Unspecified Personality Disorder (UPD) is a classification within the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), which is used when an individual exhibits traits of a personality disorder that cause significant distress or impairment, but the criteria for a specific personality disorder are not fully met (American Psychiatric Association, 2013). The presentation of UPD can be varied because it encompasses a broad spectrum of personality issues that do not fit neatly into the defined categories of other personality disorders, such as Borderline, Antisocial, or Narcissistic Personality Disorders.

Individuals with Unspecified Personality Disorder may display a range of dysfunctional patterns in their cognition, affectivity, interpersonal functioning, and impulse control. Still, these patterns are not characteristic enough to be classified under a specific personality disorder. For example, a person might exhibit impulsivity and unstable relationships akin to Borderline Personality Disorder, along with the need for admiration and lack of empathy associated with Narcissistic Personality Disorder, but not sufficiently enough to meet the full diagnostic criteria for either (Skodol, 2012).

These individuals often experience difficulties in social and occupational environments due to their personality traits. They might need help forming and maintaining relationships and a consistent sense of identity or values. Their behaviors and inner experiences often deviate markedly from the expectations of their culture, leading to various areas of potential conflict and distress (Moran et al., 2016).

UPD is a diagnosis that clinicians resort to when the personality disorder in question is problematic enough to warrant clinical attention but is not defined enough to classify otherwise. It reflects the complexities of personality psychopathology, acknowledging that not all clinical presentations fit into predefined categories. This diagnostic category allows clinicians to recognize and address the distress and functional impairment associated with personality disorder traits without being constrained by the specific criteria that might not fully encapsulate the individual's experiences (Tyrer et al., 2015).

Diagnostic Criteria

The DSM-5 describes Unspecified Personality Disorder (UPD) as a category used when the clinician chooses not to specify the reason that the criteria for a specific personality disorder are not met or when there is insufficient or contradictory information to make a more specific diagnosis (American Psychiatric Association, 2013). This diagnosis falls under the "Personality Disorders—Not Otherwise Specified" umbrella. This group captures a range of personality disorders that are significant yet do not match the exact criteria of disorders explicitly outlined in the DSM-5.

The diagnostic criteria for UPD are intentionally broad and do not have a specific set of traits, behaviors, or symptoms unique to the disorder. Instead, this diagnosis is applied when an individual exhibits features of a personality disorder that cause clinical distress or impairment in social, occupational, or other important areas of functioning but does not meet the full criteria for any one personality disorder. Furthermore, the clinician may use this diagnosis when a particular personality disorder is suspected but not confirmed due to limited information (Skodol, 2012).

Clinicians may also use the unspecified personality disorder category when an individual's symptoms span multiple personality disorders without a precise alignment to a single disorder. This approach can allow clinicians to treat significant personality pathology without being artificially constrained by the strict diagnostic thresholds that may not accommodate the complexity and nuance of individual presentations (Tyrer et al., 2019).

The use of the unspecified category acknowledges the dimensional nature of personality disorders, where symptoms may be present to varying degrees and in different combinations that do not necessarily fit within the categorical diagnoses defined in the DSM-5. The UPD category is often used in clinical settings where time constraints or lack of information prevent a thorough assessment or where symptoms may be influenced by current stressors or situational factors that make it difficult to determine the enduring nature of the personality pathology (Moran et al., 2016).

In clinical practice, the diagnosis of unspecified personality disorder is meant to be a temporary one, pending a more definitive diagnosis. It is meant to acknowledge the presence of a disorder that needs attention and intervention while providing the opportunity for further assessment and clarification over time (Skodol, 2012).

The Impacts

The impacts of Unspecified Personality Disorder (UPD) can be pervasive and profound, affecting numerous aspects of an individual's life. Individuals with UPD often experience significant interpersonal difficulties, as their behavior may be perceived as unpredictable or inappropriate by others (Moran et al., 2016). This unpredictability can lead to impaired relationships both personally and professionally, as the individual may struggle with understanding social norms or may react in ways that seem disproportionate to the situation. The resultant social isolation or conflict can further exacerbate the individual’s psychological distress.

Occupationally, people with UPD might find it challenging to maintain consistent employment due to difficulties with authority, adherence to rules, or cooperation with coworkers (Skodol, 2012). Their performance may suffer from a lack of focus or from interpersonal conflicts, which can result in job loss and financial instability.

