Medical science has come a long way in the last century, making more and more diseases survivable. But there are still some diseases that do most of their damage without you even knowing about it, so that by the time you treat them, it’s too little too late. These are the silent killers, and some of them are quite surprising.

TRANSCRIPT:

In 2010, a 40-year old woman was driving home from work in Colorado City, Texas with her two young kids in the backseat of her car. It was a normal day just like any other, nothing out of the ordinary. When she suddenly got a headache.

It came on fast and within seconds, her vision blurred, to the point that she couldn’t see the road. She pulled off to the shoulder and put the car in park, hoping that this thing would pass… but it didn’t. She passed out, slumped over… and died. Right there in the front seat.

Her kids, who I’m sure were terrified, were able to call 911 for help. But by the time they arrived, it was too late. They tried to revive her, but ultimately she was pronounced dead on the scene.

The name of the woman in this story was Catherine. And she was my first cousin.
They later determined that she had a brain aneurysm that burst and caused a cerebral hemorrhage. A brain aneurysm she probably had her entire life and just didn’t know it.
This was obviously a tragedy in our family and it affected all of us in different ways. If I’m being honest, I wasn’t really that close with Catherine, I hadn’t seen her in years at that point, but we were around each other quite a bit when I was a kid, at family reunions; holidays and whatnot.

But I think it’s safe to say that it didn’t do wonders for my chronic existential dread.
That and this pervasive feeling I’ve always had that… you never know.

Try as you might to eat well and stay healthy, take care of yourself, do all the right things, there’s just a whole host of things that can go wrong in the human body, some of which you just don’t know about… until it’s too late.

So I took it upon myself to look into some of the deadliest conditions that can happen to the human body without you even knowing that it’s happening. But don’t worry, we’ll also talk about things you can do to catch these things earlier, and look at some medical advances that might make these issues a thing of the past.

Before I get into this, I guess I should be clear that there’s a lot of diseases that don’t really show symptoms – these are called asymptomatic diseases or subclinical diseases – and not all of them are things to panic about. You probably have one yourself.
In fact, it’s kind-of hard to pin down exactly what a “normal” body is in the first place. We’re all messed up in our own special kind of way.

But there are some that kinda just sit there, under the surface, sometimes for years and even decades, before finally reaching a tipping point. And that’s when things spiral and go very wrong very fast.

In this video, I’m going to talk about a little bit of both. Some of these are absolute life-enders, some just do permanent damage. But some, like this first one… Well, they sneak up on you. And are a lot more trouble than you might think.

HIGH BLOOD PRESSURE

Our first disease is high blood pressure.

Yeah. High Blood pressure

I know many of you are thinking, “Wait, what? What are you talking about?

“What?” You may be thinkingAlmost half of you watching this video suffer from this disease and you don’t even know it.

In fact, chances are probably half of you watching this video have some level of high blood pressure, and probably think it’s not that big a deal. You have it, you deal with it, probably someone else in your family has it, and it’s not even really a disease, is it?
and are very confused how it could be on this list. To which I would say, just because it’s common doesn’t mean it’s harmless.

To which I would argue, A: just because it’s common doesn’t mean it’s harmless. And B: ]fair enough, it’s more of a condition than a disease, but it can lead to all kinds of other diseases.

High blood pressure also goes by the term “hypertension” but is often nicknamed “the silent killer,” because it can lead to things like heart disease and stroke.

High blood pressure means the force of your blood pushing against artery walls is too high, meaning the heart has to work harder to pump blood. This obviously puts extra stress on the heart which, according to various health experts – uh – you need.

It basically creates more stress on everything in your body, everything has to work a little bit harder to do its job, which causes it to wear down faster.

More stress on the walls of the arteries means more chances for burst vessels and aneurysms like I just talked about. And damaged arteries means more likelihood of debris from that damage causing a blockage, and now you’re having a stroke.

Stressed vessels in your kidneys can lead to lower kidney function and kidney disease, possibly kidney failure.

And if that’s not enough reason to take it seriously, it can damage blood vessels in your eyeballs, meaning you can lose your vision, and then you wouldn’t be able to see my pretty face on your phone while taking a dump, and none of you want that.

There’s really no one cause of high blood pressure. Lifestyle choices and diet are usually talked about but honestly, they only get talked about because those are things you can actually control. Truth is, most of the reasons are out of your control, things like genetics, age, race, stress levels…

The good news is high blood pressure is very easy to catch and there’s a whole host of treatments available so as long as you get checked and stay on top of it, you can avoid the worst outcomes.

