Borderline personality disorder (BPD) is a mental health condition characterized by pervasive patterns of instability in mood, self-image, and interpersonal relationships. People with BPD commonly have distorted perceptions of themselves and others, leading to difficulties in maintaining stable and healthy relationships. Individuals with BPD experience intense and rapidly shifting emotions, have difficulty regulating their emotions, and engage in impulsive behaviors. Fear of abandonment can drive maladaptive behaviors, including impulsivity, self-harming behaviors, and suicidality. Individuals with BPD can suffer from chronic feelings of emptiness. Mood disorders, anxiety disorders, eating disorders, posttraumatic stress disorder, other personality disorders, and substance use disorders can complicate BPD. The concept of BPD has evolved, and its history reflects changes in psychiatric understanding and diagnostic classifications. Hippocrates recorded early descriptions of intense, divergent moods. What would later be recognized as BPD can be traced back to observations in the 1930s and 1940s. Psychiatrists such as Adolph Stern and Frieda Fromm-Reichmann made observations of patients who didn't neatly fit into existing diagnostic categories. In the 1950s, borderline conditions were often considered within the spectrum of schizophrenia. Psychiatrist Kurt Schneider used the term "borderline" to describe patients who were on the border between neurosis and psychosis. The term "borderline" gained more recognition in the 1960s and 1970s as psychiatrists and psychologists began to see a distinct group of patients with specific symptom patterns that didn't neatly fit into existing diagnostic categories. Otto Kernberg and other psychoanalysts played a significant role in defining and describing borderline traits during this time.  The formal recognition of BPD as a distinct diagnosis came with the publication of the third edition of The Diagnostic and Statistical Manual of Mental Disorders (DSM) in 1980. This marked a significant shift from previous conceptualizations, providing specific criteria for diagnosis and contributing to increased research and understanding. Subsequent editions of the DSM, such as the DSM-IV in 1994 and DSM-5 in 2013, refined the diagnostic criteria for BPD. These revisions aimed to improve the reliability and validity of the diagnosis, addressing some of the controversies and criticisms associated with earlier editions. The current version of the DSM, the DSM-5-TR, divides personality disorders into Cluster A, Cluster B, and Cluster C. Each cluster encompasses a distinct set of personality disorders with commonalities regarding symptoms, behaviors, and underlying psychological patterns. Cluster A refers to personality disorders with odd or eccentric characteristics. These include paranoid personality disorder, schizoid personality disorder, and schizotypal personality disorder. Individuals within this cluster often exhibit social withdrawal, peculiar or paranoid beliefs, and difficulties forming close relationships. Cluster B comprises personality disorders with dramatic, emotional, or erratic behaviors. This cluster includes antisocial personality disorder, BPD, histrionic personality disorder, and narcissistic personality disorder. Individuals within this cluster often display impulsive actions, emotional instability, and challenges in maintaining stable relationships. Cluster C consists of personality disorders with anxious and fearful characteristics. These include avoidant personality disorder, dependent personality disorder, and obsessive-compulsive personality disorder. Individuals within this cluster tend to experience significant anxiety, fear of abandonment, and an excessive need for control or perfectionism. Despite the historical division of personality disorders into clusters, there are limitations when approaching personality disorders in this manner, and it is not consistently validated in the literature.

Personality disorders (PDs) are increasingly recognized and highly prevalent, yet remarkably poorly understood, diagnosed and treated mental conditions. Common PDs include antisocial, avoidant, borderline, dependent, histrionic, narcissistic, obsessive-compulsive personality, and paranoid disorders. Experimental (animal) models are a valuable tool to study various brain illnesses, including PDs. However, characterized by complex and frequently overlapping aberrant behaviors, PDs pose major challenges for their preclinical modeling. Here, we discuss the potential utility of zebrafish (Danio rerio) as complementary translational models relevant to studying PDs. Paralleling clinical symptoms and traits of PDs to specific behavioral phenotypes, biomarkers and paradigms in these fish, we critically evaluate the existing challenges and limitations of such models, and provide a conceptual framework for further research in this field. Despite clear conceptual and practical challenges, we argue that zebrafish models not only provide a powerful platform for elucidating neurobiological mechanisms of a wide range of key PD traits (e.g., impulsivity, aggression, emotional dysregulation), but may markedly accelerate both translational modeling of these disorders and therapeutic discovery.

