What We Are Learning About Protecting the Brain Before Symptoms Appear
For generations, Alzheimer’s disease has carried an especially frightening implication: if it is in your future, there is little you can do about it.
You might inherit the wrong genes. You might grow older and begin forgetting names, appointments or where you put your keys. Eventually, perhaps, a physician would diagnose Alzheimer’s disease. Medicine might help manage some symptoms, but the underlying trajectory would largely continue.
That fatalistic view is beginning to change.
There is still no guaranteed way to prevent Alzheimer’s disease, and there is no single lifestyle program that can promise protection. Genetics and aging remain important risk factors, and Alzheimer’s is an extraordinarily complex disease.
But an increasingly important body of research suggests something much more encouraging: brain health is influenced by many of the same factors that determine the health of the rest of the body, and many of those factors can be changed.
Author’s Note: This article was inspired by and draws in part from a conversation between Dr. Mark Hyman and neurologist Dr. David Perlmutter on The Dr. Hyman Show, presented in the video “Why 1 in 2 Seniors Get Alzheimer’s (And How to Be the Exception).”
The implications are substantial.
The CDC reports that nearly 45% of dementia cases may potentially be prevented or delayed by addressing modifiable risk factors. That does not mean 45% of Alzheimer’s cases can simply be eliminated through healthy living. It means that, across populations, a surprisingly large portion of dementia risk appears associated with factors that can potentially be modified.
Perhaps the most important lesson is that we should not wait until memory begins to fail before thinking about the health of the brain.
Alzheimer’s May Begin Decades Before We Recognize It
We tend to think of Alzheimer’s as a disease of old age because that is when its symptoms usually become apparent.
The biology is more complicated.
Changes associated with Alzheimer’s can develop for years before someone reaches the point at which memory, reasoning or everyday function becomes noticeably impaired. This long period creates both a challenge and an opportunity.
By the time someone develops substantial cognitive impairment, considerable neurological damage may already have occurred. But if some of the processes contributing to that damage develop gradually, there may also be a long period during which improving overall health could help reduce risk.
This leads to a different way of thinking about Alzheimer’s prevention:
Don’t wait for the brain to begin failing before taking care of it.
Brain health should be considered part of lifelong health, just as we think about cardiovascular health, blood pressure, diabetes and physical fitness.
There Probably Isn’t One “Root Cause” of Alzheimer’s
For many years, public discussion of Alzheimer’s focused heavily on two abnormal proteins found in the Alzheimer’s brain: beta-amyloid and tau.
They remain important components of Alzheimer’s biology, but the disease increasingly appears to involve a much larger network of interacting processes.
These include amyloid and tau pathology, neuroinflammation, immune dysfunction, vascular disease, impaired glucose and insulin regulation, mitochondrial dysfunction, oxidative stress, synaptic dysfunction, genetics and aging.
In other words, asking for the cause of Alzheimer’s may ultimately be asking the wrong question.
A better question may be:
What combination of processes causes a healthy brain gradually to become a diseased brain?
One particularly interesting area of research concerns the relationship among metabolism, inflammation and the brain’s immune system.
The Brain Has Its Own Immune Defenders
Among the most fascinating cells in the brain are microglia, specialized immune cells that constantly monitor and maintain the brain’s environment.
Under normal conditions, microglia perform essential housekeeping and protective functions. They participate in maintaining neurons, synapses and the environment in which brain cells communicate.
But immune activity can also become dysregulated.
Chronic neuroinflammation and altered microglial activity are increasingly recognized as important components of neurodegenerative disease. The video discussion that inspired this article places particular emphasis on this relationship, proposing that metabolic dysfunction, mitochondrial impairment and systemic inflammation can influence the behavior of these brain immune cells.
The biology is considerably more complicated than simply having “good” or “bad” microglia. But the broader principle is important:
The brain is not isolated from the health of the rest of the body.
Blood vessels, immune signaling, metabolism, the gut, environmental exposures and lifestyle can all influence the biological environment in which the brain operates.
Alzheimer’s Is Also a Disease of Lost Connections
A human brain contains an enormous network of neurons communicating through connections called synapses.
These connections allow us to remember, reason, speak, recognize people, navigate our surroundings and integrate countless pieces of information into a coherent understanding of the world.
