Objective
Stress plays a role in the pathology of bulimia nervosa and binge eating disorders, but it is unclear whether they involve similar disturbances of biological stress responses.
Patients and methods
We recruited 25 patients with binge eating behavior, 12 with bulimia nervosa (BN) and 13 with binge eating disorder (BED), and compared them with 13 obese non-binge eaters (NBED). We measured heart rate variability in response to mental stress tasks, and concentrations of leptin, glucose and insulin in the blood.
Results
Heart rate stress reactivity was highest in BN patients. Heart rate variability did not change during mental stress in BN and BED patients, but reduced as expected in the NBED group. During post-stress recovery, heart rate variability decreased in BN, was maintained in BED and increased as expected only in the NBED group.
Conclusions
BN and BED patients exhibit limitations in autonomic stress reactivity and recovery capacity.
Bulimia nervosa (BN) and binge eating disorder (BED) are both characterized by recurrent episodes of binge eating, but differ in compensatory behavior. Bulimic patients regularly use self-induced vomiting or misuse laxatives to control their weight, whereas individuals with binge eating disorder usually suffer from uncontrolled weight gain and obesity (Munsch and Beglinger, 2005).
It is thought that stress plays an important role in the pathology of both disorders (Pinaquy et al., 2003 and Koo-Loeb et al., 1998). Heightened negative mood has frequently been described as a precursor to binge eating episodes in BN and BED (Levine and Marcus, 1997, Eldredge and Agras, 1996 and Telch and Agras, 1996) as well as obesity. Individuals with BN and BED experience greater negative mood before binge eating episodes and perceive challenging situations as more stressful compared with healthy individuals (Pinaquy et al., 2003, Wolff et al., 2000, Hansel and Wittrock, 1997 and Kjelsas et al., 2004). Additionally, several studies have shown an increase in hunger and desire to binge following experimental stress tasks (Cattanach et al., 1988, Gluck et al., 2004 and Tuschen-Caffier and Vogele, 1999). Therefore, understanding the physiological mechanisms underlying stress responses would be useful for the identification of physiological correlates of binge eating patterns in BN and BED disorders.
There is evidence that people with BN and BED differ in autonomic functioning from healthy individuals. Patients with BN exhibit blunted sympathetic activation in response to mental stress (Koo-Loeb et al., 1998) and reduced 24 h blood pressure (Cong et al., 2004). Furthermore, results of a comparison of BED and controls suggested higher stress vulnerability in the BED population (Friederich et al., 2006). However, obesity might confound these results, as other studies on obese subjects have shown a change of stress response profiles due to obesity itself (Laederach-Hofmann et al., 2000 and Valensi et al., 1995).
Similarities in biological stress vulnerability could be a key to understanding binge eating behavior in BN and BED. But studies of autonomic stress responses in BN and BED individuals are rather scarce. The purpose of this study was to assess the stress responses of patients with similar binge eating behavior but different diagnoses. In order to investigate the capacity of the autonomic nervous system to adapt to stressful conditions, we measured heart rate variability (HRV) and assessed autonomic activity during mental stress testing. We hypothesized that BN and BED patients would show similar disturbances of autonomic stress responses in comparison with non-binge eaters (NBED).
