Co-Occurence of Personality Disorders Continued
Co-Occurrence of Personality Disorder and Substance Use Disorders
The most commonly co-occurring DSM diagnoses are personality disorders and substance use disorders (which includes alcohol and other drugs) (Verheul, van den Brink & Hartgers, 1995). A research study by Zimmerman and Coryell (1989) found that about 43-77% of people diagnosed with personality disorders would also meet the criteria for an alcohol use disorder (abuse or dependence) at some point during their lives. Other researchers, such as Verheul and colleagues (1995, 1998), have looked at the co-occurrence between personality disorders and substance use disorders from the opposite angle and have reported that 44% of people with alcohol use disorders would meet criteria for a personality disorder, and 77% of people who abuse opiates would meet criteria for a personality disorder. These researchers identified that Cluster B personality disorders (most notably Borderline Personality Disorder and Antisocial Personality Disorder) were the most common personality disorders associated with substance use disorders.
There are several hypotheses that attempt to explain this high co-occurrence between personality disorders and substance use disorders. Some experts suspect the high co-occurrence is related to impulsivity, namely that people with poorer impulse control (such as people with Antisocial and Borderline Personality Disorder) also have a hard time resisting urges and cravings to use substances. In other words, the use of the mood altering substances and the immediate "good feeling" that follows its use, is so appealing that people with poor impulse control find it too difficult to override the impulse, despite the damaging consequences that follow repeated and continuous substance use. While this rewarding and reinforcing effect of drug use applies broadly to all people who use drugs, it is especially difficult for people with impulse control problems to resist.
Another proposed explanation for the high co-occurrence between personality disorders and substance use disorders might be described as a "self-medication" hypothesis; namely, that some people tend to use mood-altering substances in order to cope with stress or with difficult emotions. This hypothesis is particularly applicable for people with Borderline Personality Disorder who tend to feel emotions with great intensity and who take a longer time to calm down than do people without this disorder. Many people with Borderline Personality Disorder use mood-altering substances in order to get immediate relief from emotionally intense situations; for instance, when feelings of anxiety or anger run very high. This "self-medication" hypothesis may also apply to people with Cluster C personality disorders, characterized by anxiety. For instance, someone with Avoidant Personality Disorder might plan to go to a party but become extremely anxious, anticipating rejection and even ridicule. Having an alcoholic beverage beforehand might serve to reduce his anxiety in the moment, but over time, with repeated use, this could lead to a substance abuse diagnosis.
A third hypothesis to explain the high co-occurrence of substance use disorders and personality disorders has to do with excitement-seeking behavior. Certain personality disorders are associated with a tendency to become easily bored. This tendency is characteristic of people with Narcissistic, Histrionic, or Antisocial Personality Disorders (Cluster B). Some experts believe that such people come to see drug use as exciting and over time may develop substance use disorders in an attempt to alleviate frequent boredom. The exciting quality of illicit drug use stems from the intrinsic effects of different drugs (i.e., the "high" associated with them) and because they are typically used with other people in socially exciting and/or risky circumstances.
Co-Occurrence of Personality Disorder and Eating Disorders
Eating disorders, including Anorexia Nervosa and Bulimia Nervosa, are another group of disorders that commonly co-occur with personality disorders. As a group, eating disorders are defined by severe dietary restriction to such a degree that it endangers one's health. Dietary restriction is generally thought to be a method used by people with eating disorders to regulate intense emotions. The Borderline Personality Disorder is characterized by this lack of emotional regulation. For people with an eating disorder, the ability to severely restrict food intake may provide them with a sense of relief that they can at least control something (hunger) even when other things in their life seem beyond their control.
The impulsively associated with Borderline Personality Disorder is also thought to be a key to this disorder's affinity with eating disorders. This is particularly true of Bulimia Nervosa in which a cyclical pattern of strict food regulation, is followed by a failure to rigidly maintain strict discipline, resulting in an impulsive binge episode. The binge episode is then followed, once again, by severe dietary restriction, coupled with shame and remorse over the failure to retain control.
The relationship between the Obsessive Compulsive Personality Disorder and eating disorders seems to revolve around two primary symptoms that are associated with both disorders: characteristic rigidity and need for control. This is particularly noticeable in people with Anorexia Nervosa as they control their caloric intake in a highly rigid and even ritualized manner.
The Avoidant Personality Disorder is characterized by feelings of inadequacy and social anxiety which may come to be expressed as a deep concern over the acceptability of one's physical appearance. This excessive concern over physical appearances can resonate with people who have eating disorders as they attempt to control their weight and body shape in a misguided effort to become more socially acceptable. Unfortunately, it is almost always the case that no amount of weight loss or dietary restriction is ever enough to make that core feeling of inadequacy go away.
Co-Occurrence of Personality Disorders with other Personality Disorders1
In addition to co-occurrence with various Axis I disorders, research suggests that personality disorders frequently co-occur with each other. About half of all people who meet the criteria for one personality disorder will also meet the criteria for at least one other (Fowler, O'Donohue & Lilienfeld, 2007). There is a particularly high rate of co-occurrence between personality disorders within the same cluster (Skodol, 2005). For example, people with Borderline Personality Disorder, a Cluster B diagnosis, are also fairly likely to meet criteria for other Cluster B diagnoses, including Narcissistic, Histrionic, or Antisocial Personality disorders. Likewise, people who meet criteria for Schizotypal Personality Disorder (a Cluster A diagnosis) are fairly likely to also meet criteria for other Cluster A diagnoses, including Paranoid or Schizoid Personality Disorder. Since the clusters are thought to consist of personality disorders that have some features in common, this pattern of co-occurrence makes sense.
1 The upcoming DSM-V may attempt to address these problems of co-occurrence through the use of a dimensional diagnostic approach rather than the current categorical approach. For more information about the strengths and weaknesses of categorical and dimensional methods of diagnosis, please refer to the section entitled “Problems with the current diagnostic system.” LINK to DIAGNOSIS/Problems p. 26