In Keep Sharp, Sanjay Gupta provides advice for improving your brain health. It’s not just about improving intelligence or memory: It’s about developing a brain that is resilient and creating a brain that can build new cells and use the cells you have more efficiently. If you have a healthy, resilient brain, you’ll be happier, more productive, and better equipped to fight off cognitive decline as you age.
As a neurosurgeon and medical reporter, Sanjay Gupta has extensive knowledge of the human brain and how it functions. For Keep Sharp, he interviewed some of the leading experts on neuroscience and reviewed the latest research. Gupta explores five key components of brain health: exercise, sleep, nutrition, discovery, and connection. While these may seem like obvious components of a healthy lifestyle, we’ll show how important they are for a healthy brain specifically.
In this guide, we’ll explore why the five components of a healthy brain are so important by examining the latest science behind them. To do this, we’ll first look at how the brain functions and the potential causes and factors that lead to cognitive decline. Then, we’ll examine the significance of each component in maintaining a healthy brain. We’ll also give simple suggestions to put this information into practice and develop a healthier, more resilient brain.
(Shortform note: For this guide, we’ll focus on the first two parts of Keep Sharp, which explain how the brain works and the five components of a healthy brain. In the third part of Keep Sharp, Gupta gives advice on what to do if you or a loved one is diagnosed with Alzheimer’s or another form of dementia. Even after such a diagnosis, you can still use Gupta’s advice on brain health provided in the first part of the book to mitigate symptoms. If you want more information on what to do after an Alzheimer’s or dementia diagnosis, we recommend buying a copy of Keep Sharp or visiting the Alzheimer’s Association or AARP websites.)
Gupta argues that to better understand how to improve your brain, you must first understand how it works. With regard to improving brain health, there are two key attributes of the brain you should understand: interconnectedness and neuroplasticity.
Gupta claims that our growing understanding of the brain has taught us that different parts of the brain function in a highly coordinated manner. Because of this, we should focus on improving the functions of every part of the brain, not just the areas we may deem most important. Not too long ago, it was thought that the brain was split up into separate parts that acted on their own: One part of the brain was used for abstract thinking, another for interpreting language. This led to the debunked theory that people are either left- or right-brain dominant. We now know, however, that much of the brain’s power and complexity comes not from the individual sections, but from the communication between each section.
Communication within the brain happens between neurons through synaptic connections, writes Gupta. There are billions of neurons, or brain cells, in the human brain, and trillions of synapses through which information is transmitted from one neuron to another via electrical signals. It is through these neural connections that our brains can perform both simple and complex tasks. These connections allow us to make decisions, communicate, analyze information, feel emotions, orient ourselves, coordinate movements, and so forth. In other words, our brains are highly dependent on the circuitry between different areas. Maintaining and strengthening this circuitry is crucial to a healthy brain.
How Independent Are Our Brains’ Separate Parts?
Gupta argues that recent research shows the brain’s separate parts are much more interdependent than previously thought, but the scientific community still seems to be split on this.
Much research confirms Gupta’s theory: A 2013 study used neuroimaging to show that the human brain doesn’t favor one side over the other. In other words, no one is right-brain or left-brain “dominant”: We use both sides of our brains for virtually every task. Another study found that the idea that certain activities are linked to particular areas of the brain may be too rigid. This research suggests that the entire cerebral cortex is activated during most tasks, not just the area associated with that task. Furthermore, this study shows that brain activity isn’t localized but moves in waves throughout the entire brain.
Despite this research, many scientists still accept the theory that the brain is made up of largely independent parts. Although the parts are connected by neural pathways, they still operate with a certain degree of autonomy. Psychologists believe this is why we have things such as cognitive dissonance and indecision, which suggest not only that the brain’s areas are independent but that they are sometimes in conflict.
Whether the different areas of our brains are working independently or not, however, does not take away from the importance of communication between them. One study found that the synchronization of neurons across different areas is responsible for maintaining our short-term memory. In other words, when we try to remember something, neurons are firing at the same time in different parts of the brain. This suggests that the functioning of our neural connections is vital to our memory and thus our overall cognitive abilities.