As Alzheimer’s progresses, synaptic function deteriorates and neurons are eventually lost.
The podcast transcript describes this as a “loss of connection,” an unusually useful way of visualizing what is happening. At the microscopic level, connections between neurons are being damaged. Eventually, at the human level, the person begins losing connections with memories, abilities, surroundings and, ultimately, aspects of their own identity.
This deterioration eventually produces the symptoms families recognize.
Early Alzheimer’s may involve difficulty learning and retaining new information, increasing repetition, problems remembering appointments, difficulty managing finances, trouble planning or completing familiar tasks, or becoming lost in familiar places. The CDC similarly identifies problems with short-term memory, paying bills, preparing meals, remembering appointments and navigating familiar areas among common manifestations.
As the disease progresses, language, judgment, orientation, behavior and the ability to perform everyday activities may increasingly be affected.
Occasional forgetfulness, however, is not Alzheimer’s disease. New, progressive or persistent cognitive problems that interfere with normal life deserve medical evaluation because Alzheimer’s is only one possible cause of cognitive impairment.
Metabolic Health and Brain Health Are Closely Connected
One of the strongest themes in the transcript is metabolic health.
The speakers emphasize blood glucose, insulin resistance, abdominal obesity and blood pressure as potentially important influences on long-term brain health.
This general principle is supported by mainstream dementia-prevention research.
Diabetes, obesity and hypertension are among the potentially modifiable factors associated with dementia risk. In CDC data examining adults 45 and older, high blood pressure, physical inactivity, obesity and diabetes were among the common modifiable risk factors associated with Alzheimer’s disease and related dementias.
This helps explain why protecting the heart and protecting the brain increasingly look like overlapping objectives.
The brain requires an extraordinary blood supply. Its neurons require energy. Its cells depend upon healthy metabolism.
Damage the vascular and metabolic systems for decades, and the consequences do not necessarily stop at the neck.
Exercise May Be One of Our Most Powerful Brain-Health Tools
If there is one intervention that consistently appears in discussions of healthy aging, cardiovascular health, metabolic health and brain health, it is physical activity.
Regular exercise improves cardiovascular function, insulin sensitivity, blood pressure, muscle health and numerous other physiological systems.
The transcript discusses evidence supporting both aerobic and resistance exercise and argues that the combination may be particularly valuable.
That is a sensible practical approach.
Aerobic activity challenges the cardiovascular system and improves fitness. Resistance exercise preserves and builds muscle, which becomes increasingly important as we age.
The CDC identifies regular physical activity as a means of reducing the risk of cognitive decline and dementia, including Alzheimer’s disease.
The lesson does not need to be complicated:
Move regularly, challenge your cardiovascular system and maintain your strength as you age.
What We Eat Matters Too
There is no single food that prevents Alzheimer’s and no diet that guarantees protection.
But the overall dietary pattern matters because diet influences several systems associated with brain health, including blood glucose, insulin sensitivity, cardiovascular health, inflammation, body composition and the intestinal microbiome.
The transcript emphasizes controlling blood sugar and favors a colorful, plant-rich diet containing fiber, polyphenol-rich foods and healthful fats while reducing ultra-processed foods.
Rather than becoming preoccupied with a single “Alzheimer’s diet,” it may be more useful to think about what the diet is accomplishing.
Does it help maintain healthy blood glucose?
Does it support a healthy weight and waist circumference?
Does it provide vegetables, fruits, legumes, nuts, whole foods and dietary fiber?
Does it support cardiovascular health?
Does it displace highly refined and ultra-processed foods?
A brain-healthy diet is, in many respects, simply a healthy diet.
The Gut-Brain Connection
One of the more intriguing areas discussed in the transcript is the intestinal microbiome.
Trillions of microorganisms inhabit the human gastrointestinal tract. They participate in digestion, produce biologically active compounds, interact with the immune system and help maintain the intestinal barrier.
The transcript proposes a chain in which disruption of the microbiome and intestinal barrier can contribute to systemic inflammation, which in turn can influence inflammatory signaling in the brain.
Research into the gut-brain axis is advancing rapidly, but it is still an evolving field. It would be premature to claim that correcting the microbiome prevents Alzheimer’s.
The broader lesson, however, is consistent with the rest of the evidence: systems throughout the body interact with one another. The brain cannot be treated as an isolated organ.
