Do you ever lose your train of thought, forget details, or feel mentally drained? You could be experiencing brain fog, a range of symptoms that affect your ability to focus and think clearly.

People with myasthenia gravis (MG) might feel caught off-guard by brain fog, mental fatigue, and other cognitive (thinking and reasoning) symptoms. MG is an autoimmune disease that causes muscle weakness. An autoimmune disease develops when the immune system mistakenly attacks the body’s cells. In MG, this affects communication between the nerves and muscles, which can sometimes lead to memory and thinking problems — especially during flare-ups.

What MGteam Members Say

MG affects everyone differently, but many people share similar experiences with cognitive symptoms. MGteam members compare their experiences with brain fog and mental fatigue:

• “I have short-term memory lags.”
• “Sometimes, I can’t remember what I was talking about.”
• “I feel that my memory is sometimes lacking. For example, I’ll forget a name and then remember 20 minutes later.”
• “My concentration and memory get better then worse, just like all my other symptoms of this disease.”
• “I find that mental or cognitive activity can be just as draining as physical activity. Is this normal?”

What the Research Says

Several studies have found connections between MG and brain fog, and scientists continue to explore the connection.

One study found that people with MG commonly experienced problems with language and memory but had normal brain activity in terms of problem-solving and paying attention. Study participants with MG were also more likely to have mood problems than people without MG.

Another study tested memory in people with MG and those without MG. About 60 percent of people with MG report having difficulty with memory. The study confirmed this, showing that those with MG had lower memory scores on recall tests compared to those without MG. Interestingly, the study found no relationship between MG severity and the extent of memory problems.

Research into the connection between MG and mental fatigue found that people with MG were more likely to have mental and physical fatigue compared to those without MG. This fatigue can contribute to depression and daytime sleepiness, especially in women, according to the journal Acta Neurologica Belgica. Mental fatigue in MG, even apart from muscle weakness, can significantly affect a person’s quality of life.

How Myasthenia Gravis Contributes to Brain Fog

There are several theories about how MG causes brain fog and mental fatigue.

One of the leading theories is that short-term memory loss and brain fog happen during MG flare-ups because of autoantibodies (immune proteins that attack healthy tissue) called acetylcholine receptor (AChR) antibodies. Around 85 percent of people with generalized MG and around 50 percent of people with ocular (affects the eyes) MG have these antibodies.

AChR antibodies block receptors for acetylcholine, a neurotransmitter (chemical messenger in the nervous system) that stimulates nerve cells in muscles so you can move or flex those muscles. Acetylcholine is also active in your brain and supports the brain cells responsible for learning, memory, and thinking. AChR antibodies may affect brain function by reducing acetylcholine activity in the brain.

How MG Symptoms Contribute to Brain Fog

Muscle weakness and fatigue, the main symptoms of MG, might also contribute to brain fog and mental fatigue. When your muscles get weaker, you use them less often. This may reflect in subtle changes in the areas of your brain that control them.

In a study, doctors used MRI scans to look at the brains of people with MG. Participants also took cognitive tests. The results showed that certain areas of the brain were smaller in those with MG than in those without MG. These brain changes were linked to lower scores on memory and learning tests.

More than half of people with MG have insomnia (trouble sleeping). Among other health benefits, good sleep supports your cognitive function. When you sleep well, you can solve problems, focus, and learn better. Sleep also helps strengthen your memory.

If your MG causes poor sleep, you may experience brain fog. One MGteam member said, “I quickly fall asleep for an hour or two but when I wake up I almost feel drugged. I have a foggy brain and little memory of the past several hours. I slowly come out of the brain fog and then just feel the normal fatigue for the rest of the day.”

Mental health conditions like depression and anxiety, both common causes of brain fog, affect many people with MG. They can worsen the brain fog that happens during MG flare-ups.

How MG Treatments Contribute to Brain Fog

Some MG treatments might contribute to brain fog and mental fatigue. Prednisone (sold as Rayos, Deltasone, and Prednisone Intensol) is a steroid commonly used to treat MG. It can dramatically improve MG symptoms by reducing immune system activity, but it can also cause side effects like insomnia, mood changes, and anxiety — factors that can contribute to brain fog. Sleep issues from prednisone, along with mood changes, may make it harder to concentrate and remember things.

If you’re experiencing these side effects, talk to your doctor about adjusting your treatment. Newer MG therapies may help reduce the need for steroids and lower the risk of brain fog related to medication.

“Prednisone always prevents me from getting a good night’s sleep. It’s so frustrating,” commented an MGteam member.

Another said, “I’m trying to adjust to my steroid being increased. I’m told to rest to recover and the meds keep me jittery and awake. I slept late after my alarm and never made it to church because I woke up sometime during the night and tossed and turned for a while. Accomplished little or nothing today.”

Talk to Your Doctor About Brain Fog

Talk to your doctor if you have MG and find yourself struggling with forgetfulness, trouble concentrating, or mental fatigue. While MG, its symptoms, and some treatments can cause or worsen brain fog, brain fog can come from unrelated causes or diseases similar to MG. Cognitive issues can stem from:

• Diabetes or low blood sugar
• Hormone changes
• Stress
• Not getting important nutrients
• COVID-19 or long COVID
• Cancer treatments
• Autoimmune conditions like lupus or fibromyalgia, which you might have alongside MG

Your healthcare provider can help you identify the cause of your cognitive symptoms. They can work with you to find ways to manage or improve brain fog so you can focus and think clearly, like getting better sleep or making a to-do list.

An MGteam member shared some helpful words of encouragement. “From everything I’ve read about MG, it sounds like difficulty concentrating and remembering things is one of the symptoms. I write everything down on a large block calendar so I don’t forget simple day-to-day tasks like doing the laundry, buying groceries, or going to the bank. It helps!”

Find Your Team

MGteam is the social network for people with myasthenia gravis and their loved ones. On MGteam, more than 2,800 members come together to ask questions, give advice, and share their stories with others who understand life with myasthenia gravis.

Have you had brain fog with myasthenia gravis? What strategies have you used to manage mental fatigue? Share your experience in the comments below, start a conversation by posting on your Activities page, or connect with like-minded members in Groups.