Gupta adds that neuroplasticity is another important concept to understand about the brain. Neuroplasticity is the brain’s ability to grow and reorganize its neural networks through learning, experience, or response to injury. According to Gupta, the plasticity of our brains may allow us to fight off cognitive decline. When you experience something new, your brain reshapes itself to integrate this new information. It does this by creating new dendrites. Dendrites are the parts of a neuron (brain cell) that receive electrical signals from another neuron. The brain’s ability to create new dendrites is what is known as plasticity. Importantly, this ability remains with us throughout our lives. No matter how old you are, you can take steps to strengthen and preserve your brain.
The brain is constantly shaping and reorganizing itself in response to the stimuli it receives, says Gupta. Because of this, what you choose to focus on shapes the brain’s circuitry. For example, if you learn a song on the guitar, you form new connections between your neurons. If you keep practicing, these connections will strengthen until eventually you can play the song easily from memory. If you stop practicing, these connections will weaken rather quickly while new ones form or others strengthen. This information is key because it suggests that we may be able to slow down, reverse, or even stop degenerative brain diseases by strengthening our neural connections.
Neuroplasticity Further Explained
Gupta argues that there are many things we can do to strengthen and preserve our brains. Neuroplasticity is at the center of this argument, and recent research supports Gupta’s claim as our understanding of the brain’s adaptability has grown immensely in the past few decades. Research from 2006 shows that the brain evolves more rapidly than previously thought: The process of creating and reconfiguring neural networks can occur in the span of just a few hours. Experts can use this information to find ways to work around certain neural pathologies.
Another significant aspect of neuroplasticity Gupta points out is the way it can be used to build stronger memories and skills simply by focusing our attention. The concept of neuroplasticity suggests it is not our genetics but rather our choices that dictate our intelligence levels. Furthermore, there is no known limit to the strength or number of our neural connections. The knowledge of our seemingly unlimited capacity to learn and grow can not only help scientists make medical breakthroughs, but it can also empower people to take control of their brains and thus their lives.
Gupta claims that maintaining the quality and quantity of our neural connections can help prevent cognitive decline, but the exact causes of dementia are still unknown. Medical scientists and researchers have discovered a lot about cognitive decline, dementia, and Alzheimer’s in the last few decades, and their research suggests it’s probably due to many factors that differ for every person. If we want to take care of our brains and take measures to prevent them from declining, it will be helpful to know the suspected factors that lead to cognitive decline.
According to Gupta, an abundance of amyloid plaque in a person’s brain is a hallmark of Alzheimer’s disease. Amyloid is a protein that helps supply food to brain cells. For unknown reasons, these proteins sometimes become damaged and fold up into a sticky plaque that accumulates outside neurons. When plaques form, they prevent synapses from effectively communicating. If enough synapses are inhibited by amyloid plaques, the brain may lose many of its functions.
Though amyloid plaque has long been connected to cognitive decline, it is still unknown if it is a cause, an effect, or both. Some autopsied brains have been filled with amyloid plaques, yet the patient never showed major signs of cognitive impairment. Also, dementia patients rarely show damage exclusively from amyloid plaques. There are many other ways a brain can be damaged that can lead to dementia.
New Research on Amyloid Plaques
Experts have long theorized that the buildup of amyloid plaques in the brain is a leading cause of Alzheimer’s. Most treatments for Alzheimer’s target these plaques, but they’ve been largely unsuccessful in improving brain function or reducing the effects of Alzheimer’s. For instance, the most recent FDA-approved drug Aducanumab, which reduces amyloid in the brain, hasn’t been shown to improve cognition. A recent study provides new evidence on why removing amyloid plaques doesn’t alleviate dementia symptoms.
There are many types of amyloid plaques, but the two most prevalent are diffuse plaques and dense-core plaques. Experts believed both plaques caused damage that led to Alzheimer’s, but a 2021 study suggests dense-core plaques may actually be beneficial or benign. The dense-core plaques may play a protective role, which is why treatments that attack both types of amyloid plaques haven’t been successful. This might also explain why some people have a large amount of amyloid plaques but no signs of dementia: The majority of the plaques may have been dense-core plaques.
