Increased schizotypy scores in normal subjects following the oral administration of d-amphetamine

Abstract

The dimensional view of schizophrenia states that psychotic symptoms can be measured along a continuum in the normal population. These sub-clinical psychotic-type experiences in normal subjects are termed schizotypal traits and are thought to reflect a fairly stable dimension of personality. The schizotypal framework views schizophrenia as representing an extreme end of the normal continuum and not as a discrete syndrome. The hypothesised relationship between schizotypy and schizophrenia is supported by findings that behavioural tasks sensitive to cognitive abnormalities characteristic of schizophrenia are also found to be abnormal in normal subjects with high schizotypal scores. Recent preliminary findings also suggest an association between schizotypy and dopamine D2 binding. A psychopharmacological study is presented where a measure of schizotypy (Eysenck's Psychoticism scale) was found to be significantly increased following a single oral dose of 5 mg or 10 mg d-amphetamine in normal subjects (F(2,57) = 3.34, p<0.04; N = 60). These results suggest that schizotypy not only reflects sub-clinical schizophrenic phenomenology but also may suggest a similar underlying neurochemistry. In addition, the results indicate that measures of schizotypy in normal subjects may not reflect stable traits but may rather measure a state variable that is prone to fluctuation, just as schizophrenic symptoms themselves may fluctuate over time.