PDF Summary:Life Lessons From A Brain Surgeon, by Rahul Jandial

The human brain is one of the most remarkable structures in existence. Your brain contains about 85 billion cells, linked with each other in a network of over 100 trillion synaptic connections. In Life Lessons From a Brain Surgeon, neuroscientist Rahul Jandial teaches how this incredible organ works and how you can best care for it.

This guide begins by discussing the human brain’s structure and how it functions. We’ll then go over Jandial’s lifestyle suggestions for keeping your brain working at its best. We conclude by listing crucial ways your brain will change as you get older and tips to protect it from the worst effects of aging. Our commentary will provide additional information about the brain to deepen your understanding of Jandial’s ideas. We’ll also compare his principles with those of other popular neuroscience books and offer concrete actionables to help you maximize your brainpower.

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(Shortform note: The MIND diet combines elements from two of the world’s most scientifically validated diets: the Mediterranean diet and the DASH (Dietary Approaches to Stop Hypertension) diet. More specifically, it merges the Mediterranean diet’s emphasis on olive oil, fish, nuts, and fresh produce with the DASH diet’s focus on reducing sodium and incorporating whole grains, lean proteins, and vegetables. Research suggests that this diet supports cognitive health by fighting inflammation and oxidative stress (cell damage caused by unstable atoms or molecules in your body). These have also been the focus of treatments for Alzheimer’s disease, suggesting that the MIND diet could have similar benefits.)

Intermittent fasting (IF) provides another evidence-based strategy for brain health. Jandial suggests fasting twice a week for a period of 16 hours (which includes time spent sleeping). These periods without food make your body run out of glucose—simple sugar, its preferred fuel—and start burning your fat reserves instead. In addition to helping you lose weight, the fat-burning process creates helpful byproducts called ketones, which help form new neural connections, as well as slowing age- or disease-related degeneration of the brain.

Alternative Explanation: Cellular Autophagy

Another possible explanation for intermittent fasting’s benefits is that it induces cellular autophagy. The term literally means “cells eating themselves,” but it refers to a natural process wherein your body breaks down damaged cells and reuses the materials to create new, healthy cells.

It’s also worth noting that many degenerative diseases—everything from Parkinson’s and Alzheimer's to arthritis and polio—occur due to cellular and tissue degeneration. Therefore, it stands to reason that promoting autophagy using methods like IF is an effective way to combat those diseases, since your body will destroy the degenerating cells. Researchers have linked autophagy to decreased risk of some cancers and obesity as well as neurodegenerative diseases, further supporting Jandial’s assertion about the benefits of IF.

Why Nutrition Matters

Jandial explains that these specific diet strategies are good for your brain because they work with the blood-brain barrier, which controls which substances cross from your bloodstream into your neural tissue. This protective mechanism ensures that only essential nutrients like oxygen, glucose, and ketones, along with some vitamins and minerals, ever reach your brain.

It stands to reason that maintaining a healthy balance of nutrients that can cross the blood-brain barrier will benefit your neurological health. Conversely, making less healthy choices like ultraprocessed foods and red meat could mean that you’re consuming a lot of calories without providing your brain the nutrients it needs (in addition to the other ways a poor diet can harm your health).

(Shortform note: Excess sugar can be especially harmful to your brain in the long run because it can cause the blood-brain barrier to develop insulin resistance. Insulin is a hormone that helps your body process glucose into usable energy, and therefore your insulin levels rise along with your glucose levels. However, if your insulin levels are too high for too long, your cells stop responding to it as effectively—in other words, they become resistant. Furthermore, your brain needs a lot of energy to function properly. So, if the cells in your blood-brain barrier become insulin-resistant, they can’t carry insulin molecules into your brain as effectively, your neurons won’t get the energy they need from glucose, and they’ll begin to die off.)

