Schizotypal personality disorder
Schizotypal personality disorder (STPD or SPD), also known as schizotypal disorder, is a mental and behavioural disorder. DSM classification describes the disorder specifically as a personality disorder characterized by thought disorder, paranoia, a characteristic form of social anxiety, derealization, transient psychosis, and unconventional beliefs. People with this disorder feel pronounced discomfort in forming and maintaining social connections with other people, primarily due to the belief that other people harbour negative thoughts and views about them. Peculiar speech mannerisms and socially unexpected modes of dress are also characteristic. Schizotypal people may react oddly in conversations, not respond, or talk to themselves. They frequently interpret situations as being strange or having unusual meaning for them; paranormal and superstitious beliefs are common. Schizotypal people usually disagree with the suggestion their thoughts and behaviour are a disorder, and seek medical attention for depression or anxiety instead. Schizotypal personality disorder occurs in approximately 3% of the general population and is more commonly diagnosed in males.The term "schizotype" was first coined by Sandor Rado in 1956 as an abbreviation of "schizophrenic phenotype". STPD is classified as a cluster A personality disorder, also known as the "odd or eccentric" cluster.

Causes
Genetic
Schizotypal personality disorder is widely understood to be a "schizophrenia spectrum" disorder. Rates of schizotypal personality disorder are much higher in relatives of individuals with schizophrenia than in the relatives of people with other mental illnesses or in people without mental illness. Technically speaking, schizotypal personality disorder may also be considered an "extended phenotype" that helps geneticists track the familial or genetic transmission of the genes that are implicated in schizophrenia pathogenesis. But there is also a genetic connection of STPD to mood disorders and depression in particular. Prediction of schizophrenia based on schizotypal traits has a higher accuracy for individuals with high genetic risk for STPD.

Social and environmental
Unique environmental factors, which differ from shared sibling experiences, have been found to play a role in the development of STPD and its dimensions. There is now evidence to suggest that parenting styles, early separation, trauma/maltreatment history (especially early childhood neglect) can lead to the development of schizotypal traits. Neglect or abuse, trauma, or family dysfunction during childhood may increase the risk of developing schizotypal personality disorder. There is also evidence indicating insults in the prenatal environment could have an effect on development of STPD. Over time, children learn to interpret social cues and respond appropriately but for unknown reasons this process does not work well for people with this disorder.Schizotypal personality disorders are characterized by a common attentional impairment in various degrees that could serve as a marker of biological susceptibility to STPD. The reason is that an individual who has difficulties taking in information may find it difficult in complicated social situations where interpersonal cues and attentive communications are essential for quality interaction. This might eventually cause the individual to withdraw from most social interactions, thus leading to asociality.

Diagnosis
Screening
There are various methods of screening for schizotypal personality. The Schizotypal Personality Questionnaire (SPQ) measures nine traits of STPD using a  self-report assessment. The nine traits referenced are Ideas of Reference, Excessive Social Anxiety, Odd Beliefs or Magical Thinking, Unusual Perceptual Experiences, Odd or Eccentric Behavior, No Close Friends, Odd Speech, Constricted Affect, and Suspiciousness. A study found that of the participants who scored in the top 10th percentile of all the SPQ scores, 55% were clinically diagnosed with STPD. A method that measures the risk for developing psychosis through self-reports is the Wisconsin Schizotypy Scale (WSS). The WSS divides schizotypal personality traits into 4 scales for Perceptual Aberration, Magical Ideation, Revised Social Anhedonia, and Physical Anhedonia. A comparison of the SPQ and the WSS suggests that these measures should be cautiously used for screening purposes of STPD.

STPD as a Personality Disorder
DSM-5
In the American Psychiatric Associations DSM-5, schizotypal personality disorder is defined as a "pervasive pattern of social and interpersonal deficits marked by acute discomfort with, and reduced capacity for, close relationships as well as by cognitive or perceptual distortions and eccentricities of behavior, beginning by early adulthood and present in a variety of contexts."At least five of the following symptoms must be present:

ideas of reference
strange beliefs or magical thinking that influences behavior and is inconsistent with subcultural norms (e.g., superstitiousness, belief in clairvoyance, telepathy, or “sixth sense”, bizarre fantasies or preoccupations)
abnormal perceptual experiences, including bodily illusions
strange thinking and speech (e.g., vague, circumstantial, metaphorical, overelaborate, or stereotyped)
suspiciousness or paranoid ideation
inappropriate or constricted affect
strange behavior or appearance
lack of close friends
excessive social anxiety that does not diminish with familiarity and tends to be associated with paranoid fears rather than negative judgments about selfThese symptoms must not occur only during the course of a disorder with similar symptoms (such as schizophrenia or autism spectrum disorder).