Sleep Is Brain Maintenance
Sleep is another essential component of long-term brain health.
The transcript recommends approximately seven to eight hours of sleep while emphasizing that sleep quality matters in addition to duration.
Poor sleep and sleep disorders are among the factors public-health authorities identify as potentially relevant to cognitive impairment.
Someone who consistently sleeps poorly should therefore not regard sleep as merely an inconvenience.
Persistent insomnia, sleep apnea or chronically inadequate sleep deserves attention for many reasons, and brain health is one of them.
Don’t Underestimate Hearing and Social Connection
Some of the most interesting dementia risk factors have little to do with what most people traditionally think of as “brain health.”
Hearing is an excellent example.
Hearing loss is recognized as an important potentially modifiable dementia risk factor. One possible explanation is that hearing impairment increases the cognitive effort required to understand the environment. Another is that hearing loss can contribute to social withdrawal and reduced intellectual stimulation.
That brings us to something even more fundamental: human connection.
When asked during the interview to identify the worst daily habit for brain health, neurologist David Perlmutter answered “lack of connection.” When asked for the best, he answered connection with other people.
That answer should not be interpreted as meaning loneliness is the singular cause of Alzheimer’s. But it reflects an increasingly important understanding of healthy aging.
Human beings are profoundly social organisms.
Conversation requires attention, memory, language, emotional interpretation and rapid processing. Relationships give us reasons to leave the house, move, communicate, solve problems and remain engaged with the world.
Social connection is not simply emotionally pleasant. It is part of a healthy life.
Protect the Brain From What Damages It
Brain-health strategies should also include reducing avoidable injury.
Smoking, excessive alcohol use, traumatic brain injury and air pollution are among exposures relevant to long-term health and cognitive risk. The transcript particularly discusses head trauma, environmental toxins and fine particulate air pollution as potential contributors to inflammatory and mitochondrial stress.
Not every exposure can be avoided, and the evidence varies considerably among individual chemicals and environmental risks.
But the practical principle is straightforward.
Wear a helmet when appropriate. Prevent falls. Don’t smoke. Limit harmful alcohol exposure. Pay attention to air quality when pollution or wildfire smoke is severe. Use reasonable precautions around occupational and environmental hazards.
Brain protection is partly about building health and partly about avoiding unnecessary damage.
Know Your Numbers
People routinely monitor indicators of cardiovascular health. We should increasingly recognize that many of those same numbers have implications for the brain.
Among the useful measurements to discuss with a healthcare professional are:
blood pressure,
fasting glucose and A1C,
lipids and overall cardiovascular risk,
body weight and waist circumference,
and, when clinically appropriate, other measures of metabolic health.
The transcript places particular emphasis on fasting insulin, fasting glucose and waist-to-hip ratio as early indicators of metabolic health.
More sophisticated Alzheimer’s biomarkers are also emerging, including blood tests related to phosphorylated tau and other indicators of neurological injury. These are important developments, but they should not yet be treated like a cholesterol test that everyone simply orders and interprets independently. Their appropriate use depends upon the clinical situation and should be discussed with a knowledgeable healthcare professional.
Genes Matter, But They Are Not the Entire Story
Genetics clearly influence Alzheimer’s risk.
Having a close relative with Alzheimer’s increases risk, and variants such as APOE ε4 can substantially alter susceptibility.
But genetic risk is not the same thing as genetic destiny.
A person cannot change the genes inherited from their parents. They can influence many of the conditions in which those genes operate.
That distinction represents one of the most encouraging developments in our understanding of cognitive aging.
The choice is not simply between “I have the Alzheimer’s gene” and “I don’t.”
Risk develops from a complicated interaction among age, genetics, cardiovascular health, metabolic health, environmental exposures, lifestyle and other factors we are still working to understand.
Build a Brain-Protective Life
We should be careful with the word prevention.
A person can exercise, eat well, maintain excellent blood pressure, remain socially engaged and still develop Alzheimer’s disease. Conversely, someone with multiple risk factors may never develop it.
Risk is probability, not destiny.
But that does not make prevention meaningless.
It makes risk reduction extraordinarily important.
The emerging picture suggests a surprisingly practical strategy:
Move your body.
Combine aerobic activity with strength training.
Protect your metabolic health.