Furthermore, the presence of UPD is associated with a higher risk for comorbid mental health conditions, such as anxiety, depression, and substance use disorders (Tyrer et al., 2015). The overlapping symptoms and the lack of a clear-cut diagnosis can make the management of these comorbid conditions more complicated, as treatment plans that might be effective for specific personality disorders may not be entirely appropriate for someone with UPD.

The ambiguity and flexibility inherent in the UPD diagnosis also impact the healthcare system. Clinicians may face challenges in treatment planning due to the broad spectrum of possible symptoms and the lack of specified criteria (Tyrer et al., 2019). This can lead to a trial-and-error approach in treatment, which may prolong the duration of therapy and increase the costs associated with mental health care.

Additionally, the diagnosis of UPD itself, being a placeholder for a more definitive diagnosis, may affect the individual's self-perception and the perception by others, potentially leading to stigma or a misunderstanding of their needs and behaviors. This can hinder the individual's willingness to seek or continue treatment and affect the support they receive from their social network (American Psychiatric Association, 2013).

Given these impacts, there is a need for comprehensive assessment and tailored interventions that address the specific manifestations of personality dysfunction in each individual, even when a precise category cannot be applied. Treatment plans that incorporate a range of therapeutic approaches, such as cognitive-behavioral therapy, dialectical behavior therapy, and psychopharmacology, may be necessary to address the diverse and complex nature of UPD (Skodol, 2012).

The Etiology (Origins and Causes)

The etiology of Unspecified Personality Disorder (UPD) is not well-defined, mainly because this diagnostic category serves as a catch-all for diverse personality disorder symptoms that do not fit neatly into a specific diagnosis. However, the underlying causes of UPD are thought to be similar to those of other personality disorders, involving a complex interplay of genetic, neurobiological, psychological, and environmental factors (Livesley, 2012).

Genetically, there is evidence to suggest that personality disorders, in general, have a heritable component. Family and twin studies have shown a moderate genetic contribution to the development of personality disorders, which implies that individuals with a family history of personality disorders may have an increased risk of developing UPD (Reichborn-Kjennerud, 2010). However, specific genetic markers have not been consistently identified due to the heterogeneity of symptoms in UPD.

Neurobiological research has indicated that brain structure and function, particularly in areas related to emotion regulation and impulse control, may contribute to the development of personality disorders. Abnormalities in these neural circuits could lead to the wide range of symptoms observed in UPD, although this relationship is not fully understood and likely varies across individuals (Siever & Davis, 2013).

Psychologically, early life experiences, including trauma, neglect, and attachment disruptions, are vital contributors to the development of personality disorders (Paris, 2010). Such adverse experiences can impact an individual's personality development, leading to maladaptive patterns of thinking, feeling, and behaving that are characteristic of UPD.

Environmentally, factors such as socioeconomic status, family dynamics, cultural and social influences, and educational opportunities can play significant roles in shaping personality and potentially contribute to developing personality disorders. Chronic stressors or unstable environments during critical periods of personality development may contribute to the symptomatic presentation of UPD (Moran et al., 2016).

Overall, the etiology of UPD is likely multifactorial, with each case resulting from a unique combination of influences. The unspecified nature of the disorder complicates the identification of specific causal pathways, as individuals with UPD might present with a wide array of symptoms influenced by various factors.

Comorbidities

Comorbidities are common in individuals diagnosed with Unspecified Personality Disorder (UPD), as the disorder often exists alongside a range of other mental health conditions. The nature of UPD's broad diagnostic criteria makes it likely to intersect with a variety of symptoms that can be part of other disorders, either as a consequence of an overarching personality pathology or as independent concurrent issues.

One of the most commonly observed comorbidities with UPD is mood disorders, including major depression and bipolar disorder. The dysregulation of affect and the instability of self-image that are characteristic of many personality disorders can predispose individuals to mood disturbances (Zimmerman et al., 2015). Anxiety disorders also frequently co-occur with UPD, with symptoms such as chronic worry, phobias, or panic common among those with personality dysfunctions (Grant et al., 2008).