Optimize Your Sleep

Jandial says that most adults need between seven and nine hours of sleep nightly in order to function at their best. He offers a number of strategies to help you get consistent, high-quality sleep, including:

• Keep your bedroom dark and cool: Your mind instinctively associates darkness and cool temperatures with nighttime, so those conditions will help you fall asleep. For the same reason, avoiding bright lights and computer screens for at least an hour before bed will help your natural sleep cycles function properly.
• Use your bedroom only as a bedroom: This will help your mind associate the bedroom with sleep, rather than with work or your hobbies. As a result, you’ll naturally start to feel tired when you enter the room.
• Stick to a schedule: You have an internal clock that will sync to your usual bedtime, helping you to fall asleep and stay asleep through the night. Therefore, maintaining a consistent sleep schedule is one of the simplest and most effective ways to get a good night’s sleep.
• Avoid caffeine after noon: Stimulants like caffeine disrupt your sleep, but many people don’t realize that caffeine can stay in your system for up to 12 hours. Therefore, try to avoid caffeine in the afternoon and evening.

A Deeper Problem: Grind Culture

While Jandial offers specific and actionable advice about how to get better sleep, some people argue that the root cause of our exhaustion and sleep deprivation is a “grind culture” that values productivity over well-being.

In Rest Is Resistance, Nap Ministry founder Tricia Hersey asserts that modern society—at least in the US—no longer has an authentic concept of rest. She argues that people living under grind culture view rest as just another tool for productivity. Such people believe that we should rest just long enough to recover our strength, and then get back to work.

Hersey also offers advice about how to rest more often and effectively, but in her view, effective rest must start with a fundamental shift in mindset: Believe that you deserve to rest. This means acknowledging that every person has an inherent, fundamental right to rest as much as they have to, with no need to “earn” rest through accomplishments or wealth. She explains that this shift is necessary because grind culture will try to make you feel guilty about getting the deep, restorative rest that you deserve.

Why Sleep Matters

The fact that people need to sleep is hardly a new insight, but Jandial goes into detail about why you need it and what happens if you don’t get enough. He explains that sleep is when your brain performs critical maintenance and optimization functions, such as forgetting unimportant information and consolidating related memories for easy access.

(Shortform note: In Why We Sleep, neuroscientist Matthew Walker adds that sleep—particularly REM sleep, and the dreams that come with it—also helps you to process traumatic events and overcome the emotional pain associated with them. Walker suggests this happens because REM sleep is the only time when your brain is completely free of norepinephrine, a stress hormone that triggers the fight-or-flight response. Without this hormone present, you’re able to relive upsetting memories without feeling threatened or hurt, and thereby come to terms with them.)

Conversely, not sleeping enough will make your brain work less effectively. This is somewhat similar to how older computers needed to defragment (reorganize) scattered pieces of stored data and became slow if they weren’t defragmented often enough. Jandial says sleep deprivation affects every aspect of cognitive functionality, from memory formation to emotional regulation. Furthermore, people who consistently sleep less than six hours a night face increased risks of physical ailments like heart disease and diabetes. As a side note, regularly sleeping for more than nine hours leads to many of the same health problems, suggesting that the ideal range is between six and nine hours per night.

(Shortform note: Walker also goes into more detail about the dangers of sleep deprivation in Why We Sleep. First of all, sleep deprivation impairs your ability to focus and concentrate. This can pose significant risks during everyday activities like driving. Secondly, the amygdala—the brain region responsible for emotional processing—can become overactive without enough sleep, amplifying your emotions and hindering your self-control. Finally, Walker suggests that getting insufficient sleep can interfere with the formation of new memories and disrupt the glymphatic system, which is responsible for clearing out the protein plaques associated with Alzheimer's disease.)

Optimize Your Breathing

Finally, Jandial says that even the way you breathe can have major, measurable impacts on your brain. Furthermore, these changes can happen in a relatively short time, and persist even if you go back to breathing how you normally do.

One simple practice the author recommends is to engage in slow, mindful breathing for 15 minutes a day: Breathe in through your nose while you slowly count to four, hold the breath in for another four-count, breathe out while counting to four, then count to four again before taking the next breath. Doing this daily for just two weeks can produce significant improvements in your self-control and emotional regulation.

