BRIEF REPORT Electroencephalographic theta activity and cognition in schizophrenia: Preliminary results ADAM WICHNIAK 1, * , LUKASZ OKRUSZEK 3, * , MAGDALENA LINKE 1 , MICHAL JARKIEWICZ 1 , MALGORZATA JĘDRASIK-STYLA 1 , AGNIESZKA CIOLKIEWICZ 1 , ALEKSANDRA WIERZBICKA 2 , WOJCIECH JERNAJCZYK 2 & MAREK JAREMA 1 1 Third Department of Psychiatry, Institute of Psychiatry and Neurology,Warsaw, Poland, 2 Department of Clinical Neurophysiology, Institute of Psychiatry and Neurology,Warsaw, Poland, and 3 Department of Neuropsychology, Faculty of Psychology, University of Warsaw,Warsaw, Poland Abstract Objectives. MATRICS Consensus Cognitive Battery (MCCB) is a contemporary standard for assessment of cognitive func- tions in schizophrenia. The aim of the study was to examine the association between electroencephalographic spectral power and a wide range of cognitive functions measured with MCCB. Methods. Thirty-nine patients with schizophrenia (27 male, mean age 28.2  5.2 years) underwent EEG recordings and were assessed with MCCB. The EEG recordings were visually inspected and manually cleaned from artifacts and subjected to spectral analysis with EEGlab. Absolute and relative power as percentage of total spectral power were computed for frequency ranges from 0.5 to 30 Hz. To compare spectral power in patients with various cognitive functioning, patients from best and worst MCCB quartiles were selected. Results. Supe- rior cognitive performance was associated with less power of theta waves. Six MCCB cognitive tests showed significant correlations with absolute theta power and three tests with relative theta power. The correlation coefficients between MCCB composite score and theta power were r p 0.45 for absolute and r p 0.36 for relative values. Increased theta power was linked especially to memory deficits. Conclusions. These preliminary results suggest that electroencephalographic resting state theta power is an indicator of cognitive deficit in patients with schizophrenia. Key words: Schizophrenia, theta activity, EEG, cognitive functions, spectral EEG analysis Introduction Cognitive deficits are a prominent feature of schizo- phrenia and are being cited as a core symptom of the disorder (Wobrock et al., 2009). Cognitive decline is observed in a vast majority of the patients and may be characterized by both decrease in general intelli- gence and subtle deficits across multiple cognitive domains (Reichenberg and Harvey 2007). Multiple research programs addressed the issue of cognition in schizophrenia. One of the largest was NIMH- MATRICS initiative, which resulted in creating a MATRICS Consensus Cognitive Battery (MCCB) – a contemporary standard for assessing the cogni- tion in schizophrenia (Nuechterlein 2008). Beyond its original scope of serving as a measure of effects of cognition-enhancing drugs in schizophrenia, MCCB has been effectively used in concordance with various neuroimaging methods. MCCB scores have been shown to be associated with the measures of white matter fractional anisotropy (Li et al. 2013) or resting state fMRI global connectivity (Argyelan et al. 2014). Theta waves are slow-wave oscillations (4-8 Hz) which are recorded using electroencephalographic (EEG) methodologies and have been shown to be associated with working and episodic memory, spatial navigation processes, top-down control and emotional regulation processes in human (Mitchell * Both authors contributed equally to this work Correspondence: Adam Wichniak, MD, Institute of Psychiatry and Neurology, Third Department of Psychiatry, Sobieskiego 9, 02-957 Warsaw, Poland. Tel:  48-22-4582745. Fax:  48-22-8424087. E-mail: wichniak@ipin.edu.pl (Received 10 June 2014; accepted 11 September 2014) The World Journal of Biological Psychiatry, 2014; Early Online: 1–5 ISSN 1562-2975 print/ISSN 1814-1412 online © 2014 Informa Healthcare DOI: 10.3109/15622975.2014.966145 World J Biol Psychiatry Downloaded from informahealthcare.com by 156.17.54.204 on 10/24/14 For personal use only.