One condition, two filing cabinets: personality disorder in America, psychotic disorder elsewhere
Schizotypal personality disorder brings odd beliefs, suspicion of others and a distinctive social anxiety, affecting roughly 3% of people. The American DSM-5 files it among personality disorders, while the international ICD-11 classification places it with psychotic conditions. Those affected rarely see it as a disorder at all.
People with the condition often find close relationships acutely uncomfortable, largely because they assume others think badly of them. Magical thinking and belief in the supernatural are common, as are ideas of reference, the sense that ordinary events carry a private message. Conversations can go awry: replies may not match expectations, and some talk to themselves. It is diagnosed more often in men, and those affected usually seek help for depression or anxiety instead of for the traits themselves.
Perception can shift in subtle ways. Colours may seem lighter or darker than they do to others, faces can look distorted or alien, and speech tends to be slower and flatter with long pauses. Déjà vu and a feeling of foreseeing events are frequent, attributed to quirks in how memories are stored. The overall picture resembles schizophrenia, but with milder cognitive problems; one suggestion is that grey matter losses in the frontal lobe, smaller than in schizophrenia, may help keep full psychosis at bay.
Biology and upbringing both seem to matter. Relatives of people on the schizophrenia spectrum face higher odds, and several genes that influence dopamine or the stress hormone response, including COMT and CACNA1C, are under suspicion, along with abnormalities on chromosome 22. Flu exposure around week 23 of pregnancy and poor childhood nutrition have been linked to the disorder, as have neglect, harsh criticism and trauma. The most severe cases usually combine a genetic basis with a difficult childhood, and cannabis can trigger onset in predisposed people.
The diagnostic rules are demanding. The current DSM-5-TR requires at least five of nine criteria, covering discomfort in close relationships, distorted thinking or perception, and eccentric behaviour, and the pattern must not be explained by schizophrenia or autism. DSM-5 also offers an alternative, dimensional model that scores personality functioning and traits on a sliding scale.
Source: Schizotypal personality disorder
