Poster A115, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
Interplay between early visual sensory processing impairments and glutathione dysregulation in early-phase psychosis.
Chrysa Retsa1, Jean-François Knebel1,2, Carina Ferrari3, Raoul Jenni3, Margot Fournier3, Michel Cuenod3, Stephanie Clarke1, Philippe Conus4, Kim Q. Do3, Micah M. Murray1,2,5,6; 1The Laboratory for Investigative Neurophysiology (The LINE), Lausanne University Hospital (CHUV), Lausanne, Switzerland, 2The EEG Brain Mapping Core, Center for Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne, Switzerland, 3Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital (CHUV), Lausanne, Switzerland, 4Service of General Psychiatry, Department of Psychiatry, Lausanne University Hospital (CHUV), Lausanne, Switzerland, 5Department of Hearing and Speech Sciences, Vanderbilt University, Nashville, TN, USA, 6Department of Hearing and Speech Sciences, Vanderbilt University, Nashville, TN, USA
Early sensory impairments are part of the core dysfunctions in schizophrenia. Deficits in the P1 component of the visual evoked potential (VEP) have been demonstrated in chronic patients and first-degree relatives. However, the subsequent N1 component is reported to be unaffected in chronic patients. In the auditory modality, impaired mismatch negativity (MMN) has been observed and may reflect NMDA hypo-function. Previous work has shown that add-on administration of the glutathione precursor N-acetyl-cysteine (NAC) improves the MMN and clinical symptoms in chronic schizophrenia patients. To date, it remains unknown whether NAC would also improve visual impairments and if its efficacy would extend to early-phase psychosis. We addressed these issues with a randomized, double-blind study of a sample (N=18) of early psychosis patients and 20 healthy controls from whom ERPs were recorded during a visual (Illusory contour) task. Patients were recorded twice: once prior to NAC/placebo administration and once after six months of treatment. Blood measures were likewise assessed of glutathione levels and key enzymes of glutathione metabolism. Analyses showed a P1 and an N1 reduction in the early psychosis patients compared to the healthy controls. Source estimation revealed reduced activity in patients in both frontal and occipital sources. Critically, NAC administration was found to improve the ERP deficits in the visual domain. In addition, further analyses suggest a linkage between the levels of the glutathione redox enzymes and the integrity of ERPs. Overall, these data indicate that NAC improves early sensory processing in this small sample of early psychosis patients.
Topic Area: PERCEPTION & ACTION: Vision