Application of the MMPI-2 inventory in the differential diagnosis of psychotic disorders - based on profile analysis of a patient diagnosed with persistent delusional disorder and personality disorder

Aim: Paranoid states or traits can be present in various mental disorders; hence, their clarification is valuable for establishing a reliable nosological diagnosis. Clinical practice and literature on the subject highlight a range of defence mechanisms specific to the discussed nosological group. These mechanisms can impede the process of psychiatric and psychotherapeutic diagnosis and treatment. In contemporary evidence -based medical practice, the prevalent clinical approach is based on qualitative methods (e.g. free interviews and observations) complemented by standardised diagnostic tools. This approach assists the clinician in supplementing, organising, and objectifying clinical data related to the patient's mental state. It is particularly beneficial for handling data that may be uncertain or unavailable in an observational study for various reasons. The article presents insightful and pragmatic theoretical, empirical, and case -related information on the potential application of the Minnesota Multiphasic Personality Inventory (MMPI-2) in the psychological diagnosis of patients with persistent delusional disorders. Methods: The paper explores theoretical issues and analyses a case study involving a female patient with a suspected diagnosis of delusional disorder and co-occurring personality disorder. In the case study, the authors employed qualitative methods, including observation and free psychological interview, and supplemented clinical data with insights gained through the use of a standardised psychometric method: the MMPI-2. Reflections and practical recommendations are divided into two groups. One group comprises the potential applications of the MMPI-2 in clinical psychological diagnosis. The other focuses on the importance of the diagnostic alliance and its roles in the process of planning the psychological diagnosis in patients with delusional disorders.