What is Post-Concussive Brain Fog?
Post-Concussive Brain Fog
Brain fog is a loosely defined term for trouble with thinking and mental effort. It can include poor concentration, trouble focusing and memory problems (1). When symptoms like these last longer than about three months after a concussion, they are considered part of post-concussion syndrome.
Brain fog is one of the most common problems people experience after a concussion. People often have trouble describing exactly what it feels like, but as soon as they hear the term “brain fog,” they know exactly what you mean. They describe trouble concentrating, trouble learning new information, memory problems, slow thinking and getting worn out by mental tasks.
Brain fog has many possible causes, including sleep problems, thyroid problems, medications and other medical conditions, so it’s important to have it evaluated by your physician. After any head injury, get emergency care right away for a headache that keeps getting worse, repeated vomiting, confusion, unusual drowsiness, slurred speech, weakness or numbness, or a seizure. If you are having thoughts of harming yourself, call or text 988 to reach the 988 Suicide & Crisis Lifeline, or call 911.
How Common Is Post-Concussive Brain Fog?
An estimated 1.8 to 3.8 million concussions happen each year in the U.S. Brain fog is one of the key symptoms used to diagnose a concussion, but many people continue to struggle with it long after their other symptoms have faded. Studies estimate that brain fog occurs in at least 11% and as many as 38% of concussions (2).
What Causes Post-Concussive Brain Fog?
Brain fog after a concussion can come from injury to several different areas of the brain. Much of our thinking happens in the frontal lobe. When the brain is jolted inside the skull, the frontal lobe can be affected, slowing down thinking.
The inner ear is a key part of your vestibular system, which tells your brain where your head is in space. The inner ear has two kinds of balance sensors: the otoliths, which sense head tilt relative to gravity and straight-line movement like up, down and side to side, and the semicircular canals, which sense head rotation. The otoliths rely on tiny calcium crystals called otoconia to work.
Brain fog can be linked to central vestibular dysfunction, meaning problems in the brain systems that process balance information (3). Dizziness and vertigo can come from problems in the inner ear itself, or from problems in the cerebellum, brainstem and brain systems that process balance information. These systems combine inner ear input with information from your eyes and from your muscles and joints to create a clear picture of where your body is and how it’s moving. When the signals from your eyes, inner ear and body don’t match, the brain may have to work much harder to figure out where you are in space. One way to think about it is that this extra effort may take resources away from the frontal lobe, contributing to mental fatigue and brain fog.
Certain test findings can point to a central vestibular problem, such as changing patterns of involuntary eye movements called nystagmus, trouble following a moving target with your eyes, or trouble keeping your eyes steady on a target (4). Central disorders are generally considered harder to treat than inner ear problems, and they are a major focus of our work.
Another important brainstem structure is the nucleus prepositus hypoglossi, which helps hold your eyes steady when you look at something (5). When this area isn’t working well, the eyes may drift and make small corrective movements that you may not notice. This constant small motion may blur vision slightly and make the brain work harder to keep the eyes still, which may add to mental fatigue and brain fog.
Blood flow to the brain also matters. Blood carries the oxygen and glucose your brain cells need to work well, and your autonomic nervous system has to reliably send blood up to the brain. This system can be affected after a traumatic brain injury, a condition called post-concussive dysautonomia. Your inner ear also helps your body adjust blood pressure when you change position (6). Lightheadedness, dizziness or fainting when you sit or stand up can be signs that your brain isn’t getting enough blood quickly enough (7). When your brain doesn’t have the blood flow it needs, thinking tasks can quickly lead to fatigue and brain fog.
What Are the Symptoms of Post-Concussive Brain Fog?
Some people develop brain fog right after a concussion, while for others it appears weeks or even months later. Symptoms often rise and fall depending on how much mental effort a task takes. Demanding activities like computer work, multitasking, following more than one conversation, or being in busy, stimulating environments often bring on brain fog.
Many people describe brain fog as feeling like they’re living in a cloud. It usually comes with slow thinking, trouble focusing, confusion, poor concentration, forgetfulness and hazy thoughts. Ongoing exhaustion often comes with it, and many people feel the need to sleep much more than usual. Some have even been diagnosed with chronic fatigue syndrome (7).
How Is Post-Concussive Brain Fog Diagnosed?
Brain fog is diagnosed based on your history and a neurological exam. Imaging may be used to rule out other causes of attention and focus problems, such as a tumor or a neurodegenerative disease.
How Does Post-Concussive Brain Fog Affect Your Life?
A concussion can affect every part of your life. When you can’t focus on work or school, it can feel like you’re losing your ability to engage with your own life. Simple tasks like reading can become exhausting and bring on brain fog. Following a conversation or doing basic mental tasks can wear you out. A trip to the grocery store can feel overwhelming. Driving or riding in a car can make symptoms worse and even trigger headaches, dizziness and panic. Screens and computer work can make every symptom worse. After a concussion, even the simplest tasks can feel impossible.
Depression, anxiety, post-traumatic stress disorder and emotional distress are common long-term effects of concussion, and rates of substance use problems are higher after a concussion (8).
Sleep problems (9) and chronic pain (10) are also common long-term effects. Job and school performance often suffer, leading to lost wages and higher rates of unemployment (11). Tragically, concussions also raise the risk of suicide (12), which is why getting support matters.
What Happens in the Brain With Post-Concussive Brain Fog?
