A voxel- and source-based morphometry analysis of grey matter volume differences in very-late-onset schizophrenia-like psychosis.

BACKGROUND: Very-late-onset schizophrenia-like psychosis (VLOSLP) is associated with significant burden. Its clinical importance is increasing as the global population of older adults rises, yet owing to limited research in this population, the neurobiological underpinnings of VLOSP remain insufficiently clarified. Here we address this knowledge gap using novel morphometry techniques to investigate grey matter volume (GMV) differences between VLOSLP and healthy older adults, and their correlations with neuropsychological scores. METHODS: In this cross-sectional study, we investigated whole-brain GMV differences between 35 individuals with VLOSLP (mean age 76.7, 26 female) and 36 healthy controls (mean age 75.7, 27 female) using whole-brain voxel-based morphometry (VBM) and supplementary source-based morphometry (SBM) on high resolution 3D T1-weighted MRI images. Additionally, we investigated relationships between GMV differences and cognitive function assessed with an extensive neuropsychological battery. RESULTS: VBM showed lower GMV in the thalamus, left inferior frontal gyrus and left insula in patients with VLOSLP compared to healthy controls. SBM revealed lower thalamo-temporal GMV in patients with VLOSLP. Processing speed, selective attention, mental flexibility, working memory, verbal memory, semantic fluency and confrontation naming were impaired in patients with VLOSLP. Correlations between thalamic volumes and memory function were significant within the group of individuals with VLOSLP, whereas no significant associations remained in the healthy controls. CONCLUSIONS: Lower GMV in the thalamus and fronto-temporal regions may be part of the underlying neurobiology of VLOSLP, with lower thalamic GMV contributing to memory impairment in the disorder.

Taking stock to move forward: Where the field of developmental psychopathology might be heading.

In this paper, dedicated to Dante Cicchetti's contributions and enduring influence, we explore the prospective directions of developmental psychopathology. Our focus centers on key domains where Cicchetti's significant achievements have continually shaped our evolving thinking about psychological development. These domains include (a) the concepts of equifinality and multifinality, along with the challenges in predicting developmental trajectories, (b) the imperative to integrate wider sociocultural viewpoints into developmental psychopathology frameworks, (c) the interplay of genetic and environmental influences in developmental courses, (d) the significance of mental state language, and (e) the progress, or its absence, in the development of prevention and intervention tactics for children, adolescents, and their caregivers. While many of our forecasts regarding the future of developmental psychopathology may not materialize, we maintain optimistic that the essential ideas presented will influence the research agenda in this field and contribute to its growth over the next fifty years.

Changes in Intrapersonal Factors of Participants in the Pregnancy Remote Monitoring Study Who Are at Risk for Pregnancy-Induced Hypertension: Descriptive Quantitative Study.

BACKGROUND: The peripartum period, defined as the period from the beginning of the gestation until 1 year after the delivery, has long been shown to be potentially associated with increased levels of stress and anxiety with regard to one's transition to the status of parent and the accompanying parental tasks. Yet, no research to date has investigated changes in intrapersonal factors during the peripartum period in women at risk for pregnancy-induced hypertension (PIH). OBJECTIVE: The aim of this study is to explore and describe changes in intrapersonal factors in participants at risk for PIH. METHODS: We used an explorative design in which 3 questionnaires were sent by email to 110 participants the day following enrollment in the Pregnancy Remote Monitoring program for pregnant women at risk for PIH. Women were invited to complete the questionnaires at the beginning of their participation in the Pregnancy Remote Monitoring project (mostly at 14 weeks of gestation) and after approaching 32 weeks of gestational age (GA). The Generalized Anxiety Disorder-7 Scale (GAD-7) and the Patient Health Questionnaire-9 were used to assess anxiety and depression, and adaptation of the Pain Catastrophizing Scale was used to measure trait pain catastrophizing. RESULTS: Scores were significantly higher at 32 weeks of GA than at the moment of enrollment (GAD-7 score=7, range 4-11 vs 5, range 3-8; P=.01; and Patient Health Questionnaire-9 score=6, range 4-10 vs 4, range 2-7; P<.001). The subscale scores of the Pain Catastrophizing Scale were all lower at 32 weeks of GA compared with 14 weeks of GA (rumination: 4, range 1-6 vs 5, range 2-9.5; P=.11; magnification: 3, range 1-5.5 vs 4, range 3-7; P=.04; and helplessness: 5, range 2-9 vs 6, range 3.5-12; P=.06). The proportion of women with a risk for depression (GAD-7 score >10) was 13.3% (10/75) at enrollment and had increased to 35.6% (26/75) at 32 weeks of GA. CONCLUSIONS: This study shows that pregnant women at risk for PIH have higher levels of stress and anxiety at 32 weeks of GA than at the moment of enrollment. Further research is recommended to investigate potential strategies to help pregnant women at risk for PIH manage feelings of stress and anxiety. TRIAL REGISTRATION: ClinicalTrials.gov NCT03246737; https://clinicaltrials.gov/study/NCT03246737.

