Electroencephalography in eating disorders

Neuropsychiatric Disease and Treatment Dovepress open access to scientific and medical research R evie w Open Access Full Text Article Neuropsychiatric Disease and Treatment downloaded from https://www.dovepress.com/ by 14.162.154.58 on 24-Sep-2020 For personal use only. Electroencephalography in eating disorders This article was published in the following Dove Press journal: Neuropsychiatric Disease and Treatment 23 December 2011 Number of times this article has been viewed Ignacio Jáuregui-Lobera 1,2 Behavioral Sciences Institute, Pablo de Olavide University, Seville, Spain 1 2 Introduction Correspondence: Ignacio Jáuregui-Lobera Virgen del Monte 31, Seville 41011, Spain Tel +34 95 428 0789 Fax +34 95 427 8167 Email submit your manuscript | www.dovepress.com Dovepress http://dx.doi.org/10.2147/NDT.S27302 Powered by TCPDF (www.tcpdf.org) Abstract: Clinical applications of electroencephalography (EEG) are used with different objectives, EEG being a noninvasive and painless procedure. In respect of eating disorders, in the 1950s a new line of study about the neurological bases of anorexia nervosa was started and has since been developed. The purpose of this review is to update the existing literature data on the main findings in respect of EEG in eating disorders by means of a search conducted in PubMed. Despite the fact that weight gain tends to normalize some brain dysfunctions assessed by means of EEG, the specific effect of gaining weight remains controversial. Different studies have reported that cortical dysfunctions can be found in patients with anorexia nervosa even after weight gain, whereas others have reported a normalization of EEG in respect of the initial reduced alpha/ increased beta power in those patients with refeeding. Findings of studies that have analyzed the possible relationship between eating disorders and depression, based on sleep EEG disturbances, do not support the idea of eating disorders as a variant of depression or affective disorders. Some EEG findings are very consistent with previous neuroimaging results on patients with anorexia nervosa, reporting neural disturbances in response to stimuli that are relevant to the pathology (eg, stimuli like food exposure, different emotional situations, or body images). Keywords: electroencephalography, event-related potentials, sleep, depression, refeeding, weight gain Electroencephalography (EEG) is the recording of electrical activity along the scalp produced by the firing of neurons within the brain,1 reflecting the synchronized and desynchronized oscillations of the overall cortical activity in the brain.2 Brain patterns form wave shapes that are commonly sinusoidal, and the brain state of the individual may make certain frequencies more dominant. Brain waves have been categorized into four basic groups (delta: 0.5–4 Hz; theta: 4–8 Hz; alpha: 8–13 Hz; beta: .13 Hz).3 With regard to the study of cognitive processes, the most useful application of EEG recording is the event-related potentials (ERP) technique. Mental processes (eg, perception, selective attention, language processing) occur in milliseconds; thus, whereas neuroimaging techniques localize regions of activation during mental tasks, some EEG applications can define the time course of these activations. In addition, quantitative EEG can better determine spatial structures and localize areas with brain activity or abnormality.3 EEG is an image technique that, among others, is included in the group of so-called electrobiological measurements like electrocardiography, electromyography, and magnetoencephalography. In addition to these measurements, another way to explore the human body is to apply other imaging techniques based on other physical principles. Neuropsychiatric Disease and Treatment 2012:8 1–11 1 © 2012 Jáuregui-Lobera, publisher and licensee Dove Medical Press Ltd. This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited. Dovepress Neuropsychiatric Disease and Treatment downloaded from https://www.dovepress.com/ by 14.162.154.58 on 24-Sep-2020 For personal use only. Jáuregui-Lobera Computer tomography, magnetic resonance imaging, functional magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography are the most relevant techniques in this group.3 Clinical applications of EEG are used with different objectives (eg, to investigate epilepsy, to investigate sleep disorders, to monitor alertness, in coma or brain death), EEG being a noninvasive and painless procedure. With regard to the study of cognitive processes, the most useful application of EEG recording is the ERP technique.4,5 Mental processes (eg, perception, selective attention, language processing) occur in milliseconds; thus, whereas positron emission tomography or magnetic resonance imaging localize regions of activation during mental tasks, ERP can define the time course of these activations. In addition, quantitative EEG can better determine spatial structures and localize areas with brain activity or abnormality.3 ERPs are voltage fluctuations that are associated in time with some physical or mental occurrence. These can be recorded from the human scalp and extracted from the ongoing EEG by means of filtering and signal averaging.5 In the field of eating disorders, articles by Goor6 (1954) and Martin7 (1955) started a new line of study about neurological bases of anorexia nervosa. Nevertheless, in 1973, the Royal College of Physicians (London, UK) held a clinicopathological conference on a case of anorexia nervosa and, during the course of the conference, some attendants realized that in the case report there were no EEG data and they asked for them.8 It was mainly in the 1980s when a series of studies was developed applying EEG to eating disorders. The purpose of this review is to update the existing data on the main findings in respect of EEG in eating disorders. Methods The current review was conducted by means of a search of PubMed. The following search terms were used: “EEG and eating disorders,” “neurophysiology and eating disorders,” “quantitative EEG and eating disorders,” “event-related potentials and eating disorders,” “polysomnography and eating disorders,” “electro-occulogram and eating disorders,” “haptic exploration tasks and eating disorders,” and “contingent negative variation and eating disorders.” As a result, a total of 309 articles were obtained, excluding all of those that were not specifically focused on anorexia and/or bulimia nervosa, sleeprelated eating disorders, or binge eating (BE). In respect of case reports, due to the shortage of articles specifically focused on these disorders, one related to the first mention of EEG in the literature on eating disorders was considered, as well as two case reports based on sleep-related eating disorders. 2 Powered by TCPDF (www.tcpdf.org) submit your manuscript | www (...truncated)