Your liver is part of your digestive system, so you may only think of it in terms of its role in digestion. In reality, your whole body depends on your liver. If your liver isn’t working properly, eventually other organs will struggle, too, and that includes your brain.
Many liver problems can lead to liver damage that’s severe enough to also affect the function of other organs. If you have metabolic dysfunction-associated steatotic liver disease (MASLD) or metabolic dysfunction-associated steatohepatitis (MASH), also referred to as non-alcoholic fatty liver disease, it’s important to understand how these conditions can cause problems for your brain if they’re not treated and well controlled.
Let’s take a look at what your liver does and why its function is critical to your brain health.
What Does Your Liver Do?
Your liver is your largest internal organ. By comparison, your skin is your largest organ. A liver can weigh up to 3.5 pounds and be about the size of a football.
This roughly football-shaped organ has a lot of important responsibilities.
Your liver:
- Filters toxic substances out of your blood, including those that the body makes and those that you might take in from alcohol or medications
- Helps manage blood clotting
- Makes a digestive fluid called bile, which helps digest fat and regulate gut bacteria
- Turns extra sugar (glucose) into glycogen, a form of sugar that can be stored until it’s needed for energy later
- Makes protein for blood plasma, which is needed to transport hormones and nutrients throughout your body in addition to other critical functions
- Helps with digestion
When it’s severe enough, liver damage for any reason, including MASLD and MASH, can lead to problems with brain performance, such as a difficulty remembering things or thinking clearly.
How Does Your Liver Affect Your Brain?
All the ways in which the liver impacts brain health may not be fully known. But a few of the liver’s main functions are definitely critical to the smooth operation of the brain.
What happens when your liver stops filtering toxins?
First, your liver serves as a filter for any toxic substances that may be in your bloodstream. Some normal body functions make toxins as a natural byproduct. You may also take in substances, like medicine or alcohol, that contain toxins. The liver gets rid of those for you.
If you’ve ever been drunk, you’ve seen firsthand what happens to your brain when the liver can’t filter toxins out of the bloodstream. Alcohol intoxication happens when you drink faster than the liver can filter. As a result, you may feel confused, forgetful, and clumsy, and your mood and behavior may change. But that goes away once the alcohol has gotten out of your system.
If liver damage advances so far that the liver can no longer filter out toxins whether you’re drinking or not, those toxins can build up in your bloodstream and harm your nervous system. Your nervous system includes your brain. This causes a condition called hepatic encephalopathy.
Hepatic encephalopathy can start with some of these cognitive (thinking) problems:
- Confusion
- Forgetfulness
- Personality or mood changes
- Loss of concentration
- Bad judgment
- Loss of small hand movements, such as writing
They’re not so different from some of the things you might feel when you’re drunk. But hepatic encephalopathy can continue on to worse symptoms and eventually unconsciousness or even coma.
What’s your gut got to do with it?
The liver makes a digestive fluid called bile that helps digest fat and also plays a key role in controlling gut bacteria.
You may already know that the overall composition of the bacteria in your gut (also known as the gut microbiome) has a variety of effects on your overall health. There are good bacteria and bad bacteria. They can help you or hurt you in many ways. Ideally, you want your gut microbiome to be very diverse, and you want the good stuff to outnumber the bad.
When your liver can’t produce bile, your gut bacteria can get thrown off-balance. Your microbiome can start to have too much of the bad bacteria and not enough of the good. Research has found that the liver and the gut, by way of gut bacteria, seem to be in conversation with each other. They call this “crosstalk.” Good bacteria can send signals that result in positive effects on your health, while bad bacteria can get the word out to make bad things happen.
As liver damage progresses, your gut microbiome can continue to change for the worse. At the same time, as your microbiome worsens, it can worsen your liver disease. But it’s not just your gut and liver that talk to each other. Gut bacteria send signals to your brain, too. So a gut imbalance related to liver disease can also lead to hepatic encephalopathy, causing memory loss, confusion, and mood changes.