But it can definitely be that “silent killer” if you don’t do anything about it. So, learn about it the easy way and not the hard way.

GUM DISEASE

Next let’s talk about gum disease.

Here’s the deal, if you just let out a sigh when I said gum disease because there’s nothing scary about gum disease… You are wrong. Like so very, very wrong.

It’s actually terrifying. Every last one of you will be flossing your teeth after this video.

And you should be flossing your teeth because gum disease is kind-of one of those canaries in a coal mine things. Like it’s not that dangerous itself but it can be a precursor of a lot of really bad stuff.

Stuff like…
diabetes,
heart disease,
cancer, and
Alzheimer’s disease.

Like, researchers found that men with gum disease were 49 percent more likely to develop kidney cancer and 54 percent more likely to get pancreatic cancer. Which, spoiler alert, will come up again in this video.

And gum disease has been connected with an increased buildup of beta-amyloid proteins in the brain, which is leads to Alzheimer’s disease.

In fact, there’s a type of bacteria called Porphyromonas gingivalis that’s a big part of gum disease – you’ve probably heard of gingivitis from those Listerine commercials, that’s where that comes from – but anyway, that bacteria, has been found in the brains of Alzheimer’s patients.

The exact connection between the two things is still kind-of unknown, it’s still being researched, but the mouth and nose are like, THE entry point for the body. Everything that enters your body – unless something horrible has happened – enters your body through your mouth.

This is the gate and drawbridge on the castle of your body, this is where the outside world meets the inside world. If a bacteria’s gonna get in, chances are it’ll be here.

So if you have a runaway bacterial infection, it doesn’t just erode your gums and teeth and make your breath smell bad, it gets pumped throughout your whole body.

It can cause all kinds of digestive issues, it can create a chronic immune response in your body that can cause inflammation that leads to a ton of other things, like hypertension.

Excess white blood cells in your vessels can can coagulate and cause blockages and strokes…

Like, I know, I get tired of the dentist getting onto me about flossing, I used to be terrible about it, but lately I’ve just made it a habit, part of my night routine that I do every night before I go to bed, I floss and rinse and guess what, my gums don’t bleed anymore.

But it really isn’t just about your teeth and your gums, it’s not a vanity or aesthetic thing, this is about the health of your entire body, and that really doesn’t get communicated very well.

So seriously, just take 30 seconds a day to jam some floss between your teeth. Like that and wearing sunscreen, those two habits alone could extend your lifespan by 5 years.

Is that true? I don’t know. I just made it up. Whatever, floss your damn teeth.

POLYCYSTIC OVARY SYNDROME

Now something just for the ladies, we’ve got polycystic ovary syndrome.

There was probably a better way to introduce that.

Polycystic ovary syndrome, as the name implies, only affects those with ovaries, and it affects up to 10 percent of all women of childbearing age, but only 50% of those who have it are correctly diagnosed.

It’s a condition where a female’s body overproduces male hormones. That can interfere with ovulation and increase the risk of heart disease, type 2 diabetes, and endometrial cancer.

So, a lot of women don’t know they have it until they get diagnosed with something way worse. You might be sensing a pattern here.

It’s not that it doesn’t give off any symptoms, the problem is that the symptoms it produces can look like a lot of other things.

For example, one of its most common symptoms is irregular periods, which… a lot of women have irregular periods, for all kinds of reasons.

Other possible signs might be things like adult acne, body or facial hair, or the hair on their head may start to thin.

Kind of sounds like an adult woman going through male puberty. Which I would not wish on anyone. There’s only one thing in the world worse than male puberty, and that’s… well, female puberty probably.

This is something they can check for, with physical exams, blood tests, and sometimes ultrasounds on ovaries. So if any of this is setting off alarm bells, you might want to give your doctor a call and check it out.

You might have noticed all the examples so far have been small things that can lead to worse things if you’re not careful.

Now we’re going to talk about the worse things.

We’ve gotten better as a society in detecting cancer earlier and developing better treatments for it.

But it’s still a disease that’s often not discovered until its later stages.

CANCERS

The number one thing you can do to survive cancer is catch it early. Fortunately, we’ve gotten a lot better at that over the years.

But there are still some cancers that are frustratingly hard to know you have until it’s way too far along.

One of them is ovarian cancer, which kills up to 14,000 women yearly in the U.S.

