When it comes to your brain, size matters. I am talking about one structure in particular, a small seahorse-shaped region called the hippocampus. It sits at the center of learning and memory, and its size has a lot to say about your future.

A great deal of research has shown that the hippocampus can shrink, driven by the way you live and by certain medical conditions. As it shrinks, your risk of Alzheimer’s disease rises. Keep it large and strong, and your odds of staying sharp late into life improve dramatically.

Most of what shapes it is in your hands. Below are six habits that shrink the hippocampus, followed by six that grow it. Read both, then decide which list you want to live by.

The Six Things That Shrink Your Brain

1. Sleeping fewer than six hours a night: Short sleep is hard on the brain, and the longer you live with insomnia, the more the hippocampus tends to shrink. Sleep is not idle time. It is when the brain does some of its most important maintenance.

2. Untreated sleep apnea: If you snore, carry weight around your middle, and feel tired through the day, sleep apnea is worth ruling out. When you have apnea, your breathing stops and starts through the night, and your brain is repeatedly deprived of oxygen. The longer that goes on untreated, the more the brain suffers from the constant shortage.

3. Chronic stress and anxiety: Getting stressed before a deadline now and then is normal and harmless. The damage comes from feeling angry and stressed most of the time. Ongoing stress keeps your cortisol high, and cortisol is especially toxic to the hippocampus. Protecting your brain means finding ways to bring those levels down.

4. A poor diet: If you eat junk food regularly, you are working against your own brain. Studies have linked higher intake of trans fats, the kind found in processed food, to a smaller brain. Excess body weight points in the same direction. As a rough rule, the bigger the belly, the smaller the hippocampus.

5. Untreated depression: Depression that is being treated is manageable, and people do well. Depression that is left untreated for years is different. Over time, it wears the hippocampus down further and further, which is one more reason to take it seriously and get help.

6. Vitamin deficiency, especially B12: Low levels of certain vitamins are a significant risk factor for brain shrinkage, and B12 stands out. When B12 runs low, the likelihood of losing brain volume goes up.

Think of Your Brain as a Garden

Here is the hopeful part. Can you reverse these things and rebuild the hippocampus? Yes, you can.

I find it useful to picture the brain as a garden. Neglect it, and it goes to weeds. Tend it with a little daily care, and it grows green and healthy. So what does tending your garden actually look like? Six habits, and each one has real science behind it.

The Six Things That Grow Your Brain

1. Sleep seven to eight hours a night: During deep sleep, your brain clears out amyloid, a protein that builds up in Alzheimer’s disease. When you fall short on sleep, and especially on deep sleep, amyloid levels climb. When you sleep well, your brain rinses that amyloid away. Aim for seven to eight hours whenever you can.

2. Exercise three hours a week: You can split it however works for you, whether that is one hour three times a week or ninety minutes twice a week. Three hours is the minimum for a healthy brain. And exercise earns its place at the top of the list for one reason above all: when you exercise, you grow new neurons. Actual new brain cells form. Nothing else does that.

3. Cut out junk food: Keep processed food off your plate as much as you can, and build your meals around fruits and vegetables. The Mediterranean diet is the pattern I recommend and follow.

4. Meditate: Sit down, close your eyes, and repeat a mantra. If sitting with a mantra feels difficult, try a breathing exercise instead. Breathe in for a count of seven, hold for a count of seven, and breathe out for a count of seven. Ten minutes a day, five days a week, will do a great deal for you, and this has been shown scientifically.

5. Learn something new every day: Keep a sense of curiosity, and take on things you have never done before. Better still, practice memorizing. There are many apps built for this, and the more you practice recall, the sharper your memory becomes and the larger your hippocampus grows. Using your brain is good for your brain. Use it or lose it.

6. Be kind to yourself and to others: Let things go. Try not to take everything so seriously. As my daughter would say, it’s not that deep.

Every day you do a few things from one list and a few from the other. The balance you strike, repeated over years, becomes the brain you carry into your seventies, eighties, and nineties. You get to choose which list wins.

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.

6 Habits Neurologist Recommend for a Sharper Brain

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I want to talk to you about sleep, and why it matters so much more than most people realize, both in the short term and over the course of your life.

Most of us think of sleep as simply rest, a time when the brain switches off. It’s the opposite. When you sleep, your brain goes into a rinsing and washing cycle. And once you understand how that cycle works, you start to treat your sleep very differently.

The Nightly Wash Cycle

Here is what actually happens inside your head at night.

With each beat of your heart, the arteries in your brain pulsate a little. That small pulsation pushes the fluid in your brain, the cerebrospinal fluid, or CSF, through the brain tissue. As it moves, it rinses away debris and waste. The now-dirty CSF is then collected and carried out of the brain.

This cleaning process is particularly active during deep sleep. It is, in a very real sense, your brain’s waste management system.