Substance use disorders are another notable comorbidity. The impulsivity and sometimes poor decision-making associated with UPD can lead to increased vulnerability to substance abuse and dependence, which may be used by some individuals as a form of self-medication or escapism from the distress caused by their personality disorder symptoms (Trull et al., 2010).

Eating disorders may also co-occur with UPD. The control issues and self-image disturbances that feature in both eating and personality disorders suggest a potential overlap in the psychological processes underlying these conditions (Cassin & von Ranson, 2005). Attention-deficit/hyperactivity disorder (ADHD) and other impulse-control disorders can present alongside UPD, compounding difficulties with self-regulation (Miller et al., 2007).

Furthermore, other personality disorders may be comorbid with UPD, especially when specific personality disorder criteria are not fully met, creating a complex clinical picture where multiple personality disorder features are present (Skodol, 2012).

These comorbidities can complicate the clinical management of UPD, as they may obscure the underlying personality pathology and thus impact the treatment approach. Clinicians must assess for and address these comorbid conditions to provide comprehensive care for the individual (Tyrer et al., 2015).

Risk Factors

The risk factors for Unspecified Personality Disorder (UPD) are generally consistent with those identified for personality disorders as a broad category. Due to the heterogeneous nature of UPD, pinpointing specific risk factors can be challenging; however, several recognized contributors can increase the likelihood of developing UPD or another type of personality disorder.

Genetic predisposition plays a significant role in the development of personality disorders and, by extension, UPD. A family history of personality disorders or other mental health conditions can raise the risk, suggesting a heritable component to these disorders (Livesley, 2012; Reichborn-Kjennerud, 2010). This genetic risk is likely polygenic, involving variations in multiple genes that affect personality traits and their regulation.

Childhood trauma is a well-established risk factor for personality disorders, including physical, sexual, or emotional abuse, neglect, and early loss or separation from caregivers. These adverse childhood experiences can disrupt the development of secure attachment styles and the ability to regulate emotions and behaviors, contributing to the symptomatic patterns seen in UPD (Paris, 2010; Battle et al., 2004).

Environmental factors during critical developmental periods can also influence the risk of developing UPD. This includes familial instability, parental psychopathology, and social factors such as poverty, neighborhood crime, or exposure to violence (Moran et al., 2016). Such stressors can interact with an individual's genetic makeup and psychological disposition, potentially leading to the development of a personality disorder.

Poor social support and social isolation are also considered risk factors. Individuals who lack a stable support network may be more vulnerable to developing personality disorder symptoms, as they have fewer resources to cope with stress and may adopt maladaptive coping mechanisms (Cohen, 2004).

Personality traits themselves can be risk factors. Specific personality characteristics, such as high neuroticism, impulsivity, or aggression, can predispose individuals to develop a more comprehensive array of maladaptive personality features consistent with UPD (Samuel & Widiger, 2008).

Substance use and its effects can not only be a comorbidity but also a risk factor for UPD. Early onset of substance use and substance abuse can contribute to the development of personality disorder symptoms, mainly if the substances are used in a way that impacts social and emotional development (Trull et al., 2010).

Understanding these risk factors is crucial for preventing and early intervention of UPD and tailoring treatment strategies to the individual's background and needs.

Case Study

Abstract: This case study examines the therapeutic journey of "Elena," a 28-year-old woman diagnosed with Unspecified Personality Disorder (UPD). Elena's case illuminates the intricate challenges in diagnosing and treating individuals with non-specific personality disorder symptoms that do not align with a singular, defined category.

Presenting Concerns: Elena presented to the clinic with a history of unstable relationships, mood swings, and an inability to maintain consistent employment. She described a pervasive sense of emptiness and uncertainty about her identity. Her previous encounters with mental health services resulted in a variety of partial diagnoses, including borderline, avoidant, and histrionic personality disorder traits. Still, none sufficiently encompassed the complexity of her symptoms.

History: Elena grew up as an only child in a home marked by parental conflict and emotional neglect. She reported experiencing bullying throughout her school years, contributing to a persistent sense of low self-esteem. Elena's early adult years were characterized by impulsive decisions, including sporadic job changes and a pattern of entering and abruptly ending romantic relationships.

Assessment: An extensive psychological assessment was conducted, including a clinical interview, self-report measures, and a review of prior health records. Despite the presence of multiple personality disorder traits, Elena did not meet the full criteria for a specific personality disorder, leading to the diagnosis of UPD. Comorbid anxiety and depressive symptoms were also noted.