Childhood adversity and adolescent acting-out behaviors: the mediating role of mentalizing difficulties and epistemic vigilance.

Childhood adversity is a well-established risk factor for adolescent acting-out behaviors such as self-harm, bingeing, substance abuse, and aggressive behavior. From a mentalizing perspective, acting-out behaviors are understood as resulting from a combination of impairments in mentalizing and epistemic vigilance that are a consequence of childhood adversity. Yet, few studies have investigated these assumptions. The current study investigated the potential mediating role of mentalizing impairments and epistemic vigilance in the relationship between childhood adversity and acting-out behaviors in adolescents, oversampled for risk status for psychopathology (N = 451, mean age = 15.40 years). Structural equation modeling showed a strong, direct relationship between childhood adversity and acting-out behaviors, confirming the importance of traumatic childhood experiences for adolescent acting-out behaviors. This relationship was partially mediated by both mentalizing difficulties and epistemic vigilance, explaining about 40% of the total variance. These results support the importance of focusing on strengthening mentalizing abilities and lowering epistemic hypervigilance in psychotherapeutic work with adolescents who have experienced childhood trauma.

Therapist responsiveness in the blank landscape of depression: A qualitative study among psychotherapists.

OBJECTIVE: Evidence about the high burden of depression on society and the immediate environment of patients has accumulated over the past decades. Yet, empirical data about the impact of depression on the environment of psychotherapy are limited. The present study investigates the phenomenon of therapist responsiveness in the treatment of depression. Specifically, this qualitative study examines the influence of a client's severe depressive symptomatology on psychotherapists' immediate experience and reflections about interventions. METHOD: The responses of 26 Flemish psychotherapists and counselors to a questionnaire with open questions and as part of a focus group were investigated by using Consensual Qualitative Research methodology. RESULTS: First, experiences with a negative valence were most common in the responses of the psychotherapists and counselors. A particular negative experience, a sense of "constriction", affecting the therapist's relational, cognitive, emotional, and bodily level of experiencing, was a predominant response. Second, most psychotherapists and counselors considered a therapeutic attitude of being present for the client and the different aspects in the client's experience to be crucial, although most of them experienced difficulty in maintaining an attitude of presence. CONCLUSIONS: The results of this study suggest that exploration of the different aspects of the clients' experience and working with the self-split of the client might be essential in the psychotherapeutic treatment of depressive disorder.

Day hospital versus intensive outpatient mentalization-based treatment: 3-year follow-up of patients treated for borderline personality disorder in a multicentre randomized clinical trial.

BACKGROUND: Two types of mentalization-based treatment (MBT), day hospital MBT (MBT-DH) and intensive outpatient MBT (MBT-IOP), have been shown to be effective in treating patients with borderline personality disorder (BPD). This study evaluated trajectories of change in a multi-site trial of MBT-DH and MBT-IOP at 36 months after the start of treatment. METHODS: All 114 patients (MBT-DH n = 70, MBT-IOP n = 44) from the original multicentre trial were assessed at 24, 30 and 36 months after the start of treatment. The primary outcome was symptom severity measured with the Brief Symptom Inventory. Secondary outcome measures included borderline symptomatology, personality and interpersonal functioning, quality of life and self-harm. Data were analysed using multilevel modelling and the intention-to-treat principle. RESULTS: Patients in both MBT-DH and MBT-IOP maintained the substantial improvements made during the intensive treatment phase and showed further gains during follow-up. Across both conditions, 83% of patients improved in terms of symptom severity, and 97% improved on borderline symptomatology. No significant differences were found between MBT-DH and MBT-IOP at 36 months after the start of treatment. However, trajectories of change were different. Whereas patients in MBT-DH showed greater improvement during the intensive treatment phase, patients in MBT-IOP showed greater continuing improvement during follow-up. CONCLUSIONS: Patients in both conditions showed similar large improvements over the course of 36 months, despite large differences in treatment intensity. MBT-DH and MBT-IOP were associated with different trajectories of change. Cost-effectiveness considerations and predictors of differential treatment outcome may further inform optimal treatment selection.

