Serotonin Builds Your Brain
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Often referred to as the natural “feel-good” chemical in the body, serotonin is a brain chemical that is integral to a person’s sense of well-being. It is most often associated with its role in the central nervous system, helping with mood regulation, self-confidence, and satisfaction. Doing your favorite hobby or planning the perfect Valentine’s Day with your sweetheart can all trigger the release of serotonin in the brain. But it turns out that serotonin doesn’t just make you feel good – it may also be responsible for the development of a large neocortex, which allows you to speak, calculate, make decisions, and handle complicated tasks.
Serotonin and Brain Size
The size of the human brain gradually increased during human evolution, with the neocortex being a major affected region. The neocortex enables humans to think, speak, drive, calculate, and make decisions.
Researchers from the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden in coordination with those at University Hospital Carl Gustav Carus in Dresden sought to better understand the cause of the expansion of the neocortex and identified numerous molecular players that act as a growth factor for brain cells, which contribute to the expansion of the outer cortex.
More recently, the researchers found another important role in the neocortex of the developing brain of humans – but interestingly, not in mice. The researchers theorize that serotonin from the placenta may have contributed to the evolutionary expansion of this region of the human brain.
The research team led by Wieland Huttner, a founding director of the Max Planck Institute of Molecular Cell Biology and Genetics, further investigated studies associated with neocortex’s expansion that has taken place over the course of humankind. One study from Huttner’s lab looks specifically at serotonin in the expansion process, which hasn’t been explored in detail. It is known that serotonin is produced in the placenta and delivered to the developing embryo via the umbilical cord and blood circulation. From there, it makes its way to the brain (in both humans and mice). However, the function of this neurotransmitter derived from placenta was previously unknown.
A Pivotal Factor
Serotonin is a naturally occurring substance that works to carry signals between neurons (or nerve cells) throughout the body. One scientist, Lei Xing, in Huttner’s group previously researched neurotransmitters and further investigated their role in the developing brain, finding that a certain serotonin receptor, identified as HTR2A, was found in the human neocortex, but not that of mice. Xing questioned whether the HTR2A receptor was part of the answer to the question of why humans have a larger brain. Researchers then sought to answer this question in a new study.
To determine if HTR2A was a factor in the growth of the human brain, researchers induced the production of the receptor in the neocortex of embryonic mice. The presence of the HTR2A receptor led to a chain of reactions that caused a heightened production of brain cells. The increase in the number of cortical neurons encourages a larger brain, especially in the neocortex.
According to Huttner, this study sheds light on an important growth factor role that serotonin has in highly developed human brains. Certain psychiatric and neurodevelopmental disorders have been associated with an abnormal signaling of serotonin as well as a mutated or disturbed expression of the HTR2A receptor, including ADHD, autism, and Alzheimer’s disease. The findings in this recent study may help us to better understand serotonin and the important receptor linked to it during brain development, possibly suggesting new approaches for treatment of certain neurological disorders.
Some studies have shown that increasing serotonin levels in the brains of elderly with cognitive impairment can slow down the rate of atrophy in their brains. Medications such as Zoloft, Prozac, and Lexapro can help these patients both feel better and have less cognitive decline.
The Bottom Line – Serotonin Grows Your Brain
The neurotransmitter serotonin has the capacity to act as a growth factor for fetal human brain stem cells that are responsible for determining the size of the brain. In addition the possibility of greater-than-average brain grow, this research offers hope for therapeutic treatments of neurodevelopmental and psychiatric disorders, such as autism, attention deficit hyperactivity disorder, Down Syndrome, and Alzheimer’s disease.
Base on these studies and other research in the field of neuroplasticity to reverse the effect of aging, Dr. Fotuhi has developed a 12-week brain rehabilitation program. This program includes several interventions which when combined can result in a larger and stronger brain. To learn more about this program, please visit drfotuhi.com
This blog was written by Mrs. Courtney Cosby and edited by Dr. Majid Fotuhi.
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Your Knees and Your Brain Want the Same Five Things
Here is something surprising about the link between your knees and your brain: the same five habits that keep your knees from wearing out are the ones that keep your brain from wearing out.