Treatment: Elena's treatment plan included dialectical behavior therapy (DBT) to address her emotion dysregulation and impulsivity and cognitive-behavioral therapy (CBT) to challenge and reframe her maladaptive thought patterns. A psychodynamic approach was also incorporated to explore underlying issues related to her self-identity and history of interpersonal difficulties.

Progress and Outcomes: Over two years, Elena made significant progress in therapy. She reported improved emotional stability and developed healthier coping strategies for managing stress and interpersonal conflict. Although periodic setbacks occurred, these were used as opportunities for learning and growth within the therapeutic context.

Conclusion: Elena's case underscores the complexity of UPD and highlights the importance of a flexible, integrative therapeutic approach tailored to the individual's unique symptomatic presentation. It also emphasizes the need for ongoing research to understand better and delineate the etiology and most effective treatment modalities for UPD.

Discussion: The case of Elena demonstrates the variability in the presentation of UPD and the potential for positive outcomes with a comprehensive and individualized treatment approach. It also suggests the necessity for clinicians to remain adaptable and open to employing various therapeutic techniques in response to the evolving needs of individuals with UPD.

Recent Psychology Research Findings

Research on Unspecified Personality Disorder (UPD), previously termed Personality Disorder Not Otherwise Specified (PD-NOS) under DSM-IV, has gained more attention in recent years as clinicians and researchers strive to understand and treat this complex diagnosis. UPD is characterized by an array of symptoms that do not neatly fit into the specific personality disorder categories outlined in the DSM-5.

A recent study by Smith and colleagues (2020) highlighted the diagnostic challenges of UPD, noting that individuals with this condition often exhibit a mixture of symptoms that cross traditional diagnostic boundaries. The researchers found that UPD is frequently used as a provisional diagnosis when patients do not meet the full criteria for other personality disorders but still show significant impairment in functioning. The study emphasized the need for a dimensional approach to personality pathology, as proposed for future iterations of the DSM, to capture UPD's nuances better.

Another study by Jones et al. (2021) examined the treatment outcomes for individuals diagnosed with UPD. The findings suggested that patients with UPD often respond well to treatments that are not specifically tailored to one particular personality disorder, such as dialectical behavior therapy and cognitive-behavioral therapy. This supports the clinical observation that UPD, while not fitting a single disorder category, may still be amenable to established treatments for personality disorders.

In terms of comorbidity, research by Anderson and Thomas (2019) revealed that UPD often co-occurs with mood and anxiety disorders, implying a shared underlying psychopathology or a possible causal relationship. This study also found that patients with UPD might be at a higher risk for substance abuse, which can complicate the clinical picture and necessitate integrated treatment approaches.

Klein and Miller (2020) investigated the longitudinal stability of UPD diagnoses. They found that while some individuals retain the UPD diagnosis over time, others go on to develop the full criteria for a specific personality disorder or achieve remission. This suggests that UPD may represent a transitory diagnostic stage for some, while it may persist as a stable pattern of personality pathology for others.

Finally, in a review of the literature, Patel and Kim (2018) discussed the potential genetic and environmental risk factors for UPD. They argue that UPD likely results from a combination of genetic vulnerabilities and adverse childhood experiences, much like other personality disorders. This review advocates for early intervention strategies that focus on risk factors to prevent the development of UPD.

These studies collectively underscore the importance of recognizing UPD as a significant clinical entity that requires further study. The findings also call for a more nuanced understanding of personality disorders, encouraging a shift toward a more flexible, dimensional classification system in future diagnostic manuals.

Treatment and Interventions

Treatment and interventions for Unspecified Personality Disorder (UPD) often necessitate a multimodal approach that is flexible and tailored to the individual's array of symptoms, given the heterogeneity of the disorder. A combination of psychotherapy, medication management, and psychosocial interventions is typically recommended.

Dialectical Behavior Therapy (DBT), created by Marsha Linehan, is a structured, skills-based approach that has shown particular promise in treating a range of personality disorder symptoms that are common in UPD, such as affective instability and impulsive behavior. DBT is grounded in dialectics, which involves synthesizing opposite perspectives, such as acceptance and change. The therapy includes four main modules of skills training: mindfulness, distress tolerance, emotion regulation, and interpersonal effectiveness. In DBT, clients attend both individual therapy sessions and group skills training sessions, where they learn and practice these skills in a supportive environment. The therapist and client work together to identify and target the symptoms that are most distressing or disabling for the client (Linehan, 2015).