Your brain is made up of several types of cells. The ones most people think of as “brain cells” are neurons, which carry the brain’s electrical signals. You have billions of them, constantly sending messages to each other. Your brain also has supporting cells called glia, which do everything from helping neurons communicate efficiently to clearing away waste.
Neurons have a cell body, branches called dendrites that receive signals from other neurons, and long, thin fibers called axons that send signals. Most cell bodies are in the brain’s outer layer, the cerebral cortex, also called gray matter. Much of the rest of the brain is white matter, made up of axons running between neurons. Axons can be very short or several inches long. Because they are long, thin extensions of a single cell, they are fragile and easily damaged by stretching and shearing.
When the brain is hit or twisted quickly, or both, axons can be damaged. Depending on the injury, this may affect one group of axons or cause widespread injury across many brain regions and pathways, called diffuse axonal injury. Neurons in these pathways may work less efficiently or be lost.
When brain cells are injured, immune cells in the brain called microglia become active and start an inflammatory response to help heal the damaged tissue. Sometimes this response is stronger than it should be, which may cause additional damage. Injured neurons may also have trouble getting the oxygen, nutrients and blood sugar they need, which can add to the injury (13).
As the brain heals, the remaining neurons have to take over for those that were damaged or lost. Depending on the extent of the injury, this may be easy or very hard. Unlike muscles, which get stronger when you push them to the point of failure, injured brain pathways can be set back when pushed too far past their limits. In post-concussion syndrome, pathways may tire quickly because they’re doing their own job and also covering for injured cells. That’s why knowing when to push and when to rest matters so much in concussion recovery.
Many of the neurons involved in post-concussive brain fog are part of the major systems your brain uses to figure out where you are in space: the vestibular system, the visual system and the body-position system. These systems come together in the brainstem, which can be injured in a concussion. An injury to any of these systems can create a sensory mismatch that may contribute to brain fog.
How Is Post-Concussive Brain Fog Usually Treated?
There is no widely accepted treatment specifically for brain fog. People with post-concussion symptoms are often treated with medications, such as vestibular suppressants, anti-nausea medications or medications for anxiety, and sometimes antidepressants. These can help reduce some symptoms.
Many people are also referred to physical therapists for vestibular rehabilitation. Many programs use habituation, which helps the brain gradually get used to movements and situations that trigger symptoms. This can be very helpful for many people.
How the NeuroRescue Program Can Help
Our care is designed to work alongside your physician and other providers, never in place of them. Please don’t change or stop any medication without talking with your prescriber.
One of the brain’s most important jobs is figuring out where you are in the world. It uses your inner ear to sense where your head is in relation to gravity and how it’s moving, your muscles and joints to sense where your body is and what it’s doing, and your eyes to sense where you are in relation to everything around you. Your brain combines all of this into a picture of where you are, so you can respond to the world around you.
A concussion is rarely just an injury to the eyes, the inner ear or the neck alone. It often affects how well these systems work together. That’s why we look at all of these systems together, and at how they work as a team.
Depending on your needs and test results, your program may include eye exercises to improve gaze stability (14) and the accuracy of your eye movements (15); exercises for reflexes involving your inner ear, neck or both (16); balance training under specific conditions and vision training that combines several types of input at once (17); care for the muscles and joints of your neck, including chiropractic adjustments when appropriate; electrical stimulation (18); and exercises in a virtual reality environment (19). Transcranial magnetic stimulation (TMS) has been studied for symptoms after brain injury (20). At our clinic, TMS is provided by our psychiatric mental health nurse practitioner, who will evaluate whether it may be appropriate for you. Your program may also include computerized cognitive training to support attention, memory and processing speed. A randomized trial in people with ongoing symptoms after mild traumatic brain injury found that a computerized, brain plasticity-based training program improved overall thinking skills more than ordinary computer games (21).
Studies of approaches that combine several of these therapies after brain injury have reported improvements in symptoms, in some cases lasting over time (22, 23, 24). The therapies we recommend are always chosen based on your testing and exam findings.
How the NeuroRescue Program Works
Your NeuroRescue Program begins with your Discovery Day. We start with a detailed history of your condition and your life on a timeline. This helps us understand the factors that may have contributed to where you are now, and identify related conditions that may be making it harder to move forward.
We measure how your visual, vestibular and balance systems are working through computerized analysis of your eye movements, inner ear reflexes and balance under different conditions. Our testing includes videonystagmography and saccadometry to measure several types of eye movements, the video head impulse test to measure how each semicircular canal is working, and CAPS computerized posturography to assess your balance under different sensory conditions. We also use NeuroSensoryMotor Integration testing to evaluate hand-eye coordination and cognition, and Virtualis testing to assess dynamic eye tracking and your perception of vertical in a virtual reality environment.
We combine this with a thorough physical and neurological exam of your sensory, motor, autonomic and cognitive systems. We also review any relevant lab work, imaging and prior testing, and integrate it with our findings.
Together, this helps us understand which parts of your nervous system are working well, which are struggling, and how quickly they tire. We use that information to design your personal NeuroRescue Program, aimed at improving function in the systems that need support and helping them work together. Our testing also helps us decide when to push and when to let you rest.
Our goal is to help lift the fog, so you can think more clearly, follow a conversation and get through your day without running out of steam.
Your Next Step
Living with brain fog after a concussion can be frustrating and isolating, especially when people can’t see what you’re going through. You don’t have to keep pushing through alone. To find out if the NeuroRescue Program is right for you, contact one of our patient care coordinators to schedule your Discovery Day.
It’s never too late to take the next step.
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