What's the science?
In adults, brain activity in response to food cues has been shown to predict overeating and weight gain. We do not yet understand the relationship between the brain’s response to food and overeating across the lifespan, including in children, who are especially vulnerable to food cues. Recently in Neuroimage, Charbonnier and colleagues show how certain brain regions activate in response to food depending on hunger level in different age groups.
How did they do it?
They recruited children, teens, adults and elderly participants who were scanned twice using functional MRI, once in a hungry state after fasting all night and once in a full (‘sated’) state after being fed. Before the scan, participants rated how much they liked various foods. In the scanner, participants performed a food-viewing task where they viewed images of high and low calorie foods. The viewing of non-food images was a control task. Brain activity was compared while participants viewed high versus low calorie foods, in the hungry or full state, across different age groups.
What did they find?
Brain activation in the hungry state was greater across the lifespan when viewing high calorie foods (compared to low calorie foods) in two regions of the prefrontal cortex: the dorsolateral prefrontal cortex (involved in controlling actions) and the dorsomedial prefrontal cortex (involved in processing reward and value). Hunger state alone did not affect brain activation when viewing food. Age also did not affect brain activation for high compared to low calorie foods, even though younger participants rated liking high calorie food more.
What's the impact?
This is the first study to look at the effects of hunger and different food cues on brain activation in different age groups. The activation of the dorsolateral prefrontal cortex could reflect inhibition of eating, whereas the dorsomedial prefrontal cortex could be activating to process the reward value of the food, however this needs to be investigated further. It is important to understand brain mechanisms for eating behaviors across the lifespan in order to develop strategies to prevent obesity.
Reach out to study author Dr. Daniel Crabtree on Twitter @DanielCrabtree9
L. Charbonnier et al., Effects of hunger state on the brain responses to food cues across the life span. Neuroimage. 171, 246–255 (2018). Access the original scientific publication here.