Cancer Brain Fog

Cancer doesn’t just affect your body—it settles into your mind. Even when it’s not at the forefront, it lingers in the background, quietly shaping your thoughts and feelings. Then, without warning, that invisible weight can pull you under. You might find yourself lost in a fog—struggling to focus, forgetting words, feeling scattered and unlike yourself. It’s not just frustrating; it’s deeply disorienting.

This feeling isn’t unique to just one or two people—it’s shared by many. Yet, those who experience what’s often called “brain fog” can feel isolated. The purpose of this message is to remind you: if you’re feeling something similar, you are not alone. Up to 75% of cancer patients and survivors, including those with non-central nervous system (non-CNS) cancers, suffer from “brain fog” or impairments in cognitive functions such as attention, memory, learning, and decision-making (Gu et al., 2024).

So, not only are there others who understand, but furthermore there’s also a reason behind it. It’s not because you’re weak or fragile. It’s because the experience of living with cancer—the toll of the treatments and medications—can lead to this. You made the courageous choice to face cancer head-on, and brain fog is one of the many side effects of that fight. So now the question becomes: what causes it—and how can we begin to lessen it?

One theory behind brain fog centers on its neurological origins. It’s been proposed that cancer treatments can directly disrupt the structure and function of neurons—the cells responsible for sending messages throughout the body and supporting essential brain processes (Pan, 2024). When these cells are compromised, even routine tasks that require focus or quick thinking become more difficult. You sit down to write an email, wash the dishes, or exercise—simple, everyday activities—but everything feels slower. That email that once took three minutes might now take ten. And over time, those added minutes begin to pile up, leaving you wondering where your day has gone.

This doesn’t mean you’re incapable of doing the things you once could. Rather, your body and mind have been altered as a consequence of confronting cancer. And it takes time to adjust to that change.

Unfortunately, this neurological impact isn’t limited to one type of cancer treatment. As Pan (2024) explains, nearly all forms of cancer therapy carry the potential to affect the central nervous system. Increasing use of emerging treatments like immunotherapy, while life-saving, are among those linked to cognitive impairments and immune-related complications in the brain.This leads to a host of symptoms, with brain fog among the most common.

You might be wondering: how can the very treatments that fight cancer also take such a toll on the mind and body? It’s a fair question—and one without a simple answer. The truth is, cancer is a formidable enemy, and defeating it requires a powerful arsenal. That means using aggressive, high-impact therapies designed to eliminate cancer—and keep it from coming back. But in doing so, they can also affect the very systems we rely on to think, feel, and function day to day.

So, what can we do now? You're already fighting cancer—and now, brain fog feels like a battle of its own. The hard truth is that, despite growing research into cancer therapy–related cognitive impairment, there are currently no FDA-approved treatments to prevent or reverse these neurological effects (Pan, 2024).

But here’s the good news: there are steps you can take to support your cognitive health and reclaim a sense of control.

According to the OHSU Cancer Institute, just as regular physical exercise strengthens your body, mental exercises and healthy habits can strengthen your brain. They recommend the following strategies:

• Cognitive therapy – Working with a therapist can help you retrain your brain. Treatment might last a few weeks or several months, depending on the severity and duration of your symptoms.

• Regular exercise – Harvard Health notes that engaging in consistent, moderate-intensity exercise for six months to a year has been linked to increased brain volume. Exercise also indirectly boosts cognition by improving mood, sleep, and reducing stress—all common contributors to brain fog.

• Improve sleep quality – Prioritizing good sleep hygiene can help your brain function more efficiently during the day.

• Reduce stress – Practices like mindfulness, yoga, and acupuncture can help calm your nervous system and improve mental clarity.

• Adopt a brain-healthy diet – A diet rich in whole, nutrient-dense foods, omega-3 fatty acids, antioxidants, and proper hydration has been shown to support cognitive function and reduce brain fog (Nava Center, n.d.).

• Use coping strategies – Simplify your daily life. Make lists, stick to routines, and build habits that reduce the mental load. Give your brain fewer things to juggle.

These steps may feel like yet another thing to manage—but they also represent small, meaningful ways to take back control of your life, and your mind. Visit the Resource page on HIS Breast Cancer Awareness website for additional support.

Sources

Pan Y, Hu J. Hormonal basis of brain fog in cancer treatment. J Exp Med. 2024 May 6;221(5):e20231942. doi: 10.1084/jem.20231942. Epub 2024 Apr 10. PMID: 38597926; PMCID: PMC11009970.

Gu, Q., Wang, L., King, T.Z. et al. Seeing through “brain fog”: neuroimaging assessment and imaging biomarkers for cancer-related cognitive impairments. Cancer Imaging 24, 158 (2024). https://doi.org/10.1186/s40644-024-00797-

Harvard Health Publishing. (2014, April 9). Exercise can boost your memory and thinking skills. Harvard Health. https://www.health.harvard.edu/mind-and-mood/exercise-can-boost-your-memory-and-thinking-skills

Nava Center. (n.d.). How your diet influences brain fog. Nava Health. https://navacenter.com/how-your-diet-influences-brain-fog/