Manfield adds "This huge discrepancy [from the ten percent reported by therapists for the condition] is probably largely because someone with a schizoid disorder is less likely to seek treatment than someone with other axis-II disorders. "A 2008 study assessing personality and mood disorder prevalence among homeless people at New York City drop-in centres reported an SzPD rate of 65% among this sample. The study did not assess homeless people who did not show up at drop-in centres, and the rates of most other personality and mood disorders within the drop-in centres was lower than that of SzPD. The authors noted the limitations of the study, including the higher male-to-female ratio in the sample and the absence of subjects outside the support system or receiving other support (e.g., shelters) as well as the absence of subjects in geographical settings outside New York City, a large city often considered a magnet for disenfranchised people.A University of Colorado Colorado Springs study comparing personality disorders and Myers–Briggs Type Indicator types found that the disorder had a significant correlation with the Introverted (I) and Thinking (T) preferences. History
The term "schizoid" was coined in 1908 by Eugen Bleuler to designate a human tendency to direct attention toward ones inner life and away from the external world, a concept akin to introversion in that it was not viewed in terms of psychopathology. Bleuler labeled the exaggeration of this tendency the "schizoid personality".
These blackouts often occur during exercise or as a response to emotional stress—situations in which chemical messengers known as catecholamines, such as adrenaline, are released within the body. Blackouts may be misinterpreted as being caused by simple faints or epilepsy, often leading to delays in reaching the correct diagnosis. In a third of those affected, the first manifestation of the disease may be cardiac arrest, potentially leading to sudden death. This can occur in very young children, presenting as sudden infant death syndrome or cot death. Approximately 30% of those with CPVT will have a family member who has experienced blackouts, seizures, or sudden death in response to exercise or stress.In those with CPVT, catecholamine release can lead to an abnormal heart rhythm or arrhythmia known as ventricular tachycardia. The ventricular tachycardia may take a characteristic form known as bidirectional ventricular tachycardia. This form of ventricular tachycardia occurs relatively infrequently, but if seen is suggestive of an underlying diagnosis of CPVT or the related condition Andersen-Tawil syndrome. These ventricular arrhythmias in some cases terminate by themselves, causing a blackout from which the person then recovers. However, if the abnormal heart rhythm continues, it can degenerate into a more dangerous arrhythmia known as ventricular fibrillation causing a cardiac arrest and, if untreated, sudden death.There are typically very few abnormal signs on clinical examination in persons with CPVT. However, those with CPVT may develop a less serious heart rhythm disturbance called atrial fibrillation, which can be detected on examination as an irregular pulse.