(Shortform note: This specific technique is commonly known as box breathing, or square breathing. In addition to the long-term benefits Jandial describes, it can also be a powerful tool in the short term to calm yourself down, refocus your attention, and even help yourself get to sleep. Another common breathing exercise is the 4-7-8 Technique: Breathe in for four counts, hold it for seven, then exhale for eight. However, since you exhale more air than you’re taking in, it’s recommended that you only do four to eight cycles of this technique at a time.)

Why Breathing Matters

The obvious reason why breathing exercises like the one above are helpful is because they encourage you to breathe deeply and efficiently. Doing so enriches your blood and your brain with the oxygen you need to function properly. However, Jandial argues that such exercises are also beneficial because they train you to concentrate and maintain control over your body—this is why they’re often a crucial part of practicing meditation or yoga. Therefore, recalling our earlier discussion of neuroplasticity, these exercises physically strengthen the areas of your brain related to those skills.

(Shortform note: In Breath, James Nestor provides one possible explanation for mindful breathing’s power to affect our bodies and minds. Nestor says breathing is the one bodily function that can be either automatic or deliberate—most of the time we breathe without thinking about it, but we can consciously control our breathing if we choose to. Therefore, he argues that breathing practices create a sort of “back door” into the nervous system: By deliberately breathing in certain ways, you can trigger specific reactions within your body and brain. To give a counterexample to Jandial’s suggestions, if you focus on taking short, rapid breaths, you can intentionally put yourself into a highly energized “fight or flight” state.)

How Aging Affects Your Brain

We’ve talked about how to take care of your brain so you can get the most out of it, but one of the biggest concerns people have about their cognitive health is simply getting older, and the changes that come with age. However, Jandial reassures us that the effects of aging are predictable and aren’t always negative—you can focus on maintaining your cognitive strengths while compensating for areas you’re growing weaker in.

We’ll start this final section by discussing the different types of memory and how aging impacts them in different ways. We’ll then conclude with Jandial’s strategies for keeping your brain healthy as you age: lifelong learning, an active social life, and regular physical exercise.

How Aging Affects Memory

One of the most common fears about aging is losing your memory. However, Jandial says the human brain actually has four distinct ways to store memories. Each of those storage systems serves a unique purpose and is affected differently by aging.

The four kinds of memory are:

1) Working memory. This is essentially your brain’s workspace, meaning that it allows you to manipulate information mentally. For example, you use working memory while doing math or trying to follow complex instructions. However, working memory has a very limited storage capacity—you can only work with a few pieces of information at a time—and that capacity decreases as you get older.

2) Episodic memory. This deals with your personal experiences and specific events from your past. Like working memory, this system naturally weakens with age, which is why, for instance, you might vividly remember your favorite childhood TV show, but struggle to remember the plot of a book you read last week.

3) Semantic memory. This is how your brain stores general knowledge about the world: facts, concepts, and basic information like the definitions of words. Barring brain damage from an injury or illness, this type of memory remains strong as you age, allowing you to continue learning new things throughout your life.

4) Procedural memory. This handles your learned skills and habits. This type of memory is highly stable, which explains why you never forget how to ride a bicycle or tie your shoes. As such, age has little impact on your procedural memory.

Crystallized Intelligence Increases With Age

Jandial’s list of the different kinds of memory closely resembles the two types of intelligence that Arthur C. Brooks discusses in From Strength to Strength. Citing the work of psychologist Raymond Cattell, Brooks says we have two methods of solving problems, and our capacity for each method changes as we age.

According to Brooks, young people tend to have very high fluid intelligence, which he describes as the ability to innovate, make new discoveries, and come up with creative solutions to problems. This is, in essence, the same as working memory: your capacity to use information to get the results you want. Scientific research also supports this connection, as studies have shown that working memory capacity declines with age, just like Brooks argues that fluid intelligence declines.

