Background. 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.
Methods. 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.
Results. 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.
Conclusions. 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.