains unclear whether the ToM deficits demonstrated are genuine deficits or are a result of information-processing overload. However, it is clear that difficulties interpreting interpersonal contexts, as shown by some schizophrenia patients, are state rather than trait characteristics.