Gupta claims that blood flow abnormalities in the brain may also be an important factor in the development of Alzheimer’s disease. For one, amyloid plaques are seen more frequently in people with vascular diseases (diseases that affect the blood vessels). The brain requires a lot of nutrients and oxygen from our blood. Because of this, problems with the vascular system often lead to a dysfunctional brain.
Because the brain is so important, it is protected by a barrier between the brain and the blood supply. This blood-brain barrier lets oxygen, glucose, and other nutrients in while keeping toxic substances out. Due to aging, infections, or vascular damage, gaps sometimes form in this blood barrier. When this happens, toxic substances from the blood can damage neurons and impair memory and other brain functions.
(Shortform note: Recent research provides further evidence that disrupted blood flow to the brain may lead to cognitive decline. Immune cells known as microglia are known to help protect the blood-brain barrier, but a new study suggests they also help regulate blood flow and maintain the brain’s blood vessels. Because of this, the loss of microglia could potentially lead to reduced blood flow and smaller capillaries in the brain. Scientists hope this discovery leads to more effective therapies or treatments for cognitive decline.)
Metabolic disorders include diabetes, obesity, and high blood pressure. They are extremely common in the West, and Gupta argues that these disorders are heavily associated with risk for dementia. Alzheimer’s disease often involves a problem with insulin, the hormone responsible for delivering glucose from the bloodstream to the cells.
Without insulin, the cells don’t get the glucose they need to produce energy, explains Gupta. In Type 2 diabetes, there is so much sugar in the blood, and so much insulin is pumped out by the pancreas in response, that the cells become desensitized to insulin. Some believe this insulin resistance plays a key role in cognitive decline, with studies suggesting those with Type 2 diabetes may be twice as likely to develop Alzheimer’s disease. In fact, Alzheimer’s is sometimes referred to as Type 3 diabetes. Not only this but high blood sugar, even without meeting diabetic conditions, has also been linked to cognitive decline. The higher your blood sugar, the more likely you are to develop dementia.
By the Numbers: Obesity, Diabetes, and Alzheimer’s in the United States
As Gupta points out, metabolic disorders are a leading cause of cognitive decline. The increasing rates of metabolic and cognitive disorders are both telling and alarming. Approximately 40% of adult Americans are obese. While obesity is often measured by body-mass index (BMI), and BMI is far from a scientific measure of obesity, the numbers are still a cause for concern.
A total of 37.3 million people in the US have diabetes, or 11.3% of the population. Furthermore, an estimated 96 million people are prediabetic, meaning their blood sugar levels are higher than normal but not high enough to be considered diabetic. Because most people with Type 2 diabetes are also obese, and because of the link between Type 2 diabetes and Alzheimer’s, it is estimated that the number of Americans with Alzheimer’s will rise from 6 million to 13 million by 2050. If we wish to lower these estimates, lowering sugar intake is a crucial first step.
Gupta suggests that chronic inflammation is also at the center of neurodegenerative diseases such as Alzheimer’s. Inflammation is the body’s defense against infections, injuries, and toxins. It is meant to protect our bodies, but when it becomes chronic, it can be damaging.
Research indicates that chronic inflammation both adds to and kick-starts the process of cognitive decline. For instance, some studies have linked dementia to higher levels of cytokines, which are released by cells during bouts of inflammation. Also, chronic inflammation in middle-aged adults has been linked to dementia later in life. Both of these findings suggest that chronic inflammation likely plays an important role in cognitive decline.
Understanding Chronic Inflammation
Since, according to Gupta, chronic inflammation likely contributes to cognitive decline, it is vital to understand what it is, how it works, and its potential causes. Chronic inflammation occurs when the immune system’s response lingers longer than normal, and this response can also damage healthy cells. Not only is chronic inflammation linked to dementia, obesity, and diabetes, but it can also lead to asthma, heart disease, arthritis, and cancer.
Chronic inflammation can be caused by many factors, including untreated infections or injuries, autoimmune disorders, or exposure to pollution or harmful chemicals. Things like smoking, alcohol use, and chronic stress can also lead to chronic inflammation, another reason to try to live a healthy, happy lifestyle.