But here is the part that surprised even me, after forty years in neurology. Knee pain that goes untreated does not stay in the knee. It can quietly trigger the start of accelerated brain aging. Pain leads you to slow down, and inactivity speeds up cognitive decline faster than almost anything else.
That chain reaction from a sore knee to a fading brain is what I want to walk you through. And I am going to show you exactly how to stop it and reverse it, so you can become more mobile and regain your brain vitality at the same time.
Different Tissue, Same Fire
Why would your knees and your brain care about the same things? Because they share the same enemy: chronic, low-grade inflammation.
In your joints, that inflammation breaks down cartilage. In your brain, that same inflammatory process contributes to significant atrophy and cognitive decline. Different tissue, same fire.
This is the key insight, and it changes how you should think about your health. The habits that put out the inflammatory fire don’t protect one organ or the other. They protect both at the same time.
The Five Pillars for Your Knees and Your Brain
Let me walk you through the five pillars that are essential for your knees and your brain, whether your joints are perfectly healthy or already hurting.
Pillar one: Exercise: Movement nourishes your cartilage and increases blood flow to your brain. Aim for 3,000 to 7,000 steps a day. That is just walking, not a serious workout. If you have the time, add some vigorous exercise for about three hours a week.
Pillar two: Diet: Eat fatty fish like salmon or sardines twice a week. Snack on fruit, such as a cup of blueberries. Avoid junk food, cook at home as much as possible, and use extra virgin olive oil instead of other oils. You can also take an omega-3 supplement with DHA and EPA at a dose of 1,000 mg a day. Curcumin is another great anti-inflammatory supplement worth trying. These food choices calm inflammation in your joints and your brain at once.
Pillar three: Sleep: Sleep seven to eight hours, and pay attention to when you go to bed, not just how long you sleep. Late, irregular sleep raises joint inflammation and disrupts your brain’s overnight clean-up process.
Pillar four: Weight and Metabolic health: Even a modest amount of weight loss meaningfully reduces the inflammatory load on both your joints and your brain. You do not need to lose a lot to feel a real difference.
Pillar five: stress reduction: A daily five-to-ten-minute practice of meditation or slow, deliberate breathing lowers the same inflammatory markers that damage cartilage and neurons alike.
Five daily habits. Two organs protected at once.
The Trap That Catches So Many People
Now I want to speak directly to anyone who has untreated knee osteoarthritis, because this is the moment that decides everything.
When your knee hurts, every instinct tells you to protect it by moving less. I understand that instinct. But moving less is exactly how you fall into a trap of accelerated cognitive decline. A slow, sedentary lifestyle leads to brain atrophy and a rapid decline in thinking and memory.
I have watched this happen to patients again and again. And I have also watched it reverse. Let me tell you about two of them.
Janet: When Treating the Knee Treated the Brain
I remember a patient of mine named Janet vividly. A retired teacher, she was 69 when she came to see me, worried about developing Alzheimer’s disease.
During our conversation, she mentioned in passing that she had significant pain in her left knee. As a result, she had stopped going to her pickleball games. She had also quietly withdrawn from other activities she used to love, like dancing.
I referred her to a physical therapist, who put her on a knee strengthening and stabilization program. She did it religiously, every day, for three months.
The woman who came back to see me was not just walking better. Janet was animated again, and she felt sharper. Most of her sense of cognitive decline had come from her sedentary life and her social isolation. Treating her knee pain, in a very real sense, treated her brain.
Jack: A Conversation About the Brain, Not the Knee
Another patient, Jack, was a 75-year-old accountant. He came to see me worried about “losing his marbles.”
As we talked about his overall health, I learned that he had lived with severe knee arthritis for years. Slowly, he had pulled back from his friends, his hobbies, the life he used to have. His sedentary lifestyle had led to gaining thirty pounds. His mood had darkened, and his memory was slipping.
He had tried physical therapy, but the pain persisted. His knee MRI showed advanced arthritis, and his surgeon recommended a knee replacement. But Jack refused. He wanted nothing to do with surgery.
