Personality disorders, in essence, are long term, inflexible patterns of behaviour which impact on one's daily life to such a point that they cause significant distress.
For one to be diagnosed as having a personality disorder, one must experience the following symptoms as well as the individual symptoms of the type of personality disorder they presume to suffer from:
1 General behaviour that is deviant from one's culture, manifested in at least two of the following: mood, cognition, interpersonal functioning and/or control over impulse; 2 Said behaviour is inflexible; 3 Said behaviour negatively impacts on the subject's functioning to the point of distress; 4 Said behaviour is long term and can be traced back to adolescence or early adulthood; 5 Said behaviour is not caused by another reason (for example, clinical depression); 6 Said behaviour is not the result of substance abuse, physical trauma or any other outside influence.
Additionally, the patient should be at least 18 years old; however, with the exception of Antisocial Personality Disorder, patients under the age of 18 may be diagnosed as having a personality disorder under exceptional circumstances.
There are four categories of personality disorders:
1 "Odd" or "Eccentric" disorders - Paranoid Personality Disorder, Schizoid Personality Disorder, Schizotypal Personality Disorder; 2 "Emotional", "Dramatic" or "Erratic" disorders - Antisocial Personality Disorder, Borderline Personality Disorder, Histrionic Personality Disorder, Narcissistic Personality Disorder; 3 "Anxious" or "Fearful" disorders - Avoidant Personality Disorder, Dependent Personality Disorder, Obsessive-Compulsive Personality Disorder; 4 Miscellaneous disorders: Depressive Personality Disorder, Dissociative Identity Disorder, Passive-Aggressive Personality Disorder, Personality Disorder NOS (Not Otherwise Specified), Self-Defeating Personality Disorder.
Officially, the fourth ("D") category does not exist, but is rather a collection of outmoded or unclassifiable disorders.