Researchers call this connection between the gut, the liver, and the brain the “brain-gut-liver axis.” Your liver seems to play the middleman between the other two. Your liver gets messages from gut bacteria that help it carry out its functions and keep the rest of your body, including your brain, healthy. But problems with the brain-gut-liver axis, which occur in MASLD and MASH, can cause the gut to leak harmful substances into the body, which may cause all-over inflammation and harm your brain and mess with your thinking skills.
How does blood plasma help your brain?
Besides its role in regulating gut bacteria, bile acid also has roles in your brain. Research shows it plays a part in mood regulation. It also seems to have a relationship with cognitive function, neurodegenerative diseases, and, that’s right, hepatic encephalopathy. The exact relationship between bile acids and brain health, especially dementia and aging, is a growing area of scientific research.
Not only does your liver produce bile, but it also helps it get to your brain.
Your liver makes blood plasma proteins, which transport hormones, nutrients, and bile throughout your body, including to your brain.
Your brain needs a constant supply of nutrients in order to run properly. If your liver is unable to make blood plasma proteins, your brain will be starved of the nutrients that it needs to function.
How does blood sugar affect your brain?
Your liver also helps control your blood sugar. Sugar, called glucose when it’s in your bloodstream, is your body’s main source of energy. You get it from foods and drinks that have carbohydrates. This includes fruit, starchy foods (like bread, pasta, rice, and potatoes), and sugar-sweetened foods.
When there’s glucose in your bloodstream that your body doesn’t need for energy right away, your liver turns it into glycogen and stores it for later.
If your liver is damaged to the point that it can no longer do this job, sugar levels in your bloodstream rise. When you’ve got too much sugar in your blood on an ongoing basis, it can lead to type 2 diabetes. Conditions like insulin resistance, high blood pressure, and obesity (which are common in these MASH and MASLD) can further harm your brain function and cognitive skills.
Diabetes causes vascular disease – that’s diseases related to blood flow – in your heart, legs, and brain. People who have diabetes tend to be more likely than those without diabetes to develop cognitive problems. Those problems include memory loss and trouble paying attention or organizing your thoughts to complete a multistep task. Diabetes also seems to come with a higher risk for both Alzheimer’s dementia and vascular dementia.
How Does Liver Disease Affect Your Brain?
Since liver health is crucial for brain health, it makes sense that liver diseases, such as MASLD and MASH, can have serious effects on your brain. These diseases can lead to liver damage that can eventually mess with the organ’s functions that your brain depends on.
Also, the metabolic problems that lead to MASLD and MASH come with their own risks for your brain:
Insulin resistance and diabetes. Insulin is a hormone that your cells need to turn sugar into energy. When your cells resist insulin, they can’t turn sugar into energy, and it builds up in your bloodstream, causing high blood sugar and diabetes.
High blood pressure. Hypertension, or high blood pressure, is a known risk factor for cerebrovascular disease. This is a disease that affects blood flow to and in your brain. A growing body of research shows that high blood pressure can speed up cognitive impairment, vascular dementia, and Alzheimer’s disease.
Obesity. Fat cells in your body can send inflammatory signals to your brain, which can cause brain inflammation and harm thinking skills. Obesity also tends to come with a state of all-over-body inflammation that is also known to worsen cognitive problems.
Brain Changes in Liver Disease
Research has found many ways that MASLD and MASH make their mark on the brain.
In a large study of brain MRIs, people with MASLD or MASH had smaller brains than people without these conditions. Loss of volume in the brain is a natural part of the aging process, but this study found that liver disease seemed to speed up the shrinking.
MRI studies have also shown that people with MASLD and MASH have less blood flow in their brain than people without these conditions. Less blood flow to your brain can harm your thinking skills and raise your risk for stroke.
People who have these liver diseases may also have more white matter lesions on their brains. These are seen as a sign of small blood vessel disease in the brain and they raise risk for stroke, loss of memory and thinking skills, depression, disability, and death.
These signs could explain why studies show that people at high risk for liver damage are more likely to have problems with executive function (skills you use for managing everyday tasks), abstract reason (your ability to think about ideas and concepts), and overall thinking skills.
How Can I Protect My Brain With MASLD/MASH?
The link between liver disease and cognitive decline is clear. But just because you have MASLD or MASH doesn’t mean you will lose your memory and thinking skills.