So what happens if you don’t get enough sleep? The rinsing doesn’t work properly. Debris and waste byproducts start to accumulate, and your neurons end up surrounded by dirt. Neurons sitting in their own waste are not happy neurons, and unhappy neurons do not function well.

Why I Think of New York City

Let me give you an analogy I come back to often.

Imagine New York City, and imagine that every night the garbage collection gets disrupted. For a day or two, you might not notice much. But after a couple of weeks, piles of garbage bags would start blocking the streets. Within a month or so, the whole city could grind to a halt.

The nightly collection and cleaning system is essential for a city to function. Your brain is no different. That nightly rinse is not a luxury. It is what keeps everything else working.

What Poor Sleep Does to You, Short Term and Long Term

In the short term, the effects of not sleeping enough are familiar to all of us. You feel tired and grumpy. You make mistakes at work. You become irritable. Your anxiety climbs, and your mood can sink toward depression.

The long-term consequences are far more serious, and they are the reason I take sleep so seriously with my patients.

Chronic poor sleep raises your risk of heart attacks and strokes. It can contribute to depression. And, most concerning of all, it raises your risk of Alzheimer’s disease.

I want to be precise about the timeline, because the details matter and I don’t want to frighten anyone unnecessarily. If you go through a difficult stretch and sleep fewer than six hours a night for a year or two, your brain can recover once you get your sleep back on track. Everything can be fine.

It is the long, uninterrupted years of poor sleep that cause real structural damage. A person who has lived with insomnia for twenty years may end up with a hippocampus, the memory center of the brain, that is roughly half the size it would otherwise have been.

Long-term insomnia is a major risk factor for Alzheimer’s disease. We know that for a fact.

How Do You Know If You’re Sleeping Well?

The simplest measure is how you feel when you wake up in the morning.

Beyond that, we now have plenty of tools. The rings and smartwatches many people wear can give you useful data about your nights. There are also questionnaires that can help you gauge how poor your sleep really is, such as the Pittsburgh Insomnia Rating Scale.

And if you have significant sleep problems, please see a specialist. In most cases, they will order a sleep study to understand what is actually going on.

The First Step Is Believing It Can Be Fixed

Let’s say you have insomnia. Some nights you get four hours, some nights five, and you’re frustrated. What should you do?

The first thing, and I mean this genuinely, is to adopt a positive attitude toward improving your sleep.

In my experience, too many patients tell me, “Well, everybody has sleep problems. I’m just like everybody else.” That is not true. Sleep problems are almost always treatable. But you have to make a real effort to treat your insomnia, and to make sure it is fully treated, not just partly managed. Sometimes that means addressing an underlying medical issue, like chronic pain, that is disrupting your sleep in the first place.

What Actually Works

There are some standard, well-established habits that genuinely help.

Don’t drink coffee or caffeinated products in the afternoon. Limit how much alcohol you drink at night. Wind down with a book or a warm shower. Avoid a large meal right before bed. You might try a small snack instead, like yogurt, a banana, or cherries. And some people find supplements like magnesium or melatonin helpful.

If those measures aren’t enough, the next step I recommend is cognitive behavioral therapy for insomnia. When you work with a therapist, they can go through your thought process and figure out what is keeping you up at night. Very often it is anxiety, and that anxiety has to be resolved before real sleep can return. I find this approach extremely helpful with my own patients. In fact, cognitive behavioral therapy is the most effective treatment for insomnia that I know of.

I leave sleeping medications as a last resort. Honestly, I don’t like them, and I very rarely prescribe them.

Your Brain Will Thank You

So here is what I want you to take away.

Sleep is essential for your brain health, both in the short term and across your whole life. If you have sleep problems, please take them seriously, because there are many things you can do to improve your sleep.

Do them. Your brain will thank you for it.

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 Lack of Sleep Does to Your Brain – Dr. Fotuhi

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What if the brain fog you’re feeling in your 40s or 50s isn’t just normal aging, but your brain reacting to the hormonal changes of menopause?

I want to tell you about a patient of mine, and about two brand-new studies that are changing how we think about hormones, menopause, and Alzheimer’s disease. The answer is more encouraging than you might think. Stay with me to the end, because I’ll also tell you exactly what I would do if I were you.

A few years ago, a lawyer in her late 40s came to see me.

She told me she felt slower handling her cases. She was less articulate than she used to be. She kept forgetting things: appointments and why she’d walked into a room. Her mother had died of Alzheimer’s, and she was terrified she was next. She wanted me to fix it, immediately.

She was serious. She was panicked. And honestly, I understood why.

I’ll tell you what we actually found, and what happened to her, later in this article. But first, let me explain what’s happening in women like her.

Why Menopause Can Change How Your Brain Feels

When a woman goes through menopause, her estrogen levels drop dramatically.

