The Bloch’s Multidimensional Drawing Test: A revised approach to the assessment of paranoid schizophrenia and schizoaffective disorder

Background. Paranoid schizophrenia (PS) and schizoaffective disorder (SD) are complex neurodevelopmental conditions with overlapping clinical features, making their differentiation challenging. Bloch’s Multidimensional Drawing Test (MDZT), a projective psychological assessment tool, offers potential for improved differentiation between these disorders. This study aims to refine the MDZT by developing a logistic regression-based equation utilizing variables such as gender, personality shape mode (f%), and percentage of human content (M%) to enhance diagnostic accuracy.Methods. Data were collected from 94 clinical protocols of patients diagnosed with PS or SD (mean age = 34.4 ± 9 years; 80.8% male). Statistical analyses included independent samples t-tests and logistic regression applied to create an adjusted diagnostic model (Combined Variable No. 4). Key variables included personality shape mode (f%), emotional tuning index (AML), and affective irritability indicator (s).Results. Significant differences were observed between PS and SD patients in personality shape mode (f%), AML, and s variables. A strong correlation was identified between AML and s indices. While the original diagnostic equation demonstrated random accuracy, the revised logistic regression model achieved improved diagnostic precision, correctly classifying 78.7% of cases.Conclusion. The adjusted MDZT represents an improvement over previous versions and can serve as a valuable addition to a comprehensive diagnostic battery; it contributes significantly to clinical decision-making by offering unique insights into the differentiation of PS and SD. Future research should focus on validating the test in broader populations and exploring its longitudinal applications for monitoring symptom progression and treatment outcomes.