A four-year multi-wave prospective study on the role of parental reflective functioning and parenting stress in the development of socio-emotional problems in internationally adopted children.

Parental reflective functioning (PRF) plays a protective role in the development of children with histories of early adversity, including adopted children. This is the first study to investigate the developmental trajectories of PRF and children's socio-emotional problems in the first 4 years after international adoption (N = 48 families, mean age (T1) = 20.7 months) and to examine the mediating role of parenting stress in the relation between PRF and child socio-emotional problems. Multilevel modeling indicated that age at adoption and parent gender moderated the development of PRF and child socio-emotional problems. Moreover, decreases in PRF were associated with more socio-emotional problems in the children. These relations were mediated by parenting stress, and particularly feelings of incompetence and marital dissatisfaction.

Culture and psychopathology: An attempt at reconsidering the role of social learning.

This paper proposes a model for developmental psychopathology that is informed by recent research suggestive of a single model of mental health disorder (the p factor) and seeks to integrate the role of the wider social and cultural environment into our model, which has previously been more narrowly focused on the role of the immediate caregiving context. Informed by recently emerging thinking on the social and culturally driven nature of human cognitive development, the ways in which humans are primed to learn and communicate culture, and a mentalizing perspective on the highly intersubjective nature of our capacity for affect regulation and social functioning, we set out a cultural-developmental approach to psychopathology.

Integrating and differentiating personality and psychopathology: A psychodynamic perspective.

Several strands of research converge to suggest that personality and psychopathology can be integrated in the form of a hierarchical model of individual differences. The notion that personality and psychopathology are intrinsically linked has a long tradition within psychodynamic approaches. In this article, we first summarize empirical evidence supporting two related key assumptions of psychodynamic approaches to personality and psychology: that a developmental, person-centered approach is needed to complement a static, disorder-centered approach in the conceptualization and treatment of psychopathology; and that personality and psychopathology are best conceptualized as dynamic attempts at adaptation. Research in each of these areas supports the notion that personality and psychopathology are difficult to separate and may be moderated by severity (i.e., general psychopathology) such that increasing levels of severity result in increased intrinsic coupling between the two. We then discuss these findings in the context of a newly emerging social-communicative approach to human development that suggests that personality and psychopathology are better conceptualized in terms of a disorder of social communication, and that the purported rigidity and stability typically attributed to them are largely explained by the stability of the environmental mechanisms that underpin them, rather than by stable intrapersonal traits. The implications of these new views for the future of the science of personality and psychopathology, and for treatment strategies, are discussed.

Mapping the journey from epistemic mistrust in depressed adolescents receiving psychotherapy.

Although the theory of epistemic trust has started informing research in clinical populations and psychotherapy, no study has yet explored the phenomenon of epistemic trust and mistrust in depressed adolescents receiving psychotherapy. The present study aims to address this gap by creating a typology of depressed adolescents' experiences regarding their different journeys through the course of psychotherapy in relation to issues of epistemic trust and mistrust over a 2-year period. This study is based on a post hoc analysis of interview data collected for a broader purpose. A total of 45 semistructured interviews at three time points were conducted with 15 adolescents (80% female; Mage = 15.28, SD = 1.79) who entered treatment with indications of epistemic mistrust or hypervigilance. These interviews were qualitatively analyzed using ideal type analysis. Three distinct journeys of adolescents' experiences were identified. Some experienced a shift from epistemic mistrust to epistemic trust which seemed to be associated with the experience of therapy; other adolescents also showed a shift but did not consider it as an outcome of therapy; and finally, some adolescents reported continued mistrust over the 2-year period. An interpersonal component within or beyond therapy may be the key to breaking the vicious cycle of epistemic mistrust and generating epistemic trust; but not all depressed adolescents in therapy achieve this. Particular attention should be drawn to depressed adolescents who have difficulty making use of therapy and/or their broader social environment. Psychological interventions may need to openly address their issues of mistrust in early sessions as epistemic mistrust or hypervigilance may hinder paths to learning both within and beyond therapy. Treatments that intervene at the level of the wider social system are encouraged. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Trauma and Outcomes of Mentalization-Based Therapy for Individuals With Borderline Personality Disorder.