Gupta claims that maintaining a healthy brain is a key to overall health and that prevention is the most effective antidote to neurodegenerative diseases and cognitive decline. We rarely think about Alzheimer’s or cognitive impairment until later in life. According to Gupta, this is a mistake because brain-related illnesses can start decades before symptoms appear. A decline in cognitive abilities begins in your 20s, and the brain’s structure can start to decay at age 30. However, if you can focus on living a healthy lifestyle from a young age, with a particular focus on your brain, you will be much more likely to avoid cognitive decline. At the very least, you will be able to delay it.
(Shortform note: Gupta claims that brain health is inextricably tied to your overall health and that cognitive skills begin declining much earlier than most people think. Recent studies support these claims: Neuropsychological research found that most people see declines in spatial reasoning in their mid-20s, declines in memory in their early 30s, and declines in the speed of information processing in the mid-30s. Another study found that young adults who showed signs of aging in other organs such as their hearts or lungs showed greater cognitive decline as well, suggesting that brain and body health are closely related.)
Gupta gives five areas to focus on when trying to improve your brain’s health: exercise, sleep, nutrition, discovery, and social connection. We’ll examine each of these in turn.
Gupta claims that regular exercise is the single most important thing to do for your brain’s health. While there are many other benefits to brain and body, exercise helps the brain in two main ways:
1. Exercise controls blood sugar: When you exercise, the sugar in your blood is used to fuel the muscles in your body instead of staying in your bloodstream. This prevents consistently high blood sugar and keeps your insulin levels stable.
(Shortform note: Although exercise generally lowers blood sugar levels, it can also have the opposite effect. Some workouts, like heavy weightlifting, sprinting, and competitive sports, can increase hormones such as adrenaline, which raises glucose levels. Also, consuming too many carbs before a workout can lead to high blood sugar. To avoid this, experts recommend you choose moderately intense aerobic exercises or light weight training and that you avoid too many carbs before exercising.)
2. Exercise reduces stress: When you’re stressed, your body releases a hormone called cortisol, which has been linked to changes in the brain. People who experience chronic stress early in life are much more likely to suffer from mental problems and mood disorders later in life.
(Shortform note: How does exercise reduce stress? Research shows it’s through a release of hormones. Exercise, especially aerobic exercise, increases your body’s production of endorphins, or chemicals that naturally boost your mood and reduce pain. They are responsible for the “runner’s high” some feel after a long aerobic workout.)
Physical inactivity, on the other hand, sharply increases the risk of cognitive decline. Gupta points to a study that states that lack of exercise is the most significant risk factor in developing dementia. Prolonged sitting (sitting for eight or more hours a day) can be especially harmful. Not only does prolonged sitting increase blood sugar levels, but it also negatively affects blood fats, cholesterol, blood pressure, and leptin (the hormone that tells you when to stop eating). When your muscles are dormant for too long, they begin to break down and atrophy, and your body’s ability to break down calories is weakened.
(Shortform note: Gupta claims that prolonged sitting, even with regular exercise mixed in, can lead to an early death, but some studies refute this claim. A 2015 study of over 5,000 people found there were no associations between prolonged sitting and increased mortality rates. Another study examined the link between sitting and diabetes and came to a similar conclusion. The researchers from both studies recommend regular exercise, as no significant health effects were seen in participants who both exercised and sat for long periods of time.)
Knowing how important exercise is, how much do we need to do? Gupta says the good news is that it doesn’t take a lot to counteract the negative effects of inactivity. Aim for at least 30 minutes of exercise a day, five times a week. However, Gupta claims that if you want to get the most out of exercise, exercising more than an hour a day is now recommended. This is because, from an evolutionary perspective, humans have usually spent most of their day moving.
(Shortform note: Most health experts and doctors agree that you should exercise at least 30 minutes a day or 150 minutes a week. As Gupta points out, though, ideally you should get more than that. A 2011 study found that the optimal amount of moderate aerobic exercise is around 90 to 100 minutes a day, or around 700 minutes a week. Alternatively, 350 minutes of intense exercise (as opposed to moderate) will also suffice. This may seem like a lot, but to achieve this, researchers recommend two things: Start at a young age, and find what motivates you.)
To get the most out of exercise, also aim for a mix of three forms of exercise: aerobic, strength, and interval training.
