Electroencephalography in eating disorders

Figures & data

Table 1 Studies on sleep electroencephalography and eating disorders

Authors	Year	Sample	Technique	Results
Crisp et al^Citation9	1971	10 AN women	Sleep EEG	Total time asleep/night increases with treatment
Lacey et al^Citation10,Citation11	1975, 1976	10 AN (1 man, 9 women)	EOG, EEG, EMG	Increase of sleep and REM sleep during refeeding
Walsh et al^Citation12	1985	8 AN, 16 BN (normal weight), 14 control (normal weight) – all women	Sleep EEG	Patients with AN spent less time asleep and less time in stage 1 sleep than patients with BN and normal controls
Delvenne et al^Citation14	1992	11 AN women, 11 depressed, 11 healthy patients	Sleep EEG	Patients with AN showed less sleep efficiency, longer awakenings, and less REM sleep. Patients with AN-purging had an increase in stage 3 sleep
Nobili et al^Citation16	1999	10 AN women, 10 matched controls	Sleep EEG	Patients with AN showed an increase of wakefulness after sleep onset, and a reduction of SWS
Nobili et al^Citation15	2004	20 AN women, 12 matched controls	Polysomnography	Patients with AN showed an increase of wakefulness after sleep onset, a higher number of arousals, and a reduction of SWS and SWA during total sleep time

Abbreviations: AN, anorexia nervosa; BN, bulimia nervosa; EEG, electroencephalography; EOG, electrooculogram; EMG, electroencephalography; REM, rapid eye movement; SWA, slow-wave activity; SWS, slow-wave sleep.

Table 2 Studies on electroencephalography, refeeding, and weight gain

Authors	Year	Sample	Technique	Results
Rothenberger et al^Citation25	1991	39 AN inpatients, 27 cross-section, 12 longitudinal, 12 emotionally disturbed inpatients	AEP	Tendency to normalize modulation of sensory information after weight gain in AN
Bradley et al^Citation26	1997	20 AN, 20 control women	ERP	Brain dysfunction in AN only partially normalizes with weight gain
Grunwald et al^Citation28	2001	10 AN women, 10 control women	EEG during haptic exploration tasks	Cortical dysfunction and deficits in somatosensory integration processing of the right parietal cortex in AN even after weight gain
Grunwald et al^Citation29	2004	10 AN, 10 healthy controls	EEG during haptic exploration tasks	Theta asymmetry over central regions was observed in AN during starvation as well as after weight gain while performing the tasks
Hatch et al^Citation30	2011	37 AN first admission, 45 controls, 28 AN after refeeding	Resting EEG	“Eyes open” (underweight AN): reduced relative alpha power and increased beta power in frontal regions. Increase in alpha and decrease in beta were found when refeeding. “Eyes closed” (underweight AN): elevated theta in parietal-occipital regions, which remained after refeeding

Abbreviations: AN, anorexia nervosa; AEP, auditory event-related potentials; ERP, event-related potentials.

Table 3 Stimuli presentation and electroencephalography in eating disorders

Authors	Year	Sample	Technique	Results
Tóth et al^Citation38	2004	9 patients with AN (7 women), 10 healthy controls	Multichannel EEG, gustatory stimuli – unpleasant (bitter tea), pleasant (chocolate)	Patients with AN showed lower-dimensional complexity than healthy controls. No hemispheric difference in patients with AN
Tóth et al^Citation39	2004	9 outpatients with AN (7 women), 9 matched controls	EEG, gustatory stimuli – sweet (milk chocolate), bitter (black tea)	Higher percent of theta and lower percent of alpha-1 in AN, irrespective of the type of taste effects and hemisphere
Pollatos et al^Citation50	2008	12 AN women, healthy controls	VEP, visual stimuli – emotional faces	Increased N200 to all emotional categories, decreased VEP to unpleasant emotional faces in the P300 time range
Hatch et al^Citation51	2010	28 AN at admission and after gaining weight, healthy controls	ERP, stimuli – overt and covert presentation of emotion expressions	Irrespective of stimuli, early and late components of ERP were reduced in patients with AN at admission and after weight gain
Tammela et al^Citation40	2010	Obese women with binge eating and without binge eating	qEEG, resting state (eyes open/closed), visual stimuli – landscape, meal	Binge-eating patients showed greater frontal beta activity (eyes open and eyes closed)
Franken et al^Citation41	2011	32 healthy subjects	ERP, taste conditioning task	A clear P1/N1/P2 complex and a late positive potential (P3) in response to the taste stimuli
Blechert et al^Citation42	2011	Patients with AN and BN, and healthy controls	ERP, RT, subjective ratings, stimuli – weight/shape-related prime sentences	Stronger affective priming effects in ED compared with controls on RT and subjective ratings. ERP showed affective priming only in BN

Abbreviations: AN, anorexia nervosa; BN, bulimia nervosa; ED, eating disorders; EEG, electroencephalography; ERP, event-related potentials; qEEG, quantitative EEG; RT, reaction times; VEP, visual-evoked potentials.

Table 4 Electroencephalography in eating disorders: main findings

Sleep EEG of eating disorder patients, mainly in anorexia nervosa, shows almost complete normalization after refeeding. In respect of the neurobiological similarities between patients with eating disorders and those with depression, EEG findings do not support that association. In respect of the EEG changes/weight changes, there is wide controversy mainly based on methodological problems (eg, age, body mass index, chronicity, medication, experimental tasks, time of EEG testing). Some differences between patients with anorexia nervosa and healthy controls in respect of ERP to emotional stimuli have been found, and to some extent those differences remain after weight gain. The reduced CNV found in some studies among patients with anorexia nervosa might represent impaired cognitive processes, which reflect impaired appetitive behavior. During food presentation, binge-eating obese patients show greater frontal beta activity than nonbinge-eating obese patients in both the eyes closed and eyes open groups, independently of the stimulus. It has been reported that alpha-1 sources in temporal area show greater amplitude in controls when compared with patients with anorexia and bulimia nervosa as well as in patients with bulimia nervosa compared with patients with anorexia nervosa.

Abbreviations: CNV, contingent negative variation; EEG, electroencephalography; ERP, event-related potentials.

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