Schizotypal personality disorder
Schizotypal personality disorder (StPD or SPD), also known as schizotypal disorder, is a cluster A personality disorder.[4][5] The Diagnostic and Statistical Manual of Mental Disorders (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 harbor negative thoughts and views about them.[6] 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.[6] They frequently interpret situations as being strange or having unusual meanings for them; paranormal and superstitious beliefs are common. Schizotypal people usually disagree with the suggestion that their thoughts and behaviors are a 'disorder' and seek medical attention for depression or anxiety instead.[7]
Not to be confused with Semantic pragmatic disorder, Schizotypy, Schizoid personality disorder, or Schizoaffective disorder.Schizotypal personality disorder
Schizotypal disorder
10–20 years old
chronic
Based on symptoms
Typically poor, although significant improvements can be made
Estimated 4% of general population
Epidemiology[edit]
The reported prevalence of StPD in community studies ranges from 1.37% in a Norwegian sample, to 4.6% in an American sample.[12] A large American study found a lifetime prevalence of 3.9%, with somewhat higher rates among men (4.2%) than women (3.7%).[7] It may be uncommon in clinical populations, with reported rates of up to 1.9%.[12] It has been estimated to be prevalent among up to 5.2% of the general population.[13] Together with other cluster A personality disorders, it is also very common among homeless people who show up at drop-in centers, according to a 2008 New York study. The study did not address homeless people who do not show up at drop-in centers.[14] Schizotypal disorder may be overdiagnosed in Russia and other post-Soviet states.[15]
Etiology[edit]
Genetic[edit]
Although environmental factors likely play an important role in the onset of the disorder, people who have relatives with schizotypy,[30][31][32] mood disorders,[33] or other disorders on the schizophrenia spectrum are at a higher likelihood of developing StPD.[34][32][35] The COMT Val158Met polymorphism and its Val or Met allele are suspected to be associated with Schizotypal personality disorder.[36][37][38][39] These genes affect dopamine production in the brain,[40][41][42] a neurochemical thought to be associated with schizotypal traits.[43][44] The gene may also contribute to decreased levels of gray matter in the prefrontal cortex.[45][46] This may lead to impaired capacities for decision-making,[47] speech,[48] cognitive flexibility,[49] and altered perceptual experiences.[50] The rs1006737 polymorphism of the CACNA1C gene is also believed to have a part in schizotypal symptoms.[51] It may lead to a significantly increased physiological response to stress through the cortisol awakening response in the brain.[52][53][54][55] It may also negatively affect reward processing in the brain and lead to anhedonia or depression in patients.[56][57] These factors possibly lead to the development of Schizotypal traits.[58] The zinc-finger protein ZNF804A likely affects the levels of paranoia, anxiety, and ideas of reference in StPD.[59][60][61] This gene is also thought to negatively impact attention in people with StPD.[62] It may lead to an increased level of white matter volume in the frontal lobe.[63] Another gene, the NOTCH4 is thought to relate to Schizophrenia spectrum disorders.[64][65] It can lead to disruptions in the occipital cortex, and therefore symptoms of schizotypy.[66] The GLRA1 and the p250GAP genes are also potentially associated with StPD.[67][68][69] It may lead to abnormally low levels of Glutamic acids in the NDMA receptors, which impairs memory and learning.[70][71][72][73] StPD may stem from abnormalities in Chromosome 22.[74][75][76]
Neurological[edit]
Exposure to influenza during week 23 of gestation is associated with a higher likelihood of developing StPD. Poor nutrition in childhood may also contribute to the onset of StPD by altering the course of brain development.[77] Numerous areas of the brain are thought to be associated with StPD. Higher levels of dopamine in the brain,[78][79] possibly specifically the D1 receptor,[80][81][82] might contribute to the development of StPD. StPD is associated with heightened dopaminergic activity in the striatum.[83][84][85][86] Their symptoms may also stem from higher presynaptic dopamine release.[87][88][89][90] People with StPD may also have decreased volumes of grey or white matter in their caudate nucleus,[91][92] which leads to difficulties in speech.[93][94][95][96] People with StPD likely have a reduced volume in their temporal lobes,[97][98][99] possibly specifically the left hemisphere. The reduced levels of gray matter in these areas may be linked to their negative symptoms.[100] Reduced volume of gray or white matter in the superior temporal gyrus or the transverse temporal gyrus are thought to lead to issues with speech,[23][101][102][103] memory, and hallucinations.[104][105] Deficits in the gray matter volume of the temporal lobe and prefrontal cortex are likely associated with impairments in cognitive function, sensory processing, speech, executive function, decision-making, and emotional processing present in people with StPD.[106][107] StPD symptoms may also be influenced by reduced internal capsule,[108][109][110] which carries information to the cerebral cortex.[111] People with StPD can also have impairments in the uncinate fasciculus, which connects parts of the limbic system.[112] People with StPD have reduced levels of gray matter in their middle frontal gyrus and Brodmann area 10.[113] Although, not as reduced as patients with Schizophrenia.[113] Possibly preventing them from developing schizophrenia.[114] Increased gyrification in gyri by the cerebellum may lead to dysconnectivity in the brain, and therefore, schizotypal symptoms.[115][116] They may also have a hyporeactive,[117] or hyperreactive amygdala.[118] As well as hyperactive pituitary glands and putamens.[119][120] It is also possible that lower capacities for prepulse inhibition plays a role in StPD.[121][122][123][124] Research has suggested that people with StPD can have higher concentrations of Homovanillic acids.[125] Abnormalities in the cave of septum pellucidum may also be present.[126] In people predisposed to the development of Schizophrenia spectrum disorders, the consumption of cannabis can induce the onset of StPD or other disorders with psychotic symptoms.[127][128][129][130]
Environmental[edit]
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 evidence to suggest that parenting styles, early separation, childhood trauma, and childhood neglect can lead to the development of schizotypal traits.[131][132][133] Neglect, abuse, stress,[134] trauma,[135][136][137] or family dysfunction during childhood may increase the risk of developing schizotypal personality disorder.[138][139][140] There is also evidence indicating that disruptions in brain development during the prenatal period could affect the development of StPD.[141] 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.[142] During childhood, people with StPD may have seen little emotional expression from their parents. Another possibility is that they were excessively criticized or felt like they were constantly under threat,[143] potentially resulting in the onset of social anxiety, strange thinking patterns,[144] and blunted affect present in StPD.[145][144][146] Their difficulties in social situations might eventually cause the individual to withdraw from most social interactions, thus leading to asociality.[147] Children with schizotypal symptoms usually are more likely to indulge in internal fantasies,[148] more anxious, socially isolated, and more sensitive to criticism.[149] People with the most severe cases of StPD usually have a combination of childhood trauma and a genetic basis for their condition.[150][151]