The cognitive effects tend to come when the disease is advanced and your liver is damaged. You can take steps to slow or stop the progress of your disease and, in some cases, reverse it.
Get diabetes, blood pressure, and cholesterol under control
These conditions lead to MASLD/MASH. If you have any of them, follow all your doctor’s instructions to treat them. Take all of your medications as your doctor tells you to, try to make the recommended lifestyle changes, and stay on top of follow-up appointments.
Work on weight loss with your doctor
A healthy weight is important to a healthy liver and, in turn, a healthy brain. For some people, weight loss can reverse liver disease. Ask your doctor what might be the most effective weight loss strategy for you. Besides the standard recommendations for diet and exercise, your doctor can prescribe weight loss medications and, in some cases, refer you for weight loss surgery.
Make exercise a habit
Besides the fact that it can help with weight loss, regular physical activity is very important for liver health. Even if you are taking weight loss medications that are helping you lose weight, your liver needs you to move your body in order for it to function.
Drink black coffee
Black caffeinated coffee may slow the progress of ongoing liver damage. In fact, the more the better. If you like black coffee, go for three cups a day.
Get up-to-date on vaccines
If you’re due for any vaccines, schedule them right away. First and foremost, make sure you’re vaccinated against hepatitis A and B. These viruses can speed up liver failure in people who have MASLD/MASH. But those aren’t the only vaccines that are important for people with chronic liver disease. Ask your doctor which ones you need.
Avoid substances that harm your liver
Alcohol can make nonalcoholic fatty liver disease worse. Fructose, a type of sugar, can make it worse, too. The fructose that’s naturally in fruit is fine. But the high-fructose corn syrup that’s in sweets and sugar-sweetened drinks is not, so try to steer clear. Finally, don’t try any “liver detox” supplements. You might think those would help you, but when you have MASLD/MASH, you don’t want to challenge your liver to process these untested substances that could hurt you.
Recap
- Your liver plays an important role in keeping you healthy by filtering toxins from your blood, making bile for digestion, and storing energy in the form of glycogen.
- Damage to your liver can affect important functions in your body like memory and your ability to think clearly
- When your liver is damaged, toxins can build up. This can lead to conditions like hepatic encephalopathy, which causes confusion, memory loss, and mood changes.
- MASLD and MASH can be linked to problems like high blood pressure, high blood sugar, and obesity. These issues can shrink your brain, reduce blood flow, and damage brain tissue. This can lead to a higher risk of memory loss, stroke, and thinking problems.
- If you have MASLD or MASH, you can protect your brain by keeping your liver healthy. Focus on managing diabetes, blood pressure, and cholesterol.
- Losing excess weight, exercising regularly, and drinking black coffee can also support your liver. Avoid alcohol, sugary drinks, and certain supplements. Make sure you're up to date on vaccines as well.
Show Sources
Photo Credit: iStock/Getty Images
SOURCES:
American Liver Foundation: “Liver functionality.”
National Library of Medicine: “Loss of brain function - liver disease.”
Alzheimer’s Discovery Foundation: “How does the liver affect brain health?”
Medical Science Monitor: “From Liver to Brain: How MAFLD/MASLD Impacts Cognitive Function.”
Nature Reviews Microbiology: “The gut-liver axis in gut microbiota in health and liver disease.”
Biomedicines: “The Gut Microbiota: How Does It Influence the Development and Progression of Liver Disease.”
VCU School of Medicine: “Stravitz-Sanyal Institute for Liver Disease and Metabolic Health.”
Harvard Medical School: “What's the connection between the gut and brain health?”
International Journal of Molecular Sciences: “Metabolic Crosstalk between Liver and Brain: From Diseases to Mechanisms.”
Cleveland Clinic: “Plasma,” “Glycogen,” “Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD).”
National Institutes of Health: “Can Diabetes Lead to Cognitive Impairment?”
National Library of Medicine: “White Matter Lesions.”
British Liver Trust: “Physical activity and exercise.”
Mayo Clinic: “Lifestyle do’s and don’ts when managing MASLD, MASH and liver health.”
