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

Summary

This talk by a neuroscientist delves into the impact of junk food on our brains and behaviors. It explains how junk food overstimulates the brain's reward system, leading to a cycle of increased consumption and tolerance. The speaker discusses the effects on cognitive control, memory, and the role of the prefrontal cortex in resisting temptations, especially in young people. The talk also highlights the negative influence of diets high in junk food on memory and learning, and offers insights into how a healthy diet and lifestyle can counteract these effects.

Takeaways

• 🧠 The brain's reward center is activated by junk food, releasing dopamine which makes us feel good and crave more.
• 🍕 Overconsumption of junk food leads to an increase in dopamine receptors, requiring more of the food to achieve the same pleasurable effect.
• 🍔 High sugar and junk food intake can make individuals, including a quarter of young Australians, overweight or obese.
• 🧐 The prefrontal cortex, responsible for cognitive control and behavior, is the last part of the brain to mature, making younger individuals more susceptible to junk food cravings.
• 🐀 Research with rats, who share similar brain areas and neurochemistry with humans, helps study the impact of diet on behavior without involving people.
• 🔍 Adolescent rats fed a sugary solution showed impaired rule-following and decision-making abilities compared to those on a healthy diet.
• 🧠 The hippocampus, critical for memory, can be negatively affected by a diet high in junk food, leading to neuroinflammation and memory impairment.
• 🍎 Consuming healthy foods like fruits and vegetables, which are rich in antioxidants, can help fight inflammation and neuroinflammation.
• 🥑 Foods rich in omega-3, such as avocados and oily fish, can boost neurogenesis, the process of generating new neurons in the brain.
• 🏃‍♂️ An active lifestyle not only aids in weight loss but also enhances neuroplasticity, the ability of neurons to adapt and form new connections.
• 🍰 It's important to treat junk food as a reward rather than a staple in our diets to prevent negative impacts on both body and brain health.

Q & A

What is the main focus of the speaker's research as a neuroscientist?

The speaker's research focuses on understanding how our brains control our behaviors, particularly how the food we consume, especially junk food, affects both our bodies and our brains.

Why do people find junk food so hard to resist according to the speaker?

Junk food is hard to resist because it is rewarding and tastes good, activating the brain's reward center and releasing dopamine, which makes us feel good.

How does overconsumption of junk food affect the brain's dopamine system?

Overconsumption of junk food overwhelms the brain with pleasurable experiences, leading to an increase in dopamine receptors, and thus a need for more of these foods to achieve the same pleasurable effect.

What role does the prefrontal cortex play in controlling urges and temptations related to food?

The prefrontal cortex is responsible for cognitive control and behavioral regulation in the world. It helps control urges and temptations, but it is the last part of the brain to mature, making it harder for young people to resist junk food.

What is the speaker's approach to studying the impact of diet on behavior without involving human subjects?

The speaker uses rats for research because they have similar brain areas and neurochemistry to humans, allowing the study of diet impacts on behavior without the complexities of human subjects.

Why is adolescence considered a vulnerable period for the development of cognitive deficits due to junk food consumption?

Adolescence is a critical period because the prefrontal cortex, responsible for cognitive control, is still maturing. The consumption of junk food during this time can lead to cognitive deficits and difficulty in resisting temptations.

How does a high-sugar diet affect the performance of rats in cognitive tasks?

Rats fed a high-sugar diet show impairments in following rules and performing tasks that require cognitive control, decision-making, and adherence to rules.

What part of the brain is responsible for memory and how can junk food consumption affect it?

The hippocampus is responsible for memory. Junk food consumption can lead to neuroinflammation in the brain, impairing the ability to learn and remember facts due to the malfunction of neurons.

How can a diet high in junk food affect feelings of hunger and fullness?

A high-junk food diet can disrupt the hippocampus, which is critical for receiving fullness signals from the gut, leading to a constant feeling of hunger and overconsumption.

What is neurogenesis and how can junk food consumption impact it?

Neurogenesis is the process of new neuron birth in the brain, particularly in the hippocampus, throughout life. High-fat diets and mental health disorders can reduce neurogenesis, affecting memory formation and potentially contributing to depression.

What are some ways to counteract the negative effects of junk food on the brain as suggested by the speaker?

Eating healthy foods rich in antioxidants, omega-3s, and engaging in physical activity can help counteract the negative effects of junk food on the brain by fighting inflammation, boosting neurogenesis, and enhancing neuroplasticity.

Outlines

00:00

🧠 The Impact of Junk Food on Brain and Behavior

Neuroscientist Mirjana Čutura explores the effects of junk food on our brains, highlighting the rewarding nature of such foods that trigger dopamine release, leading to a cycle of increased consumption and tolerance. She discusses how this cycle can lead to 'sugar junkies' and the brain's adaptation to require more of these foods to achieve the same pleasurable effect. The speaker also touches on the role of the prefrontal cortex in controlling urges and how its immaturity in young people can make it difficult to resist junk food. Using rats as subjects, she studies the impact of a high-sugar diet during adolescence on cognitive control and decision-making abilities, finding impairments in rule-following tasks.

05:02

🔬 Junk Food's Effects on Memory and Neuroplasticity

This paragraph delves into how junk food consumption affects memory and the brain's hippocampus, causing neuroinflammation that impairs learning and memory. The speaker explains that even without obesity, a diet high in junk food can negatively impact memory performance. Furthermore, she discusses the hippocampus's role in receiving fullness signals and how a high-fat diet can disrupt this function, leading to overeating and a vicious cycle of obesity and brain damage. The paragraph also addresses the importance of neurogenesis in the hippocampus and how high-fat diets and mental health disorders can reduce this process, potentially leading to a decrease in mood and cognitive function. The speaker concludes by emphasizing the importance of a healthy diet and lifestyle to counteract these effects.

