Auditory steady-state EEG response across the schizo-bipolar spectrum

Area of Science:

• Neuroscience
• Psychiatry
• Biomarkers

Background:

• Auditory steady-state responses (aSSRs) in the gamma range (30-90 Hz) are potential biomarkers for schizophrenia.
• Investigating aSSR deviations' specificity across the psychosis spectrum is crucial.

Purpose of the Study:

• To determine if aSSR deviations are specific to schizophrenia across the psychosis dimension.
• To assess if aSSR deviations are specific to particular frequency bands.
• To examine the presence of aSSR deviations in bipolar I disorder without psychosis (BDNP).

Main Methods:

• Compared gamma-range aSSRs (20, 40, 80 Hz) using EEG in schizophrenia (SZ), schizoaffective disorder (SAD), bipolar disorder with psychosis (BDP), BDNP, and healthy controls (HC).
• Quantified standard aSSR measures (STP, ITC), evoked responses, and pre-stimulus power.
• Utilized multivariate canonical discriminant analysis for group differentiation.

Main Results:

• Psychosis groups exhibited reduced ITC at 20 Hz and reduced STP/ITC at 40 and 80 Hz, indicating dimensional aSSR reductions across the psychosis spectrum.
• Elevated pre-stimulus power was observed in all probands, potentially affecting neural entrainment.
• Onset/Offset and 80 Hz ITC responses were key for group discrimination, showing dimensional reduction across the schizo-bipolar spectrum.

Conclusions:

• Deviant aSSRs are present across the schizo-bipolar spectrum.
• Psychosis status and severity correlate with greater aSSR reductions, particularly at low and high gamma frequencies.
• These findings support aSSR deviations as potential biomarkers for psychosis spectrum disorders.