There is some disagreement about how to recognise personality disorders, but basically, one could be defined as having a personality disorder when their basic character traits cause severe problems either to themselves or to the people around them on a regular basis, to the extent that it prevents them from leading a normal life.

The DSM-1V categories the different personality disorders into three main clusters.
Cluster A - Paranoid, Schizoid, Schizotypal personality disorders
Cluster B - Antisocial, Borderline, Histrionic, and Narcisstic personality disorders
Cluster C - Avoidant, Dependent and Obsessive Compulsive personality disorders

The following is a brief description of these ten different types of personality disorders:

Paranoid Personality Disorder

People with paranoid personality disorder tend to be extremely distrustful and suspicious of others, including those closest to them although they will often avoid or be unable to form close relationships. They are often highly critical and hostile and so will receive a hostile response from others as a result, which of course serves to validate their original distrust and suspicion.

Schizoid Personality disorder

This is a particularly rare type of personality disorder. Someone with Schizoid personality disorder will show little or no emotion, including humour, and appear quite happy to be alone. They tend to lack social skills and do not make any effort to attain popularity, acceptance or any attention from others.

Schizotypal Personality Disorder

Characterised by abnormal or bizarre ways of thinking and will often isolate themselves from others. In some cases they may believe they have extra sensory powers beyond what other people have and believe they can influence the world and make things happen. This type of personality disorder has a high degree of overlapping with other types of personality disorders.

Antisocial Personality Disorder (also known as Dissociate)

This type can be described as lacking in a social conscience with no regard or compassion for others so prone to carrying out criminal acts such as violence towards others and stealing. Will often display aggressive behaviour and show no concern for their "victims" and will act without thinking of the consequences. Deceit and manipulation are characteristic of this type of personality disorder.

Avoidant Personality Disorder

Avoidant personality or anxious personality disorder is characterised by extreme sensitivity to rejection, criticism and confrontation. Sufferers will avoid social situations and interactions due to their feelings of inadequacy and fear of rejection. They feel alienated from society.

Borderline Personality Disorder

This is a serious mental illness characterised by unstable moods, low self esteem and poor self image. Sufferers tend to see things as black and white. They can be prone to sudden bouts of anger, which they may take out on themselves, including threatening or actual suicide. Relationships with others whether they are at work, at home or socially, are often intense, volatile and riddled with conflict.

Dependent Personality Disorder

This type is submissive in their nature and indulges in repeated patterns of dependency on others even to the extent they rely on others to make decisions for them. They are clingy, needy, and sensitive to criticism and rejection and will often go to great lengths to gain reassurance from others. They feel unable to look after themselves and are often preoccupied with fears about being alone so when one relationship ends they will embark on another.

Obsessive Compulsive Personality Disorder

Someone with obsessive compulsive personality disorder is a perfectionist and will often take on too much responsibility in their drive for perfection. They often find difficulty adapting to new situations and can be overly concerned with rules and doing things the way they think they should be done, particularly with regard to time, money, cleanliness and relationships. They may be preoccupied with lists, organisation and order and be overly committed to their work. Many people will show traits of this type of personality but it is not diagnosed unless it is severe enough to hinder them from leading a normal life.

Histrionic Personality Disorder

Characterised by attention seeking behaviour, dominating conversations, exaggerating normal everyday events including illness, constantly seeking praise, can involve dressing outrageously in order to attract attention, or anything else that will get them noticed. They thrive on drama, may be sexually provocative, exaggerate their emotions and be extremely sensitive to criticism.

Narcisstic Personality Disorder

This type of personality disorder is characterised by an inflated sense of self importance and what they can achieve in the world believing they are special or unique and are often preoccupied by fantasises of success, power, beauty and ideal love. They will often take advantage of others to suit their own needs.

What causes personality disorders?

Personality disorders tend to start during young adulthood and persist thereafter. No one really knows for sure what causes someone to develop a personality disorder although there are a number of theories in existence involving environmental, social, biological and genetic factors.

A significant number of people who develop a personality disorder have suffered some sort of abuse or neglect during childhood and there is also evidence that the tendency can be inherited through the genes.

Treating a personality disorder

Treatment will usually involve some sort of psychotherapy or antipsychotic, antidepressant medication or mood stabilisers depending on the type or types of personality disorder or disorders involved.