10:04

🍏 Balancing Junk Food with Healthy Habits

In the final paragraph, the speaker acknowledges the allure of junk food and suggests a balanced approach to diet. She advises treating junk food as a reward rather than a dietary staple. The speaker encourages the consumption of healthy foods like fruits and vegetables, which are rich in antioxidants that combat inflammation, and foods rich in omega-3, such as avocados and oily fish, which can boost neurogenesis. Additionally, she promotes an active lifestyle as a means to enhance both physical health and brain function, suggesting that physical activity can increase neuroplasticity and help maintain a healthy weight.

Keywords

💡Neuroscience

Neuroscience is the scientific study of the nervous system, which includes the brain, spinal cord, and nerves. It is central to understanding how our brains control our behaviors. In the video, the speaker, a neuroscientist, uses this field to explore how the foods we eat, particularly junk food, impact not only our bodies but also our brain functions.

💡Junk Food

Junk food typically refers to food items that have little nutritional value but are high in calories, sugar, and unhealthy fats. The script discusses how junk food is rewarding to our brains due to its taste, leading to overconsumption and negative health effects, including weight gain and potential cognitive impairments.

💡Dopamine

Dopamine is a neurotransmitter associated with the brain's reward system. The script explains that when we consume junk food, our brain's reward center releases dopamine, creating a pleasurable sensation that can lead to an overconsumption of these foods and a subsequent tolerance, making us crave more.

💡Overconsumption

Overconsumption refers to the act of eating more food than the body needs. In the context of the video, it is linked to the addictive nature of junk food and its impact on the brain's reward system, leading to an increase in the number of dopamine receptors and a need for more of the food to achieve the same level of satisfaction.

💡Prefrontal Cortex

The prefrontal cortex is a part of the brain involved in cognitive control and decision-making. The video highlights that this area is not fully mature until our 20s, which may explain why young people find it difficult to resist junk food and why their brains are more vulnerable to the impacts of poor diet on behavior and memory.

💡Cognitive Control

Cognitive control refers to the mental processes that enable us to control our thoughts and actions in the face of temptations or distractions. The script discusses how a diet high in junk food can impair cognitive control, affecting the ability to follow rules and make decisions.

💡Neuroinflammation

Neuroinflammation is the inflammation in the brain, which can be caused by a consistently unhealthy diet. The video describes how neuroinflammation can impair memory and learning by affecting the function of neurons in the hippocampus, the brain's memory center.

💡Hippocampus

The hippocampus is a region of the brain that plays a critical role in memory and learning. In the script, it is mentioned that a diet high in junk food can lead to neuroinflammation in the hippocampus, which in turn can impair one's ability to form and retain memories.

💡Neurogenesis

Neurogenesis is the process by which new neurons are generated in the brain, particularly in the hippocampus, throughout life. The video explains that high-fat diets can reduce neurogenesis, which is also linked to mental health disorders like depression, suggesting a connection between diet and mental well-being.

💡Neuroplasticity

Neuroplasticity refers to the brain's ability to change and adapt as a result of experience. The script mentions that a healthy lifestyle, including physical activity, can boost neuroplasticity, which is important for learning and memory, counteracting the negative effects of a junk food diet on the brain.

💡Antioxidants

Antioxidants are substances that can fight against the harmful effects of oxidation in the body. In the context of the video, antioxidants found in fruits and vegetables are highlighted as beneficial for combating inflammation and neuroinflammation, thus supporting brain health.

💡Omega-3

Omega-3 fatty acids are a type of polyunsaturated fat that is essential for health. The video script notes that foods rich in omega-3s, such as avocados and oily fish, can boost neurogenesis, which is beneficial for brain health and memory.

Highlights

Neuroscientist's fascination with how brains control behaviors and recent interest in environmental and dietary impacts on the brain.

Junk food's rewarding taste triggers dopamine release in the brain's reward center, leading to overconsumption.

Brain adapts to excessive junk food intake by creating more dopamine receptors, increasing cravings.

Dopamine also plays a role in learning and attention, making junk food hard to resist.

The prefrontal cortex, responsible for cognitive control and behavior, matures fully only in the 20s.

Young people struggle to resist junk food temptations due to immature prefrontal cortex function.

Research with rats mirrors human brain responses to junk food, providing a model for studying dietary impacts on behavior.

Adolescence is a vulnerable period for cognitive deficits caused by junk food consumption.

Teenage rats fed sugary solutions show impaired rule-following and decision-making abilities.

Junk food diets affect the hippocampus, the brain area responsible for memory, leading to neuroinflammation.

Neuroinflammation impairs learning and memory by causing neurons to malfunction.

People with high junk food consumption perform worse on memory tests compared to those on healthy diets.

Damage to the hippocampus can lead to constant feelings of hunger due to disrupted fullness signals.

High-fat diets and mental health disorders like depression are linked to lower neurogenesis in the hippocampus.

Comfort eating junk food can diminish neurogenesis, potentially worsening mental health in the long run.

Being mindful of dietary choices is crucial for both physical and cognitive health.

Eating healthy foods like fruits, vegetables, avocados, and oily fish can counteract negative effects of junk food on the brain.

Physical activity boosts neuroplasticity and helps combat the impacts of unhealthy diets on the brain.

Moderation is key - junk food should be treated as a reward, not a dietary staple.

Transcripts

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)