NREM sleep EEG and wake ERP summary: The first wave of the Global Research Initiative on the neurophysiology of schizophrenia (GRINS)

Motivated by the potential of objective neurophysiological markers to
index thalamocortical function in patients with severe psychiatric
illnesses, we comprehensively characterized key NREM sleep parameters
across multiple domains, their interdependencies, and their relationship
to waking event-related potentials and symptom severity. In 72
schizophrenia (SCZ) patients and 58 controls, we confirmed a marked
reduction in sleep spindle density in SCZ and extended these findings to
show that fast and slow spindle properties were largely uncorrelated. We
also describe a novel measure of slow oscillation and spindle interaction
that was attenuated in SCZ. The main sleep findings were replicated in a
demographically distinct sample, and a joint model, based on multiple NREM
components, statistically predicted disease status in the replication
cohort. Although also altered in patients, auditory event-related
potentials elicited during wake were unrelated to NREM metrics. Consistent
with a growing literature implicating thalamocortical dysfunction in SCZ,
our characterization identifies independent NREM and wake EEG biomarkers
that may index distinct aspects of SCZ pathophysiology and point to
multiple neural mechanisms underlying disease heterogeneity. This study
lays the groundwork for evaluating these neurophysiological markers,
individually or in combination, to guide efforts at treatment and
prevention as well as identifying individuals most likely to benefit from
specific interventions.