Most people associate cancer with physical symptoms; pain, hair loss, and fatigue that shadow every movement. But what often goes unspoken is a very different kind of struggle: one that happens inside the mind. It's called chemobrain, a term used by many cancer survivors to describe the mental cloudiness they experience during and long after chemotherapy.
To some, it feels like a form of forgetfulness. For others, it’s a slow, frustrating difficulty in focusing, processing, or multitasking. And though it’s not as visible as the physical scars of cancer treatment, its impact can be just as life-altering.
We spoke to Dr Rajeev Vijayakumar, HOD and Senior Consultant - Medical Oncologist, Hemato Oncologist and BMT Physician, Gleneagles BGS Hospital, Kengeri, Bengaluru, who explained chemobrain and how to deal with this cognitive fog during and after cancer treatment
What Is Chemobrain?
Chemobrain isn’t a medical diagnosis in itself, but rather a cluster of cognitive issues commonly reported by cancer patients. These include:
- Trouble concentrating
- Slower thinking or difficulty processing information
- Memory lapses (especially short-term memory)
- Difficulty multitasking or organising
- Mental fatigue that doesn’t go away with rest
While it's often linked to chemotherapy, research shows it can also occur due to radiation, immunotherapy, hormone treatments, or even the cancer itself. It’s more accurately termed cancer-related cognitive impairment, but the term chemobrain has stuck because it’s what many patients relate to.
Also Read: Game-Changing CAR-T Cancer Therapy Linked To ‘Brain Fog,’ Study Warns Of Cognitive Side Effects
What Causes It?
“The exact cause isn’t fully understood, but we believe it’s multifactorial. Chemotherapy can cross the blood-brain barrier, affecting brain cells directly. Inflammatory cytokines released during treatment also play a role, potentially triggering neuroinflammation. Add to this the emotional and physical toll of cancer, sleep disruption, anxiety, depression, and anaemia, and it becomes clear why the brain is affected. In some patients, hormone therapy or targeted therapy contributes to these symptoms,” explained Dr Vijayakumar. For example, women with breast cancer on long-term hormone blockade often report cognitive fog even years after treatment ends.
It's Not 'All in the Head'
What’s deeply frustrating for patients is when these symptoms are brushed off. Many are told, “You’re just stressed,” or “It’s normal to feel tired after treatment.” But those of us who work closely with survivors know that chemobrain is real.
“It can affect a person’s ability to return to work, manage daily routines, or even engage in social conversations. Some describe it as feeling like they’re operating a step behind everyone else as if their thoughts are stuck in slow motion. Acknowledging this isn’t about scaring patients, it’s about validating their experience and helping them find ways to cope and recover,” added Dr Vijayakumar.
Who Is Most at Risk?
Anyone undergoing cancer treatment may experience cognitive changes, but the risk appears to be higher in:
- Patients receiving high-dose or combination chemotherapy
- Older individuals
- Those with pre-existing mental health concerns
- Women with breast cancer (particularly those on hormone therapy)
- Individuals with sleep disturbances or high stress during treatment
However, even young, otherwise healthy patients can be affected. It doesn’t follow a strict pattern, which makes it even more important to talk about openly.
How Long Does It Last?
For some, chemobrain improves within a few months of treatment. For others, the fog lingers, sometimes for years. According to a 2016 study, as many as 30% of patients might show signs of cognitive impairment before treatment, 75% could experience it during treatment, and up to 35% of survivors may deal with cognitive issues months or even years after treatment ends.
This doesn’t mean it’s permanent or untreatable. The brain is capable of remarkable plasticity and recovery, but it often needs support.
Also Read: "What? Never Mind, Got It": Expert Explains Why Your Brain Feels Like It’s Lagging
How To Manage Effects Of Chemobrain?
There’s no magic pill for chemobrain, but a combination of strategies can make a significant difference. Here are some expert-recommended measures to manage cognitive fog due to cancer treatment.
Cognitive Rehabilitation
Working with occupational therapists or neuropsychologists can help retrain the brain. Structured mental exercises, memory strategies, and organisational techniques can reduce day-to-day frustration.
Exercise
Physical activity isn’t just good for the body, it benefits the brain, too. Even light walking or yoga can improve focus, boost mood, and reduce fatigue.
Sleep and Nutrition
Poor sleep amplifies cognitive issues. We encourage patients to establish regular sleep routines and avoid stimulants late in the day. Including foods rich in antioxidants, omega-3s, and B vitamins may support brain health.
Mindfulness and Stress Reduction
Meditation, breathing exercises, and journaling can reduce the stress that often worsens cognitive symptoms. An 8-week mindfulness and self-compassion program in a public hospital improved the psychological well-being of cancer patients and their families, as stated in a 2025 study.
Professional Support
Don’t hesitate to involve mental health professionals. Anxiety and depression often coexist with chemobrain and can amplify its impact.
Talking to Patients and Listening
"As oncologists, we spend a lot of time discussing chemotherapy’s physical side effects. However, we need to discuss further what happens afterwards, particularly in the realms of mental health and cognition. A patient who feels heard is far more likely to feel empowered in their recovery," highlighted Dr Vijayakumar.
Chemobrain may not be visible, but its weight is real. And just like we create individualised cancer treatment plans, we must now also focus on personalised survivorship plans that include brain health.
Bottomline
Dr Vijayakumar concluded, “Chemobrain isn't a sign of weakness, and it’s certainly not something patients are imagining. It’s a genuine post-treatment challenge that deserves attention, research, and compassion. By acknowledging it, we not only validate our patients’ experiences, but we help them reclaim a sense of control in a time that often feels uncertain. If you or someone you know is facing this invisible burden after cancer, know that you’re not alone, and there is support.”
[Disclaimer: This article contains information provided by an expert and is for informational purposes only. Hence, we advise you to consult your professional if you are dealing with any health issue to avoid complications.]