Objectives:
An idiographic evaluation of the effectiveness of including Mindfulness Skills Training in Virtual Reality (MST-VR) in the treatment of patients with schizophrenia disorders and its comparison with the results of a group effects analysis.

Methods:
Twenty-five patients with schizophrenia and schizoaffective psychosis were assessed at 4-week intervals (one month before training, at the beginning and the end of training) using: Positive and Negative Syndrome Scale (PANSS-6), Quick Inventory of Depressive Symptomatology (QIDS), Beck Depression Inventory (BDI®-II), Beck Anxiety Inventory (BAI), State-Trait Anxiety Inventory (STAI), Perceived Stress Scale (PSS-10) and Addenbrooke’s Cognitive Examination III (ACE-III). The Reliable Change Index (RCI) was used for statistical evaluation, and Cohen’s d was used to assess effect size.

Results:
Twenty patients (80%) achieved improvements in the severity of general symptoms, positive and negative symptoms, stress, anxiety, depression, and cognitive functioning. Individual patients showed deterioration in anxiety (2 patients, 8%) and stress (1 patient, 4%). The RCI method showed greater sensitivity in detecting changes than standard monographic statistical methods.

Conclusions:
The MST-VR intervention as an adjunctive treatment for patients with schizophrenia and schizoaffective psychosis is safe and beneficial. The RCI method is valuable in assessing the dynamics of individual patient outcomes.