Cognitive-Behavioral Therapy (CBT) is another well-established treatment that is adaptable to the needs of individuals with UPD. CBT operates on the principle that maladaptive thinking patterns can give rise to maladaptive behaviors and emotions. Through techniques like cognitive restructuring, clients learn to identify and challenge distorted thought patterns and replace them with more adaptive ones. Behavioral interventions within CBT, such as behavioral activation or exposure therapy, can also be utilized to help individuals with UPD engage more fully in their lives and reduce avoidance behaviors. Given the varied symptom presentation in UPD, CBT may be particularly beneficial as it targets a range of cognitive and behavioral patterns across different contexts and relationships (Wright et al., 2017).

Schema Therapy integrates elements of cognitive-behavioral, experiential, interpersonal, and psychoanalytic therapies to address deep-seated patterns of thinking and behaving, known as schemas, that are often present in individuals with personality disorders, including those with UPD. It is beneficial for individuals who have chronic interpersonal difficulties or a negative self-image that does not fit neatly into a specific personality disorder diagnosis. This approach often involves the use of techniques such as limited reparenting, in which the therapist provides the support and validation that the client may not have received in their early development, and imagery and chair work to process and heal emotional memories that underlie maladaptive schemas (Bamelis et al., 2014).

In terms of pharmacotherapy, while there are no medications approved specifically for the treatment of UPD, psychotropic medications can be used off-label to target specific symptom clusters or co-occurring disorders. For example, SSRIs may be beneficial for clients with UPD who are struggling with depressive symptoms or anxiety. At the same time, mood stabilizers can be helpful for those experiencing significant mood swings or impulsivity. The use of medication must be closely monitored by a psychiatrist and tailored to the individual's changing symptom profile (Paris, 2010).

Psychosocial interventions, including community integration and vocational support, are also vital. These interventions help address some of the social and occupational challenges faced by individuals with UPD. Such supports can range from assisting the individual in developing social skills through role-playing and social stories to providing support in job searching or workplace adaptation. The goal is to help individuals with UPD build a more structured and supportive environment to facilitate overall functioning (Skodol, 2012).

Treatment for UPD is multi-faceted and highly individualized, reflecting the diverse manifestations of the disorder. It requires clinicians to be flexible and responsive to clients' unique needs and symptom presentations.

Implications if Untreated

The implications of untreated Unspecified Personality Disorder (UPD) can be profound and pervasive, affecting virtually all areas of an individual's life. Without appropriate treatment, the symptoms of UPD can lead to significant impairments in personal, social, and occupational functioning. Untreated UPD is often associated with poor quality of life, increased risk of substance abuse, and higher rates of self-harm and suicidal behavior (Paris, 2010). Individuals may struggle with establishing and maintaining healthy relationships, leading to a cycle of unstable interpersonal connections and social isolation.

Occupationally, the lack of treatment can result in difficulty maintaining consistent employment. The symptoms can interfere with an individual's ability to work collaboratively with others, manage stress, and maintain productivity, which can lead to job loss and financial instability (Skodol, 2012). Moreover, untreated UPD can exacerbate co-occurring mental health disorders such as depression, anxiety, and substance use disorders, compounding the challenges the individual faces and potentially leading to an increased reliance on health and social services (Goodwin & Jamison, 2007).

The long-term implications can also extend to physical health. Research has shown a link between personality disorders and increased morbidity and mortality from cardiovascular disease, diabetes, and other chronic conditions, potentially due to the impact of chronic stress and poor self-care behaviors (El-Gabalawy et al., 2010). In the absence of treatment, these risks may be elevated in individuals with UPD due to the potential for ongoing emotional dysregulation and impulsivity affecting health behaviors.

The societal implications are also notable. Untreated UPD can result in a higher burden on legal and criminal justice systems due to the increased risk of impulsive and sometimes antisocial behavior. Furthermore, family members and loved ones often experience increased stress and burden when supporting individuals with untreated personality disorder symptoms (Friedman et al., 2002).

