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9.5 Comorbidity and Etiology

Section Learning Objectives

  • Describe the comorbidity of personality disorders.
  • Describe the various factors that contribute to personality disorders

9.5.1 Comorbidity

Among the most common comorbid diagnoses with personality disorders are other personality disorders, mood disorders, anxiety disorders, and substance abuse disorders (Lenzenweger, Lane, Loranger, & Kessler, 2007). Indeed, many individuals are diagnosed with more than one personality disorders.

A large meta-analysis exploring the data on the comorbidity of personality disorders and mood disorders indicated a high level of comorbid diagnoses of MDD, PDD, and bipolar disorder (Friborg, Martinsen, Martinussen, Kaiser, Overgard, & Rosenvinge, 2014). Further exploration of MDD suggested the lowest rate of diagnosis in cluster A disorders, higher rate in cluster B disorders, and the highest rate in cluster C disorders. While the relationship between bipolar disorders and personality disorders has not been consistently clear, the most recent findings report a high comorbidity with OCPD as well as with the cluster B personality disorders.

Clear relationships between personality disorders and anxiety disorders have also been established (Skodol, Geier, Grant, & Hasin, 2014). More specifically, individuals diagnosed with borderline and schizotypal personality disorders were found to have elevated rates of additional diagnoses of each of the four main anxiety disorders. Individuals with narcissistic personality disorders were more likely to be diagnosed with GAD and panic disorder. Schizoid and avoidant personality disorders reported significant rates of GAD; avoidant personality disorder had a higher diagnosis rate of social phobia.

Finally, substance abuse disorders are frequently found in individuals diagnosed with antisocial, borderline, and schizotypal personality disorders (Grant et al., 2015).

9.5.2 Etiology

Research regarding the development of personality disorders is limited compared to that of other mental disorders. The following is a general overview of contributing factors to personality disorders as a whole. While there is some research lending itself to specific causes of specific personality disorders, we will review the overall contribution of biological, psychological, and social factors globally for all of the personality disorders.

9.5.2.1 Biological

Research across the personality disorders suggests some underlying biological or genetic component. However, identification of specific mechanisms has not been identified for most personality disorders, with the exception of the cluster A personality disorders which show a genetic link with schizophrenia. Because of the lack of specific evidence of biological causes, researchers argue that it is difficult to determine what role genetics plays in the development of these disorders compared to that of environmental influences. Therefore, while there is likely a biological predisposition to personality disorders, exact causes cannot be determined at this time.

Research on the development of schizotypal personality disorder has identified similar biological causes to that of schizophrenia, specifically, high activity of dopamine and enlarged brain ventricles (Lener et al., 2015). Similar differences in neuroanatomy may explain the high similarity of behaviors in both schizophrenia and schizotypal personality disorder.

Antisocial personality disorder and borderline personality disorder are also related to neurological dysfunctions. More specifically, individuals with both disorders reportedly show deficits in serotonin activity (Thompson, Ramos, & Willett, 2014). These low levels of serotonin activity in combination with deficient functioning of the frontal lobes, particularly the prefrontal cortex which is used in planning, self-control, and decision making, as well as an overly reactive amygdala, may explain the impulsive and aggressive nature of individuals with antisocial and borderline personality disorder (Stone, 2014). 

9.5.2.2 Psychological 

Psychodynamic, cognitive, and behavioral theories are among the most common models used to explain the development of personality disorders. Although much is still speculation, the following are general etiological views with regards to each specific theory.

9.5.2.2.1 Psychodynamic

The psychodynamic theory places a large emphasis on negative early childhood experiences and their impact on an individual’s ability to establish healthy relationships in adulthood. More specifically, individuals with personality disorders report higher levels of childhood stress such as living in impoverished environments, exposure to family/domestic violence, and experiencing repeated abuse and maltreatment (Kumari et al., 2014). Additionally, high levels of neglect and parental rejection are observed in people with personality disorders, with early parental loss and rejection leading to fears of abandonment throughout life (Caligor & Clarkin, 2010; Newnham & Janca, 2014; Roepke & Varter, 2014).

Psychodynamic theorists believe that because of these negative early experiences, their sense of self, and consequently, their beliefs of others are negatively impacted, thus leading to the development of a personality disorder. For example, an individual who was neglected as a young child and deprived of love may report a lack of trust in others as an adult, a characteristic of paranoid and antisocial personality disorders (Meloy & Yakeley, 2010). Difficulty trusting others or beliefs that they are unable to be loved may also impact their ability or desire to establish social relationships as seen in many personality disorders, particularly schizoid, avoidant and dependent personality disorders. Because of these early childhood deficits, individuals may also overcompensate in their relationships in efforts to convince themselves that they are worthy of love and affection as may be the case in histrionic and narcissistic personality disorders (Celani, 2014). Conversely, individuals may respond to their early childhood experiences by becoming emotionally distant, using relationships as a sense of power and destructiveness.