So we talked- not about his knee, but about his brain. About how movement protects against cognitive decline, and how staying sedentary was quietly raising his risk of Alzheimer’s. That conversation changed his mind, and he agreed to the surgery.
Three months later, Jack was walking two to three miles a day. He was happier. He was sharper. And he told me, with real excitement in his voice, that he felt like he was starting an entirely new chapter of his life.
Don’t Let Pain Shrink Your Life
I share these two stories because they are not the exception. They are what happens when you refuse to let joint pain shrink your life.
Treat it aggressively. Set a goal to stay strong and active, not just to manage pain quietly in the background. Do not let anything stand between you and an active lifestyle.
Protecting your knees is not separate from protecting your brain. They both need the same five things: exercise, anti-inflammatory foods like a Mediterranean diet, adequate sleep, a healthy weight, and a calm mind.
And if your knees are already hurting, do not let that pain become the quiet beginning of accelerated aging. Strengthen them, treat them seriously, and stay in the life you have built.
Dr. Majid Fotuhi is a Harvard- and Johns Hopkins-trained neurologist, bestselling author of The Invincible Brain (USA TODAY Bestseller), and one of the world’s leading experts on brain health and cognitive performance. He has spent more than three decades studying the brain’s capacity for growth and repair. To discover your brain health score and receive a personalized 10-page report, take the free Invincible Brain Assessment at invincible.drfotuhi.com.
📺 Watch the full video on Dr. Fotuhi’s YouTube Channel.
The Best Morning Routine for a Sharper Brain
What you do in the first hour after you wake up matters more for your brain than anything else you do all day.
I know that sounds like a big claim. But once you understand what’s happening inside your head first thing in the morning, I think you’ll agree, and you’ll want to treat that hour differently starting tomorrow.
Let me explain the science, and then walk you through the exact four-step routine I recommend.
Why the First Hour Matters So Much
While you sleep, your brain runs a kind of cleanup crew called the glymphatic system. It flushes out the cellular waste your neurons produce throughout the day. So the moment you wake up, your brain is at its cleanest and most primed state.
That’s exactly why the first hour of your day carries so much weight. Your brain doesn’t just react to your day; it helps create it. What you feed it in those early minutes, in thoughts and in actions, sets the tone for everything that follows.
Here’s how I recommend using that hour, step by step.
Step 1: Don’t Rush Out of Bed
When you open your eyes, resist the urge to jump up, and whatever you do, don’t reach for your phone yet.
Instead, take a few minutes to think through your life. I like to focus on three sets of thoughts.
First, reconnect with your passions and your long-term goals. Visualize the life you’re working toward and the things that bring you the most joy.
Second, remind yourself that you’re capable of far more than you give yourself credit for. Most of the people you admire got where they are through effort, not luck. You can achieve any goal you set for yourself.
Third, tell yourself that things today will work out in your favor. Picture having a great day. And remind yourself that even when setbacks happen, they often become the first step toward something better.
A couple of minutes of this is enough to shift your whole mindset before your feet even touch the floor.
Step 2: Breathe and Feel Grateful
Still in bed, spend about five minutes on slow breathing or a short meditation.
Use this time to think about all the wonderful things you already have in your life. As you take each deep breath, remind yourself how fortunate you truly are. This isn’t about ignoring your challenges. It’s about setting the emotional tone of your day with energy and enthusiasm instead of stress and rush.
This step matters more than it might seem, and here’s why.
Chronically high levels of the stress hormone cortisol are toxic to your brain. When cortisol stays elevated day after day, it acts almost like a slow poison to the hippocampus, the part of your brain responsible for learning and memory, and the very region that shrinks first in Alzheimer’s disease.
A few minutes of gratitude and calm breathing is one of the simplest ways to keep that stress response in check. You are, quite literally, protecting the part of your brain you rely on to stay sharp and remember your life.
Step 3: Get Up and Move
By now you’ve spent about seven minutes still in bed, and your mind is already in a good place. Now it’s time to actually get up and move.
If you can, do some exercise or yoga every morning. A short run, a bike ride, a swim, or a simple stretching routine gets your neurons firing even if it’s only for 10 to 15 minutes.
