Madiha Shaikh1, Anirban Dutt2, Matthew R Broome3, Alberto G Vozmediano4, Siri Ranlund5, Alvaro Diez5, Olalla Caseiro6, Julia Lappin2, Susan Amankwa2, Francesco Carletti2, Paolo Fusar-Poli2, Muriel Walshe2, Mei-Hua Hall7, Oliver Howes2, Lyn Ellett8, Robin M Murray2, Philip McGuire2, Lucia Valmaggia2, Elvira Bramon9. 1. NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK; Department of Psychology, Royal Holloway, University of London, UK. Electronic address: Madiha.1.Shaikh@kcl.ac.uk. 2. NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK. 3. University of Warwick, Warwick Medical School, Coventry, UK. 4. Psychiatry Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain. 5. Division of Psychiatry & Institute of Cognitive Neuroscience, University College London, W1W 7EJ, UK. 6. University Hospital Marqués de Valdecilla, IFIMAV, Spain. 7. Psychology Research Laboratory, Harvard Medical School, McLean Hospital, Belmont, MA, USA. 8. Department of Psychology, Royal Holloway, University of London, UK. 9. NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, King's College London, The South London and Maudsley NHS Foundation Trust, London, UK; Division of Psychiatry & Institute of Cognitive Neuroscience, University College London, W1W 7EJ, UK.
Abstract
BACKGROUND: Individuals with an "Attenuated Psychosis Syndrome" (APS) have a 20-40% chance of developing a psychotic disorder within two years; however it is difficult to predict which of them will become ill on the basis of their clinical symptoms alone. We examined whether P50 gating deficits could help to discriminate individuals with APS and also those who are particularly likely to make a transition to psychosis. METHOD: 36 cases meeting PACE (Personal Assessment and Crisis Evaluation) criteria for the APS, all free of antipsychotics, and 60 controls performed an auditory conditioning-testing experiment while their electroencephalogram was recorded. The P50 ratio and its C-T difference were compared between groups. Subjects received follow-up for up to 2 years to determine their clinical outcome. RESULTS: The P50 ratio was significantly higher and C-T difference lower in the APS group compared to controls. Of the individuals with APS who completed the follow-up (n=36), nine (25%) developed psychosis. P50 ratio and the C-T difference did not significantly differ between those individuals who developed psychosis and those who did not within the APS group. CONCLUSION: P50 deficits appear to be associated with the pre-clinical phase of psychosis. However, due to the limitations of the study and its sample size, replication in an independent cohort is necessary, to clarify the role of P50 deficits in illness progression and whether this inexpensive and non-invasive EEG marker could be of clinical value in the prediction of psychosis outcomes amongst populations at risk.
BACKGROUND: Individuals with an "Attenuated Psychosis Syndrome" (APS) have a 20-40% chance of developing a psychotic disorder within two years; however it is difficult to predict which of them will become ill on the basis of their clinical symptoms alone. We examined whether P50 gating deficits could help to discriminate individuals with APS and also those who are particularly likely to make a transition to psychosis. METHOD: 36 cases meeting PACE (Personal Assessment and Crisis Evaluation) criteria for the APS, all free of antipsychotics, and 60 controls performed an auditory conditioning-testing experiment while their electroencephalogram was recorded. The P50 ratio and its C-T difference were compared between groups. Subjects received follow-up for up to 2 years to determine their clinical outcome. RESULTS: The P50 ratio was significantly higher and C-T difference lower in the APS group compared to controls. Of the individuals with APS who completed the follow-up (n=36), nine (25%) developed psychosis. P50 ratio and the C-T difference did not significantly differ between those individuals who developed psychosis and those who did not within the APS group. CONCLUSION: P50 deficits appear to be associated with the pre-clinical phase of psychosis. However, due to the limitations of the study and its sample size, replication in an independent cohort is necessary, to clarify the role of P50 deficits in illness progression and whether this inexpensive and non-invasive EEG marker could be of clinical value in the prediction of psychosis outcomes amongst populations at risk.