Electrophysiologic abnormalities in patients with eating disorders

Increased frontal electroencephalogram theta amplitude in patients with anorexia nervosa compared to healthy controls

OBJECTIVE

To conduct a blind study of quantitative electroencephalogram-band amplitudes in patients with anorexia nervosa (AN) and healthy controls.

METHODS

Twenty-one patients with AN and 24 controls were examined with eyes-closed 16-channel electroencephalogram. Main variables were absolute alpha, theta, and delta amplitudes in frontal, temporal, and posterior regions.

RESULTS

There were no significant differences between the AN patients and controls regarding absolute regional band amplitudes in μV. Borderline significance was found for anterior theta (P=0.051). Significantly increased left and right frontal electrode theta amplitude was found in AN patients (F3, P=0.014; F4, P=0.038) compared to controls. Significant differences were also observed for secondary variables: lower values for relative parietooccipital delta and frontocentral alpha activity among AN patients than among controls.

CONCLUSION

We observed slight excess frontal theta and lower relative alpha and delta amplitudes among AN patients than among controls. This pattern is possibly related to a slight frontal lobe dysfunction in AN, or it may reflect increased attention/vigilance or another state-related change in patients with AN compared to healthy controls.

Electroencephalography in eating disorders

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).

EEG in adolescent anorexia nervosa: impact of refeeding and weight gain

OBJECTIVE

To examine resting awake EEG in adolescent AN participants before and after refeeding to determine if EEG abnormalities in Anorexia Nervosa (AN) are reversible.

METHOD

In 37 adolescent first admission AN patients and 45 healthy controls, EEG was recorded during short duration "eyes open" and "eyes closed" awake resting conditions. Repeat testing occurred in 28 AN participants after refeeding and subsequent weight gain.

RESULTS

In "eyes open," underweight AN participants exhibit reduced relative alpha power and increased beta power in frontal brain regions. A significant increase in alpha, and decrease in beta and delta power was observed within participants after refeeding. In "eyes closed", underweight AN participants had elevated theta in parietal-occipital regions which remained after refeeding.

DISCUSSION

EEG abnormalities (reduced alpha/increased beta power) in AN normalizes with refeeding, while increased theta power persists in parietal-occipital regions in an eyes closed context.

Cortical sources of awake scalp EEG in eating disorders

OBJECTIVE

To investigate quantitative EEG (qEEG) in anorexia nervosa (AN) and bulimia nervosa (BN) in comparison with healthy controls.

METHODS

Resting EEG was recorded in 30 healthy females (age: 27.1+/-5.5), 16-AN females (age: 26.4+/-9.5) and 12-BN females (age: 27.0+/-6.3). Cortical EEG sources (delta, theta, alpha 1, alpha 2, beta 1, beta 2) were modeled by LORETA solutions. The statistical analysis was performed considering the factors Group, power Band, and region of interest (central, frontal, parietal, occipital, temporal, limbic).

RESULTS

Alpha 1 sources in central, parietal, occipital and limbic areas showed a greater amplitude in Controls versus AN and BN groups. Alpha 2 sources in parietal, occipital and limbic areas showed a greater amplitude in Controls than in both AN and BN groups. Alpha 1 sources in temporal area showed a greater amplitude in Controls compared to both the BN and AN groups as well as in the BN group compared to AN group. Central alpha 1 source correlated significantly with BMI in patients.

CONCLUSIONS

These results support the hypothesis that eating disorders are related to altered mechanisms of cortical neural synchronization, especially in rolandic alpha rhythms.

SIGNIFICANCE

To our knowledge this is the first study by LORETA able to detect modifications of cortical EEG activity in eating disorders.

Physical illness encountered in patients with eating disorders

Careful evaluation for medical illness with a severity rating scale of 276 eating-disorder patients admitted to hospital revealed that patients with anorexia and bulimia were at risk for developing medical complications. Severe cardiovascular complications were most likely to occur in eating-disorder patients who were also diuretic and/or laxative abusers. Forty percent of patients with bulimia had significant medical complications. The findings suggest that a medical work-up should be carefully undertaken in both anorexic and bulimic patients admitted to hospital. A mixed history of severe anorexia nervosa alternating with periods of bulimia was most likely to lead to severe life-threatening illness. Seventy percent of the bulimic patients admitted required some medical treatment. Five percent were considered severely medically ill, while 34% suffered from a significant medical disorder. Ten percent of patients with restrictive anorexia or anorexia alternating with binge/purge required intensive care unit (ICU) placement. Most illnesses requiring medical treatment were unknown to the patient and the patient's physician at the time of admission.