Acute stress and food-related reward activation in the brain during food choice, during eating in the absence of hunger

Replacement Stress Article

Studies suggest that high cortisol levels lead to altered food choice. Stress is thought to result in food choice for items with higher fat content and sweet, which the brain perceives as rewarding. Eating behavior that may be influenced by stress is divided into two components: the first component is homeostatic eating, which relates to hunger and satiety, and ultimately to energy balance and steady body weight. The second component is non-homeostatic eating, which is influenced by food reward, and is observed as eating in the absence of hunger. It has been shown in previous studies that in the central nervous system, reward activates dopamine-mediated signaling in key areas of the brain. In studies that researched food reward specifically, using food images, smells and tastes, the brain areas that were involved were the amygdala, striatum, hippocampus anterior cingulated cortex and orbitofrontal cortex. In this study, the researchers aim to determine the effects of acute stress on food reward-related brain activation that was induced by food choice.

Ten subjects participated in this study. All females with mean age of 24.1 years and body mass index mean of 21.5. After fasting, the subjects came to the study on two random occasions, one in the rest condition, and one in the stress condition. The two occasions were at least a week apart. To create the stress versus rest, an unsolvable (stress) and solvable (rest) mathematical test was given before each scan. Each session included five questionnaires and five blood samples, two functional MRI scans and two meals. The two meals included breakfast after the first scan and a postprandial meal after the second scan. The meals were offered immediately after the questionnaires and blood samples were obtained quickly after the scan. To determine the effect of the two meals, a visual analog questionnaire was given. Example questions were ‘How hungry are you?’ and ‘How full do you feel?’ Rewarding value was determined as liking and wanting. The foods were given numerical scales in separate experiments. Images of pairs of the food were shown in the scan and the participants picked which ones they wanted to eat. Those foods had to be consumed immediately after the scan.

When comparing the stress condition to the rest conditions during breakfast, lower activation was present in multiple brain areas: the orbitofrontal cortex, frontal cortex and the putamen. The amygdala, the cingulated cortex and the hippocampus showed lower activation in the stress condition compared with the rest condition. The researchers found that the food choice under stress compared with rest was different in terms of the food characteristics. The subjects chose food items which were higher in crispiness and fullness of taste in the stress condition than the rest condition. Overall, the research shows that stress interferes with the effect s of hunger on energy intake, a shift in food choice toward foods that were higher in carbohydrates, proteins, and that had a tendency to have higher density on average. 

Born, J., Lemmens, S., Rutters, F., Nieuwenhuizen, A., Formisano, E., Goebel, R., & Westerterp-Plantenga, M. (2010). Acute stress and food-related reward activation in the brain during food choice during eating in the absence of hunger. International Journal of Obesity, 34(1), 172-181. doi:10.1038/ijo.2009.221

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