Manage blood pressure, blood glucose, diabetes, weight and cardiovascular risk.
Eat well.
Favor minimally processed foods and a diverse, nutrient-rich diet that supports metabolic and cardiovascular health.
Sleep well.
Treat persistent sleep problems rather than accepting them as an inevitable consequence of aging.
Protect your senses.
Have hearing problems evaluated and corrected when possible.
Stay connected.
Maintain relationships, community, conversation and purpose.
Keep using your brain.
Learn, read, write, solve problems, travel, create and remain intellectually curious.
Protect the brain physically.
Avoid smoking, excessive alcohol, repeated head trauma and unnecessary environmental exposures.
And perhaps most importantly:
Start before you think you need to.
Alzheimer’s Doesn’t Begin With Forgetfulness
The most important shift may ultimately be conceptual.
For too long, we have treated brain health as something mysterious and largely beyond our control. We routinely tell people in their 40s and 50s to think about cholesterol, blood pressure, diabetes, exercise and cardiovascular disease, while Alzheimer’s remains something to worry about decades later.
The evidence increasingly suggests that these are not separate conversations.
The cardiovascular system supplies the brain. Metabolism supplies its energy. Sleep affects its function. Exercise changes its physiology. Hearing helps keep us engaged with our environment. Relationships keep us connected. Diet affects metabolic and vascular health. And the immune system communicates continuously between the brain and the rest of the body.
Alzheimer’s disease remains complex. There is no single proven root cause, no guaranteed preventive diet, supplement or exercise program, and currently no cure.
But there is an increasingly compelling reason to reject the opposite extreme: the belief that nothing can be done.
The better message is both more scientifically accurate and more useful:
You cannot completely control whether you develop Alzheimer’s disease. But you can influence many of the factors that help determine how your brain ages.
And the best time to begin protecting that brain is not when you start forgetting.
It is now.The implications are substantial.
Alzheimer’s May Begin Decades Before We Recognize It
There Probably Isn’t One “Root Cause” of Alzheimer’s
The Brain Has Its Own Immune Defenders
Alzheimer’s Is Also a Disease of Lost Connections
Metabolic Health and Brain Health Are Closely Connected
Exercise May Be One of Our Most Powerful Brain-Health Tools
What We Eat Matters Too
The Gut-Brain Connection
Sleep Is Brain Maintenance
Don’t Underestimate Hearing and Social Connection
Protect the Brain From What Damages It
Know Your Numbers
Genes Matter, But They Are Not the Entire Story
Build a Brain-Protective Life
Alzheimer’s Doesn’t Begin With Forgetfulness
Why 1 in 2 Seniors Get Alzheimer’s, and How to Be the Exception
In this conversation, Dr. Mark Hyman and neurologist Dr. David Perlmutter explore an emerging way of thinking about Alzheimer’s disease: not simply as an inevitable consequence of aging or genetics, but as a complex neurodegenerative disease influenced by metabolism, inflammation, immune function, mitochondrial health and many of the lifestyle factors that affect the rest of the body.
Central to the discussion are microglia, the brain’s resident immune cells. Perlmutter describes how these normally protective cells can become chronically activated in an inflammatory environment, potentially contributing to synaptic damage and neurodegeneration. The conversation connects this process with insulin resistance, elevated blood sugar, visceral fat, poor diet, gut dysfunction, environmental exposures, inadequate exercise, poor sleep and other influences on metabolic and inflammatory health.
Most importantly, the discussion challenges the fatalistic belief that there is nothing we can do about our cognitive future. While some of the prevention and treatment claims made in the conversation remain debated and Alzheimer’s cannot currently be considered fully preventable, there is strong evidence that many dementia risk factors are modifiable. The practical message is compelling: the time to protect the brain is long before memory problems begin.
View the video here
Video Highlights
00:00 | The scale of Alzheimer’s and dementia
Perlmutter opens with the prevalence of Alzheimer’s and dementia in older adults and introduces the central argument that people have considerably more influence over their long-term brain health than is commonly believed.
02:00 | Neuroinflammation and the brain’s immune system
The discussion introduces neuroinflammation and microglia, specialized immune cells that normally help maintain neurons, synapses and the blood-brain barrier.
