Following is the full transcript of neuroscientist Amy Reichelt’s talk titled “This Is Your Brain On Sugar” at TEDxYouth@Sydney conference.
Amy Reichelt – Author of Impact of Diet on Learning, Memory and Cognition
So, as a neuroscientist, I’m fascinated by how our brains control our behaviors in our dynamic and changing world.
But recently, I’ve become really interested not only in the environment that we live in, but what we’re putting into our environments, our bodies, in the form of the food that we eat.
Now, we all eat junk food. I’m not going to lie — I’ve eaten pizza twice this week.
But we know it’s bad for us, yet we continue to eat it. It’s so tasty, and it’s everywhere, and it’s really hard to resist.
So, one of the things I’ve been really interested in is how this not only is affecting our bodies — now that a quarter of all young Australians are overweight or obese — but also what it’s doing to our brains.
These foods are so hard to resist because they’re rewarding, they taste so good. And when we consume these foods, our brain’s reward center activates, and it releases the chemical dopamine.
Dopamine makes us feel good, and we really like it. So actually, when we overconsume these foods, our brains become overwhelmed with the pleasurable experiences that we’re having.
So, our brain’s pretty clever, and it adapts. It creates more receptors for dopamine.
And what happens then is that we need more of these foods to get the same kick out of them. Our brain is basically hardwired to seek and want these foods, but we’re building up a tolerance to them, so we eat more.
So we’re basically becoming sugar junkies. Dopamine is really cool as well. It does things that make you learn about how good these things are.
Because we really like them, it directs our attention to them, so we see them when we’re there getting our coffee in the morning, feeling a little bit shabby.
We see the doughnut, and we can’t resist it. We’re like, “Yeah, that’s a healthy breakfast.” And we just can’t resist these things.
But we need a part of the brain that controls our urges and temptations because, otherwise, we’d just be, you know, eating doughnuts for every meal of the day.
The brain has an area called the prefrontal cortex. This area is responsible for your cognitive control. It controls your behaviors in the world. It’s also the last part of your brain to mature, and it doesn’t actually fully mature until you’re in your 20s.
And this means that when we think about all these people who are developing obesity because of their environment, they’re finding it really hard to resist these temptations at a young age because their brain isn’t yet fully functioning.
So, I actually do my research with rats, not people. And they really like junk food as much as people do.
What’s great about rats is that they have the same areas of the brain as humans, and they have the same neurochemistry, so we can use them to study how their diet impacts on their behavior without having to deal with people.
So, in my lab, we’ve been thinking about how adolescence is a particularly vulnerable period for the development of cognitive deficits caused by the consumption of these foods.
So, I’ve been feeding teenage rats — so, rats go through adolescence and puberty as well — with this highly sugary solution, which is about the same, really, as a can of Coca-Cola in terms of the amount of sugar, all through their adolescence.
And then I test them on tasks that require them to use their brains, use cognitive control, make decisions, and follow rules.
What I’ve found is that rats that are fed these sugary solutions aren’t able to follow the rules as well as healthily diet-fed rats. When we ask them to press a lever according to a certain signal — be it an auditory or visual cue — what actually happens is they show impairments at this sort of rule-following.
And we think about our population now developing more and more obesity, it’s not surprising that, in the face of “don’t eat the doughnut,” that these people are overeating causing them to develop obesity.
But these diets don’t just affect our behavioral control, they affect the area of the brain that’s responsible for memory. This is the hippocampus.
Now, when you consume these foods, your body has a response to them. And if your diet is really consistently full of them, you develop a form of inflammation, but in your brain. So this is called neuroinflammation — so neuroscientists, we put “neuro” in front of things — and it’s kind of like getting hives when you consume something that you’re allergic to.
And this is happening in the memory center of your brain, so it’s actually impairing your ability to learn and remember facts because the inflammation is causing the neurons, the brain cells in your brain, to malfunction.
This means that people who consume lots and lots of junk foods don’t perform as well on memory tests as those who eat healthy diets. And this research actually showed that these people didn’t actually have obesity — they were the same weight as the controlled people who eat healthy diets.