Credo Reference-Personality DisorderA mental disorder the essential features of which are deeply ingrained, enduring, maladaptive patterns of relating to, thinking about and perceiving the environment that are so extreme they cause impairment in social and behavioural functioning. Recent classification systems break this group into three ‘clusters‘ based on the manner in which the behavioural aspects of the disorder are manifested. Specifically, there is a dramatic cluster including BORDERLINE, ANTISOCIAL, NARCISSISTIC and HISTRIONIC PERSONALITY DISORDERS all of which are characterized by overt, dramatic displays and personal styles; an anxious cluster including DEPENDENT, AVOIDANT and OBSESSIVE-COMPULSIVE PERSONALITY DISORDERS where the emotions and behaviours are characterized by excessive anxiety, and the quaintly named odd cluster which includes PARANOID, SCHIZOID and SCHIZOTYPAL PERSONALITY DISORDERS each of which is marked by socially inappropriate behaviours. Note that several of these subtypes are used with more than one of the focal meanings. See each for additional details. Personality disorders are generally recognizable in childhood or adolescence and continue through most of adult life. Note, however, if diagnosed before age 18, the proper diagnostic category is DISORDER OF *CHILDHOOD.