06:29 | The brain is not necessarily destined to decline
Hyman and Perlmutter discuss how diet, exercise, sleep, metabolic health, the microbiome, nutritional status and environmental exposures may influence brain health.
07:38 | Immunometabolism: connecting metabolism and brain immunity
Perlmutter introduces immunometabolism, the relationship between cellular metabolism, mitochondrial function and immune-cell behavior, as a framework for understanding neuroinflammation.
10:53 | Alzheimer’s may begin decades before symptoms
The conversation emphasizes that biological changes associated with neurodegeneration can begin long before obvious memory problems emerge, making midlife brain health particularly important.
16:16 | Metabolic health: know your numbers
Blood pressure, glucose regulation, fasting insulin, A1C and abdominal fat are discussed as indicators of metabolic health that may also have implications for long-term brain health.
17:21 | Alzheimer’s as a loss of connection
At the microscopic level, cognitive deterioration involves loss of synaptic connections between neurons. The speakers use this as a powerful metaphor for the larger loss of connection that occurs as Alzheimer’s progresses.
18:59 | Challenging the amyloid-centered model of Alzheimer’s
Perlmutter presents his critique of the traditional amyloid hypothesis and argues for looking farther upstream at inflammation, metabolism and immune dysfunction. His position here is more categorical than the current scientific consensus, but it represents an important part of the discussion.
25:45 | Mitochondria, metabolism and immune function
The conversation explores how impaired mitochondrial function may alter immune-cell behavior and contribute to chronic inflammatory processes affecting the brain.
28:59 | Emerging biomarkers and earlier intervention
Hyman and Perlmutter discuss APOE genetics and emerging biomarkers including p-tau217, neurofilament light and GFAP, as well as conventional metabolic markers. The larger theme is moving from late-stage diagnosis toward earlier recognition of risk.
35:50 | What can we actually change?
Diet, physical activity, stress, sleep, environmental exposures and the microbiome are presented as potentially modifiable influences on metabolic and brain health.
37:43 | Modifiable dementia risk
Perlmutter discusses the 2024 Lancet Commission’s work on modifiable dementia risk factors and transitions into practical prevention strategies.
38:53 | Exercise as brain medicine
The discussion reviews evidence connecting exercise with cognitive health and preservation of brain function.
40:58 | Aerobic exercise or strength training? Both.
The speakers discuss evidence suggesting that combining aerobic and resistance exercise may provide particularly broad benefits, including cardiovascular fitness, insulin sensitivity and maintenance of muscle.
45:01 | What does a brain-healthy diet look like?
Rather than promoting one rigid diet, Perlmutter emphasizes blood-sugar control, minimally processed foods, colorful plant foods, dietary fiber and healthful fats.
47:07 | The gut-brain connection
The discussion turns to the microbiome, intestinal barrier function and the possibility that gut-derived inflammation can contribute to systemic and neurological inflammatory signaling.
51:22 | Ultra-processed food and brain health
Hyman and Perlmutter discuss research associating greater consumption of ultra-processed foods with increased Alzheimer’s risk and explore possible connections involving blood sugar, inflammation and the microbiome.
54:52 | Environmental toxins and the brain
The conversation examines environmental exposures and their potential effects on mitochondrial function, immune regulation and neurodegeneration.
1:02:08 | Air pollution, wildfire smoke and neuroinflammation
Fine particulate matter, particularly PM2.5, is discussed as a source of systemic inflammation and a potential contributor to neurological injury.
1:05:37 | Rapid-fire: practical habits for brain health
The final section addresses social connection, alcohol, sleep, exercise, fasting insulin, abdominal fat, diet and other practical questions about maintaining cognitive health.
1:09:05 | The final message: start today
Perlmutter concludes with the central theme of the conversation: rather than waiting for cognitive decline, begin protecting metabolic, physical and brain health decades earlier.
(Note: About Us, and if relevant, a reference bibliography, related books, videos, and apps can be found at the end of this article.)
Disclaimer: As a Senior Health Advocacy Journalist, I strive to conduct thorough research and bring complex topics to the forefront of public awareness. However, I am not a licensed legal, medical, or financial professional. Therefore, it is important to seek advice from qualified professionals before making any significant decisions based on the information I provide.
Copyright: All text © 2026 James M. Sims and all images exclusive rights belong to James M. Sims and Midjourney unless otherwise noted.
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