OBJECTIVE: Recent meta-analyses suggest that many patients with borderline personality disorder have a history of complex trauma. Although trauma is central in mentalization-based approaches to the understanding of borderline personality disorder, surprisingly little is known about the effects of trauma on outcomes of mentalization-based treatment (MBT). This article investigates the prevalence and impact of childhood trauma among patients with borderline personality disorder participating in a randomized controlled trial (RCT) comparing day hospital MBT (MBT-DH) and intensive outpatient MBT (MBT-IOP). METHODS: All 114 patients from the original multicenter RCT in the Netherlands were included in this study. Childhood trauma was assessed at baseline (with the Childhood Trauma Questionnaire), and its impact on symptom severity, interpersonal functioning, and borderline pathology was investigated through multilevel modeling for 36 months after the start of treatment. RESULTS: Childhood trauma was common among patients with borderline personality disorder referred to MBT, with more than 85% meeting cutoff criteria for substantial childhood trauma. Childhood trauma had little impact on outcomes of either MBT-DH or MBT-IOP in terms of improved borderline personality disorder features or interpersonal functioning. However, patients with substantial childhood trauma seemed to improve more rapidly with MBT-DH, as compared with MBT-IOP, in terms of symptom severity. In addition, patients with a history of emotional neglect showed more rapid changes in symptoms of borderline personality disorder with MBT-DH compared with MBT-IOP. CONCLUSIONS: Findings are discussed in the context of a social communicative approach to borderline personality disorder, with a focus on the need to address trauma in MBT.

Mentalizing in mothers and children with type 1 diabetes.

Studies suggest that the relationship between psychosocial well-being and type 1 diabetes (T1D) is bidirectional, with T1D typically having a negative influence on psychological functioning, which in turn negatively affects the course of T1D. Here, we investigate the potential role of the capacity for mentalizing, or reflective functioning, in children and their mothers in diabetes control. We tested differences in mentalizing as assessed by the Reflective Functioning Scale in two groups of mother-son dyads with good (GDC) versus poor (PDC) diabetes control. Fifty-five boys (8-12 years old) and their mothers were recruited from the Juvenile Diabetes Foundation in Santiago, Chile. The mothers were interviewed with the Parental Development Interview and the children with the Child Attachment Interview, and both were scored for reflective functioning by using the Reflective Functioning Scale. Self-report measures of stress and diabetes outcomes were completed by the mothers and children, and levels of glycated hemoglobin (HbA1c) were assessed as an index of diabetes control. The results showed that both maternal and child reflective functioning were higher in the GDC than the PDC group and were negatively correlated with HbA1c in the total sample. Our findings suggest an important role for mentalizing in diabetes outcomes, but further prospective research is needed.

Daily ups and downs in adolescents' depressive symptoms: The role of daily self-criticism, dependency and basic psychological needs.

INTRODUCTION: Although associations between Blatt's personality dimensions of self-criticism and dependency and adolescents' depressive symptoms are well-established, only few studies have examined associations between these variables at the level of daily, within-person fluctuations. Moreover, our understanding of the mechanisms underlying this personality vulnerability to depressive symptoms is limited. Therefore, we studied (a) daily fluctuations in both personality and depressive symptoms over a 7-day period and (b) the possible interplay between daily variations in personality vulnerability, need-based experiences (as conceptualized in Self-Determination Theory), and depressive symptoms. This interplay was examined in terms of both a mediational and a moderating role of the need-based experiences. METHODS: Participants were 121 Belgian adolescents (Mage = 15.81; SDage = 1.50; 52 % male) who completed questionnaires tapping into daily self-criticism, dependency, need-based experiences, and depressive symptoms every evening during seven consecutive days. RESULTS & CONCLUSIONS: Multilevel analysis revealed that self-criticism and dependency fluctuated substantially on a daily basis. These daily fluctuations in personality were related to daily fluctuations in depressive symptoms, with daily variation in need-based experiences mediating these associations. We found no evidence for interactions between personality and the need-based experiences. The findings underscore the importance of considering daily fluctuations in individuals' personality vulnerability and point to the explanatory role of need-based experiences in the relation between personality and depressive symptoms on a daily basis.

Depression and mentalizing: A psychodynamic therapy process study.

