Exploratory study on the base-rate of paranoid ideation in a non-clinical Chinese sample

Recent findings from several large-scale community surveys suggest that delusions tend to occur in non-clinical samples as a continuous phenotype rather than as an all-or-none phenomenon. However, the majority of studies on the prevalence of delusions and paranoid ideation are limited to Western samples. The present study aims to examine the phenomenon and base-rate of paranoid ideation in a Chinese non-clinical sample. A total of 4951 undergraduates (65.9% male) completed a checklist for paranoid ideation and the Schizotypal Personality Questionnaire (SPQ). Participants were classified into individuals with and without schizotypal personality disorder (SPD) features based on the SPQ. For the frequency subscale, 2.1-18.2% of the participants without SPD features experienced certain types of paranoid ideation at least once a week during the survey. The prevalence rate even elevated to a higher proportion in conviction and distress dimensions. For the conviction subscale, 93-53.5% of the participants somewhat believed of the ideations. For the distress subscale, 14.7-31.3% of the participants felt somewhat distressing in the experienced paranoid ideation. Participants with SPD features reported significantly higher prevalence in most items across these three dimensions. Findings indicate a high base-rate of attenuated forms of psychotic-like symptoms in a non-clinical Chinese sample, and provide further evidence for the continuity of psychotic phenomenon in non-clinical samples. (C) 2009 Elsevier Ireland Ltd. All rights reserved.