Fasting enhances extinction retention and prevents the return of fear in humans

Le Shi,Jie Shi,Yekun Sun,Xiujun Zhang,Jiahui Deng,Xiao Lin,Sijing Chen,Zhong Wang,Xiaojie Guo,Wen Xie,Ying Han,Jianyu Que,Lin Lu,Yuxin Zhou

doi:10.1038/s41398-018-0260-1

Abstract

Fear is prone to return following extinction that is the basis of exposure therapy for fear-related disorders. Manipulations that enhance the extinction process can be beneficial for treatment. Animal studies have shown that fasting or caloric restriction can enhance extinction and inhibit the return of fear. The present study examined the effects of fasting on fear acquisition, extinction, and the return of fear in humans. One hundred and twenty-five male participants were randomized into a fasting group and food group and exposed to a Pavlovian fear conditioning paradigm. Changes in plasma cortisol and ghrelin levels were examined using enzyme-linked immunosorbent assays. One-night fasting had no effect on fear acquisition but enhanced fear extinction retention and prevented the return of fear, and this effect persisted for at least 6 months. This procedure was also effective for remote fear memory. Plasma ghrelin levels were elevated after fasting and had a negative relationship with the fear response in spontaneous recovery test. However, overnight fasting did not affect cortisol levels. These findings indicate that fasting enhances extinction retention and prevents the return of fear, without influencing fear memory formation. We propose that this novel procedure may open new avenues for promoting extinction-based therapies for fear-related disorders.

Highlights

Emotional memory is vital to the survival and development of individuals
This analysis revealed significant main effects of conditioned stimulus (CS) (F(1, 33) = 34.867, P < 0.001) but no main effect of group (F(1, 33) = 0.817, P = 0.373) and no CS × group interaction (F(1, 33) = 0.311, P = 0.581; Fig. 1b). Both groups showed greater skin conductance response (SCR) to CS+ compared with CS− during fear conditioning. This indicates that the subjects in both groups achieved successful and comparable acquisition of Fasting enhanced extinction retention and prevented the return of fear In Experiment 2, we investigated whether fasting affected the extinction memory (Fig. 2a)
We evaluated the effects of short-term fasting on fear acquisition, extinction, and the return of fear

Summary

Introduction

Emotional memory is vital to the survival and development of individuals. excessive fear and anxiety can cause fear-related disorders, such as posttraumatic stress disorder[1]. Fear memory may be erased under certain circumstances[3,4,5], but extinction training alone does not erase the original fear memory, and the decreased fear response often returns under some conditions, such as reinstatement[6], renewal[7], or spontaneous recovery[8]. This suggests that extinction training forms a new extinction memory that competes with the fear memory. Enhancing extinction memory may be helpful for achieving better treatment outcomes with extinction-based behavioral interventions

Methods

Results

Conclusion