If morning exercise isn’t possible for you, use this time for your daily family routines instead, like getting the kids ready for school. Either way, you’re moving your body and your mind into the rhythm of the day. Consistency matters far more here than intensity.
And if you need to check your emails or messages, this is the time. But don’t waste any of your precious morning on social media.
There’s real evidence behind the exercise piece specifically. A 2024 study found that twelve weeks of exercise was associated with significant changes in the hippocampus and improved neuroplasticity, your brain’s ability to learn and adapt. Your muscles aren’t the only thing that gets larger and stronger when you exercise. Your brain does too.
Step 4: Fuel Your Brain
Once you’ve moved your body or handled your morning chores, it’s time to eat.
An ideal breakfast for a sharper brain is built around protein and fiber, with coffee or tea if you like. You can alternate through the week so it never gets boring. One morning, try an omelet with vegetables and a slice of whole-grain toast. Another, oatmeal with blueberries and milk.
Rotate in nuts, berries, olive oil, leafy greens, poultry, or fish when you can. These are staples of the Mediterranean diet, which research shows can slow cognitive decline.
None of this requires a complicated meal plan. It just takes a little intention before you walk out the door.
The Bigger Picture: You Can Shape Your Brain
Having gone through a series of rejuvenating thoughts, some movement, and a healthy breakfast, you head out the door full of energy, ready to take on the world.
Here’s what I most want you to remember. Neuroplasticity is the most remarkable property of the human brain. It means you are not stuck with the brain you have today. You can actively shape and strengthen it, improving both how you experience life right now and how sharp you stay decades from now.
The morning is the single best window each day to prime your brain for the highest levels of neuroplasticity. And the routine itself is not complicated:
Warm up your mind with positive thoughts for two minutes. Add five minutes of deep breathing and gratitude. Move your body for 10 to 15 minutes. Finish with a high-protein, high-fiber breakfast. Then step out of the house full of positive thoughts and energy.
These four simple morning steps will help you have a great day today and stay sharp for years to come.
Dr. Majid Fotuhi is a Harvard- and Johns Hopkins-trained neurologist, bestselling author of The Invincible Brain (USA TODAY Bestseller), and one of the world’s leading experts on brain health and cognitive performance. He has spent more than three decades studying the brain’s capacity for growth and repair. To discover your brain health score and receive a personalized 10-page report, take the free Invincible Brain Assessment at invincible.drfotuhi.com.
📺 Watch the full video on Dr. Fotuhi’s YouTube Channel.
What Sugar Really Does to Your Brain (and How Ozempic Fits In)
What if I told you that eating a donut can do something to your brain that looks a lot like what cocaine does to it?
I know that sounds dramatic. But by the time you finish reading this, I think you’ll see it differently. Because the truth is that sugar isn’t just fattening, it’s actually toxic to your brain. Obesity can shrink your brain at any age. And the new class of weight-loss drugs everyone is talking about may be doing something in the brain that goes well beyond the number on the scale.
Let me walk you through what actually happens when you eat.
The Sugar Spike and the Crash That Follows
When you eat sugar, your blood glucose rises. Your pancreas responds by releasing insulin, a hormone that works like a key, unlocking your cells so glucose can get inside and be turned into energy.
The type of food matters enormously here. Complex carbohydrates like fruits and vegetables cause a slow, gentle rise in blood sugar. But a donut or a bowl of ice cream causes a sharp spike, which triggers a flood of insulin. That surge of insulin then pushes your blood sugar too low, and that crash is what leaves you hungry and craving sugar again an hour later.
Repeat that cycle day after day, and it often leads somewhere you don’t want to go: diabetes and obesity.
Three Ways This Cycle Quietly Damages Your Health
Over time, this pattern of sugar spikes and insulin surges causes three deeper problems.
First, your cells can become resistant to insulin. Sugar starts building up in your blood instead of getting inside your cells where it belongs. This is called insulin resistance, and it’s an early step toward metabolic syndrome and diabetes.
