ORIGINAL INVESTIGATION Acute effects of methadone on EEG power spectrum and event-related potentials among heroin dependents Farid Motlagh 1,2 & Fatimah Ibrahim 1,2 & Rusdi Rashid 3 & Niusha Shafiabady 4 & Tahereh Seghatoleslam 3 & Hussain Habil 5 Received: 12 March 2018 /Accepted: 7 September 2018 /Published online: 11 October 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Methadone as the most prevalent opioid substitution medication has been shown to influence the neurophysiological functions among heroin addicts. However, there is no firm conclusion on acute neuroelectrophysiological changes among methadone-treated subjects as well as the effectiveness of methadone in restoring brain electrical abnormalities among heroin addicts. This study aims to investigate the acute and short-term effects of methadone administration on the brain’ s electrophysiological properties before and after daily methadone intake over 10 weeks of treatment among heroin addicts. EEG spectral analysis and single-trial event-related potential (ERP) measurements were used to investigate possible alterations in the brain’ s electrical activities, as well as the cognitive attributes associated with MMN and P3. The results confirmed abnormal brain activities predominantly in the beta band and diminished information processing ability including lower amplitude and prolonged latency of cognitive responses among heroin addicts compared to healthy controls. In addition, the alteration of EEG activities in the frontal and central regions was found to be associated with the withdrawal symptoms of drug users. Certain brain regions were found to be influenced significantly by methadone intake; acute effects of methadone induction appeared to be associative to its dosage. The findings suggest that methadone administration affects cognitive performance and activates the cortical neuronal networks, resulting in cognitive responses enhancement which may be influential in reorganizing cognitive dysfunctions among heroin addicts. This study also supports the notion that the brain’ s oscillation powers and ERPs can be utilized as neurophysiological indices for assessing the addiction treatment traits. Keywords Neuro-electrophysiology . Spatial-spectral analysis . Methadone maintenance treatment (MMT) . Cognitive dysfunction Introduction Brain electrical activity properties including electroencephalo- graphic (EEG) activities and brain event-related potentials (ERPs) measurements have been used for detailed investigation of brain electrophysiological changes, as well as cognitive biases and information processing related to pre-attentive processing, attentional deficit, and response inhibition among heroin addicts (Motlagh et al. 2016). Previous EEG and ERP studies in the field confirmed that chronic opioid abuse leads to impairments in the central nervous system (CNS) activity, attention, and working memory (Davydov and Polunina 2004; Fingelkurts et al. 2006; Franken et al. 2004; Morie et al. 2014; Polunina and Davydov 2004; Polunina and Davydov 2006; Yang et al. 2009). Methadone as the most prevalent opioid substitution ther- apy has been used to prevent symptoms of substance with- drawal (Ball and Ross 1991; Simpson and Sells 1982). A small number of studies, investigating EEG characteristics among the methadone-treated subjects, showed positive Highlights • Acute effects of methadone administration on the brain ’s electrophysiological properties • EEG spectral analysis and single-trial ERP measurements were uti- lized in this study • Methadone enhances the cognitive responses and alternates the brain spectral oscillations * Farid Motlagh farid_motlaq@hotmail.com 1 Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia 2 Centre for Innovation in Medical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia 3 Centre of Addiction Sciences, University of Malaya, 21st Floor, Wisma Research and Development, Jalan Pantai Baru, 59200 Kuala Lumpur, Malaysia 4 International Medical University, Kuala Lumpur, Malaysia 5 The head of psychiatry department, Mahsa University, Kuala Lumpur, Malaysia Psychopharmacology (2018) 235:3273–3288 https://doi.org/10.1007/s00213-018-5035-0