Observational study identifies sensory perception differences in schizophrenia and first-episode psychosis

Objective: Characterization of psychosis typically relies on cognitive and behavioral assessments. This study suggests the use of feature-specific sensory experiments to detect subtle perceptual alterations in early psychosis. Methods: Patients (N=120) diagnosed with schizophrenia (SCHZ, N=45), bipolar disorder (BIP, N=36), or first-episode psychosis (FEP, N=39), recruited from public mental health facilities in Brazil, were compared with age-matched healthy controls (HCSCHZ, HCBIP, and HCFEP; pooled from N=94). Independent psychophysical measurements were obtained within each group. The Pictorial-Size-Test (PST) assessed pictorial size perception. Sound-Appreciation-Test (SAT) assessed auditory discomfort. Results: SCHZ circled larger perceived sizes than HCSCHZ (power=95%, d=0.63, p<0.0001), FEP circled larger perceived sizes than HCFEP (power=99%, d=2.86, p<0.0001), but BIP did not perceive larger sizes than HCBIP in PST. SCHZ reported higher levels of discomfort than HCSCHZ (power=99%, d=1.29, p<0.0005), BIP reported higher levels of discomfort than HCBIP (power=99%, d=2.73, p<0.0001) and FEP reported higher levels of discomfort than HCFEP (power=99%, d=1.46, p<0.0003) on SAT. Conclusions: The findings suggest that low-cost psychophysical measurements can provide information about sensory alterations in early psychosis revealing dissimilar patterns between schizophrenia and bipolar disorder. Such patterns are not readily perceived by physician-patient interaction but may add to overall clinical judgement.