The ketogenic diet in Alzheimer’s disease: how ketones affect the brain

Alzheimer how ketones affect the brain
Alzheimer how ketones affect the brain

Can the Keto Diet Help With Alzheimer’s Disease? Everything about the advantages and disadvantages of a ketogenic diet for Alzheimer’s.

And what role the ketones play in it, as well as the benefits of the keto diet.

Around 5 million people currently live with dementia in USA. Most of them are affected by Alzheimer’s disease.

As a result of demographic changes, there are far more new cases than deaths among those who are already sick. For this reason, the number of people with dementia is increasing continuously.

Currently, the standard treatment for Alzheimer’s dementia aims to address symptoms and behavioral problems. Unfortunately there is no cure (yet).

However, recent research on ketones and the keto diet suggests that a ketogenic diet could have beneficial effects on the disease.

While the science of keto and Alzheimer’s is relatively new, there is already a lot to discuss.

Read on to learn more about the pros and cons of Alzheimer’s disease, whether the ketogenic diet could prevent or reverse the disease, and for a careful, evidence-based analysis of the risks and benefits of the keto diet.

What is Alzheimer’s?

The Alzheimer’s disease , on the German psychiatrist Alois Alzheimer first reported in 1907, is a form of progressive dementia.

Researchers estimate that over 25 million people worldwide have Alzheimer’s disease. It is the cause of the majority of dementia cases.

Women are more likely to develop Alzheimer’s than men, and they are more likely to develop Alzheimer’s earlier in life.

Doctors typically divide the disease into early, middle, and late stages.

Early Alzheimer’s disease is difficult to spot and can mimic the normal effects of aging on memory . The cognitive decline usually starts gradually and gets worse over time.

Most patients are only diagnosed when learning disabilities and memory loss interfere with their daily life.

Symptoms include:

  • Episodes of forgetfulness
  • Forgot the names of friends
  • Confusion in unfamiliar situations
  • Difficulty remembering recently learned information
  • Repeating conversations
  • Confusion deepens over time
  • Broken sleep
  • Inability to understand where you are
  • Problems speaking
  • Emotional and “acting out” symptoms such as depression, fear, verbal abuse or paranoia

Over time, challenges such as the inability to recognize people, wandering around, and aggression lead to increased need for care.

Eventually, the progression of Alzheimer’s disease leads to a complete loss of patient independence. In the advanced stages, they can be totally dependent on caregivers for basic needs such as eating and using the toilet.

Life expectancy is three to nine years from the time of diagnosis.

Most of the time, complications of the disease such as dehydration, muscle wasting, or infection lead to death.

What Causes Alzheimer’s Disease?

The causes of Alzheimer’s disease are complex, and not all researchers agree on them.

In fact, it is a little misleading to even speak of a “cause” of Alzheimer’s disease.

Here’s a more scientific way to consider why and how the disease manifests itself:

  • Risk factors: characteristics that increase a person’s risk of developing Alzheimer’s disease.
  • Etiology: a triggering event or process that triggers the disease.
  • Pathophysiology or pathogenesis: the disease process itself, or the exact way in which the disease affects the individual.

Unsurprisingly, research in all of these areas is critical to understanding, preventing, and treating Alzheimer’s disease.

For example, if you become familiar with risk factors , you can better understand your risk. This is useful for risk reduction, early detection and making important decisions in advance.

Studying the etiology of Alzheimer’s disease, which is relatively the least understood aspect, could lead to more effective prevention strategies.

And the better scientists and doctors understand the pathophysiology of Alzheimer’s disease, the greater the hope for improved treatments that will slow or reverse the course of the disease.

Read on to learn more about Alzheimer’s disease risk factors, as well as leading theories about how it develops and how it progresses.

Risk Factors for Alzheimer’s Disease

According to scientific knowledge, these are the most important risk factors for Alzheimer’s disease:

  • The age
  • Carrier of one or two copies of the APOE4 gene
  • Family History
  • Traumatic brain injuries (TBI), also called concussions
  • Insulin Resistance
  • High blood pressure
  • Chronic Inflammation
  • Overweight or Obesity
  • Smoking

While age is the most predictive risk factor, it isn’t very helpful on a personal level. After all, everyone gets older.

The only genetic marker with the highest predictive value for Alzheimer’s disease is at least one copy of the APOE4 gene mutation , which can increase your risk by two to three times. On the other hand, the APOE2 gene mutation can protect against Alzheimer’s.

It is known that having a close relative with Alzheimer’s disease increases one’s risk of Alzheimer’s disease by up to 73%.

Other factors, such as concussions, insulin resistance, and high blood pressure, can have a significant impact on risk. For example, mid-life high blood pressure can increase your risk of Alzheimer’s disease by 60-95%.

A 2017 study published in the journal Alzheimer’s Research & Therapy concluded that up to a third of Alzheimer’s cases could be preventable if people take steps to avoid modifiable risk factors.

And, as you’ll learn in the next section, risk factors like inflammation, high blood pressure, and obesity are also related to leading theories about how Alzheimer’s disease begins and progresses.