Developing a Balanced Exercise Routine
In Awaken the Giant Within, Tony Robbins advises finding the proper balance between aerobic and anaerobic exercise. Anaerobic exercise (like strength training and interval training) helps build muscle and improve flexibility, but it can also be harmful when done incorrectly. Too much anaerobic exercise can burn through your body’s glucose and lead to anxiety, circulation problems, fatigue, headaches, and injuries. To avoid this, Robbins recommends building an aerobic base, as this trains your body to burn fat instead of glucose.
If you are starting from scratch, build an aerobic base by running, swimming, or biking for at least 30 minutes a day, three times a week for two to three months. Then, you can begin adding anaerobic exercises like weightlifting or high-intensity interval training.
Gupta claims that chronic inadequate sleep leads to higher risk of many health issues including dementia and cognitive decline. Extensive research on the effects of sleep shows that sleep is more than just the body’s chance to relax: It’s a vital phase of neural activity and regeneration. In this section, we’ll first look at what happens in our brains when we sleep. Once we understand this, we’ll go over some of Gupta’s tips for consistently getting a better night’s rest.
Gupta claims that our brains perform billions of molecular tasks while we sleep. Because of this, sleep keeps us sharp, creative, and able to process information. Sleep keeps our brains healthy in three key ways, says Gupta:
1. Sleep controls our hormonal cycles: Our circadian rhythms revolve around our sleeping habits, and these rhythms dictate our hormonal patterns. These hormonal patterns help regulate our appetites, stress levels, and cellular recovery. People who don’t get enough sleep on a regular basis are likely to have issues with their metabolism and stress levels—and thus, their brain’s function.
(Shortform note: Sleep also appears to reduce stress by mitigating the stress from our daily lives. Research indicates that during REM sleep, our stress neurochemicals weaken while the brain processes emotional experiences. This suggests that this dream stage of sleep acts as a sort of therapy, potentially taking the edges off difficult experiences of the day. This insight may also explain why people with post-traumatic stress disorder (PTSD) have a difficult time with flashbacks: They often have disrupted sleep patterns, so they aren’t effectively removing the emotional impact of their memories during sleep.)
2. Sleep helps us encode memories and process information: A recent theory suggests that our brains consolidate our memories during sleep. Essentially, while we sleep, our brains move information from our short-term to our long-term memory. Furthermore, when we don’t sleep enough, our brains lose the ability to process information at all. In other words, not only do we struggle to remember things later on, but we also struggle to even take in the information in the first place.
(Shortform note: In Why We Sleep, Matthew Walker explains that during sleep, our brains move information from the hippocampus to the cortex. This not only transfers memories from the short to the long term but also clears out short-term memories that are deemed unnecessary. In other words, sleep helps you remember things and make room for new information.)
3. Sleep helps our brain’s cleansing process: Recent studies show that our brains remove excess waste through something called the glymphatic system. When we sleep, this system greatly increases its output. Sleep helps get rid of the waste from our metabolic system, which includes the amyloid plaques that have been linked to dementia.
(Shortform note: The glymphatic system was first discovered in 2012, and some researchers suggest the biological need for sleep across most of the animal world may be because of our need to remove neurotoxic waste. Also, recent research has linked sleep position to changes in the glymphatic system. Patients with dementia were found to spend a much longer time sleeping in the supine position (face up). For most efficient glymphatic transport, sleeping on your side is recommended.)
Gupta goes over several studies that exhibit the different effects sleep deprivation has on the body. They are all related to each other, and they all can lead to brain impairment.
(Shortform note: A recent study found that too little and too much sleep can increase your risk for a heart attack or stroke. People who slept less than six hours or more than seven hours a night were more likely to die from a heart attack or stroke.)
(Shortforn note: Why does this happen? Sleep can affect blood sugar for several reasons. Even one night of sleep deprivation can lead to increased insulin resistance, the main factor behind Type 2 diabetes.)
(Shortform note: One study found that poor sleep increased inflammatory biomarkers in women 2.5 times more than in men. A possible explanation is that testosterone somehow helps to limit the inflammatory effects of sleep deprivation.)
Gupta provides some easy-to-follow advice on getting more consistent rest:
Stay on schedule: Irregular sleep patterns are harmful to your health. Try to get up and go to sleep at roughly the same time every day. It can also help to establish bedtime rituals in which you take time to unwind and do something you find relaxing.