Given these potential outcomes, early identification and treatment are crucial for individuals with UPD to mitigate these risks and improve prognosis.

Summary

Unspecified Personality Disorder (UPD) presents significant challenges not only due to the diversity and variability of symptoms but also because of the complexities involved in its diagnosis and management. Historically, personality disorders have been viewed through a lens of skepticism and stigma, often attributed to character flaws rather than recognized as legitimate mental health conditions (Skodol & Bender, 2003). Over time, however, perspectives have shifted towards a more empathetic understanding, recognizing the deep-seated psychological distress and impairments in functioning that characterize these disorders. This evolution in thought has paved the way for more inclusive diagnostic criteria in the DSM-5, which acknowledges the spectrum of personality disorders and allows clinicians to account for symptoms that do not neatly fit into predefined categories (American Psychiatric Association, 2013).

The relational aspect of UPD is perhaps one of the most profound challenges. The disorder can severely disrupt personal relationships, leading to patterns of instability and chaos in interpersonal connections. The core symptoms of UPD—such as difficulty in consistent identity, affective instability, and impulsivity—can erode the trust and mutual understanding necessary for healthy relationships, frequently resulting in a painful cycle of conflict and detachment (Gunderson & Lyons-Ruth, 2008).

Moreover, the impact on self-identity and self-esteem can be debilitating. Individuals with UPD may struggle with a coherent sense of self, leading to chronic feelings of emptiness and confusion about one's place in the world. The inconsistency in their self-image often reflects and reinforces the instability in their relationships, creating a self-perpetuating loop of identity disturbance and social dysfunction (Jørgensen et al., 2012).

Despite the challenges, the current therapeutic landscape offers hope. With increased awareness and improved treatments, individuals with UPD can work towards a more stable and satisfying life. As research continues to elucidate the nuances of UPD, treatment approaches are anticipated to become even more effective, tailored, and compassionate, reflecting a growing understanding of the disorder's complexity (Gabbard, 2014).

In conclusion, while UPD remains a challenging disorder that can profoundly affect relationships, identity, and life satisfaction, there is an evolving recognition of the importance of addressing it with sensitivity and a multimodal therapeutic approach. The movement towards more compassionate care reflects broader changes in the mental health field, emphasizing the dignity and potential of all individuals living with mental health challenges.

References

Anderson, P., & Thomas, N. (2019). Comorbidity of mood and anxiety disorders in the unspecified personality disorder population. Journal of Clinical Psychology, 75(4), 689-705.

Bamelis, L. L., Evers, S. M., Spinhoven, P., & Arntz, A. (2014). Results of a multicenter randomized controlled trial of the clinical effectiveness of schema therapy for personality disorders. The American Journal of Psychiatry, 171(3), 305-322.

Battle, C. L., Shea, M. T., Johnson, D. M., Yen, S., Zlotnick, C., Zanarini, M. C., ... & Morey, L. C. (2004). Childhood maltreatment associated with adult personality disorders: Findings from the Collaborative Longitudinal Personality Disorders Study. Journal of Personality Disorders, 18(2), 193-211.

Cassin, S. E., & von Ranson, K. M. (2005). Personality and eating disorders: a decade in review. Clinical Psychology Review, 25(7), 895–916.

Cohen, P. (2004). The developmental course of personality disorders. Journal of Personality Disorders, 18(3), 207–219.

El-Gabalawy, R., Cox, B. J., Clara, I., & Mackenzie, C. S. (2010). Personality disorders and physical comorbidities in adults from the United States: Data from the National Epidemiologic Survey on Alcohol and Related Conditions. Psychosomatic Medicine, 72(5), 541–550.

Friedman, J. N. W., Oltmanns, T. F., & Turkheimer, E. (2002). Interpersonal perception and personality disorders: Utilization of a thin slice approach. Journal of Research in Personality, 36(3), 253-271.

Gabbard, G. O. (2014). Gabbard's treatments of psychiatric disorders (5th ed.). American Psychiatric Publishing.

Goodwin, F. K., & Jamison, K. R. (2007). Manic-depressive illness: Bipolar disorders and recurrent depression (2nd ed.). Oxford University Press.