Leading theories on Alzheimer’s disease

Family history and risk genes do not explain nearly 100% of Alzheimer’s cases.

So something needs to be done that will result in some people getting the disease while others being spared Alzheimer’s.

Previously, the leading theory of Alzheimer’s disease was the beta-amyloid plaque theory .

Researchers had observed for decades that the brain changes during Alzheimer’s disease. During autopsies, they found chaotic “tangles” caused by a type of plaque called beta-amyloid in the brains of deceased patients.

Since these changes were apparently related to the progression of the disease, it seemed like a safe bet that targeted plaque buildup could treat or even reverse Alzheimer’s disease.

Drug manufacturers then developed drugs to reduce the build-up of beta-amyloid plaque. Unfortunately, none of these drugs have given results in clinical trials.

The disappointing results suggest that while beta-amyloid formation in Alzheimer’s disease is definitely an issue, it is most likely a defense mechanism of the body or a side effect of the disease rather than the main cause.

New and improved theories on Alzheimer’s disease

  • The vascular hypothesis , which is based on the knowledge that blood flow to the brain was reduced in Alzheimer’s patients.
  • The glucose metabolism hypothesis , based on the observation of MRI and PET scans, that less sugar reaches the brain cells of Alzheimer’s patients and that the cells have difficulty using it as an energy source.
  • Mitochondrial dysfunction , which suggests that damaged mitochondria (the “powerhouses of cells”) in Alzheimer’s patients are not delivering energy to brain cells.
  • The radical oxidative species (ROS) damage hypothesis, which theorizes that poorly functioning cells negatively affect the brain by producing harmful free radicals.

The chances are pretty high that several of these theories are correct. In fact, they could all be correct.

Essentially, decreased blood flow to a person’s brain can lead to cell damage that prevents glucose metabolism.

This could lead to mitochondrial damage and further damage to brain cells, creating huge amounts of free radicals that get out of control and lead to Alzheimer’s disease.

And contrary to the beta-amyloid plaque theory, the more recent theories correlate with known risk factors for Alzheimer’s disease.

For example:

  • Traumatic brain injuries and concussions impede blood flow to the brain and create free radicals.
  • Obesity, high blood pressure, and smoking damage the delicate lining of the blood vessels.
  • Insulin resistance, inflammation, and obesity all lead to mitochondrial dysfunction and excessive free radical production.

This is where things get really interesting.

The ketogenic diet can directly impact blood flow, glucose metabolism, and mitochondrial dysfunction, as well as related risk factors such as high blood pressure, inflammation, and obesity.

In the next section, you will learn the currently known facts about ketosis and brain health .

What does ketosis do to the brain?

Ketosis refers to the natural production of ketone bodies in the liver. Ketone bodies, or ketones for short, are energy-rich molecules that your body produces in the absence of carbohydrates.

When you’re making ketones, it means your body is running on fat for fuel instead of relying on carbohydrates and sugars.

In order to achieve and maintain the state of ketosis, you must not consume more than 30-50 grams of carbohydrates per day .

When it comes to the brain, there are two key things to understand about ketosis and the keto diet:

  • Ketones have measurable effects on your brain.
  • The lack of carbohydrates also has effects on brain tissue and brain function.

In other words, certain effects of ketosis on the brain are due to the presence of ketones, while others are due to the lack of carbohydrates in your diet.

You can also achieve some of the effects of ketosis through the use of supplements like medium chain triglyceride oil (MCT oil) without minimizing carbohydrates.

What you need to know about ketones and the brain:

  • Brain’s most efficient fuel and are more easily absorbed than glucose (simple sugars).
  • It have anti-inflammatory and antioxidant effects in the brain, meaning they can prevent or limit cell damage.
  • Ketones in your brain cause epigenetic changes, including DNA methylation and gene expression.

And this is what happens to your brain when you drastically reduce your intake of carbohydrates:

  • Less free radicals are produced from glucose, which means less cell damage.
  • Your body, including your brain, becomes more sensitive to the effects of the hormone insulin.
  • Similar to fasting , autophagy and mitophagy occur – meaning your brain can eliminate or “recycle” damaged tissue, cells, and mitochondria.

Remember, the facts above are what we know from current peer-reviewed research. These findings are general and not specific to people with Alzheimer’s disease.

By now, you may be wondering what the effects of a keto diet on Alzheimer’s disease. Read on to find out!

Can a Keto Diet Prevent Alzheimer’s Disease?

Let’s start with one essential fact: There is no research yet that definitely proves that keto can prevent Alzheimer’s.

However, there are many promising findings. In this section you will learn how keto can lower your risk of Alzheimer’s disease by improving modifiable risk factors.

Keto and Modifiable Risk Factors

As discussed in an earlier section, up to a third of all Alzheimer’s cases can be prevented by deliberately altering risk factors (as opposed to aging, genes, or family history, which cannot be changed).