Pay attention to diet: What you eat and drink can affect your sleep. Caffeine after 2 p.m. can make it harder to fall asleep. Too much water before bed can cause you to wake up in the night to use the bathroom. Late meals and alcohol use can also disturb normal sleep cycles.
Keep your room dark at bedtime: Most forms of light, including sunlight and artificial light from lightbulbs or electronic devices, contain blue wavelengths. These wavelengths suppress melatonin, the hormone that makes you sleepy, and stimulate other areas of the brain that keep you alert.
Sleeping Pills: Why to Avoid Them
Why We Sleep echoes Gupta’s advice in many ways. Walker also recommends maintaining a sleep schedule, reducing light, and eating a healthy diet. One thing Walker adds to the discussion is the use of sleeping pills. Sleeping pills are bad for you for several reasons:
Most sleeping pills are sedatives that affect the quality of sleep. Although you might get seven or eight hours of sleep when taking sleeping pills, you won’t get enough deep, restorative sleep.
Sleeping pills lead to a brutal cycle. Sleeping pills may cause drowsiness in the daytime, which leads to more caffeine use or long naps, which makes it harder to fall asleep at night, which makes you more dependent on the sleeping pills. As you use the sleeping pills more and more, you build up a tolerance, making them both less effective and harder to quit.
There is a correlation between sleeping pill use and mortality. People who take sleeping pills are more likely to get in a car accident, get cancer, and have a weaker immune system.
Gupta claims a healthy diet is a vital part of brain health. As we’ve discussed, metabolic disorders are thought to be a leading factor in cognitive decline. While there is no general consensus on the perfect diet for brain health, there is plenty of evidence to suggest that you should eat certain foods regularly and avoid other foods as much as possible. In this section, we’ll look at why certain foods are good for your brain and why others can be potentially harmful.
Most of the foods that are good for your brain should not come as a surprise. Gupta claims that, although it’s difficult to know exactly how foods interact in our bodies, recent studies point to certain diets as being particularly healthy. For example, a Mediterranean diet is extremely beneficial to brain health. This diet consists largely of olive oil, nuts, fish, and a wide variety of fruits and vegetables.
Of these foods, Gupta mentions that berries and leafy green vegetables are especially good for the brain. One reason for this is that they are high in fiber. Fiber is beneficial because it changes the way your body metabolizes food. If you don’t have enough fiber in your diet, the carbs you consume will be absorbed more quickly, which increases your blood sugar and insulin levels, contributing to cognitive decline. Gupta also points out the benefits of omega-3 fatty acids, which are found in fish, nuts, seeds, and plant-based oils like olive oil. Omega-3 fatty acids are crucial in the maintenance of neurons.
Why the Mediterranean Diet Is Healthy
Gupta cites several studies that show the benefits of a plant-based Mediterranean diet. But why, other than being rich in fiber, are leafy greens and berries so good for us? What exactly are omega-3 fats doing in our brains? What other nutrients does a Mediterranean diet provide?
Leafy greens, such as kale, spinach, romaine lettuce, and cabbage, contain many essential nutrients. Vitamin K, magnesium, B vitamins, and calcium are found in leafy greens and are essential for cell function as well as bone density. Leafy greens are also high in vitamin A, which improves the immune system. Studies show that increasing your intake of greens by one serving a day can lower your risk of diabetes by up to 9%. This is due not only to the low sugar content but also to the high levels of magnesium, which helps regulate blood sugar levels.
Like greens, berries contain many nutrients. Berries also contain antioxidants, which help reduce oxidative stress. Oxidative stress has been linked to brain aging and neurodegenerative diseases such as Alzheimer’s. Berries also have strong anti-inflammatory properties. Dark-colored berries are especially helpful in fighting chronic inflammation.
Furthermore, getting omega-3 fatty acids from your diet is important because the body can’t make them from scratch, and they play an integral role in the function of cell membranes. Omega-3 fats also help make hormones that regulate blood clotting, blood flow, and the inflammatory process.
