Evidence for a relationship between mentalising deficits and paranoia over the psychosis continuum.

Objective: Failing of mentalising has been suggested to underlie certain symptoms of psychosis. An as yet unresolved issue is whether mentalising deficits reflect a characteristic which can also be detected in people at risk for psychosis or people with evidence of subclinical expression of psychosis. This study wanted to assess an aspect of mentalising in four groups with different levels of psychosis vulnerability, and to examine associations between mentalising and symptoms of psychosis.

Method: The study included i) 40 patients with psychosis, ii) 49 non-psychotic first-degree relatives (familial risk), iii) 41 subjects from the general population with a high level of positive psychotic experiences (psychometric risk) and iv) 54 healthy controls. All subjects performed the 'Hinting Task'.

Results: There was a significant association between psychosis risk and impairment on the Hinting Task (beta linear trend=0.37, p<0.001). Using the control group as the reference, the association with impairment on the Hinting Task was highest for the patient group (beta=0.46, p<0.001), whereas the familial risk group (beta=0.16, p=0.06) displayed an intermediate probability of failure. The psychometric risk group did not significantly differ from the control group (beta=0.04, p=0.653). In the patient group, impairment on the Hinting Task was associated with current hallucinations and paranoid symptoms. In the familial risk group, there was an association between the Hinting Task and paranoid symptoms.

Discussion: These results suggest that vulnerability to psychosis is expressed as an impairment in mentalising, which may have a mediating role in the formation of certain positive symptoms of psychosis.