First, let’s look at the known modifiable risk factors:

  • Traumatic Brain Injury (TBI)
  • Insulin resistance
  • High blood pressure
  • Chronic inflammation
  • Overweight or obesity
  • Smoke

Now is the time to take a look at how keto interacts with each of these risk factors.

Traumatic Brain Injury (TBI)

While no one chooses to get traumatic brain injury or concussions, there is substantial evidence that keto reduces the harmful effects of traumatic brain injury in animals and possibly humans.

These effects certainly apply after TBI, but if you are already in ketosis before you suffer a head injury, the benefits of ketosis for TBI are even more pronounced.

In other words, traumatic brain injuries increase your risk of Alzheimer’s, but keto appears to decrease the damage caused by TBI.

Insulin resistance

Next up: insulin resistance.

Some researchers have started to refer to Alzheimer’s as “type 3 diabetes” because severe insulin resistance increases the risk of the disease by up to four times .

The pathogenesis of Alzheimer’s dementia also has a lot in common with diabetes . Both diabetes and Alzheimer’s disease result in glucose hypometabolism, mitochondrial dysfunction, and free radical damage.

Insulin resistance is mainly caused by excessive carbohydrate intake. So it’s hardly surprising that a low-carb keto diet is a fantastic way to improve insulin sensitivity, including in the brain.

Numerous studies show that on a keto diet you can get better results on blood tests such as fasting insulin, fasting blood sugar, and glycated hemoglobin.

In other words, insulin resistance increases your risk of Alzheimer’s, but keto can improve insulin sensitivity.

For even better results, you should combine keto with regular exercise .

High blood pressure

So far so good! What about the blood pressure?

According to a systematic review from the British Journal of Nutrition , keto can lead to significant reductions in blood pressure.

And not only that, the effects go beyond what can be explained by sodium restriction and weight loss .

In other words, the ketogenic diet may have a unique ability to lower blood pressure not found on other diets. This is excellent news when it comes to reducing your risk of dementia and Alzheimer’s disease.

Chronic inflammation

Chronic inflammation in the body can increase your risk of Alzheimer’s disease and dementia.

For example, high blood sugar is a known cause of chronic inflammation and also correlates with the risk of Alzheimer’s disease.

A ketogenic diet improves your mitochondrial health and reduces oxidative stress . It also increases your body’s natural ability to suppress inflammation.

Overweight or obesity

The fact that keto is fantastic for losing weight is hardly a secret.

But unlike other diets, the ketogenic diet allows you to lose weight with minimal hunger and lots of energy.

Not only that, most people don’t even have to count calories to lose weight with keto.

All you have to do is calculate your keto macronutrients, compile a keto food list and shopping list, and follow them consistently.

It is also a good idea to measure your ketone levels to make sure that you are actually in ketosis.


Quitting smoking can lower your risk of Alzheimer’s disease by up to 58%.

But how is smoking related to the ketogenic diet?

Believe it or not, a 2010 study published in the journal Trials concluded that obese adults on the keto diet might even find it easier to quit smoking.

A win-win situation!

Can Keto Reverse Alzheimer’s Disease?

The short answer: Nobody knows yet whether keto can reverse Alzheimer’s disease.

There are no randomized controlled trials of the diets of Alzheimer’s patients, so there simply isn’t enough data to confirm one thing or the other.

However, some doctors are currently using the ketogenic diet to treat Alzheimer’s disease.

There is also promising evidence of improved cognition from studies of patients with mild cognitive impairment (MCI) who were given ketogenic supplements such as MCT oil and exogenous ketone bodies.

And according to the authors of a 2019 study from the prestigious journal Nutrition:

“… the ketogenic diet could be an effective treatment and prevention of Alzheimer’s disease, but this could require both ketone production and carbohydrate restriction”.

Next, we’ll look in depth at how ketosis interacts with known mechanisms that contribute to the progression of Alzheimer’s disease.

Ketosis and Alzheimer’s Pathogenesis

As mentioned earlier, here are the four main pathways that appear to contribute to the progression of Alzheimer’s disease:

  1. Vascular dysfunction and blood-brain barrier problems
  2. Glucose hypometabolism (insufficient glucose)
  3. Mitochondrial dysfunction, which leads to decreased energy production in the brain
  4. Free radical damage which, when combined with the other three mechanisms, creates a vicious circle

So can the ketogenic diet help address these mechanisms of disease progression?

Here are the latest insights.

Recent research has shown that following a ketogenic diet can increase cerebral blood flow and help repair the vascular damage that occurs in Alzheimer’s patients.

There is also evidence that the keto diet balances glucose hypometabolism by adding ketones as an alternative fuel source.

And a study of 23 adults with mild cognitive impairment, which may be a precursor to Alzheimer’s disease, found that ketones improved memory and cognitive function in participants.

Finally, ketones and ketosis also work to improve mitochondrial function by adding more energy to the brain. As a result, they also reduce inflammation and free radical damage.

In conclusion, the keto diet appears to address the four known pathways that contribute to the progression of Alzheimer’s disease.

To what extent it can stop or even reverse the progression of the disease remains to be explored..

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