We usually think of estrogen as a reproductive hormone. But it does far more than that. There are estrogen receptors throughout the brain. Estrogen helps brain cells communicate with one another. It supports the connections between neurons. It affects the neurotransmitters involved in mood, sleep, and memory. It even influences the parts of the brain in charge of temperature regulation, appetite, and weight management.

So when estrogen falls during menopause, it makes sense that some women notice changes in how their brain functions. It makes sense that they might experience brain fog, trouble finding the right word, mood swings, or a feeling of being less sharp than they used to be.

Many women also experience hot flashes, weight gain, sleep apnea, and metabolic issues around this time, all of which can affect memory and thinking indirectly.

For years, scientists have wondered whether losing estrogen might help explain why women are so much more likely than men to develop Alzheimer’s disease. We still don’t have a definitive answer. But two brand-new studies are giving us some real clues. If you’ve heard conflicting things about hormone replacement therapy over the past twenty years, these two studies are a big part of why that conversation is finally starting to change.

Two New Studies Worth Knowing About

The first was published on August 12 in the journal Neurology, by researchers at Stanford.

Instead of simply asking women whether they had memory problems, the researchers looked inside their brains. They studied more than 21,000 women, including thousands whose brains were examined after they passed away. Women who had used estrogen-only hormone therapy had 35% lower odds of showing Alzheimer’s-related damage in their brains, and 39% lower odds of ever being diagnosed with any form of dementia.

The second study was published on August 26 in the journal Alzheimer’s & Dementia. Researchers from the University of Exeter and the University of East Anglia followed more than 183,000 postmenopausal women in the UK for over 13 years.

Women who had used HRT had a 16% lower risk of Alzheimer’s disease. And among women who had gone through a surgical menopause, those who used HRT had about a 26% lower risk of developing any form of dementia. This study found the biggest benefit in women who started HRT between the ages of 46 and 56.

Both studies point to something researchers call the window of opportunity. The idea is that estrogen may help the brain most when it is started around the time of menopause, rather than decades later. In other words, timing may matter more than we used to think.

I do want to be careful here. Both of these are observational studies. They show an association between hormone therapy and lower dementia risk, not proof that HRT prevents dementia. The researchers behind both studies have said the same thing, and they’ve called for randomized clinical trials to test the question properly. I agree with them. But after twenty years of fear and confusion around this topic, findings this large and this consistent are genuinely reassuring.

What Actually Happened to My Patient

Now, back to the terrified lawyer: she had Alzheimer’s.

Her workup told a very different story than the one she feared. She was sleeping poorly. She was working full time, raising three teenage sons, and taking on extra projects after hours to try to earn a promotion. On top of all that, she had gained weight, and she was not exercising.

When we went through it together, she understood that her symptoms were not caused by Alzheimer’s disease. They were the product of exhaustion, stress, poor sleep, and a body under strain. And that meant they were fixable.

She completed our 12-week Brain Fitness Program, and my brain coaches helped her improve her exercise routine, her diet, her sleep, her stress levels, and her brain training. In parallel, her own doctor started her on hormone replacement therapy.

Twelve weeks later, her memory had gone from the 40th percentile for her age to the 80th percentile. She was thrilled. And she stopped worrying about Alzheimer’s disease.

Her story is the whole point, really. Her fog was real. But it was not what she was most afraid of, and it responded to the right combination of changes.

So Should You Take HRT to Protect Your Brain?

This is the question I get most often, so let me answer it honestly.

Not for that reason alone, and not yet. We do not yet have the gold-standard proof from a randomized clinical trial to recommend HRT specifically for cognitive symptoms.

But if you are also struggling with hot flashes, vaginal dryness, or other menopausal symptoms, then HRT for a couple of years can be a very reasonable option, one worth discussing seriously with your doctor. And these new studies are reassuring, not alarming.

Please keep one thing in mind. Your brain does not exist in isolation. Sleep, exercise, nutrition, stress, brain training, and your hormones are all connected. Hormones may be one piece of the puzzle, but they are not the whole picture, exactly as I saw with my patient.

What I Want You to Do

If you are at this stage of life and wondering whether HRT is right for you, talk to your doctor about your own personal history and risk factors. That conversation is the single most important next step you can take. Every woman’s situation is different, and this is a decision to make with a physician who knows your history, not one to make from a newsletter or a video.

And regardless of what your hormones are doing, you should always work on the five pillars of brain health:

• Walk daily, and exercise about three hours a week.
• Sleep 7 to 8 hours a night.
• Eat a Mediterranean diet.
• Reduce your stress, and consider meditation or yoga.
• Challenge your brain with a fun hobby at least once a week.

The fog you’re feeling is not a life sentence. Very often, like it was for my patient, it’s a signal, and a signal is something you can act on.

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.

How to Fix your brain fog in 40s & 50s | Dr. Fotuhi

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