Personality Disorder

Personality disorders, formerly referred to as character disorders, are a class of personality types and behaviors. Personality disorders are noted on Axis II of the Diagnostic and Statistical Manual of Mental Disorders or DSM-IV-TR (fourth edition, text revision) of the American Psychiatric Association.
Personality disorders are also defined by the International Statistical Classification of Diseases and Related Health Problems (ICD-10), which is published by the World Health Organization. Personality disorders are categorized in ICD-10 Chapter V: Mental and behavioural disorders, specifically under Mental and behavioral disorders: 28F60-F69.29 Disorders of adult personality and behavior. Personality, defined psychologically is the behavioral and mental traits that distinguish human beings. Hence, personality disorders are defined by experiences and behaviors that differ from societal norms and expectations. Those diagnosed with a personality disorder experience difficulties in cognition, emotiveness, interpersonal functioning and control of impulses. In general, personality disorders are diagnosed in 40-60 percent of psychiatric patients, which is the greatest of all psychiatric diagnoses.
These behavioral patterns in personality disorders are typically associated with severe disturbances in the behavioral tendencies of an individual, usually involving several areas of the personality, and are nearly always associated with considerable personal and social disruption. Additionally, personality disorders are inflexible and pervasive across many situations, due in large part to the fact that such behavior is ego-syntonic (i.e. the patterns are consistent with the ego integrity of the individual) and are, therefore, perceived to be appropriate by that individual. This behavior can result in maladaptive coping skills, which may lead to personal problems that induce extreme anxiety, distress and depression.
The onset of these patterns of behavior can typically be traced back to early adolescence and the beginning of adulthood and, in rarer instances, childhood. General diagnostic guidelines applying to all personality disorders are presented below; supplementary descriptions are provided with each of the subtypes.
Because the theory and diagnosis of personality disorders stem from prevailing cultural expectations, their validity is contested by some experts on the basis of invariable subjectivity. They argue that the theory and diagnosis of personality disorders are based strictly on social, or even sociopolitical and economic considerations.

Source : Wikipedia