The present study aimed to explore the relationship between changes in depressive symptoms and the capacity to mentalize over the course of a 3-month inpatient psychodynamic therapy in a sample of 56 patients with depression. Depressive symptoms and mentalizing were assessed weekly during treatment and at 1-year follow-up with the Beck Depression Inventory and the Reflective Functioning Questionnaire (RFQ). Data were analyzed using Latent Growth Curve (LGC) modeling with structured residuals. In the total sample, depressive symptoms improved on average from baseline to the end of treatment, while mentalizing skills did not. However, individual variations were observed in mentalizing skills, with some patients improving while others did not. Within-patient residual changes in mentalizing skills did not predict residual changes in depressive symptoms. Accordingly, the results did not support mentalizing as a mechanism of change at this level. Nonetheless, between-patient effects were found, showing that patients with higher levels of mentalizing at baseline and patients whose mentalizing skills improved over the course of therapy also had greater reductions in depressive symptoms. We suggest that the presence of relatively higher mentalizing skills might be a factor contributing to moderately depressed individuals' ability to benefit from treatment, while relatively poor or absent mentalizing capacity might be part of the dynamics underlying treatment resistance in individuals with severe depression. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Depression in Belgian first-year university students: A longitudinal study of self-definition, interpersonal relatedness, mentalizing, and integration.

Despite evidence of increasing prevalence of depression in university students, few studies investigated how depression evolves over the first months at university. We investigate severity of depression among first-year university students during their first semester at university, and whether it was associated with impairments in personality, mentalizing (or reflective functioning), and social and academic integration. Participants in this two-wave prospective study were 377 Belgian first-year students in 2018 and 2019. Results showed that maladaptive interpersonal relatedness and self-definition at the start of the first semester (T1) were prospectively associated with increases in the prevalence and severity of depression at the end of the semester (T2). Uncertainty, but not certainty, with regard to mentalizing was positively associated with severity of depression at T2 and mediated the association between personality dimensions and severity of depression. The implications of these findings for depression prevention and intervention strategies in first-year university students are discussed.

Day hospital versus intensive out-patient mentalisation-based treatment for borderline personality disorder: multicentre randomised clinical trial.

BACKGROUND: Two types of mentalisation-based treatment (MBT) have been developed and empirically evaluated for borderline personality disorder (BPD): day hospital MBT (MBT-DH) and intensive out-patient MBT (MBT-IOP). No trial has yet compared their efficacy. AIMS: To compare the efficacy of MBT-DH and MBT-IOP 18 months after start of treatment. MBT-DH was hypothesised to be superior to MBT-IOP because of its higher treatment intensity. METHOD: In a multicentre randomised controlled trial (Nederlands Trial Register: NTR2292) conducted at three sites in the Netherlands, patients with BPD were randomly assigned to MBT-DH (n = 70) or MBT-IOP (n = 44). The primary outcome was symptom severity (Brief Symptom Inventory). Secondary outcome measures included borderline symptomatology, personality functioning, interpersonal functioning, quality of life and self-harm. Patients were assessed every 6 months from baseline to 18 months after start of treatment. Data were analysed using multilevel modelling based on intention-to-treat principles. RESULTS: Significant improvements were found on all outcome measures, with moderate to very large effect sizes for both groups. MBT-DH was not superior to MBT-IOP on the primary outcome measure, but MBT-DH showed a clear tendency towards superiority on secondary outcomes. CONCLUSIONS: Although MBT-DH was not superior to MBT-IOP on the primary outcome measure despite its greater treatment intensity, MBT-DH showed a tendency to be more effective on secondary outcomes, particularly in terms of relational functioning. Patients receiving MBT-DH and MBT-IOP, thus, seem to follow different trajectories of change, which may have important implications for clinical decision-making. Longer-term follow-up and cost-effectiveness considerations may ultimately determine the optimal intensity of specialised treatments such as MBT for patients with BPD.

Dynamic interpersonal therapy for moderate to severe depression: a pilot randomized controlled and feasibility trial.

