Early somatosensory processing in individuals at risk for developing psychoses

Area of Science:

• Neuroscience
• Psychiatry
• Neurophysiology

Background:

• Somatosensory evoked potentials (SEPs) are crucial for understanding thalamocortical and early cortical processing.
• Previous research indicates altered SEPs in schizophrenia patients.
• This study investigates SEPs in individuals at risk for schizophrenia and bipolar disorders.

Purpose of the Study:

• To determine if SEP alterations are present in individuals at clinical high risk for schizophrenia or bipolar disorders.
• To compare early cortical processing between these at-risk groups and healthy controls.
• To explore potential neurophysiological markers of psychosis vulnerability.

Main Methods:

• Median nerve SEPs were recorded using multichannel EEG.
• Participants included individuals at risk for bipolar disorder, high-risk and ultra-high-risk for schizophrenia, and a healthy control group.
• Dipole source analysis was used to compare low- and high-frequency SEP components between groups.

Main Results:

• Reduced low- and high-frequency source activity in SEPs was observed in both schizophrenia risk groups compared to the bipolar risk group.
• High-frequency oscillation (HFO) amplitudes were significantly reduced in high-risk schizophrenia subjects versus controls.
• These SEP alterations were more pronounced in cannabis non-users and correlated with positive symptom severity.

Conclusions:

• Early cerebral somatosensory processing impairments may be specific to the risk for schizophrenia, distinguishing it from bipolar disorder risk.
• Neurophysiological alterations in SEPs might precede psychosis onset, serving as a vulnerability indicator for schizophrenia.
• These findings highlight the potential of SEPs as a biomarker for schizophrenia risk.