Cluster B personality disorders are characterized by pervasive emotional dysregulation and rigid interpersonal patterns, and they remain challenging to treat. Mindful hypnotherapy (MH), which integrates mindfulness and clinical hypnosis, may offer a transdiagnostic approach to cognitive and emotional inflexibility. This randomized controlled trial compared the efficacy of MH with an active control condition in reducing symptoms of Cluster B personality disorders. One hundred and twenty adults who met DSM-5 criteria for histrionic, narcissistic, antisocial, or borderline personality disorder were randomized to MH (n = 60) or an active control (n = 60) comprising selected cognitive behavioral therapy (CBT) and dialectical behavior therapy (DBT) skills. Both conditions consisted of eight weekly 60-minute individual sessions. Symptom severity was assessed pre- and post-treatment using the Millon Clinical Multiaxial Inventory-III (MCMI-III). Post-treatment scores on each Cluster B scale were compared between groups using ANCOVA, controlling for baseline values. Relative to the active control condition, MH produced significantly greater reductions in histrionic, narcissistic, and antisocial personality disorder symptoms (all p values < .05, partial η[2] ≈ .16-.21). No significant between-group difference emerged for borderline personality disorder symptoms (p = .31). MH appears to be an effective brief intervention for histrionic, narcissistic, and antisocial personality disorders when compared with an active CBT/DBT-based control condition. Its effects on borderline personality disorder remain inconclusive and warrant further investigation in longer and more intensive treatment protocols.

Cluster B personality disorders, including Borderline, Histrionic, Narcissistic, and Antisocial personality disorders, collectively affect up to 5.5% of the population. These disorders are characterized by strong emotional responses; however, little research compares specific symptomatology with emotion regulation ability. The current study examines the relationship between subscales of the Difficulties in Emotion Regulation Scale and symptomatology across Cluster B disorders in a mixed non-clinical sample. In Study 1 (N = 325), participants completed self-report measures assessing emotion regulation and personality disorder symptoms. Primary findings showed that difficulties with emotion-related impulse control significantly predicted symptoms of all four Cluster B disorders, highlighting its importance in understanding these conditions. Study 2 (N = 530) was conducted to examine more specifically the different facets of impulsivity that are associated with these disorders. This study had participants complete self-report measures on emotion regulation, impulsivity, and personality disorder symptoms and found differential associations between facets of impulse control and Cluster B personality disorder symptoms. Impulse control difficulties also explain a large amount of variance in these disorders. These results suggest the necessity for targeted interventions focusing on impulse control and emotion regulation strategies to enhance treatment outcomes for individuals affected by Cluster B personality disorders.

Antisocial personality disorder (ASPD) is a deeply ingrained and rigid dysfunctional thought process that focuses on social irresponsibility with exploitive, delinquent, and criminal behavior with no remorse. Disregard for and violation of the rights of others are common manifestations of this personality disorder, which displays symptoms that include failure to conform to the law, inability to sustain consistent employment, deception, manipulation for personal gain, and incapacity to form stable relationships.[1] The Diagnostic and Statistical Manual of Mental Disorders (DSM 5) classifies all ten personality disorders into three clusters (A, B, and C). ASPD falls into 1 of 4 cluster-B disorders, which also includes borderline, narcissistic, and histrionic. All of these disorders characteristically demonstrate by dramatic, emotional, and unpredictable interactions with others.[2] Antisocial personality disorder is the only personality disorder that is not diagnosable in childhood. Before the age of 18, the patient must have been previously diagnosed with conduct disorder (CD) by the age of 15 years old to justify diagnostic criteria for ASPD.[1] Many researchers and clinicians argue this diagnosis, with concerns of significant overlap with other disorders, including psychopathy. However, others counter that psychopathy is simply a subtype of ASPD, with a more severe presentation. Recent literature states that although a heterogeneous construct that can subdivide into multiple subtypes that share many similarities and are often comorbid but not synonymous, individuals with antisocial personality disorder must be characterized biologically and cognitively to ensure more accurate categorization and appropriate treatment.[3] The estimated lifetime prevalence of ASPD amongst the general population falls within 1 to 4%.[4][5] Due to the predicting factor of the initial diagnosis of conduct disorder before the age of 15, this assumption can be quite broad as CD is not always evaluated properly.[6] Gender distribution tends to be skewed towards males, with 3 to 5 times more likelihood of being diagnosed with ASPD than females, with 6% men and 2% women within the general population.[7] Substance abuse has been found to show a significant correlation to the diagnosis of antisocial personality disorder,[8] while education and intelligence displays a negative correlation,[7][9] with a higher prevalence of ASPD amongst those with lower IQs and reading levels [10]. Research shows reductions in the prevalence rate with increasing age in criminal populations,[11] as well as epidemiological samples.[7] Changes in personality traits with age and increased mortality with the behavior of ASPD have been hypothesized to justify this age-dependent alteration.[12]

