The term "personality disorder" is relatively new in the field of mental health. The traits seen with these disorders used to be considered part of a person's natural personality and therefore untreatable. The exact causes of personality disorders are unclear but are likely to be a combination of factors that may vary between individuals.

Some of the possible causes of personality disorders include:

• Unpleasant childhood experiences - There may be a history of physical or sexual abuse or neglect in early years. Being abused as a child or living in an environment that does not foster the growth of social skills can be detrimental to a child's personality and may give rise to character traits that cause personality disorders.
• Drugs or alcohol abuse may be found among individuals with personality disorders, who may try to use the vices as a means of helping them cope with their perceived inadequacies or differences. This can create a vicious cycle, as drug or alcohol use in itself can cause problems that are difficult to cope with.
• Avoidant (anxious) personality disorder - This personality disorder manifests with low self-esteem, anxiety, fear of being judged negatively by others and lack of social skills. Individuals with this condition may experience relationship and work-related problems.
• Borderline personality disorder - This is one of the most common types of personality disorder and describes a state between psychosis and neurosis. People with this condition have poor self image, struggle with relationships and may have extreme mood swings and outbursts.
• Antisocial personality disorder - Antisocial personality disorder refers to a lack of regard for fellow human beings and a lack of remorse for actions that may hurt other people's feelings. These individuals commonly have a criminal record.
• Dependent personality disorder - This manifests as a lack of self confidence that leads individuals to put the needs of others before their own in order to please people.
• Narcissistic personality disorder - This describes a severe overrating of one's own importance, leading to grandiose plans and ambitions and usually a self-centredness and intolerance of others.
• Histronic personality disorder - This disorder typically manifests with hysterical outbursts and the need to be the centre of attention.
• Paranoid personality disorder - People with this condition feel highly suspicious of and bitter towards others, making it difficult for them to form lasting relationships.
• Obsessive-compulsive personality disorder - This condition causes individuals to make exaggerated attempts to be perfect and do things their way only, while overruling others.
• Schizoid personality disorder - Affected people have difficulty expressing their emotions, remaining aloof or withdrawn and failing to form long lasting relationships.
• Schizotypal personality disorder - This condition is characterized by paranoia and thought patterns that are mostly suspicious and eccentric.