But the Mediterranean diet is good for your brain for other reasons, too. One study examined the substances that a Mediterranean diet provides, and identified eight nutrients linked to healthier cognitive functions. These include omega-3 fatty and omega-6 fatty acids, lycopene, vitamin D, and the B vitamins riboflavin and folate. The researchers also mention that it’s not just the individual nutrients that affect brain health, but the way they are collectively processed, which is why a varied, balanced diet is so important.
In a typical Western diet, there are three ingredients we consume too much: sugar, salt, and saturated fats. We’ll go through each one and discuss why Gupta feels they are bad for the brain.
Sugar: The average American consumes 163 grams of sugar per day. Most of this usually comes in liquid form or from processed foods. Earlier in the guide, we discussed why high levels of sugar in the blood can be bad for the brain: They can make us insulin resistant, leading to diabetes. They can also lead to high levels of inflammation, which can lead to cognitive decline.
(Shortform note: Insulin resistance can be especially harmful to the brain because of the way the blood-brain barrier works. The brain requires a lot of glucose, so much that the level of glucose in your cerebrospinal fluid (the fluid surrounding your brain) is 60% higher than in your bloodstream. As glucose levels rise, however, the blood-brain barrier can also become resistant to insulin and restrict it from entering the brain. It’s not too much insulin that is the problem here, but too little. Without insulin, brain cells can’t convert glucose into the energy they need to function.)
Salt: Although Gupta doesn’t go into much detail about why salt is bad for you, he does recommend limiting your intake of it as it has been linked to higher levels of heart disease, stroke, and dementia.
(Shortform note: The main reason high sodium diets are harmful is because of the effects on the vascular system, which, as Gupta points out, also harm the brain. Too much salt in the bloodstream leads to high blood pressure. As sodium builds up in the blood, the body dilutes it with water. This leads to a higher volume of blood in the bloodstream, which means more work for the heart and higher blood pressure.)
Saturated Fats: Saturated fats are in foods that are typically solid at room temperature, like cheese, butter, and full-fat yogurt. They can also be found in fatty red meats and milk. Saturated fats raise cholesterol and blood pressure levels and, like salt, have been linked to higher levels of chronic diseases.
(Shortform note: There is much debate surrounding saturated fats in the scientific community. Some researchers suggest that the fight against saturated fats, especially in America, is based on flawed data. The argument against saturated fats comes from a 1952 study that linked them to heart disease. While diets high in saturated fats do seem to raise cholesterol levels, the link to heart disease is now in question. Sugary, carb-rich, and processed foods are now considered to be more harmful when it comes to heart health.)
Gupta argues that keeping your brain active is a vital part of maintaining its health. Learning or discovering new things stimulates the brain, and this stimulation builds a brain more resistant to disease by creating new neural connections (and strengthening existing ones). With stronger neural connections, you are less susceptible to cognitive disruption. With a greater quantity of neural connections, you can offset the disruption through the use of the other networks. This may be how some people whose brains show all the physical signs of Alzheimer’s don’t manifest any symptoms of the disease.
Can the Brain’s Adaptability Be Harmful?
Gupta argues that increasing neural networks through learning can help the brain offset disrupted communications. This neuroplasticity is a vital function, but some suggest that it can also have harmful long-term implications, especially when related to a brain injury.
After a head injury, the brain can rewire itself to maintain the connection between two regions of the brain. In the short term, this is extremely beneficial, as the brain can keep performing at a high level after sustaining damage. In the long-term, however, it may be harmful. Neural networks are usually designed to be as efficient as possible. When alternative routes are used, the brain may use more energy and be less efficient. In other words, it may take your brain slightly more time and energy to process and transmit information. Over time, the consistent use of more energy in the brain may lead to neurological disorders, such as Alzheimer’s.
Gupta says that the best way to stimulate the brain is through challenging and novel activities. Doing this will increase the brain’s ability to adapt to damage or other challenges (or what scientists call your “cognitive reserve”). When many people think of brain stimulation, they think of brain games or puzzles. While these are helpful for working memory, they aren’t as beneficial for things like problem-solving or reasoning, which are also a big part of cognitive reserve. For this reason, you are much better off taking a class on something you enjoy, learning a language, or doing some other complex skill that gets you out of your comfort zone.