Antisocial personality disorder (ASPD) is a deeply ingrained and rigid dysfunctional thought process that focuses on social irresponsibility with exploitive, delinquent, and criminal behavior with no remorse. Disregard for and the violation of others' rights are common manifestations of this personality disorder, which displays symptoms that include failure to conform to the law, inability to sustain consistent employment, deception, manipulation for personal gain, and incapacity to form stable relationships.[1] The Diagnostic and Statistical Manual of Mental Disorders (DSM 5) classifies all ten personality disorders into three clusters (A, B, and C). Antisocial personality disorder falls into 1 of 4 cluster-B disorders, which also includes borderline, narcissistic, and histrionic. All of these disorders characteristically present with dramatic, emotional, and unpredictable interactions with others.[2] Antisocial personality disorder is the only personality disorder that is not diagnosable in childhood. Before the age of 18, the patient must have been previously diagnosed with conduct disorder (CD) by the age of 15 years old to justify diagnostic criteria for ASPD.[1] Many researchers and clinicians argue this diagnosis, with concerns of significant overlap with other disorders, including psychopathy. However, others counter that psychopathy is simply a subtype of antisocial personality disorder, with a more severe presentation. Recent literature states that although a heterogeneous construct that can subdivide into multiple subtypes that share many similarities and are often comorbid but not synonymous, individuals with ASPD must be characterized biologically and cognitively to ensure more accurate categorization and appropriate treatment.[3]

The decision of the Federal Constitutional Court permitting assisted suicide raises important questions regarding clinical and procedural standards in the care of vulnerable patients. In particular, the assessment of decision-making capacity in individuals with mental disorders presents significant challenges. This case report describes a patient with recurrent depressive disorder and histrionic personality disorder who died during day-clinic psychiatric treatment with the support of a right-to-die organization. The external psychiatric assessment was based on a single video consultation conducted twelve days prior to her death. The case illustrates how depressive symptomatology and ambivalent treatment attitudes may complicate the evaluation of a self-determined wish to die. It highlights the need for clear, context-sensitive criteria for assessing decisional autonomy, as well as reliable institutional quality assurance procedures.

Observational studies have suggested the associations between personality disorders (PDs) and cardiometabolic diseases (CMDs), though these may be biased by unmeasured confounding, including lifestyle factors or reverse causality. Mendelian randomization (MR) provides a novel approach to address these limitations by using genetic variants as instrumental variables, thereby minimizing environmental confounding and enabling causal inference. This study leverages MR to systematically evaluate causal relationships across 9 clinically relevant PDs and 8 major CMDs, offering genetic evidence to clarify previously observed epidemiological associations. Data for 9 kinds of PDs (including anankastic personality disorder, anxious personality disorder, dependent personality disorder, dissocial personality disorder, emotionally unstable personality disorder, histrionic personality disorder, paranoid personality disorder, organic personality disorder, and schizoid personality disorder) were obtained from the FinnGen consortium R10 release and data for 8 kinds of CMDs (including myocardial infarction, atrial fibrillation, type 2 diabetes, hypertension, stroke, coronary atherosclerosis, ischemic stroke and peripheral artery disease) were obtained from UK biobank. Instrumental variables were selected using single-nucleotide polymorphisms meeting a genome-wide significance threshold (P < 5 × 10[-6]) and clumped (R2 < 0.001) to ensure independence. Primary causal estimates were generated via inverse-variance weighted regression, with sensitivity analyses MR-Egger, Cochran Q intercept analysis, and leave-one-out analysis to assess robustness. Genetically predicted organic personality disorder had a positive association with coronary atherosclerosis (OR = 1.001, 95% confidence interval, 1.000-1.002, P = .029). No other significant differences (P > .05) were found. Results were stable across sensitive analyses. Our findings contrast with prior observational studies, suggesting that reported associations may reflect residual confounding from environmental or behavioral risk factors, rather than biological causation. Future research should investigate behavioral or environmental mediators underlying these epidemiological correlations.

Dissociation is a complex and transdiagnostic phenomenon defined as a disruption of, or discontinuity in, the normal, subjective integration of one or more aspects of psychological functioning. Dissociation has been identified as one of the most frequently occurring adverse effects associated with the use of esketamine nasal sprays. Individuals with high trait dissociation may be at a higher risk of experiencing an induced dissociative state and a significantly higher risk of experiencing severe induced dissociation. High esketamine-induced dissociation may act as a predictor of optimal therapeutic response, rather than solely an adverse effect. This case report describes an unusually intense and persistent dissociative reaction in a patient with histrionic personality disorder (HPD) undergoing esketamine therapy. The patient's marked dissociation upon treatment initiation raises the possibility that certain personality traits characteristic of HPD may heighten vulnerability to esketamine-induced dissociation. By explicitly examining a potential link between HPD and dissociation severity, this case highlights the importance of identifying patient-level factors that may amplify dissociative responses. Such knowledge has practical clinical implications for risk stratification, patient education regarding expected side effects, ensuring increased attention during the procedure.