Aberrant Affective Salience Attribution as a Risk Factor for Psychosis-Proneness: Insights from the Twinsscanchina Study

Abstract

BACKGROUND: Individuals with psychosis are frequently affected by auditory hallucinations. These aberrant perceptual experiences might arise from mis-assignment of salience to irrelevant auditory stimuli. For example, it was previously shown that aberrant emotional-meaning assignment to white noise (affective speech illusion) was more prevalent in patients with a psychotic disorder than in healthy controls. Furthermore, there was a progressively greater incidence of affective speech illusion with increasing familial vulnerability to psychosis. It was also found that in healthy controls, any type of speech illusions was strongly associated with positive schizotypy, but not with negative schizotypy. This study seeks to clarify the relationship between affective speech illusion and psychotic experiences in a Chinese subclinical population. It is hypothesized that presence of affective speech illusion predicts higher positive schizotypy scores. METHODS: Data were collected from 72 pairs of healthy Chinese adolescent twins (Mean age = 16.75) with no known familial or personal history of mental disorder. White noise speech illusion was measured using the White Noise Task: participants rated white noise clips as being speech with positive, negative, neutral, or uncertain valence; or no speech. Endorsements of positive and negative speech indicated “affective” speech illusion. Psychosis proneness was measured using the Community Assessment for Psychic Experiences (CAPE): a self-report 42-item questionnaire designed to measure the frequency and level of distress of psychotic-like experiences in the general population. The CAPE includes dimensions of positive psychotic experiences, negative psychotic experiences and depressive experiences. RESULTS: Multilevel linear modelling revealed that “negative speech illusion” significantly predicted CAPE positive dimension scores (b=0.26, 95% CI = 0.022, 0.51; p=0.033). Participants who assigned negative meaning to white noise reported more positive psychotic experiences. Negative speech illusion was also a marginally significant predictor of CAPE total scores (b=0.22, 95% CI = −0.02, 0.46; p=0.075). Specifically, there was a trend for participants who assigned negative meaning to white noise to report more psychotic experiences overall. DISCUSSION: Negative speech illusion independently predicted positive psychotic experiences, as well as showed a marginal effect in predicting overall psychotic experiences. The finding suggests that negative-meaning attribution to random noise in incoming auditory information might be the mechanism underlying positive psychotic experiences such as auditory hallucination. Auditory hallucinations that carried a negative emotional value then had to be “explained”, resulting in delusions over time and hence maintaining or exacerbating positive schizotypy symptoms. Through the use of a subclinical population, our findings suggest that negative speech illusion was not due to the illness experience in psychotic patients, supporting it as potential vulnerability markers for positive psychotic symptoms.