Stress, epileptiform symptoms in schizophrenia and neural information transmission.

Background: Several findings indicate that stress may influence epileptiform discharges manifesting in temporal-limbic areas, which may become a potential trigger of psychosis that may manifest without neurologically diagnosed epilepsy. Some findings suggest that measures assessing levels of inter-hemispheric information connection may reveal the spread of subclinical epileptiform neural activity associated with psychotic and seizure-like symptoms. Recent research also suggests that electrodermal activity (EDA), which is related to limbic activations, may allow indirect measurement of interhemispheric information transmission. These findings about the interhemispheric spread of information suggest a hypothesis that heightened spread of information between the brain hemispheres might indirectly indicate epileptiform discharges spreading between hemispheres.

Methods: We have analyzed and measured EDA and also cognitive and affective epileptic-like symptoms (CPSI, complex partial seizure-like symptoms), symptoms of chronic stress (Trauma Symptoms Checklist-40, TSC-40), and psychotic symptoms in 31 schizophrenia patients and compared these data with 31 healthy controls.

Results: The results indicate that in schizophrenia patients, the values of pointwise transinformation (PTI) calculated from right and left EDA time series are related to CPSI symptoms (Spearman correlation between CPSI and PTI is R = 0.48; p < 0.01) and symptoms of chronic stress (Spearman correlation between TSC-40 and PTI is R = 0.37, p < 0.05); both during mild stress conditions caused by conflicting (incongruent) Stroop task.

Conclusion: The analysis indicates potentially diagnostically useful results suggesting that heightened PTI values may reflect autonomic activations that hypothetically might be linked to higher interhemispheric transmission related to spreading of epileptiform discharges between hemispheres.