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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Falling in Love Is a Brain Function
“I love you from the bottom of my heart.”
We have all said it, or heard it. It is one of the oldest ways we express love, and most of us never stop to question it. We imagine that love lives deep in our heart.
But here is the surprising truth: your heart is made up of muscle, and it is not capable of experiencing emotions. Love does not begin in your heart. Love begins in your brain.
Let me explain what actually happens.
The Message Starts in Your Brain and Ends in Your Chest
The feeling of love emerges from the interactions of several brain areas the regions that handle emotion, motivation, reward, and social bonding. When you fall in love with someone, these areas glow with activity. They, in turn, stimulate the part of your brain that regulates hormones in your blood, such as adrenaline.
The adrenaline then makes your heart beat faster. That is why, when you see someone you love, your heart pounds.
The message begins in your brain and ends up in your heart. You cannot feel the glowing of activity in your brain, but you can feel the pounding of your heart in your chest. And so, understandably, we have spent centuries believing it is the heart that sparks with love.
Every Emotion You Feel Is Built by Your Brain
I am a neurologist, and I have spent much of my career studying the brain, mostly at Johns Hopkins and Harvard Medical School. One thing that never stops amazing me is this: every emotion we experience fear, joy, excitement, pride, sadness is created by the brain.
Different emotions involve different groups of brain regions working together as a network. Love is no exception. In fact, love gives us a beautiful window into how the human brain works when it comes to bonding and forming lasting relationships.
Feelings of love also engage the dopamine reward and motivation system. It is the activity of dopamine pathways in the brain that leads to the pleasure, joy, excitement, and motivation that make you want to keep seeing the person you love, over and over again.
What Scientists Saw Inside the Brain of Someone in Love
The research that uncovered this is fascinating.
Helen Fisher and her colleagues studied people who were intensely in love. While these volunteers lay inside a brain MRI scanner, the researchers showed them photographs of the person they loved. Something remarkable happened. The dopamine-rich areas deep inside the brain, including a region called the ventral tegmental area, or VTA, became intensely more active.
That surge of dopamine is what gives you the intense sense of pleasure about the person you love, and it is what motivates you to want to be near them at all times.
Animal studies help us understand the biology of love and lasting relationships even further. Prairie voles are small, monogamous rodents that form long-lasting pair bonds. Researchers have found that the dopamine system in their brains surges when these animals have to climb over a fence to seek out and reach their partner.
In other words, it appears that even the act of seeking the one you love can give you some of the same joy you feel when you are with them. The dopamine pathways in the brain, along with a hormone called oxytocin, help people who love each other bond and stay together.
Love Is Bigger Than Romance
As we research the biology of love, we have discovered something profound: our brains have evolved to connect with other human beings. Love and connection are part of what makes us human.
And this is where I want to expand the meaning of love. When we hear the word “love,” we often think about romance. But the human brain does not reserve something as important as love for romance alone. There is also the love between parents and children.
A few years ago, I saw something in the news that I will never forget. After the tsunami in Japan, photographs surfaced of mothers who had been found still holding their children, having used the last moments of their lives shielding them from the water. These women, in the most extreme situation imaginable, sacrificed their own lives for their children. Their love for their child outlived their instinct to save themselves.
I remember looking at those images and thinking, “I would do that too.” As I am sure almost every parent would. That is the power of love in the brain.
These relationships may look different from one another. But they all involve the same dopamine and oxytocin network in the brain that helps us connect, care, trust, and protect one another.
Why Heartbreak Physically Hurts
There is another side to this.
When an important relationship is lost, the pain can be very real. Research on social rejection and loss has shown that social pain can engage some of the same brain regions involved in physical pain.
So if you have ever experienced heartbreak and thought, “Why does this hurt so much?” there is a neurological reason for it. Some of the same brain areas that light up with physical pain also light up with the emotional pain of losing someone you love.
Your brain takes social connection seriously. From an evolutionary point of view, belonging to a group was essential for survival.
The Lesson From the Longest Study of Human Life
This brings me to something I believe is even more important than romantic love: human connection is a genuine part of brain health.
One of the longest-running studies of human life is the Harvard Study of Adult Development, which has followed people for more than eight decades. One of its most important lessons is remarkably simple: the quality of our relationships matters enormously for our health and happiness. People who have stronger, more supportive relationships tend to be healthier and live longer.
