A PET study found that variation in schizotypal personality traits was associated with amphetamine-evoked dopamine-related changes. The finding concerned a research sample screened for psychiatric illness; it was not a diagnostic test for schizophrenia.
Woodward and colleagues studied 63 healthy individuals using a self-report Schizotypal Personality Questionnaire and fluorine-18 fallypride PET. Imaging was performed at baseline and after oral d-amphetamine, 0.43 mg/kg.
The investigators related changes in radioligand binding to questionnaire scores using regional and voxel-wise analyses. The binding change was interpreted as an index of dopamine release under the challenge conditions.
Overall schizotypal traits correlated positively with the dopamine-related response in the striatum, particularly its associative subdivision. Other analyses identified associations in cortical regions. Exploratory factor analyses linked disorganized traits with responses in several additional areas.
The exploratory results should remain distinguished from the main analyses. A regional correlation also does not establish that every person with a higher questionnaire score has the same physiological response.
Fallypride displacement is not a blood amphetamine concentration, and a questionnaire score is not a clinical diagnosis. The study does not establish a direct conversion between either measure and acute impairment.
The authors called for replication across a broader range of traits. They also noted that screening did not rule out all personality-disorder diagnoses and that interview-based trait assessment might produce different results from self-report.
The findings do not show that amphetamine caused schizophrenia or that a particular participant would develop psychosis. Establishing future clinical risk requires prospective evidence and validated prediction beyond a sample correlation.
The study supports investigation of individual differences in dopamine responsivity. It cannot establish a person’s diagnosis, credibility, decision-making capacity or functional impairment during a separate event.
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