Stress increases cue-triggered “wanting” for sweet reward in humans.

Abstract

Stress can increase reward pursuits: This has traditionally been seen as an attempt to relieve negative affect through the hedonic properties of a reward. However, reward pursuit is not always proportional to the pleasure experienced, because reward processing involves distinct components, including the motivation to obtain a reward (i.e., wanting) and the hedonic pleasure during the reward consumption (i.e., liking). Research conducted on rodents demonstrates that stress might directly amplify the cue-triggered wanting, suggesting that under stress wanting can be independent from liking. Here, we aimed to test whether a similar mechanism exists in humans. We used analog of a Pavlovian-Instrumental Transfer test (PIT) with an olfactory reward to measure the cue triggered wanting for a reward but also the sensory hedonic liking felt during the consumption of the same reward. The analog of a PIT procedure, in which participants learned to associate a neutral image and an instrumental action with a chocolate odor, was combined with either a stress-inducing or stress-free behavioral procedure. Results showed that compared with participants in the stress-free condition, those in the stress condition mobilized more effort in instrumental action when the reward-associated cue was displayed, even though they did not report the reward as being more pleasurable. These findings suggest that, in humans, stress selectively increases cue-triggered wanting, independently of the hedonic properties of the reward. Such a mechanism supports the novel explanation proposed by animal research as to why stress often produces cue-triggered bursts of binge eating, relapses in drug addiction, or gambling. Keywords: stress, incentive salience, wanting, liking, human Pavlovian-Instrumental TransferSupplemental materials: http://dx.doi.org/10.1037/xan0000052.supp Have you ever eaten more high-calorie foods during a stressful period? As documented by a consistent corpus of literature (e.g., O'Connor & Conner, 2011), stress cannot only increase the consumption of high-calorie foods, but it can also increase the use of other kinds of rewards, such as drugs (Sinha, 2001) or sexual stimuli (Chumbley et al., 2014). Although these effects of stress have been proven to have a large impact on public health problems (e.g., addiction relapses or binge eating; Lo Sauro, Ravaldi, Cabras, Faravelli, & Ricca, 2008), the underlying psychological mechanisms remain poorly understood.It has been proposed that rewards are used to reduce the negative effects of stress, which are compensated by the hedonic pleasure triggered by their consumption (Koob & Le Moal, 2001). According to this proposal, stress increases the pursuit of rewards, as consumption is made even more pleasurable by relieving the negative effects of stress.The incentive salience theory proposes an alternative mechanism in which the key principle is independent of the hedonic properties of the reward (Berridge & Robinson, 1998). According to this theory, the pursuit of a reward is not always dir...

Is comfort food really comforting? Mechanisms underlying stress-induced eating

“…1A and B). These effects have been recently replicated in humans (Pool, Brosch et al, 2014a) through behavioral stress induction. In this experiment, a stressful state was induced by asking participants to keep their hand in ice-cold water while being observed and videotaped.…”

“…Classic studies show that the perception of a stimulus (e.g., a sound) that has previously been associated with a rewarding outcome (e.g., sucrose) increases the amount of energy invested in the instrumental action (e.g., pressing a lever to obtain sucrose; for reviews, see Bindra, 1974;Bolles, 1972;Toates, 1998). This phenomenon is known as Pavlovian-instrumental transfer and its existence has been largely replicated in animals (e.g., Corbit & Balleine, 2005Wassum, Ostlund, Balleine, & Maidment, 2011;Wyvell & Berridge, 2001) and in humans (e.g., Allman et al, 2010;Bray, Rangel, Shimojo, Balleine, & O'Doherty, 2008;Pool, Brosch, Delplanque, & Sander, 2014a;Prevost et al, 2012;Talmi et al, 2008;Trick, Hogarth, & Duka, 2011).…”

Measuring wanting and liking from animals to humans: A systematic review

“…This number of studies confirms that among researchers investigating human reward, there is a great deal of interest in testing predictions of the incentive salience hypothesis. Basic research tested whether results from animal studies could be replicated in human studies by using brain imagining techniques (e.g., fMRI, PET; Born et al, 2011;Leyton et al, 2002), dopaminergic manipulations (e.g., dopaminiergic drug administration; Leyton et al, 2002Leyton et al, , 2005 or methods that are as similar as possible to the original animal studies (e.g., Pool et al, 2015b). More applied research explored whether the potential independence of wanting and liking might represent a mechanism underlying a variety of problematic behaviors such as excessive food consumption (e.g., Lemmens et al, 2011c), substance addiction (e.g., Goldstein et al, 2010) or behavioral addictions (e.g., gambling, excessive video game playing; Thalemann et al, 2007;Wölfling et al, 2011).…”

“…amygdala, nucleus accumbens) increases after the perception of the cue and decreases during reward receipt (Kumar et al, 2014). This translates behaviorally into an increase in cue-triggered wanting without a parallel increase in liking (Pecina et al, 2006;Pool et al, 2015b).…”

The anterior medial temporal lobes: Their role in food intake and body weight regulation

“…For instance, Pool et al [128] have recently shown that stress affects one of the components of reward but not others. More specifically, stress increases "wanting" (i.e., the motivation to obtain a reward), but not "liking" (i.e., the hedonic pleasure during the reward consumption) for a sweet reward.…”