BACKGROUND: Improving Access to Psychological Therapies (IAPT) services treat most patients in England who present to primary care with major depression. Psychodynamic psychotherapy is one of the psychotherapies offered. Dynamic Interpersonal Therapy (DIT) is a psychodynamic and mentalization-based treatment for depression. 16 sessions are delivered over approximately 5 months. Neither DIT's effectiveness relative to low-intensity treatment (LIT), nor the feasibility of randomizing patients to psychodynamic or cognitive-behavioural treatments (CBT) in an IAPT setting has been demonstrated. METHODS: 147 patients were randomized in a 3:2:1 ratio to DIT (n = 73), LIT (control intervention; n = 54) or CBT (n = 20) in four IAPT treatment services in a combined superiority and feasibility design. Patients meeting criteria for major depressive disorder were assessed at baseline, mid-treatment (3 months) and post-treatment (6 months) using the Hamilton Rating Scale for Depression (HRSD-17), Beck Depression Inventory-II (BDI-II) and other self-rated questionnaire measures. Patients receiving DIT were also followed up 6 months post-completion. RESULTS: The DIT arm showed significantly lower HRSD-17 scores at the 6-month primary end-point compared with LIT (d = 0.70). Significantly more DIT patients (51%) showed clinically significant change on the HRSD-17 compared with LIT (9%). The DIT and CBT arms showed equivalence on most outcomes. Results were similar with the BDI-II. DIT showed benefit across a range of secondary outcomes. CONCLUSIONS: DIT delivered in a primary care setting is superior to LIT and can be appropriately compared with CBT in future RCTs.

Short-Term Psychodynamic Psychotherapy for Functional Somatic Disorders: A Meta-Analysis of Randomized Controlled Trials.

INTRODUCTION: Functionalsomatic disorders (FSD) are common and costly, thereby driving the need for the development of effective brief treatment options. Short-term psychodynamic psychotherapy (STPP) is one candidate treatment method. OBJECTIVE: To review and meta-analyze, where possible, randomized controlled trials (RCTs) of STPP for FSD. METHODS: Following a systematic search of the literature, we performed a meta-analysis of available RCT groups to determine the effects of STPP on a range of outcomes after treatment, and medium- and long-term follow-ups. RESULTS: In meta-analyses of 17 RCTs, STPP significantly outperformed minimal treatment, treatment as usual, or waiting list controls on somatic symptom measures at all time frames, with small to large magnitude effect sizes. Descriptive reviews of 5 RCTs suggest that STPP performed at least as well as other bona fide psychological therapies. Limitations of this meta-analysis include small samples of studies and possible publication bias. CONCLUSIONS: STPP is a valid treatment option for diverse FSD conditions resulting in somatic symptom reductions that persist over time. STPP should be included in FSD treatment guidelines.

The Mentalizing Approach to Psychopathology: State of the Art and Future Directions.

Mentalizing is the capacity to understand others and oneself in terms of internal mental states. It is assumed to be underpinned by four dimensions: automatic-controlled, internally-externally focused, self-other, and cognitive-affective. Research suggests that mental disorders are associated with different imbalances in these dimensions. Addressing the quality of mentalizing as part of psychosocial treatments may benefit individuals with various mental disorders. We suggest that mentalizing is a helpful transtheoretical and transdiagnostic concept to explain vulnerability to psychopathology and its treatment. This review summarizes the mentalizing approach to psychopathology from a developmental socioecological evolutionary perspective. We then focus on the application of the mentalizing approach to personality disorders, and we review studies that have extended this approach to other types of psychopathology, including depression, anxiety, and eating disorders. We summarize core principles of mentalization-based treatments and preventive interventions and the evidence for their effectiveness. We conclude with recommendations for future research.

Borderline personality disorder, complex trauma, and problems with self and identity: A social-communicative approach.

Borderline personality disorder (BPD) is a relatively highly prevalent psychiatric disorder that is associated with very high personal and socioeconomic costs. This paper provides a state-of-the-art review of the relationship between complex trauma and key features of BPD, with a focus on problems with self-coherence and self-continuity. We first review evidence for the high prevalence of complex trauma in BPD patients. This is followed by a discussion of emerging knowledge concerning the biobehavioral mechanisms involved in problems related to self and identity in BPD. We emphasize three biobehavioral systems that are affected by complex trauma and are centrally implicated in identify diffusion in BPD: the attachment system, mentalizing or social cognition, and the capacity for epistemic trust-that is, an openness to the reception of social communication that is personally relevant and of generalizable significance. We formulate a new approach to personality and severe personality disorders, and to problems with self and identity in these disorders, rooted in a social-communicative understanding of the foundations of selfhood. We also discuss how extant evidence-based treatments address the above-mentioned biobehavioral systems involved in identity diffusion in BPD and related disorders, and the supporting evidence. We close the paper with recommendations for future research.