Kinda like the polycystic ovary syndrome I talked about earlier, it’s symptoms are fairly mild and look a lot like other symptoms, so they often go overlooked until the cancer gains a foothold, that’s why most of the time when they’re finally detected, the cancer is already at a stage 3 or 4.

And the scary part is there’s no screening test for it, you just have to wait for symptoms to show up.

Which is why, if you’re experiencing things like bloating, loss of appetite, or pelvic pain, please see your doctor. Your best defense is to take those symptoms seriously.

Oh, and I want to take a second here to remind everyone that I’m not a doctor. Neither is Google or Bing or DuckDuckGo.

Your doctor will have the final say on whatever is ailing you.

The one that freaks me out though, is pancreatic cancer. And again, this may be more personal because I’ve lost people to pancreatic cancer, my uncle died like 5 years ago from it and it was like 6 weeks after they found it, he was gone.

I know some of you are going to say in the comments that you’d prefer to go quick like that but assuming you want to survive cancer, pancreatic is not a good one.

It’s just totally asymptomatic until gets into the later stages, at which point it’s often too late.

This is also true of colorectal cancer, which is why there’s been such a big push for colonoscopies in recent years. At least with those you can get up there and take a look. So, you know… get up there.

The one on here that kinda surprised me was prostate cancer, I didn’t realize it was so widespread but 30,000 men die from it every year.

It’s actually the most common cancer among males after skin cancer, with more that 270,000 cases diagnosed every year.

But this is one that they can screen for by testing prostate-specific antigens, so it’s a good idea to do regular blood tests for that to catch it early.

NEUROLOGICAL DISEASES

Moving away from cancer, let’s look at some neurological diseases that you may not know you have until it’s too late.

One of the most nightmarish ones for me is Huntington’s disease, which causes nerve cells in your brain to deteriorate.

You can kinda describe Huntington’s as like having Parkinson’s and dementia at the same time.

It eats away at your memory and your cognitive abilities but it also attacks your motor cortex, making you stumble and drop things until you can’t walk anymore.

As is the case with a lot of these neurological conditions, the damage happens at a cellular level, so you don’t notice it for a very long time, but once it does enough damage that you do notice it, it’s already gotten exponential and it develops quickly from there.

So you might have Huntington’s for decades with no symptoms and have no idea that it’s slowly eating away at your brain.

But there is a way to test to see if you have it. It’s actually a very simple test – look at your parents.

Huntington’s is a genetic disease, basically if your parents have it, there’s a 50% chance that you will have it. Only like 2% of cases are from someone who’s parents didn’t have it.

There are genetic tests you can do if one of your parents had the gene, and they can test in utero, so parents can know if they’re passing it on when they get pregnant.

So it’s definitely less scary if you don’t have a history of it in your family, but if you do… you might want to get tested. I think there are some treatments they can do that might slow the progress early on.

So I mentioned Alzheimer’s Disease a minute ago, it’s the same thing with that one, it kinda does most of its damage asymptomatically, so by the time you start seeing symptoms, there’s only so much you can do.

Alzheimer’s disease, of course, affects parts of the brain that control language, memory, and thoughts.

Almost 5.8 million people in the U.S. were living with Alzheimer’s in 2020. That number is projected to increase to 14 million people by 2060.

And yet, we still don’t fully understand what causes it. The leading theory is that it’s a buildup of amyloid plaques in the brain –
floss your teeth people –
But we still don’t know the best way to prevent or combat that buildup.

Those symptoms include memory problems that disrupt daily life, like getting lost in a store or asking the same questions over and over.

Familiar tasks may become harder, or someone’s personality will noticeably change.

And while there have been a flurry of drugs to help slow down or reduce symptoms, there’s unfortunately still no cure for Alzheimer’s.

But you know how I started off this video talking about high blood pressure and how it can lead to worse things and all that? Well, here are some of those worse things.
Yeah, I know I already covered a few of them but these will just straight up end your life.

HIGH BLOOD PRESSURE: PART DEUX

Like my cousin at the beginning of this video, she died very suddenly and unexpectedly from an aneurysm. That can be caused by high blood pressure.

An aneurysm is basically a spot in your blood vessel where the wall gives way like a balloon. And that’s not dangerous in and of itself, you could live your entire life with an aneurysm and be just fine… Unless that aneurysm bursts.

Yeah, it’s not the aneurysm that kills you, it’s the burst. Kinda like it’s not the fall that kills you, it’s the hitting the ground.

