Relationship between the Rorschach Perceptual Thinking Index (PTI) and the Positive and Negative Syndrome Scale (PANSS) in psychotic patients: a validity study

The aim of this study is to demonstrate the validity of the Rorschach Perceptual Thinking Index (PTI) in the assessment of reality testing in patients with psychosis. We evaluated the relationship between the PTI criteria and the Positive and Negative Syndrome Scale (PANSS) scores in 98 psychotic disorder affected patients. Thirty four were evaluated during the acute episode (AP) and 64 were chronically treated and stable (CP). The PANSS positive score resulted significantly higher in AP than in CP group, but no significant difference was found in the PTI score. The PTI positively correlated with the PANSS total score. The PTI1 and PTI2 criteria significantly correlated with the PANSS negative score, the PTI4 and PTI5 with the positive. The Rorschach variable X-% significantly correlated with the negative symptoms; the WSum6 with thought disorders; and the M- with delusions. PTI score, X-% and WSum6 predicted impaired judgment and insight. These results suggest that PTI is a valid instrument to assess impairment in reality testing, regardless of the patient's current psychiatric presentation. The presence of conceptual disorganization, delusions, lack of judgment and insight don't have effects on the PTI, supporting its strength as an assessment tool for psychotic disorders