9.5.2.2.2 Cognitive

While psychodynamic theory places an emphasis on early childhood experiences, cognitive theorists focus on the maladaptive thought patterns and cognitive distortions displayed by those with personality disorders. Overall deficiencies in thinking place individuals with personality disorders in a position to develop inaccurate perceptions of others (Beck, 2015). These dysfunctional beliefs likely originate from the interaction between a biological predisposition and undesirable environmental experiences. Maladaptive thought patterns and strategies are strengthened during aversive life events as a protective mechanism and ultimately come together to form patterns of behaviors displayed in personality disorders (Beck, 2015).

Cognitive distortions such as dichotomous thinking, also known as all or nothing thinking, are observed in several personality disorders. More specifically, dichotomous thinking helps to explain rigidity and perfectionism in OCPD, and the lack of independence observed in those with dependent and borderline personality disorders (Weishaar & Beck, 2006). Discounting the positive helps explain the underlying mechanisms for avoidant personality disorder (Weishaar & Beck, 2006). For example, individuals who have been routinely criticized or rejected during childhood may have difficulty accepting positive feedback from others, expecting to only receive rejection and harsh criticism. In fact, they may employ these misattributions to support their ongoing theory that they are constantly rejected and criticized by others.

9.5.2.2.3 Behavioral

There are three major behavioral theories of the etiology of personality disorders: modeling, reinforcement, and lack of social skills. With regards to modeling, personality disorders are explained by an individual learning maladaptive social relationship patterns and behaviors due to directly observing family members engaging in similar behaviors (Gaynor & Baird, 2007). While we cannot discredit the biological component of the familial influence, research does support an additive modeling or imitating component to the development of personality disorders (especially antisocial personality disorder; APA, 2013).

Second, reinforcement or rewarding of maladaptive behaviors can also help explain personality disorders. Parents may unintentionally reward aggressive behaviors by giving into a child’s desires in efforts to cease the situation or prevent escalation of behaviors. When this is done repeatedly over time, children (and later as adults, particularly those with antisocial and borderline personality disorder) continue to display these maladaptive behaviors as they are effective in gaining their needs/wants. On the other side, there is some speculation that excessive reinforcement or praise during childhood may contribute to the grandiose sense of self-observed in individuals with narcissistic personality disorder (Millon, 2011).

Finally, a failure to develop normal social skills may explain the development of some personality disorders, such as avoidant personality disorder (Kantor, 2010). While there is some discussion as to whether lack of social skills leads to avoidance of social settings OR if social skills deficits develop as a result of avoiding social situations, most researchers agree that the avoidance of social situations contributes to the development of personality disorders, whereas, underlying deficits in social skills may contribute more to social anxiety disorder (APA, 2013).

9.5.2.3 Social 

9.5.2.3.1 Family Dysfunction 

High levels of psychological or social dysfunction within families have also been identified as a contributing factor to the development of personality disorders. High levels of poverty, unemployment, family separation, and witnessing domestic violence are routinely observed in individuals diagnosed with personality disorders (Paris, 1996). While formalized research has yet to further explore the relationship between socioeconomic status and personality disorders, correlational studies suggest a relationship between poverty, unemployment and poor academic achievement with increased levels of personality disorder diagnoses (Alwin, 2006).

9.5.2.3.2 Childhood Maltreatment 

Childhood maltreatment is among the most influential arguments for the development of personality disorders in adulthood. Individuals with personality disorders often struggle with a sense of self and with the ability to relate to others — something that is generally developed during the first four to six years of a child’s life and is affected by the emotional environment in which the child was raised. This sense of self is the mechanism in which individuals view themselves within their social context, while also informing attitudes and expectations of others. A child who experiences significant maltreatment, whether it be through neglect or physical, emotional, or sexual abuse, is at-risk for under or lack of development of a sense of self. Due to the lack of affection, discipline, or autonomy during childhood, these individuals are unable to engage in appropriate relationships as adults as seen across the spectrum of personality disorders.

Another way childhood maltreatment contributes to personality disorders is through the emotional bonds or attachments developed with primary caregivers. The relationship between attachment and emotional development was thoroughly researched by John Bowlby as he explored the need for affection in Harlow monkeys (Bowlby, 1998). Based on Bowlby’s research, four attachment styles have been identified: secure, anxious, ambivalentand disorganizedWhile securely attached children generally do not develop personality disorders, those with anxious, ambivalent, and disorganized attachment are at an increased risk to develop various disorders. More specifically, those with an anxious attachment are at-risk for developing internalizing disorders, those with an ambivalent attachment are at-risk for developing externalizing disorders, and those with disorganized attachment are at-risk for dissociative symptoms and personality disorders (Alwin, 2006).

Chapter Recap

Chapter 9 covered the personality disorders which are arranged in three clusters: cluster A which includes paranoid, schizoid, and schizotypal; cluster B which includes antisocial, borderline, histrionic, and narcissistic; and cluster C which includes avoidant, dependent, and obsessive-compulsive. We covered the clinical description, diagnostic criteria, epidemiology, treatment, comorbidity, and etiology of personality disorders.

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