Placing A Person-Centered Approach Back At The Center Stage of The Assessment Process: The Contribution of The New Psychodynamic Diagnostic Manual (PDM-3) to Treatment Monitoring and Therapy Outcomes In Eating Disorders

Introduction: The second edition of the Psychodynamic Diagnostic Manual (PDM-2) strongly recommended and promoted a diagnostic approach that is not only symptom-oriented but also devoted to individuals’ idiographic characteristics and psychological functioning in different life stages. In its new and extensively revised edition, the upcoming PDM-3 Adulthood section (Lingiardi & McWilliams, 2025) further enhances its clinical utility by including the following main changes: (a) in the P Axis, to promote better integration with the Shedler-Westen Assessment Procedure, an “emotionally dysregulated personality” replaces the previous borderline personality, and a conceptual separation of masochistic psychology from its close relative, depressive personality style, has been included; (b) in the M Axis, some relevant aspects of mental functioning that involve trust, bodily experiences and representations, and capacity to explore one's inner life have been added; (c) in the S Axis, several structural changes and reformulations have been made according to the current empirical findings on affective states, cognitive patterns, somatic states, and relationship patterns in psychopathology. Of note, the chapter devoted to eating disorders (EDs) has been extensively revised to offer a psychodynamic diagnostic framework that emphasizes how every ED patient may have a unique and individual potential, treatment need, and response to treatment. This improvement has significant implications for treatment planning. For instance, several domains assessed by the PDM have been found to determine the responses of ED patients to specialized treatment programs (Muzi et al., 2021). Furthermore, longitudinal studies indicate that treatment monitoring and follow-up are essential for sustained recovery and relapse prevention in EDs (Guarda et al., 2018). While monitoring body weight, BMI, and symptom severity is crucial for managing immediate health risks for ED patients, some studies suggest that changes in underlying personality, cognitive, affective, and relational patterns may precede and support deeper therapeutic changes. However, to the best of our knowledge, no previous study has tested the validity of the PDM in providing a regular, quantitative assessment of therapeutic change throughout treatment. Thus, this study aimed at exploring the empirical validity of the PDM approach in both treatment monitoring and therapy outcomes of EDs by considering long-term changes in patients’ unique self-experiences and the meaning/function of their symptoms over time. Methods: A national sample of cisgender women with an eating disorder (ED) (n= 198) was evaluated using both the Structured Clinical Interview for DSM-5 (SCID-5-CV) and the Psychodiagnostic Chart (PDC)—a PDM-derived clinician-rated tool—at treatment admission and discharge. At the same time points, participants were asked to complete self-report questionnaires on ED symptoms (Eating Attitudes Test, EAT-40), severity of bulimic symptoms (Bulimic Investigatory Test, Edinburgh, BITE), and depressive symptoms (Beck Depression Inventory, BDI). A subsample of n = 95 patients was also evaluated with the PDC and filled out the same questionnaires at a 6-month follow-up after discharge, with a response rate of 47.9%. The inclusion criteria were: (a) aged at least 18 years; (b) a pre-treatment diagnoses of DSM-5 anorexia nervosa (AN) or bulimia nervosa (BN) based on the SCID-5-CV; (c) presenting no organic syndromes, psychotic disorder, or syndrome with psychotic symptoms that could complicate the assessment of any variable in the study. In the present sample, n = 133 patients (67.2%) were diagnosed with AN, and n = 65 (32.8%) with BN. Results: Findings showed that patients with AN and BN, as diagnosed by the SCID-5-CV, did not significantly differ either in overall personality organization and personality organization’s dimensions (P Axis). Similarly, no significant differences emerged between AN and BN patients in mental functioning capacities (M Axis) or symptomatic impairment (S Axis), whereas BN patients showed lower levels in the M-Axis capacity for impulse control and regulation. With respect to the empirical validity of the PDM-approach in treatment monitoring of EDs, statistically significant changes in several PDC dimensions emerged at both discharge and 6-month follow-up over and above the DSM- based ED categories. More specifically, with respect to P Axis dimensions, there was a significant pre- post increase in the identity (ES= .13, p <.001), quality of object relations (ES= .10, p <.001), defensive functioning (ES= .03, p=.013), and reality testing (ES= .11, p <.001) dimensions, as well as in overall personality organization (ES= .12, p <.001). For several personality organization dimensions these differences were even more pronounced at the 6-month follow-up, such as in the identity (ES= .17, p <.001) dimension and overall personality organization (ES= .17, p <.001). Furthermore, with respect to M-Axis mental functions, findings also showed a significant pre-post increase in affective functioning (ES= .07, p <.001), mentalizing abilities (ES= .13, p <.001), self-esteem regulation (ES= .20, p <.001), psychological mindedness and insight (ES= .07, p <.001), and agency and purpose (ES= .05, p = .001), the latter also influenced by the ED categorical diagnosis. Similar results emerged when considering the 6-month follow-up, with higher effect sizes in mentalization (ES= .25, p <.001) and self-esteem (ES= .26, p <.001). Of note, baseline quality of object relations and overall personality organization (P Axis) were found to predict therapeutic change (i.e., residualized change scores) in eating, bulimic, and depressive symptoms at both discharge and 6-month follow-up, as well as identity integration and self-coherence (M Axis). Conclusion: These findings suggest that, over and above the DSM-based categories, the PDM-3 S Axis works jointly with the P and M Axes to create a comprehensive representation of therapeutic change in ED patients (Mirabella et al., 2023). According to previous studies (e.g., Koelen et al., 2012), these findings also suggest the need to consider personality organization and mental functioning as potentially stable variables that should be regularly assessed during treatment and after its termination.