But just like a balloon, when that blood vessel gets stretched and bulged, the vessel wall gets weaker, and becomes more likely to tear, and if that happens to an important enough artery, it can be a serious problem.

So you’ve got weak spots in vessels in important places in your body… How do you think high blood pressure affects that?

Yeah. it greatly increases the chance of ruptures.

And if that rupture happens in the brain and causes bleeding, you have what they call a hemorrhagic stroke.

Unfortunately, there’s no real symptoms to having an aneurysm in your brain, in fact I’d bet many of you watching this have one and don’t even know it.

They can be found with CAT scans, but in general, insurance doesn’t cover it unless there’s some reason to look. Most aneurysms are found by accident while looking at something else.

Like that happened to a good friend of mine, she has an aneurysm in her brain that could go off at any moment. So she has to be aware of that.

Usually the biggest symptom of a rupture is a sudden and severe headache, usually followed by blurred or double vision, nausea, or confusion.

So if you’re suddenly hit with that out of the blue, don’t be a hero, get help immediately.

In that same… vein…
Because we’re talking about blood vessels… Vein…
Vein…

High blood pressure can also cause a DVT, or deep vein thrombosis. If you’ve ever heard anybody say, don’t have a thrombo, this is what they’re talking about.

This is when a blood clot breaks off the inside of a vessel and travels to your lungs, where it blocks arteries and causes a pulmonary embolism – basically it blocks blood flow to the lungs.

What does that have to do with high blood pressure? Well, when arteries are stretched, little microtears can happen, and in the process of repairing these tears, clots can form.

Those clots can collect and get bigger and cause plaques, and if the blood pressure is high, it increases the likelihood that one of those plaques can tear off the side of the vessel wall, and now you’re in trouble.

DVT usually happen in the legs and may not cause any symptoms at first. But if you start feeling cramping or soreness in your calf that won’t go away, and especially if the kin is tender and warm to the touch on the lower leg, you might want to get to a doctor as soon as possible.

But some to look out for are cramping or soreness in your calf, swelling, tender or warm skin to the touch, or redness on the skin on the lower leg.
If they can catch it in your leg before it gets to your lungs, you stand a good chance of surviving. But if you suddenly experience chest pain, shortness of breath, or a fainting spell, that might mean that the clot got to your lungs and you should seek medical attention right away.

And one more high-blood pressure related one – silent heart attacks.

In case you weren’t afraid enough of normal-volume heart attacks, now there’s silent heart attacks.

According to the American Heart Association, there are around 805,000 heart attacks in the U.S. every year. Out of those, 170,000 of them are silent.

And by “silent” they mean that the person who had the heart attack showed little to no symptoms.

Meaning these people had a heart attack and didn’t even know it.

A silent heart attacks are usually found by accident, usually when the patient is being given an electrocardiogram.

I know a guy who didn’t know he had a heart attack, but he got blood taken for some kind of test and found that his C-reactive protein was through the roof, which tracks with a heart attack.

So while a silent heart attack is obviously survivable, even not unpleasant, it does damage the heart significantly and can increase your risk of heart failure by 35 percent. It can also increase your risk of having a stroke.

Some of the symptoms include indigestion, feeling like there’s a strained muscle in your chest or upper back, and excessive fatigue that lasts a long time.

And now… it’s time for some real nightmare fuel.

RABIES

We really don’t hear much about rabies anymore, mostly because we’ve done a really good job of vaccinating ourselves and our pets against it, so it’s very uncommon now, but the reason we did such a good job of vaccinating against rabies is because rabies is… a… nightmare.

It’s a disease that’s easy to prevent but if you somehow fail to prevent it and you get it and you start showing symptoms… you will die.

There is no treatment for rabies once you have it. You are done. It has a 100% kill rate. And you will be lucky to last a week.

During that week what you can expect is a fever and a headache at first, then some nausea and vomiting, and then things will start getting confusing, you’ll be anxious and agitated, you might not know where you are and lose your balance, you’ll hypersalivate and drool all over the place while your limbs begin to do an uncontrollable nervous shake. And that’s when things get really weird.

Because people in the later stages of rabies develop hydrophobia – a fear of water so severe that it prevents them from drinking.

Like something in their brain just sends them into convulsions if they try to drink.

This has been captured a few times and it’s harrowing. You can see that they’re just not fully in control of their brain anymore. And it’s also just harrowing because these people absolutely died within a few days of this being taken.

But yeah, in the final stages, you basically just lose your mind, you can’t sleep, there are constant hallucinations, and your body becomes paralyzed until you just stop breathing.

