Event-related potentials and changes of brain rhythm oscillations during working memory activation in patients with first-episode psychosis

Event-related potentials and changes of brain rhythm oscillations during working memory activation in patients with first-episode psychosis


J Psychiatry Neurosci 2012;37(2):95-105

Pascal Missonnier, PhD, MedSc; François R. Herrmann, MD; Adriano Zanello, MSc; Maryse Badan Bâ, PhD; Logos Curtis, MD; Diana Canovas, MD; Fabrice Chantraine, MD; Jonas Richiardi, PhD; Panteleimon Giannakopoulos, MD; Marco C.G. Merlo, MD

Missonnier — Department of Psychiatry, Geneva University Hospitals and University of Geneva; Herrmann — Department of Internal Medicine, Rehabilitation and Geriatrics, University Hospitals of Geneva; Zanello, Badan Bâ, Curtis, Canovas, Chantraine, Merlo — Division of General Psychiatry, University Hospitals of Geneva; Richiardi — Medical Image Processing Lab, École Polytechnique Fédérale de Lausanne and University of Geneva; Giannakopoulos — Department of Psychiatry and Division of Old Age Psychiatry, University Hospitals of Geneva and University Hospitals of Lausanne, Switzerland


Background: Earlier contributions have documented significant changes in sensory, attention-related endogenous event-related potential (ERP) components and θ band oscillatory responses during working memory activation in patients with schizophrenia. In patients with first-episode psychosis, such studies are still scarce and mostly focused on auditory sensory processing. The present study aimed to explore whether subtle deficits of cortical activation are present in these patients before the decline of working memory performance.
Methods: We assessed exogenous and endogenous ERPs and frontal θ event-related synchronization (ERS) in patients with first episode psychosis and healthy controls who successfully performed an adapted 2-back working memory task, including 2 visual n-back working memory tasks as well as oddball detection and passive fixation tasks.
Results: We included 15 patients with first-episode psychosis and 18 controls in this study. Compared with controls, patients with first-episode psychosis displayed increased latencies of early visual ERPs and phasic θ ERS culmination peak in all conditions. However, they also showed a rapid recruitment of working memory– related neural generators, even in pure attention tasks, as indicated by the decreased N200 latency and increased amplitude of sustained θ ERS in detection compared with controls.
Limitations: Owing to the limited sample size, no distinction was made between patients with first-episode psychosis with positive and negative symptoms. Although we controlled for the global load of neuroleptics, medication effect cannot be totally ruled out.
Conclusion: The present findings support the concept of a blunted electroencephalographic response in patients with first-episode psychosis who recruit the maximum neural generators in simple attention conditions without being able to modulate their brain activation with increased complexity of working memory tasks.

Submitted Apr. 4, 2011; Revised July 25, Sept. 1, 2011; Accepted Sept. 6, 2011.

Acknowledgments: This project was funded by the Swiss National Foundation for Scientific Research, grant 3100A0/103770/1, and the Research and Development Hospital, grant 02-1-122.

Competing interests: None declared for P. Missoner, F.R. Hermann, A. Zanello, M. Badan Bâ, L. Curtis, D. Canovas, F. Chantraine, J. Richiardi and P. Giannakopoulos. M.C.G. Merlo declares board membership at Sandoz and declares having received speaker fees from AstraZeneca, Bristol-Myers Squibb, Essex Chemie AG, GlaxoSmith Kline, Janssen-Cilag, Eli Lilly, Lundbeck, Mepha, Novartis, Pfizer, Sandoz, Sanofi, Servier, Vifor Pharma and Zeller. He also received funding for travel, accommodations and meeting expenses from Eli Lilly and Pfizer.

Contributors: P. Missonnier, P. Giannakopoulos and M.C.G. Merlo designed the study. P. Missonnier, L. Curtis, D. Canovas, F. Chantraine and J. Richiardi acquired the data. P. Missonnier, F.R. Hermann, A. Zanello, M. Badan Bâ, P. Giannakopoulos and M.C.G.Merlo analyzed the data. P.Missonnier, F.R. Hermann, L. Curtis, P. Giannakopoulos and M.C.G.Merlo wrote the article. All authors reviewed the article and approved its publication.

DOI: 10.1503/jpn.110033

Correspondence to: P. Missonnier, 2 chemin du Petit-Bel-Air, Chêne-Bourg, Geneva, Switzerland 1225; pascal.missonnier-evrard@hcuge.ch