Personality Disorders: Toward the DSM-V.
chapter 5
Schizotypal personality disorder
The DSM-IV diagnostic criteria for schizotypal personality disorder (SPD) include attenuated versions of the defining features of schizophrenia.
Prevalence of SPD
The prevalence of schizotypal personality disorder in the general population is 3%, according to the DSM-IV.
The concept of SPD hinges on its genetic link with schizophrenia.
SPD and schizophrenia share common features such as: odd beliefs, social impairment and abnormalities in perceptual experiences and emotional expression.
SPD criteria specify an attenuated version of the psychotic symptoms necessary for a schizophrenia diagnosis.
SPD and schizophrenia share a genetic liability. Environmental factors also play a key role.
The relationship between negative expressed emotion in family members and poor outcome in patients appears to be bidirectional.
The developmental link between SPD and schizophrenia
SPD and schizophrenia share a developmental link.
SPD signs, and even the full SPD syndrome, often predate the onset of schizophrenia.
Those who meet criteria for SPD show functional deficits and physical abnormalities that parallel those observed in schizophrenia, although the magnitude of the deficits typically is less severe in SPD.
Cognitive functioning
Adults who meet the criteria of SPD show: general cognitive impairment, including deficits in verbal fluency, learning and retention, deficits in sustained attention and mixed findings in respect to executive functioning.
Motor and physical correlates of SPD
Individuals with SPD manifest abnormalities in motor functions.
Psychophysiology
There are abnormal psychophysiological responses in both schizophrenia and SPD. Abnormalities have been found in prepulse inhibition, heart rate, electrodermal activities, and other autonomic nervous system-controlled responses.
Structural brain abnormalities
SPD patients have larger ventricular volumes, reduced cortical gray matter volumes, and smaller temporal lobes.
Functional brain abnormalities
Individuals with SPD manifest functional brain abnormalities, particularly in the frontal and temporal regions.
Neurochemistry
There are elevated dopamine levels in SPD that mimic the pattern found in schizophrenia. SPD adolescents manifest elevated cortisol levels.