STPD as a Clinical Disorder
ICD-10
The World Health Organizations ICD-10 uses the name schizotypal disorder (F21). It is classified as a clinical disorder associated with schizophrenia, rather than a personality disorder as in DSM-5.The ICD definition is:

A disorder characterized by eccentric behavior and anomalies of thinking and affect which resemble those seen in schizophrenia, though no definite and characteristic schizophrenic anomalies have occurred at any stage. There is no dominant or typical disturbance, but any of the following may be present:
Inappropriate or constricted affect (the individual appears cold and aloof);
Behavior or appearance that is odd, eccentric or peculiar;
Poor rapport with others and a tendency to withdraw socially;
Odd beliefs or magical thinking, influencing behavior and inconsistent with subcultural norms;
Suspiciousness or paranoid ideas;
Obsessive ruminations without inner resistance;
Unusual perceptual experiences including somatosensory (bodily) or other illusions, depersonalization or derealization;
Vague, circumstantial, metaphorical, over-elaborate or stereotyped thinking, manifested by odd speech or in other ways, without gross incoherence;
Occasional transient quasi-psychotic episodes with intense illusions, auditory or other hallucinations and delusion-like ideas, usually occurring without external provocation.
The disorder runs a chronic course with fluctuations of intensity. Occasionally it evolves into overt schizophrenia. There is no definite onset and its evolution and course are usually those of a personality disorder. It is more common in individuals related to people with schizophrenia and is believed to be part of the genetic "spectrum" of schizophrenia.

Diagnostic guidelines
This diagnostic rubric is not recommended for general use because it is not clearly demarcated either from simple schizophrenia or from schizoid or paranoid personality disorders, or possibly autism spectrum disorders as currently diagnosed. If the term is used, three or four of the typical features listed above should have been present, continuously or episodically, for at least two years. The individual must never have met criteria for schizophrenia itself. A history of schizophrenia in a first-degree relative gives additional weight to the diagnosis but is not a prerequisite.

Subtypes
Theodore Millon proposes two subtypes of schizotypal personality. Any individual with schizotypal personality disorder may exhibit either one of the following somewhat different subtypes (Note that Millon believes it is rare for a personality with one pure variant, but rather a mixture of one major variant with one or more secondary variants):

Treatment
Medication
STPD is rarely seen as the primary reason for treatment in a clinical setting, but it often occurs as a comorbid finding with other mental disorders. When patients with STPD are prescribed pharmaceuticals, they are usually prescribed neuroleptics of the sort used to treat schizophrenia; however, the use of neuroleptic drugs in the schizotypal population is in great doubt. While people with schizotypal personality disorder and other attenuated psychotic-spectrum disorders may have a good outcome with neuroleptics in the short term, long-term followup suggests significant impairment in daily functioning compared to schizotypal and even schizophrenic people without neuroleptic drug exposure. Antidepressants are also sometimes prescribed, whether for STPD proper or for comorbid anxiety and depression.

Therapy
According to Theodore Millon, schizotypal personality disorder is one of the easiest personality disorders to identify but one of the most difficult to treat with psychotherapy. Persons with STPD usually consider themselves to be simply eccentric or nonconformist; the degree to which they consider their social nonconformity a problem differs from the degree to which it is considered a problem in psychiatry. It is difficult to gain rapport with people with STPD due to the fact that increasing familiarity and intimacy usually increase their level of anxiety and discomfort.Group therapy is recommended for persons with STPD only if the group is well structured and supportive. Otherwise, it could lead to loose and tangential ideation. Support is especially important for schizotypal patients with predominant paranoid symptoms, because they will have a lot of difficulties even in highly structured groups.

Comorbidity
Schizotypal personality disorder frequently co-occurs with major depressive disorder, dysthymia and social phobia. Furthermore, sometimes schizotypal personality disorder can co-occur with obsessive–compulsive disorder, and its presence appears to affect treatment outcome adversely. Some people with a clinical diagnosis of OCD have been found to also possess many schizotypal personality traits resulting in what can be called ‘schizotypal OCD’. Without proper treatment, STPD tendencies, such as magical thinking and paranoid ideation, could worsen the symptoms of OCD in an individual. There may also be an association with bipolar disorder. People with Gilles de la Tourette syndrome (GTS) can commonly possess some schizotypal traits.In terms of comorbidity with other personality disorders, schizotypal personality disorder has high comorbidity with schizoid and paranoid personality disorder, the other two Cluster A conditions. It also has significant comorbidity with borderline personality disorder and narcissistic personality disorder.Some schizotypal people go on to develop schizophrenia, but most of them do not.  There are dozens of studies showing that individuals with schizotypal personality disorder score similar to individuals with schizophrenia on a very wide range of neuropsychological tests. Cognitive deficits in patients with schizotypal personality disorder are very similar to, but quantitatively milder than, those for patients with schizophrenia. A 2004 study, however, reported neurological evidence that did "not entirely support the model that SPD is simply an attenuated form of schizophrenia".

Epidemiology
Reported prevalence of STPD in community studies ranges from 0.6% in a Norwegian sample, to 4.6% in an American sample. A large American study found a lifetime prevalence of 3.9%, with somewhat higher rates among men (4.2%) than women (3.7%). It may be uncommon in clinical populations, with reported rates of up to 1.9%.Together with other cluster A personality disorders, it is also very common among homeless people who show up at drop-in centres, according to a 2008 New York study. The study did not address homeless people who do not show up at drop-in centres.Cannabis users, whether that be a lifetime use, abuse or dependence, have been found to have an increased likelihood of possessing schizotypal personality disorder or traits consistent with STPD. Another epidemiological study on suicidal behavior in STPD found that, even when accounted for sociodemographic factors, people with STPD were 1.51 times more likely to attempt suicide. The same study found that people with childhood adversities, specifically abuse by a parent or caretaker, have a strongly significant association with lifetime STPD.

See also
Boundaries of the mind
DSM-5 codes (personality disorders)
Paranoid personality disorder
Schizoid personality disorder
Schizotypy

References


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