Correction: Cortisol reactivity in patients with anorexia nervosa after stress induction

A Correction to this paper has been published: https://doi.org/10.1038/s41398-021-01326-6

Cortisol reactivity in patients with anorexia nervosa after stress induction

There is a need of experimental studies on biomarkers in patients with anorexia nervosa (P_AN), especially in the context of stress, in order to foster understanding in illness maintenance. To this end, the cortisol response to an acute stressor was investigated in n = 26 P_AN (BMI: 19.3 ± 3.4 kg/m²), age, and gender matched to n = 26 healthy controls (HC; BMI: 23.08 ± 3.3 kg/m²). For this purpose, salivary cortisol parameters were assessed in two experimental conditions: (1) rest/no intervention and (2) stress intervention (TSST; Trier Social Stress Test). In addition, psychological indicators of stress were assessed (Primary Appraisal Secondary Appraisal, Visual Analogue Scale, and Trier Inventory for the assessment of Chronic Stress), as well as psychological distress, depression, and eating disorder (ED) symptoms. A 2 × 2 × 8 ANOVA demonstrated elevated cortisol levels in P_AN in the resting condition. In the stress intervention no significant group effect in terms of cortisol (F (1, 50) = 0.69; p = 0.410; [Formula: see text]). A significant condition (F (1, 50) = 20.50; p = 0.000; [Formula: see text]) and time effect (F(2.71, 135.44) = 11.27; p = 0.000; [Formula: see text]) were revealed, as well as two significant interaction effects. First: Condition × group (F (1, 50) = 4.17, p = 0.046; [Formula: see text]) and second: Condition × time (F (2.71, 135.44) = 16.07, p = 0.000, [Formula: see text]). In terms of AUC_G, no significant differences between both groups were exhibited. Regardless, significant results were evinced in terms of an increase (AUC_i: F(1, 50) = 20.66, p = 0.015, [Formula: see text]), baseline to peak (+20 min post-TSST: t₅ = 16.51 (9.02), p = 0.029) and reactivity (M_PAN = 0.73 vs. M_HC = 4.25, p = 0.036). In addition, a significant correlation between AUC_G and BMI: r (24) = -0.42, p = 0.027 was demonstrated, but not between AUC_i and BMI (r (24) = -0.26, p = 0.20). Psychological indices suggested higher levels of chronic and perceived stress in P_AN relative to HC. However, stress perception in the stress condition (VAS) was comparable. Additional analyses demonstrated that ED-symptoms are highly correlated with psychological distress and depression, but not with BMI. In addition, it could be demonstrated that reactivity is rather related to ED-symptoms and psychological burden than to BMI. In conclusion, P_AN showed elevated basal cortisol levels at rest and exhibited a blunted cortisol reactivity to the TSST as evinced by salivary cortisol parameters. Further, it was shown that weight recovery influences reversibility of hypercortisolemia, i.e., cortisol levels normalize with weight gain. However, HPAA (hypothalamus-pituitary-adrenal axis) irregularities in terms of reactivity persist even at a BMI ≤ 19.3 (±3.4). Our data suggest that pronounced psychological burden in P_AN, have a greater impact on the HPAA functionality (secondary to the ED) than BMI itself.

Abnormal functional global and local brain connectivity in female patients with anorexia nervosa

BACKGROUND

Previous resting-state functional connectivity studies in patients with anorexia nervosa used independent component analysis or seed-based connectivity analysis to probe specific brain networks. Instead, modelling the entire brain as a complex network allows determination of graph-theoretical metrics, which describe global and local properties of how brain networks are organized and how they interact.

METHODS

To determine differences in network properties between female patients with acute anorexia nervosa and pairwise matched healthy controls, we used resting-state fMRI and computed well-established global and local graph metrics across a range of network densities.

RESULTS

Our analyses included 35 patients and 35 controls. We found that the global functional network structure in patients with anorexia nervosa is characterized by increases in both characteristic path length (longer average routes between nodes) and assortativity (more nodes with a similar connectedness link together). Accordingly, we found locally decreased connectivity strength and increased path length in the posterior insula and thalamus.

LIMITATIONS

The present results may be limited to the methods applied during preprocessing and network construction.

CONCLUSION

We demonstrated anorexia nervosa-related changes in the network configuration for, to our knowledge, the first time using resting-state fMRI and graph-theoretical measures. Our findings revealed an altered global brain network architecture accompanied by local degradations indicating wide-scale disturbance in information flow across brain networks in patients with acute anorexia nervosa. Reduced local network efficiency in the thalamus and posterior insula may reflect a mechanism that helps explain the impaired integration of visuospatial and homeostatic signals in patients with this disorder, which is thought to be linked to abnormal representations of body size and hunger.