Grant, B. F., Stinson, F. S., Dawson, D. A., Chou, S. P., Ruan, W. J., & Pickering, R. P. (2008). Co-occurrence of 12-month alcohol and drug use disorders and personality disorders in the United States. Archives of General Psychiatry, 65(4), 467–475.

Gunderson, J. G., & Lyons-Ruth, K. (2008). BPD's interpersonal hypersensitivity phenotype: A gene-environment-developmental model. Journal of Personality Disorders, 22(1), 22–41.

Jones, P. D., Smith, J. R., & Johnson, M. B. (2021). Treatment outcomes for unspecified personality disorder: A systematic review. Journal of Mental Health, 30(2), 164–173.

Jørgensen, C. R., Freund, C., Bøye, R., Jordet, H., Andersen, D., & Kjølbye, M. (2012). Outcome of mentalization-based and supportive psychotherapy in patients with borderline personality disorder: A randomized trial. Acta Psychiatrica Scandinavica, 125(4), 305-317.

Klein, R. B., & Miller, J. D. (2020). Longitudinal stability of unspecified personality disorder diagnosis. Personality and Mental Health, 14(3), 207-218.

Linehan, M. M. (2015). DBT Skills Training Manual (2nd ed.). Guilford Press.

Livesley, W. J. (2012). Handbook of personality disorders: Theory, research, and treatment. Guilford Press.

Miller, C. J., Flory, J. D., Lynam, D. R., & Leukefeld, C. (2007). A test of the four-factor model of impulsivity-related traits. Personality and Individual Differences, 43(7), 1724-1735.

Moran, P., Jenkins, R., Tylee, A., Blizard, R., & Mann, A. (2016). The prevalence of personality disorder among UK primary care attenders. Acta Psychiatrica Scandinavica, 104(5), 330–335.

Paris, J. (2010). Estimating the prevalence of personality disorders in the community. Journal of Personality Disorders, 24(4), 405–411.

Paris, J. (2010). Treatment of borderline personality disorder: A guide to evidence-based practice. Guilford Press.

Patel, R., & Kim, Y. (2018). Genetic and environmental risk factors for unspecified personality disorder: A review. Journal of Psychopathology and Behavioral Assessment, 40(2), 266-277.

Reichborn-Kjennerud, T. (2010). The genetic epidemiology of personality disorders. Dialogues in Clinical Neuroscience, 12(1), 103-114.

Samuel, D. B., & Widiger, T. A. (2008). Convergence of narcissism measures from the perspective of general personality functioning. Assessment, 15(3), 364-374.

Siever, L. J., & Davis, K. L. (2013). The pathophysiology of schizophrenia disorders: Perspectives from the spectrum. American Journal of Psychiatry, 160(3), 398-413.

Skodol, A. E. (2012). Personality disorders in DSM-5. Annual Review of Clinical Psychology, 8, 317-344.

Skodol, A. E. (2012). Psychosocial treatments for personality disorders. Psychiatry Clinics of North America, 35(3), 657-674.

Skodol, A. E., & Bender, D. S. (2003). Why are women diagnosed borderline more than men? Psychiatric Quarterly, 74(4), 349-360.

Smith, S., Williams, K., & Müller, U. (2020). The challenge of unspecified personality disorder: A potential alternative to dimensional personality pathology. Clinical Psychology Review, 78, 101852.

Trull, T. J., Jahng, S., Tomko, R. L., Wood, P. K., & Sher, K. J. (2010). Revised NESARC personality disorder diagnoses: Gender, prevalence, and comorbidity with substance dependence disorders. Journal of Personality Disorders, 24(4), 412-426.

Tyrer, P., Mulder, R., Kim, Y. R., & Crawford, M. J. (2019). The development of the ICD-11 classification of personality disorders. Crisis, 40(4), 249–255.

Tyrer, P., Reed, G. M., & Crawford, M. J. (2015). Classification, assessment, prevalence, and effect of personality disorder. The Lancet, 385(9969), 717–726.

Wright, A. G., Hopwood, C. J., Skodol, A. E., & Morey, L. C. (2017). Longitudinal validation of general and specific structural features of personality pathology. Journal of Abnormal Psychology, 126(8), 975–986.

Zimmerman, M., Rothschild, L., & Chelminski, I. (2015). The prevalence of DSM-IV personality disorders in psychiatric outpatients. American Journal of Psychiatry, 162(10), 1911-1918.