A multimethod psychometric approach to analyse the profile of mental functioning - M axis of the psychodynamic diagnostic manual, 2nd edition (PDM-2): a focus on cluster B personality disorders

Objective: Within the realm of international diagnostic systems, the Psychodynamic Diagnostic Manual – 2nd edition (PDM-2) stands out as a particularly effective instrument for evaluating mental functioning based on a psychodynamic perspective. This research aimed to explore the psychometric properties of the M Axis and to investigate the dynamics among its 12 capacities for individuals with Cluster B personality disorders. Method: A sample of 285 psychotherapists who regularly use the PDM-2 in their professional practice was involved in this research. The collected data were analysed using an integrated approach combining factor and network analyses. Results: The factor analytic approach supported the strong psychometric properties of the M Axis for the 4-factor model. Good indications of internal consistency emerged, along with evidence of both convergent and divergent validity. The network analysis approach suggested that the psychotherapists perceived the capacity for mentalization and reflective functioning as the most influential one within the network of capacities in Cluster B personality disorders. Conclusions: The M Axis emerged as a psychometrically solid assessment measure with strong theoretical and empirical bases, which can provide valuable support for enhancing both research and clinical practice.