The term 'personality disorder' describes a group of conditions in which individuals have some form of pathological abnormality of their personality. Such individuals are likely to have serious problems with their personal and social lives, stemming from a fixed approach applied to all situations. This sort of behaviour can mimic mental illnesses ranging from anxiety to schizophrenia, and so a diagnosis of personality disorder is always considered alongside other options. Though there is no age limit, it is thought that an individual's personality is not fully formed until their mid twenties, and so earlier diagnoses of personality disorder may be less useful.

Although there are a number of different personality disorders, they can be broadly divided into three groups:

• Odd/eccentric - disorders characterised by a tendency to avoid socialising for various reasons, along with the exhibition of odd or eccentric behaviour.

• Dramatic/erratic - disorders characterised by impulsive and overblown behaviour.

• Anxious/fearful - disorders involving behaviour shaped by anxiety and fear.

Odd/eccentric

Individuals with paranoid personality disorder have a deep mistrust of others, are excessively sensitive to perceived insults and criticism, and will bear even the smallest grudges. They are both highly suspicious and indignant with regards to their personal rights, and may defend themselves excessively even when no harm was intended.

Schizotypal personality disorder involves odd thinking and magical beliefs, eccentric and paranoid behaviour, and a withdrawal from society due to fear of others. They are also sensitive to criticism and rebukes by others, and may mistakenly believe that occurrences they witness have specific reference to them – for instance, they may mistakenly believe that others are laughing at them.

Schizoid personality disorder involves an emotional coldness towards others, a lack of social involvement and minimal desire for friendship or praise from others. They are socially withdrawn not so much through mistrust as through a sheer lack of interest in others, apparently created by a fear of excessive emotional stimulation by contact with other individuals.

While all these disorders may mimic schizophrenia, the social withdrawal and lack of emotion of schizoid personalities may also appear similar to Asperger's Syndrome.

Dramatic/erratic

Individuals with borderline personality disorder have various issues involving their emotions including unpredictable mood swings, impulsive behaviour, fear of abandonment, problems with anger, suicidal behaviour, and difficulty self-identifying. These individuals may also suffer from anxiety, depression, dissociation and eating disorders, and may attempt to manage their problems through substance abuse.

Antisocial personality disorder and dissocial personality disorder¹ involve a lack of respect for rules and societal norms, impulsive behaviour, problems with anger, and a repetitive tendency to break the law and inflict harm on others. These individuals are also likely to abuse drugs, and may have a history of conduct disorder, animal abuse, bed-wetting and pyromania.

Histrionic personality disorder is characterised by overblown emotions, attention-seeking behaviour and a constant need for the approval of others. Individuals with this disorder believe that their relationships are closer than they really are, and are easily influenced by the opinions of others. They tend to be impatient, self-centred, shallow and flirtatious, and may threaten self-harm if they fail to get what they want.

Narcissistic personality disorder may result in a similar picture to that of mania, with the individual believing that they are somehow better than everyone else, thus making them entitled to special treatment and universal adoration. They may spend a great deal of time preoccupied with themselves, fantasising about boundless opportunities for success and fulfilment. This degree of self-importance can lead to exploitative, one-sided relationships, with the narcissistic individual lacking empathy and adopting an arrogant attitude towards other people.

Anxious/fearful

Individuals with avoidant personality disorder are preoccupied with low self-esteem and have a fear of rejection and humiliation in social situations. They avoid interpersonal relationships, social situations and physical contact, and are highly timid and critical of themselves.

Dependent personality disorder is based around a fear of independence and leads the individual to rely heavily on others to the point that they fail to take responsibility for their own lives. Everyday decisions and personal tasks end up being performed by others, and the individual is incapable of initiating new tasks themselves. Arguments are avoided for fear of abandonment, and the individual may go to great lengths to ensure the presence of others in their life.

Anankastic personality disorder, also referred to as obsessive compulsive personality disorder, leads individuals to place heavy emphasis on regular routines and perfectionist standards to the extent that the real point of what they are doing is lost. They tend to be rigid in their thinking and are unable to delegate tasks unless their own rules are followed. Anankastic traits are commonly seen in individuals with Asperger's due to their need for routines and control over activities.

Causes

There have been suggestions that various personality disorders have a genetic component, with schizotypal and paranoid traits perhaps belonging to a 'schizophrenic spectrum'. However, such things as parenting style, neglect, abuse, and painful childhood experiences can obviously affect the development of an individual's personality, leading them to use coping strategies that are ill-adapted to society. Individual character traits can also predispose to the use of such coping strategies, and so the development of a personality disorder may not have one root cause.

Management

Although individuals with personality disorders may be diagnosed with mood disorders, anxiety, Obsessive Compulsive Disorder (OCD) or psychosis, their treatment is different from that of individuals with those conditions. There is a large body of evidence with regards to the treatment of different personality disorders, and so this entry will not attempt to cover them individually. However, talking therapies such as cognitive therapy, dialectical therapy for borderline individuals, and family therapy may be helpful depending upon the disorder, and anti-depressants and anti-anxiety medication are sometimes used.