Teens who drink lots of Coca-Cola have a different brain response to ads featuring the beverage's iconic logo than their peers who aren't Coke drinkers, according to a new pilot study.
But there was no difference in brain activity between the two groups on functional magnetic resonance imaging scans (fMRI) when they were shown advertisements focusing on the beverage itself - for example, showing the soda being poured into a glass - rather than the logo only.
"That suggests that the Coke brand, like the font or the silhouette of the bottle, is a conditioned cue for those who drink it habitually," Dr Kyle Burger of the Oregon Research Institute in Eugene, who authored the study with Dr Eric Stice, also at ORI, told Reuters Health.
The researchers presented their findings at the Obesity Society's Annual Meeting.
Earlier this year, Dr Burger and Dr Stice published a study in the American Journal of Clinical Nutrition that found differences in brain response patterns between adolescents who frequently ate ice cream and those who didn't. Specifically, the scans found that the habitual ice cream eaters had less activity in their brains' reward centres when they drank a milkshake. (They were given shakes because it's impossible to eat ice cream in an fMRI machine.)
Brain response similar to addiction
This is similar to the response seen in individuals addicted to a drug; their substance of choice will have less of an effect on their reward centres, which may drive them to consume more and more in the hopes of getting a stronger response.
In the current study, the researchers sought to determine if something similar might be going on in the brains of young people who frequently consume sweetened soda. They chose Coke, Dr Burger noted, because it's popular among adolescents and is also heavily marketed to them.
The researchers identified 13 adolescents who reported that Coke was their favourite soda, and who consumed at least five glasses of the beverage per week [one glass equals 237ml]. The comparison group consisted of 12 adolescents who consumed less than three glasses of any sugar-sweetened soda per month. Study participants' mean age was 15 years, and their average body mass index was 22.8.
During fMRI, each study participant viewed a neutral ad, an ad featuring the Coca-Cola logo, or an ad showing the beverage itself. The researchers also tested brain responses to being shown, and then drinking, a fully carbonated Coke or a tasteless beverage.
When anticipating a Coke, habitual drinkers showed less activity in the ventrolateral prefrontal cortex, a region involved in behavioural control, than the non-soda drinkers. However, there was no difference between the two groups in brain activity when they were actually drinking the beverage. "We think that they're relaxing their brake pedal a little bit when they're about to receive it," Dr Burger explained.
High in fat and sugar
The researchers conducted a sub-study in 10 teens comparing Coke to a chocolate milkshake, and found that consuming a shake elicited a stronger response in the striatum, a dopamine-related reward region.
"How we're interpreting that currently is that something that may be high in fat or high in fat and sugar is basically better at eliciting this reward-related activity," Burger said. "There's been a lot of press out there about how sugar can be addictive, this data indicates that fat matters too."
"These data provide novel, but cross-sectional data that demonstrate neural differences between those who regularly consume a soft drink relative to those who do not particularly when exposed to the brand or when anticipating intake in a manner that may perpetuate further consumption," he concluded.
"This area of research is extremely important," Dr Luke Stoeckel, the director of clinical neuroscience at Massachusetts General Hospital's Center for Addiction Medicine, said.
Dr Stoeckel, who was not involved in the current study, said, "We're learning more about the mechanisms behind why the consumption of these highly palatable and highly prevalent foods and beverages are so problematic."
Dr Stoeckel noted that given the wide variation from person to person in brain activity, and the small size of the current study, the findings are far from definitive. But, he said, "If things hold up I think it's extremely interesting. I think it's a very creative study idea."
- (Reuters Health, October 2012)
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