And this is not just one study. Large studies and meta-analyses involving hundreds of thousands of people have found associations between loneliness and a higher risk of dementia, and between social isolation and a higher risk of premature death.
I want to be careful here. That does not mean loneliness automatically causes dementia, or that one loving relationship guarantees a longer life. But the message from decades of research is remarkably consistent: we are social creatures. Our brains and bodies do better when we have meaningful connections.
Don’t Let Technology Replace What Makes Us Human
So as AI becomes more present in our lives, I think we have a responsibility: do not let technology replace the relationships that make us human.
Protect the connections you already have. Call your parents. Check on your friends. Make time for the people who matter. And be willing to let new people into your life.
Every time you reach out to someone, listen deeply, share a laugh, offer comfort, or allow someone to help you, you are participating in the life of another human being. You are also giving your own brain an experience it was designed to have. Connection. Belonging. Love.
A Challenge for You This Week
So now, I have a challenge for you.
Think of three people who matter to you. Not three people you follow. Not three people you text with an emoji. Three people who truly matter.
And sometime this week, reach out to them. Call them. Meet them. Tell them what they mean to you. Tell them you love them from the bottom of your heart, even though you now know your love for them actually resides in your brain, not your heart.
And know this: the connection you share with them will contribute to your own brain vitality and longevity 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 https://youtu.be/OwfFXOhhBKY on Dr. Fotuhi’s YouTube Channel.
Keep up with Dr. Fotuhi on LinkedIn & Instagram.
References
1. Aron, A., Fisher, H., Mashek, D. J., Strong, G., Li, H., & Brown, L. L. (2005). Reward, motivation, and emotion systems associated with early-stage intense romantic love. Journal of Neurophysiology, 94(1), 327–337.
2. Eisenberger, N. I., Lieberman, M. D., & Williams, K. D. (2003). Does rejection hurt? An fMRI study of social exclusion. Science, 302(5643), 290–292.
3. Fisher, H., Aron, A., & Brown, L. L. (2005). Romantic love: An fMRI study of a neural mechanism for mate choice. Journal of Comparative Neurology, 493(1), 58–62.
4. Holt-Lunstad, J., Smith, T. B., Baker, M., Harris, T., & Stephenson, D. (2015). Loneliness and social isolation as risk factors for mortality: A meta-analytic review. Perspectives on Psychological Science, 10(2), 227–237.
5. Liu, Y., & Wang, Z. X. (2003). Nucleus accumbens oxytocin and dopamine interact to regulate pair bond formation in female prairie voles. Neuroscience, 121(3), 537–544.
6. Livingston, G., Huntley, J., Sommerlad, A., et al. (2020). Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. The Lancet, 396(10248), 413–446.
7. Pierce, A. F., Protter, D. S. W., Watanabe, Y. L., Chapel, G. D., Cameron, R. T., & Donaldson, Z. R. (2024). Nucleus accumbens dopamine release reflects the selective nature of pair bonds. Current Biology, 34(3), 519–530.
8. Waldinger, R., & Schulz, M. (2023). The Good Life: Lessons from the World’s Longest Scientific Study of Happiness. Simon & Schuster.
Your Brain Is a Portfolio: What Every Executive Should Know About Brain Aging
If you are an executive who works long hours and lives under a heavy load of stress, I want you to read this closely. I have some good news and some bad news about your brain. But first, let me tell you about a patient of mine.
He was a 49-year-old hedge fund manager. Over two years, he had become the most successful person at his firm and had been promoted twice. On the surface, everything was going right.
Underneath, though, he had started to notice changes. He was getting grumpy with his family more easily. He would forget the names of his own clients. During afternoon meetings, he would feel foggy and struggle to keep up with everyone else in the room. And because his father had struggled with dementia late in life, he had begun to fear this was the start of Alzheimer’s disease.
My first job was to figure out what was actually driving those changes.
The Belief That Holds Most Executives Back
Most high performers assume their mental sharpness will either hold up with age or slowly slip away, and that there is very little they can do about it. They picture the brain as a fixed structure, like a computer you cannot upgrade.
That is absolutely wrong.
Your brain is much more like a portfolio. It appreciates with the right investment. It depreciates with neglect. And either way, it is compounding, for better or worse, every single day.
A short temper, memory lapses, and afternoon fog are not signs of permanent damage. They are signals that your brain portfolio needs more attention. As my patient came to learn, these warning signs can be reversed.
