Chemo Brain: Understanding Brain Fog and How to Treat It
If you’ve felt forgetful or out of sorts since beginning breast cancer treatment, you’re not alone. Most people in treatment for cancer report problems with their focus, memory, and ability to make decisions — a batch of symptoms commonly called chemo brain, called cancer-related cognitive impairment by doctors.
What is chemo brain?
Chemo brain isn’t just a side effect of chemotherapy. You may experience it when you receive a cancer diagnosis, following surgery, or during or after radiation, immunotherapy, or hormonal therapy. Symptoms can include:
difficulty remembering dates or names
taking longer than usual to finish tasks
having problems concentrating
having a hard time grasping new ideas
difficulty finding the right words to say
If you’re troubled by symptoms of chemo brain, Timothy Ahles, PhD, a behavioral psychologist and director of the Neurocognitive Research Lab at Memorial Sloan Kettering Cancer Center in New York, N.Y., recommends that you tell others what’s happening and where you could use some help.
Studies suggest that up to 75% of people with breast cancer experience some type of cancer-related cognitive impairment during chemotherapy.
“For the majority of breast cancer survivors, these issues don’t last long, gradually improve, and there are no long-term or permanent effects,” said Dr. Ahles.
He should know: For the past three decades, his research has focused on understanding cancer-related cognitive problems and finding new ways to help people manage their symptoms and reduce stress associated with having cancer.
“There is also a lot we have learned about chemo brain and there are strategies that can help people manage the effects.”
What causes chemo brain?
Research suggests there are a number of factors that may contribute to chemo brain.
A cancer diagnosis makes many people feel fearful, stressed and anxious. All of these emotions can make it hard to focus and think clearly.
Some people develop depression during diagnosis and treatment. These lasting feelings of sadness and hopelessness also can make you forgetful and make it difficult to concentrate.
Anemia, pain (and medicines used to treat pain), fatigue, sleep problems, and appetite changes, especially if you lose your appetite, also can affect your ability to think and remember.
Diabetes (as well as hyperglycemia) and high blood pressure can increase the risk of chemo brain and make any issues you’re having worse. Both high blood sugar levels and high blood pressure can damage blood vessels in the brain, reducing the flow of blood and oxygen.
Chronic inflammation from obesity or an autoimmune disorder, such as lupus or rheumatoid arthritis, also may affect your ability to think clearly by causing structural changes in the brain.
In addition, studies have shown that being physically weak or frail can contribute to chemo brain. Research also shows that people who are more active are less likely to have chemo brain.
According to the American Cancer Society, being older; being post-menopausal; and using alcohol, cannabis, or other substances that affect your brain all increase the risk of thinking and memory problems.
Treating chemo brain: Exercise helps
A number of studies, including many focusing on people receiving chemotherapy for breast cancer, have found that exercise can help reduce the risk of chemo brain and improve thinking and memory function.
A 2024 study of women starting chemotherapy for breast cancer found that those who also started an aerobic exercise program at the same time reported greater improvements in cognitive function and quality of life compared with those receiving standard care.
A 2021 study led by Michele Janelsins, PhD, MPH, of the University of Rochester, found that people with breast cancer who performed moderate to vigorous physical activity (for example, brisk walking) for 2.5 hours a week — about 20 minutes each day — before starting and during chemotherapy had better brain function immediately after chemo than people who didn’t exercise.
“Even if they stopped being as physically active during chemotherapy, this effect on their cognition remained,” said Janelsins.
“The bottom line is that the data so far suggests that being as physically active as possible can help maintain cognitive functioning throughout treatment,” Janelsins said.
Not everyone getting treatment for cancer will feel up to exercising. If you are, though, exercising before and during treatment can help alleviate chemo brain symptoms.
Michele Janelsins, PhD, MPH, is a researcher, professor, and division chief of supportive care in cancer in the Department of Surgery at the University of Rochester Medical School in Rochester, N.Y. Dr. Janelsins studies the effects of exercise on cancer-related cognitive impairment.
A 2021 study led by Dr. Janelsins revealed that people with breast cancer who performed moderate to vigorous physical activity (for example, brisk walking) for 2.5 hours a week before and during chemotherapy had better brain function immediately after chemo than people who did not do the same.
“Even if they stopped being as physically active during chemotherapy, this effect on their cognition remained,” says Dr. Janelsins. “We also observed that women who maintained physical activity guidelines [150 minutes of moderate to vigorous physical activity a week] during chemotherapy also had improved cognitive functioning post-chemotherapy.”
Another soon-to-be-published study led by Dr. Janelsins showed that, even if the exercise is less than what is considered moderate, if it was performed during chemotherapy, it helped people better maintain their attention.
“The bottom line is that the data so far suggests that being as physically active as possible can help maintain cognitive functioning throughout treatment,” Dr. Janelsins said.
Did you know that exercise can help with many breast cancer treatment side effects, including chemo brain, fatigue, and anxiety? Our video series, Exercises to Relieve Side Effects, is designed especially for people living with breast cancer — no matter your fitness or energy level.
More tips for coping with brain fog
Doctors haven’t found a medicine that directly addresses chemo brain, but there are a number of ways to manage it:
Keep the same daily routine, which can offer structure as well as peace of mind.
Minimize multitasking, if possible, which can lead to confusion and stress.
Sleep and take naps, if you can, which can help your brain to recover and recharge so it can function better.
Keep your mind active, by socializing with friends, participating in activities, volunteering, or doing puzzles or games.
Use a planner, notebook, or your phone to help you to organize tasks and responsibilities.
Listen to music, particularly instrumental music which may not cause as many mental distractions as music with vocals.
Meditate or do other mindfulness practices, such as breath work, guided imagery, journaling, yoga, and tai chi. These complementary therapies have been shown to help ease fatigue, anxiety, and stress, as well as improve sleep, all of which can help you concentrate and think more clearly.
Take medicines for other conditions, such as anxiety and depression, as prescribed.
Avoid alcohol, which can impair your judgment and interact with medications you are taking.
Eat a diet high in vegetables, lean protein, and fruit, and low in processed foods. Lower than average levels of certain vitamins, including vitamins D and B12 can contribute to chemo brain. If you’re unsure about how to make changes to your diet, you may want to ask your doctor for a referral to a registered dietitian who is a certified specialist in oncology nutrition.
Take regular breaks by separating tasks into smaller, manageable chunks, and schedule regular down time to rest and recharge. Short breaks can help you work efficiently and avoid burnout.
Pick a place to put items that get lost, like your keys or glasses. Return each item to its place after you use it.
Do your most difficult tasks when you have the most energy. For some people this may be first thing in the morning. For others, it may be after lunch or before dinner.
Keep track of any issues you’re having. Jot down in a notebook or on your phone the day and time when you notice problems and what else is going on at the time. Keeping track of medicines you’re taking and where you are when you have problems might offer clues as to what affects your memory. This also can help you figure out the best times for important tasks or appointments.
Don’t try to tough it out
For some people, the impact of chemo brain is frustrating, but manageable. But for others, it can be debilitating. If chemo brain is preventing you from the everyday things you enjoy, consider telling someone on your healthcare team. They may have more ideas to help you or connect you with additional support.
You may also want to talk with your family and friends about what’s happening and what they can do to help. Their support and understanding can help you relax and make it easier for you to focus and process information.
Read more about minimizing chemo side effects.
This content is made possible, in part, by AstraZeneca, Gilead, Lilly, and Pfizer.
— Last updated on April 29, 2025 at 9:37 PM