Reactivity of the Vestibular System to Caloric Vestibular Stimulation in Schizophrenia

In schizophrenia, there is no conclusive link between psychopathology and vestibular dysfunction and we are not aware of any data that exists on the range of responses to caloric vestibular stimulation (CVS) in persons with schizophrenia. Initial data from another CVS study from our group suggests individuals with schizophrenia have greater reactivity to body temperature (37°C) CVS, as measured by the peak slow phase velocity of the resulting nystagmus (PSPV), than would be expected from individuals without schizophrenia versus healthy participants. Intriguingly, CVS at 37°C should not theoretically produce a significant vestibulocular reflex response due to the stimulus' approximation to body temperature. Hence, the primary aim of this study is to determine if individuals with schizophrenia will have greater vestibular reactivity, as measured by nystagmus PSPV, to CVS in comparison with healthy participants. The secondary aim is to assess illness awareness pre and post CVS administration in attempts to replicate our previous observation. A total of 20 patients with schizophrenia and 20 healthy control participants will be recruited. All participants will receive three conditions bilaterally: (1) body temperature (37°C) vestibular stimulation; (2) warm CVS (44°C), and (3) cold CVS (30°C).