Tips for Stimulating the Brain
As Gupta indicates, many activities can stimulate the brain—like learning a new language or visiting a museum. However, stimulating the brain isn’t a one-time thing: We develop cognitive reserve through a lifetime of learning and curiosity. Gupta’s tips for stimulating the brain are a good start, but to keep the momentum going, seek out activities with the following characteristics that have been shown to increase cognitive reserve:
Slightly challenging: Perform tasks that are difficult and challenging without being frustrating. These are great for your brain and strengthen neural connections.
Absorbing: Seek out tasks in which you feel actively engaged and interested for maximum benefit.
Varied: To make sure you’re growing new neural connections, mix up activities periodically.
Gupta claims that social interaction is crucial to our psychological well-being and thus our brain health. There is lots of evidence to support this, as strong social connections are a better predictor of long, happy lives than social class, intelligence, or genetics. Lack of social connection has been linked to disrupted sleep patterns, higher levels of inflammation, and higher levels of stress, all of which contribute to cognitive decline.
From an evolutionary perspective, the importance of social connection makes sense. Humans are a very social species. Throughout history, we’ve survived through communal living and reliance on others for food, water, shelter, and protection. In the modern world, as Gupta points out, social isolation is on the rise. Despite being connected to many people through digital media, many people lack real, close connections. If we wish to counteract this and preserve brain health, we must focus on building community with others and establishing meaningful relationships.
Social Connections and Depression
Another reason to strengthen your social connections is to prevent depression. In Lost Connections, Johann Hari argues that one of the leading causes of depression is a disconnection from meaningful relationships. Depression can be a vicious cycle: As you become socially isolated, you may become more depressed, which leads you to further isolate yourself. Like Gupta, Hari argues that online connections, while sometimes helpful, are not enough. Experts say this is because online relationships are more about communication than real connection. To get the most out of relationships, you need to feel you are truly connecting with others.
Avoiding depression is important for your overall cognitive health because depression can cause or exacerbate many of the risk factors for dementia that Gupta presents, including insomnia, weight fluctuations, and constricted blood vessels. This can also be seen in the link between diabetes and depression. Those with clinical depression are 60% more likely to develop diabetes. Therefore, avoiding depression can help avoid many of the predictors of cognitive decline.
Gupta provides some ideas for building and maintaining social connections:
First, focus on things you enjoy: Try to spend time with people you enjoy being around and doing the activities you like the most.
(Shortform note: In The Happiness Project, Gretchen Rubin notes that many people participate in activities they believe they should enjoy instead of ones they actually enjoy. One way to avoid this is to ask yourself if you truly look forward to certain activities. If you don’t, you may just be trying to project a certain image of yourself rather than do something because you enjoy it.)
Second, volunteer: Giving back to the community can help you form and strengthen social connections. You can do this through a local school, community center, or charity.
(Shortform note: As pointed out in Lost Connections, group volunteering is often recommended to people struggling with depression. Volunteering not only provides a structured support system and social reconnection, but it can also give people a sense of purpose and increase their self-esteem.)
Third, build and maintain at least one strong relationship: Having one person in your life you can truly count on is extremely important. If possible, try to communicate with them routinely. Gupta recommends going on a walk with a close friend and talking about your anxieties.
(Shortform note: In just the past few decades, social connectedness has decreased at a steady rate in the United States. In 1985, the average person had three close confidantes. By 2004, that number had dropped to one, with a quarter of all Americans claiming that they didn’t have a single person they could confide in.)
You can strengthen your brain by making simple lifestyle changes. Use this exercise to review how well you’re taking care of your brain on a weekly basis. You can come back to this exercise regularly to check your progress.
Did you get the recommended 150 minutes of exercise this week? If not, what stopped you? How could you increase the amount of exercise you get next week?
Did you get at least six hours of sleep a night this week? If not, what might be causing this? What can you do to have a more regular sleep schedule?
On a scale of 1-10, how healthy was your diet this week? What can you do to improve your consumption of healthy nutrients and limit your salt and sugar intake?
What mentally stimulating activities did you perform this week? How can you increase the amount of challenging and engaging activities in your daily life?
In general, how strong are your social connections? What can you do to spend more time with family, friends, or your community?