Rabies is a virus that attacks the brain, but it travels from animal to animal in the salivary glands. When that animal bites another animal, the virus infects the motor neurons under the skin. This travels up the central nervous system to the brain, where it wreaks havoc.

So yeah, this is why people who work with animals are so serious about their shots, this is a terrifying disease. And it’s easy to prevent, so just do it.

PRION DISEASE

And last but probably worst are prion diseases. And yes, that’s multiple diseases.

Prions, simply put, are proteins that fold incorrectly, and then those messed up proteins reproduce themselves over and over until the cell ceases to function. When this happens in brain cells, it can cause a cascade of damage, to horrible effect.

And, in keeping with the theme of this video, you can have the disease for up to a decade before you have any idea this is churning away inside you. And once symptoms start to show, it’s too late to do anything.

Some of the various prion diseases include Creutzfeldt-Jakob disease (CJD) fatal familial insomnia, Gerstmann-Straussler-Scheinker Syndrome and Kuru.

And prion diseases are transmissible, you can get it by eating animals that have the disease or sharing food with someone that has the disease.

In fact, I talked about Kuru in my Mysteries of the Human Body series on Nebula, it’s a disease that was brought about by cannibalism in a tribe in Papua New Guinea. They would eat the bodies of loved ones as part of their funeral rites, and this brain-eating disease they called Kuru kept spreading around that way.

In cows, it’s called Mad Cow disease and in deer, it’s often called chronic wasting disease.

Research is ongoing into prion diseases but at the moment there’s no cure or even treatment to slow down the progression of the disease. Just drugs to ease the symptoms.

Some of that research includes the possibility that prions could play a role in Alzheimers and Parkinsons, and even Chronic Traumatic Encephalopathy.

So… This has been a lot.

We talked a lot about some pretty scary stuff. But scientists and researchers are working on new ways to catch some of these diseases and conditions during their early stages.

Like colorectal cancer. In July 2024, the FDA approved a blood test to detect it in people 45 years and older.

It works by screening for DNA that tumors release in the bloodstream. That said, it’s limited in its detection of early-stage colorectal cancer. And it’s not considered a replacement for the tried-and-true colonoscopy.

Researchers in the U.S. recently developed a test that can identify 18 early-stage cancers. The test works by analyzing a person’s blood proteins in plasma samples.

They discovered that a limited set of proteins could differentiate normal samples from cancer samples. They could even identify different cancer types with high accuracy.

The researchers say that the study can help create a multi-screening test in the future.

When it comes to Alzheimer’s, researchers at the Alzheimer’s Association International Conference in July offered results on several new blood tests for detecting the disease.

It was found that the Precivity AD2 blood test that measures tau and amyloid-beta ratios detected Alzheimer’s better than doctors. It had a 90 percent accuracy rate.

Another blood test that focused on tau showed that it could identify patients likely to have early Alzheimer’s even though they weren’t showing any symptoms.

And for those who have early Alzheimer’s, the FDA approved this year a drug called donanemab that has been shown to slow down the disease.

There’s also artificial intelligence that’s being used to detect diseases earlier.

In a study published in Nature Medicine in June, researchers showed they could train a machine-learning model to identify circulating tumor DNA from blood tests.

They showed success with the technology in people with breast and lung cancer, melanoma, and precancerous colorectal polyps.

The researchers used AI to figure out subtle patterns in sequencing data to distinguish patterns that could be cancer from those patterns that were sequencing errors or noise.

AI is also being used with thermal imaging to help predict a person’s health.

Researchers at Peking University in Beijing, China, are using AI to study the relationship between chronic illnesses and facial temperatures.
In a study of more than 2,800 participants, the researchers found that people with warmer cheeks had higher blood pressure.

I think by now we all know you should have your blood pressure checked.

So… time to panic? Not necessarily. Obviously if you have a family history of any of these things, I’d invite you to do some deeper research and if you’re experiencing some early symptoms, you might want to see a doctor. Otherwise, you’ll probably be fine.

Or I should say, you can focus on the other many things that can go wrong in your body.

ADon’t worry, there’s plenty more to stress out about.

Actually if there’s anything I’ve learned researching this, it’s that if you just keep your gums healthy and your blood pressure down, you can avoid a ton of problems. So focus on the little things you can do.

I, for example, have been trying to keep my blood pressure under control by eating fewer meats so I recently switched to the vegetarian options over at Factor.

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