The DSM-5 recognizes 10 personality disorders, organized into 3 different clusters. Cluster C disorders include avoidant personality disorder, dependent personality disorder, and obsessive-compulsive personality disorder (which is not the same thing as obsessive-compulsive disorder). People with these disorders often appear to be nervous and fearful.

Avoidant Personality Disorder

Defining Avoidant Personality Disorder

Avoidant personality disorder is characterized by a pervasive pattern of social inhibition, feelings of inadequacy, extreme sensitivity to negative evaluation, and avoidance of social interaction. Individuals afflicted with the disorder tend to describe themselves as ill at ease, anxious, lonely, and generally feel unwanted and isolated from others. They often consider themselves to be socially inept or personally unappealing and avoid social interaction for fear of being ridiculed, humiliated, rejected, or disliked. Avoidant personality disorder is usually first noticed in early adulthood. 

There is controversy as to whether avoidant personality disorder is a distinct disorder from generalized social phobia, and it is contended by some that they are merely different conceptualizations of the same disorder, where avoidant personality disorder may represent the more severe form. Generalized social phobia and avoidant personality disorder have similar diagnostic criteria and may share a similar causation, subjective experience, course, treatment, and underlying personality features, such as shyness.

Avoidant Personality Disorder

Avoidant personality disorder is characterized by a pervasive pattern of social inhibition, feelings of inadequacy, extreme sensitivity to negative evaluation, and avoidance of social interaction. The disorder may begin in childhood or early adulthood.

DSM-5 Diagnostic Criteria for Avoidant Personality Disorder

To be diagnosed with avoidant personality disorder, symptoms must begin by early adulthood and occur in a range of situations. Four of seven following symptoms should be present:

• Avoids occupational activities that involve significant interpersonal contact because of fears of criticism, disapproval, or rejection;
• Is unwilling to get involved with people unless they are certain of being liked;
• Shows restraint within intimate relationships because of the fear of being shamed or ridiculed;
• Is preoccupied with being criticized or rejected in social situations;
• Is inhibited in new interpersonal situations because of feelings of inadequacy;
• Views self as socially inept, personally unappealing, or inferior to others;
• Is unusually reluctant to take personal risk or to engage in any new activities because they may prove embarrassing.

Etiology of Avoidant Personality Disorder

Causes of avoidant personality disorder are not clearly defined and may be influenced by a combination of social, genetic, and psychological factors. The disorder may be related to temperamental factors that are inherited. Specifically, various anxiety disorders in childhood and adolescence have been associated with a temperament characterized by behavioral inhibition, including features of being shy, fearful, and withdrawn in new situations. These inherited characteristics may give an individual a genetic predisposition towards avoidant personality disorder. Childhood emotional neglect and peer group rejection are both associated with an increased risk for the development of avoidant personality disorder. 

Treatment of Avoidant Personality Disorder

Treatment of avoidant personality disorder can employ various techniques, such as social skills training, cognitive therapy, exposure treatment to gradually increase social contacts, group therapy for practicing social skills, and sometimes drug therapy (such as antidepressants and anti-anxiety medication). A key issue in treatment is gaining and keeping the patient's trust, as people with avoidant personality disorder will often start to avoid treatment sessions if they distrust the therapist or fear rejection. The primary purpose of both individual therapy and social skills group training is for individuals with the disorder to begin challenging their exaggerated negative beliefs about themselves. 

Dependent Personality Disorder

Defining Dependent Personality Disorder

Dependent personality disorder is characterized by a pervasive psychological dependence on other people. This personality disorder is a long-term (chronic) condition in which people depend on others to meet their emotional and physical needs, with only a minority achieving normal levels of independence. The difference between a 'dependent personality' and a 'dependent personality disorder' is somewhat subjective, which makes diagnosis sensitive to cultural influences such as gender role expectations.

DSM-5 Diagnostic Criteria for Dependent Personality Disorder

The diagnosis for dependent personality disorder includes the pervasive and excessive need to be taken care of which leads to submissive and clinging behavior and fears of separation. In order to be diagnosed, the person must allow others to take over and run their life; is submissive, clingy, and fears separation; cannot make decisions without advice and reassurance from others; lacks self-confidence; cannot do things on their own; and/or feels uncomfortable or helpless when alone. Symptoms must begin by early adulthood and be present in a variety of contexts.

