Personality disorders are a class of personality types and enduring behaviors associated with significant distress or disability, which appear to deviate from social expectations particularly in relating to others.
Personality disorders are included as mental disorders on Axis II of the Diagnostic manual of the American Psychiatric Association, and in the mental and behavioral disorders section of the ICD manual of the World Health Organization. Personality, defined psychologically, is the enduring 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 may experience difficulties in cognition, emotiveness, interpersonal functioning or control of impulses. In general, personality disorders are diagnosed in 40-60 percent of psychiatric patients, which is the most frequent of all psychiatric diagnoses.
These behavioral patterns in personality disorders are typically associated with substantial disturbances in some 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 may be 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 or depression. The onset of these patterns of behavior can typically be traced back to early adolescence and the beginning of adulthood and, in some instances, childhood.
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.