The Bad News: How Your Routine May Be Shrinking Your Brain
Let me start with the bad news, because it matters.
Sustained stress keeps a hormone called cortisol elevated in your blood. Over time, elevated cortisol is linked to shrinkage in parts of your frontal lobes and your hippocampus, the very regions responsible for decision-making, executive function, leadership, learning, memory, and emotional regulation.
Think of chronic stress as an unhedged risk exposure. It sits quietly on your balance sheet, and if you never address it, it erodes the asset every single day it goes unmanaged.
Stress is not the only factor. A sedentary lifestyle, an irregular sleep pattern, a poor diet, and a lack of downtime and relaxation all shrink your cortex and hippocampus over time. And the more your brain atrophies, the worse you function, which, for a leader whose work depends on judgment, is the entire game.
The Good News: Atrophy Can Be Reversed
Now the good news, and it is substantial.
Based on compelling scientific evidence, atrophy in the frontal lobe and hippocampus can be reversed through what I call the five pillars of brain health.
Think of the five pillars as five separate investments in your brain. Each one alone is enough to make a real difference in your cognitive performance. But when you combine them, the returns do not just add up. They compound. Imagine what your brain will look like when all five are working for you at once.
1. Exercise: Aerobic activity, such as walking for an hour, raises levels of a molecule called BDNF, which actively supports growth in the brain. This is real capital appreciation on your brain asset, not vague wellness advice. It is one of the most direct and measurable levers available to you.
2. Sleep: Your brain has an innate cleanup operation called the glymphatic system, and it runs hardest during deep sleep, clearing out the metabolic waste that builds up during a normal day of thinking and working. Sleep fewer than six hours a night, and that clearance does not finish completely. Over time, the deficit compounds night after night, the same way unpaid interest compounds on a balance. Sleep is not rest for your brain. It is an active maintenance system that protects your principal.
3. Diet: What you eat becomes the literal building material for your brain cells. The Mediterranean diet, rich in olive oil, leafy greens, fish, nuts, and berries, supplies the omega-3 fatty acids and antioxidants that calm the inflammation eroding neurons over time. Think of it as the raw material you feed into the factory. Even the best machinery produces poor output if the inputs are poor.
4. Stress regulation. This is trainable, not a personality trait, and it functions as your hedge. Something as simple as breathing slowly for two minutes has real benefits for your brain, both in the short term and the long term.
5. Novelty and cognitive challenge. Brains that keep learning something genuinely new build what is called cognitive reserve, a protective buffer that makes the whole portfolio more resilient to future stress or decline.
Where to Start: Rebalance Your Weakest Position
Now comes the most important question. What can you do right now, in the shortest amount of time, to see the best results?
Pick the one lever that is the weakest position in your portfolio, and work on it for two weeks.
If it is sleep, look for the underlying causes and make fixing it a priority. You really do not want insomnia quietly shrinking your brain and compounding over time in a way that could raise your risk for Alzheimer’s disease.
If it is stress, build a system to reduce it by ten percent over the next two weeks. Make a list of what matters most in your life, and eliminate one or two responsibilities that matter least. You are a smart person; figure out what needs to change so you can have some calm, relaxing time in your day. Try breathing slowly for two minutes, without interruption, at least once a day. Do it when you feel overwhelmed, or right before you fall asleep.
What Happened to the Hedge Fund Manager
Let me return to my patient for a moment.
Once I walked him through what was actually driving his brain changes, he had a genuine aha moment. He decided to cut back on his hours. He realized that his family and his own life mattered more to him than getting promoted at an accelerated pace. That one shift changed everything.
After six weeks of working on all five pillars of brain health, he was calmer, happier, and sharper. In fact, he stopped worrying about Alzheimer’s disease altogether.
Your Brain Is the Asset Everything Else Depends On
Here is what I want you to take from this.
Your brain is the one asset that every other asset in your life depends on. Everything else you optimize sits downstream of it. Start managing your brain like the highest ROI investment you have, and you will notice the difference within weeks, not years.
I believe what separates a good leader from a great leader is how they care for their company and their people while also caring for themselves and their own brains. Sacrificing your wellbeing to drive company revenue takes a toll on brain vitality and accelerates decline in the prefrontal cortex and hippocampus, the very regions essential for making decisions under pressure, and for memory and learning.
Build the five pillars into your daily routine as much as you can, and you will notice a clear improvement in your brain function within weeks.
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.
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.