Etiology of Dependent Personality Disorder

Dependent personality disorder occurs in about 0.6% of the general population, and occurs more frequently in females. A 2004 twin study suggests a heritability of .81 for developing dependent personality disorder. Because of this, there is significant evidence that this disorder runs in families. Children and adolescents with a history of anxiety disorders and physical illnesses are more susceptible to acquiring this disorder. A study in 2012 found that two-thirds of this disorder stemmed from genetics while one-third came from the environment

Treatment of Dependent Personality Disorder

Various forms of psychotherapy are used to treat dependent personality disorder, often with the goal of assisting the patient in becoming more independent and making independent decisions related to their life. Various medications may also be used to treat comorbid (co-occurring) disorders, such as depression or anxiety. 

Obsessive-Compulsive Personality Disorder

Defining Obsessive-Compulsive Personality Disorder

Obsessive-compulsive personality disorder (OCPD) is characterized by a general pattern of concern with orderliness, perfectionism, excessive attention to details, mental and interpersonal control, and a need for control over one's environment, at the expense of flexibility, openness, and efficiency. Workaholism and miserliness are also seen often in those with this personality disorder. Rituals are performed to the point of excluding leisure activities and friendships. Persons affected with this disorder may find it hard to relax, always feeling that time is running out for their activities and that more effort is needed to achieve their goals. They may plan their activities down to the minute—a manifestation of the compulsive tendency to keep control over their environment.

OCPD is distinct from obsessive-compulsive disorder (OCD), which is an anxiety (rather than a personality) disorder, and the relation between the two is contentious. Some, but not all, studies have found high comorbidity rates between the two disorders, and both may share outside similarities (for example, rigid and ritual-like behaviors). Hoarding, orderliness, and a need for symmetry and organization are often seen in people with either disorder. However, attitudes toward these behaviors differ between people affected with either of the disorders: for people with OCD, these behaviors are unwanted and seen as unhealthy, being the product of anxiety-inducing and involuntary thoughts. For people with OCPD, these behaviors are experienced as rational and desirable, being the result of, for example, a strong adherence to routines, a natural inclination towards cautiousness, or a desire to achieve perfection.

DSM-5 Diagnostic Criteria for Obsessive-Compulsive Personality Disorder

In order to be diagnosed with OCPD, symptoms must appear by early adulthood and in multiple contexts. At least four of the following should be present:

• Is preoccupied with details, rules, lists, order, organization, or schedules to the extent that the major point of the activity is lost.
• Shows perfectionism that interferes with task completion (e.g., is unable to complete a project because his or her own overly strict standards are not met).
• Is excessively devoted to work and productivity to the exclusion of leisure activities and friendships (not accounted for by obvious economic necessity).
• Is overconscientious, scrupulous, and inflexible about matters of morality, ethics, or values (not accounted for by cultural or religious identification).
• Is unable to discard worn-out or worthless objects even when they have no sentimental value.
• Is reluctant to delegate tasks or to work with others unless they submit to exactly his or her way of doing things.
• Adopts a miserly spending style toward both self and others; money is viewed as something to be hoarded for future catastrophes.
• Shows rigidity and stubbornness.

Etiology of Obsessive-Compulsive Personality Disorder

Researchers have set forth both genetic and environmental theories for what causes OCPD. Under the genetic theory, people with a form of a particular gene (the DRD3 gene) are more likely to develop OCPD and depression, particularly if they are male. However, genetic factors may lie dormant until triggered by events in the lives of those who are predisposed to OCPD. These events could include trauma faced during childhood, such as physical, emotional, or sexual abuse, or other psychological trauma. Under the environmental theory, OCPD is seen as a learned behavior.

Treatment of Obsessive-Compulsive Personality Disorder

Treatment for OCPD includes psychotherapy, cognitive-behavioral therapy, behavior therapy, or self-help. Medication may also be prescribed. In behavior therapy and cognitive-behavioral therapy, a patient discusses with a psychotherapist ways of changing compulsions into healthier, productive behaviors. 

Treatment is complicated if the patient does not accept that they have OCPD or does not view their thoughts or behaviors as problematic. Medication alone is generally not indicated for this personality disorder, but fluoxetine has been prescribed with success. Selective serotonin reuptake inhibitors (SSRIs) may be useful in addition to psychotherapy.