However, crystallized intelligence—the knowledge you accumulate over your lifetime—keeps increasing. In the context of Jandial’s work, crystallized intelligence is a combination of your semantic and procedural memories. Brooks encourages people in their middle years and beyond to look for opportunities to leverage crystallized intelligence instead of continuing to rely on fluid intelligence. This usually means finding training or leadership roles—positions that are less hands-on where you can use your knowledge and experience to guide others.

Protect Your Brain as You Age

While some effects of aging are inevitable, Jandial says that you can keep your brain healthy—and minimize your risk of dementia—with a few key lifestyle choices.

Protection Strategy #1: Lifelong Learning

First, Janidal says that continual, lifelong learning is one of the best protections against age-related cognitive decline. This is because learning drives your brain to keep building and strengthening neural connections, helping to counteract the damage that aging can cause. For example, reading challenging books, learning new skills, and engaging with unfamiliar ideas are all ways to keep your mind sharp and resilient.

The author adds that it’s crucial to find the right level of mental challenge: something that’s possible with your current abilities, but pushes you outside your comfort zone. For instance, learning a new instrument is an enjoyable challenge, but not if you have arthritis that makes it physically difficult for you to play.

(Shortform note: Jandial explains the benefits of finding new and interesting challenges for yourself, but doesn’t give any guidance on just how challenging something should be. In Atomic Habits, James Clear says that the ideal challenge is one where you succeed about half of the time. Clear argues that you’ll get bored if it’s much easier than that and frustrated if it’s much harder.)

Protection Strategy #2: A Healthy Social Life

Second, Jandial says that your social life can protect against cognitive decline. Citing the work of neuroscientist Emily Rogalski, he explains that elderly people with active social lives tend to have better memories and cognitive abilities than peers who aren’t as social. Multiple studies support this pattern, showing that maintaining strong friendships throughout your life can reduce your dementia risk by as much as 50%. Even online social networks can provide such benefits.

(Shortform note: Jandial urges you to make and maintain close friendships as you get older, but it’s notoriously hard for adults to make friends—for example, one study showed that in 2004, the average American adult had zero close friends. One reliable way to make new friends at any age is to join a group that interests you, where you’ll naturally meet people who share that interest. However, making new friends may also require a certain amount of boldness—to make friends you wouldn’t make otherwise, you might have to accept invitations you’d normally turn down or try making the first move to start a new friendship.)

With that said, Jandial emphasizes that your personal satisfaction with your social life is what really matters. Therefore, he urges you to socialize just enough to be happy, rather than forcing yourself to be around people as much as possible. The cognitive risks of age come from feeling lonely, not from actually spending time alone.

(Shortform note: Naturally, Jandial focuses on the impact loneliness can have on an aging brain, but feeling lonely has serious effects on your mental and physical health regardless of your age. Loneliness increases your risk of conditions ranging from anxiety and depression to heart disease and stroke—in fact, feeling alone can be as bad for you as smoking a pack of cigarettes a day.)

Protection Strategy #3: Regular Exercise

Finally, Jandial says that regular physical exercise has significant benefits for aging brains. This is because exercise promotes the production of hormones called growth factors that enter your cerebrospinal fluid, nourish your brain, and promote the formation of new neural connections. The author adds that resistance training (exercises like pushups and lifting weights) provides the greatest benefits for elderly people. For reasons that aren’t fully understood, cardiovascular exercises like running are much less effective at protecting and strengthening an elderly brain.

(Shortform note: Exercise is a form of healthy stress—the kind that makes you stronger instead of weaker, a phenomenon called hormesis. In Jellyfish Age Backwards, molecular biologist Nicklas Brendborg suggests another way you can take advantage of hormesis: Eat fruits and vegetables that have natural defense mechanisms. For example, most peppers produce an irritant called capsaicin (which gives them their spicy flavor), and pineapples contain an enzyme that breaks down proteins. Neither of these are powerful enough to cause any serious harm, but Brendborg asserts that they’re enough to induce hormesis.)