This Is Your Brain On Sugar | Amy Reichelt | TEDxYouth@Sydney

This Is Your Brain On Sugar | Amy Reichelt | [email protected]

Translator: Mirjana Čutura
Reviewer: Rhonda Jacobs 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.” (Laughter) 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. (Laughter) 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, you know,
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 control people
who eat healthy diets. Research has also shown that people
with damage to the hippocampus – so, the memory center – report feeling hungry all the time. When I read about this research, I thought maybe they just
don’t remember eating. (Laughter) But actually, the hippocampus
is a critical area of the brain for receiving fullness
signals from the gut. So we’re setting up another vicious cycle where, if you’re consuming
a lot of these foods, you’re developing obesity –
overconsuming – because you’re not getting
the same fullness signals from the gut. So you’re eating more junk food,
which is, in turn, damaging your brain. This means that your brain can be reduced
in terms of its neuroplasticity, which is how these neurons
are firing together and wiring together to form your memories. But also, these neurons are born
in your brain throughout life, particularly in the hippocampus. This is called neurogenesis,
and it occurs throughout your life. These new neurons
are particularly plastic. They form memories readily,
and they’re really important. We know that people
who consume high-fat diets – from research with rodents – have got lower amounts of neurogenesis. But people with mental health disorders, such as depression, also have lower levels of neurogenesis, which again brings about
another idea of a vicious cycle. We know that these foods are really tasty. They release dopamine;
dopamine makes us feel good. So if we comfort-eat these foods, we’re actually then diminishing
our neurogenesis, which is actually making us
sadder in the long run. So that’s kind of a depressing point. I’m really sorry. But it’s really important
for us to be mindful of what we’re putting into our bodies and how it’s affecting
both our body and our brains. And for young people,
it’s especially important because this is such
a critical period in your life for learning about the world
and learning new things and concepts. So when you’re stressed out,
you can think, “Oh, I just want to comfort-eat
and just consume pizza and doughnuts and then revise for my exam
tomorrow morning.” But this isn’t going to be ideal for your brain
to remember all these facts. But research provides us
with these methods that the brain is being affected by
in terms of these diets. And so it provides us with ways
that we can counteract these effects. I’m sorry, but you can eat healthy foods. I mean, fruit and veg
are really good for you. They contain antioxidants. And these fight inflammation
and neuroinflammation. If you eat avocados and oily fish, these contain a lot of omega-3s,
and these are able to boost neurogenesis. And by being active in your lifestyle,
getting out and running around, it doesn’t just help you lose weight
by burning off excess calories, but it also boosts neuroplasticity
mechanisms in the brain. So, I’m not going to tell you
to never eat junk food ever again. We all do it. But we need to treat these foods in the same way that our brain
treats these foods – as a reward, as opposed to the major part of our diets. (Applause)