PSYCHOMETRIC INVESTIGATION OF SELF-REPORTED THOUGHT DISORDER IN NON-CLINICAL SAMPLES

Abstract Background Some dimensional models of psychosis predict that clinical phenomena are continuous with non-clinical phenomena. As such, Barrera et al. (2015) developed a self-report questionnaire to measure experiences akin to thought disorder (TD) in non-clinical populations. However, this measure requires further psychometric investigation. The current work seeks to replicate the three-factor structure of responses to the questionnaire that have been reported previously in a non-clinical sample, and to determine whether these responses predict other measures of schizotypal experiences, as well as measures of other personality characteristics (neuroticism and extraversion), and social adversity. Methods The 29-item questionnaire was used within an anonymous online survey to collect self-reported TD ratings from samples of 300 university students and 166 people from the general population. The survey also included the Schizotypal Personality Questionnaire (SPQ), neuroticism and extraversion scales from the International Personality Item Pool (IPIP), and the Social Defeat Scale. Results Of the self-report TD ratings collected from the student sample, an exploratory minimum rank factor analysis indicated the presence of three factors (Odd Speech, Poor Memory and Monitoring of Speech, and Difficulties with Initiating and Sustaining Conversation), which explained 56.5% of the variance and showed internal consistency (ordinal α ≥ 0.88). Odd Speech and Poor Memory and Monitoring of Speech factor scores showed stronger correlations with scores from the Odd Speech Scale of the SPQ (r ≥ 0.55, p < 0.001) than with other SPQ scale scores and IPIP personality scores. However, Difficulties with Initiating and Sustaining Conversation factor scores correlated strongly with other negative-like symptom scales from the SPQ, as well as with IPIP extraversion scores. A multiple regression analysis showed that, out of the three factors, Poor Memory and Monitoring of Speech scores predicted greater Social Defeat Scale scores independently of SPQ total scores and the IPIP extraversion and neuroticism scores, though the latter was the most important predictor. The results were very similar when the correlation and regression analyses were repeated in the non-student sample from the general population. Discussion The findings replicate Barrera et al.’s (2015) work, suggesting that TD-like experiences are multidimensional when measured in non-clinical samples using the self-report questionnaire. Although items intended to capture negative TD-like experiences might reflect introversion, items assessing oddities of speech and speech monitoring may not be entirely accounted for by existing measures of personality and schizotypy. Furthermore, since social defeat is linked to the risk factors of psychosis, some aspects of self-reported TD might prove useful in exploring the mechanisms of developing psychosis. Additional data is currently being collected to further investigate the replicability and generalizability of these findings.