Allostasis in health and food addiction

Abstract

Homeostasis is the basis of modern medicine and allostasis, a further elaboration of homeostasis, has been defined as stability through change, which was later modified to predictive reference resetting. It has been suggested that pleasure is related to salience (behavioral relevance), and withdrawal has been linked to allostasis in addictive types. The question arises how the clinical and neural signatures of pleasure, salience, allostasis and withdrawal relate, both in a non-addicted and addicted state. Resting state EEGs were performed in 66 people, involving a food-addicted obese group, a non-food addicted obese group and a lean control group. Correlation analyses were performed on behavioral data, and correlation, comparative and conjunction analyses were performed to extract electrophysiological relationships between pleasure, salience, allostasis and withdrawal. Pleasure/liking seems to be the phenomenological expression that enough salient stimuli are obtained, and withdrawal can be seen as a motivational incentive because due to allostatic reference resetting, more stimuli are required. In addition, in contrast to non-addiction, a pathological, non-adaptive salience attached to food results in withdrawal mediated through persistent allostatic reference resetting.

Figure 1. Radar image representing percentage of people exhibiting each food related symptom.

The food addicted obese group (high YFAS) behaves differently from the lean and the non-food addicted obese group (low YFAS). The lean and non-food addicted group show exactly the same food related behaviour.

Figure 2. Pleasure is related to salience in all groups, as is allostasis to withdrawal.

However, salience is related to allostasis and withdrawal only in the addicted group. Furthermore, the influence of salience on withdrawal is indirect, mediated via allostasis.

Figure 3. Correlation analyses between pleasure (top panel), withdrawal (mid panel), allostasis (bottom panel) and source localized (sLORETA) brain activity.

Warm colors (yellow-red) represent positive correlations, cold colors (blue) represent negative correlations.

Figure 4. Conjunction analyses for food-addicted, non-food-addicted and lean individuals between allostasis and withdrawal (top panel, left), between pleasure and salience (top panel, right) and between allostasis, withdrawal, pleasure and salience (lower panel).

Figure 5. A comparison between low (non-addicted to food) and high YFAS (food addicted) participants shows increased beta1 and beta2 activity in the rACC/dmPFC bilaterally as well as in the premotor/motor cortex on the left for the high YFAS group.

Figure 6. A conjunction analysis for the High YFAS participants between salience and allostasis demonstrates shared activity in the posterior cingulate cortex extending to the precuneus for the delta, theta, and alpha1 band.

In addition, for the theta frequency band shared activity was identified in the superior parietal lobe. For the gamma band shared activity is noted in the PCC bilaterally as well as in the left VLPFC, insula and anterior temporal pole (lower right quadrant of Fig. 5).

Figure 7. For the gamma frequency band, a comparison between the addicted group and the control group shows a significant increased connectivity (the log of F-ratio = 1.76, p < 0.05) between the pregenual anterior cingulate cortex, dorsal anterior cingulate cortex and the posterior cingulate cortex for the addicted group.

Figure 8. A correlation analysis between the lagged phase coherence and allostasis showed a significant effect (r = 0.38, p < 0.05) for delta, theta, alpha1, alpha2, beta1, beta2, beta3 and gamma frequency band for the addicted group.