Is the intensity of Schneiderian symptoms related to handedness and speech disorder in subjects with psychosis?

Objective: To explore the links between Schneiderian first-rank symptoms (FRS), handedness and speech disorder in subjects with psychosis.

Methods: A Schneiderian score was calculated by summing seven items of the Scale for the Assessment of Positive Symptoms (SAPS) exploring first-rank symptoms in 33 hospitalized patients presenting with psychotic symptoms. Speech disorder was rated using the Scale for the Assessment of Thought, Language and Communication Disorders (TLC). Handedness was assessed using the Edinburgh Handedness Inventory.

Results: Higher Schneiderian score was independently predicted by reduced right-hand preference and by lower TLC score. The associations between Schneiderian score and lateralisation or speech disorder were independent from level of psychotic and depressive symptoms, and from categorical diagnosis.

Conclusion: The present study adds further support to the hypothesis that loss of normal cerebral asymmetry may be implicated in the emergence of FRS.