Second, excess sugar binds to proteins throughout your body in a process called glycation. Too much glycation impairs how those proteins function. This is part of why patients with poorly controlled diabetes can lose sensation in their toes, lose their vision, or damage their kidneys to the point of needing dialysis.
Third, high sugar levels generate free radicals and inflammation everywhere — throughout your body and inside your brain.
Why Sugar Is Toxic to Your Brain
This is where it gets personal for me as a neurologist.
In animal studies, high sugar levels reduce the number of dendrites, the branches on your neurons that receive connections from other neurons. Fewer connections mean less communication between brain cells, and that shows up in real life as brain fog and memory loss.
A high-sugar diet also reduces neurogenesis, the birth of new neurons in your hippocampus, which is your brain’s memory center. In other words, sugar makes it harder for your brain to build the very cells you rely on to learn and remember.
And in human studies, obesity is consistently linked to a smaller hippocampus and a higher risk of disease.
Brain Shrinkage Happens at Every Age
Here’s what surprises most people: this isn’t just a concern for older adults.
Brain atrophy linked to excess body fat shows up across every age group. Even children are not spared. When obesity affects a young brain, some of the academic struggles we see in kids may actually be tied to changes in the hippocampus and other brain regions.
There’s also a circulation piece to this story. In people with multiple risk factors, researchers have found lower blood flow throughout the brain, along with lower scores on memory and other brain functions. Less fuel reaching the brain means less capacity to think, focus, and remember.
Why We Eat and Why Willpower Isn’t the Whole Story
So why do we eat in the first place, and what actually controls our eating behavior?
Part of the answer is hormonal. Chemicals in your blood, leptin, insulin, and others, tell your brain when to stop eating, while ghrelin, the “hunger hormone,” tells your brain to eat more.
But eating isn’t only about hunger. Your brain’s reward system, the same circuitry involved in addiction, lights up when you eat, and especially when you eat sugar. Over time, this creates craving and tolerance. You crave sugar constantly, and you need more of it to feel the same satisfaction you once got from less.
Your prefrontal cortex is supposed to act as the brake on all of this, the part of your brain that helps you stop after the first bite. But in obesity, the prefrontal cortex doesn’t work as well, and your willpower around food shrinks along with it.
I want to be clear about what this means: eating too much is not simply a lack of discipline. For many people, it reflects a genuine addiction to food. That’s not an excuse; it’s a starting point for real solutions.
Where Ozempic Fits In
This brings us to the newest piece of the puzzle.
Medications like Ozempic work in three places at once. In the pancreas, they increase insulin and lower a hormone called glucagon. In the stomach, they slow digestion so you feel full faster and for longer. And in the brain, they reduce appetite directly, quieting the cravings that drive addictive eating.
Many patients on these drugs describe something fascinating: a quieting of what’s been called “food noise,” the constant mental chatter about food that runs in the background all day. Researchers are now studying whether these same medications might help with Alzheimer’s prevention, and even with addiction to alcohol, smoking, or other behaviors, since they appear to turn down the brain’s reward and addictive pathways.
But turning down the reward system isn’t free of trade-offs. Some patients report depression, fatigue, or even brain fog. This is still very much an active area of research, and I’ll be watching it closely.
What I Want You to Remember
Your brain is not separate from the food you eat. Every sugar spike and every extra pound leaves a mark on every organ in your body and on your brain.
If you want to stay sharp, the path is clear. Eat healthy food in reasonable portions. Exercise often. When you are fit, your brain simply works better.
People have known the essence of this for centuries: healthy body, healthy mind. What’s different now is that, for the first time, we have the scientific data to understand exactly how it works and how you can use that knowledge to take back control of your eating and protect your brain for decades to come.
Dr. Majid Fotuhi is a Harvard- and Johns Hopkins-trained neurologist, bestselling author of The Invincible Brain (USA TODAY Bestseller), and one of the world’s leading experts on brain health and cognitive performance. He has spent more than three decades studying the brain’s capacity for growth and repair. To discover your brain health score and receive a personalized 10-page report, take the free Invincible Brain Assessment at invincible.drfotuhi.com.
📺 Watch the full video on Dr. Fotuhi’s YouTube Channel.