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Cancer Brain Fog

What Causes It and What You Can Do About It

by Pamela Joyce Shapiro, PhD

Cancer survivors face a number of physical, mental, and psychosocial challenges that diminish quality of life and alter one’s sense of self. Brain changes that affect a person’s cognitive identity – the thinking, capable, intelligent self – can be especially troubling.

What is cancer brain fog?
Following a cancer diagnosis, many survivors experience a sense of cognitive loss – the feeling that one’s mental abilities are slower and less acute than before – as if the brain is in a fog. Problems with memory and concentration are the most common cognitive complaints, and some people report difficulties following directions, finding the right words, or performing simple calculations. Complex tasks, like planning or organizing activities, can be especially challenging for survivors with cognitive symptoms, and multitasking may seem impossible.

Although cancer-related cognitive changes are sometimes called chemo brain or chemo fog, these terms are misleading. Symptoms of cognitive loss often occur before cancer treatment begins and can affect people who are treated with surgery, radiation, and hormonal therapy, as well as those who undergo a course of chemotherapy or immunotherapy.

Many survivors experience a sense of cognitive loss, as if the brain is in a fog.

Approximately 20 to 50 percent of survivors are affected by cognitive loss. Some of these survivors have clinically significant cognitive impairment that persists months or years after treatment. But for most survivors with cognitive loss, the impairment is mild and transient. These deficits may not be noticeable to others, but they weigh heavily on the survivor and are a source of frustration and embarrassment. Because cognition is fundamental to navigating life, communicating with others, and completing tasks, even subtle changes in cognitive abilities can interfere with everyday function.

What causes cancer brain fog?
The causes of cancer-related cognitive changes are unclear. The issue is complicated because many factors can affect cognitive function. Cancer and the drugs used during the course of treating cancer can affect the balance of chemicals and hormones in the brain and contribute to cognitive loss. Fatigue, depression, or feeling stressed or anxious can also affect cognitive function. It’s important to remember that all of these are potential causes of cancer brain fog. Results of studies examining these factors are mixed, and no definitive large-scale studies have been completed.

Inflammation is one potential cause of cancer-related cognitive change. Cancer and many chemotherapeutic agents trigger the release of cytokines, proteins that signal the immune system and cause inflammation. Circulating peripheral cytokines signal cytokine release in the central nervous system, causing structural and functional changes in areas of the brain that support cognitive function. These changes can reduce mental acuity, memory, and processing speed.

Other drugs that may affect cognitive function include hormonal treatments that reduce levels of estrogen or testosterone, drugs given to reduce anxiety, and corticosteroids. Many drugs used for cancer treatment can cause anemia, a risk factor for cognitive loss in older adults.

Psychological distress is a well-known cause of cognitive impairment. Certainly, being diagnosed with cancer is stressful, and cancer treatment presents additional ongoing stressors. Depression, anxiety, stressful life events, and chronic stress cause neural degeneration and volume loss in the hippocampus, an area of the brain essential for learning and memory.

Fatigue is associated with attention difficulties and memory complaints in cancer survivors. It’s unclear if cognitive difficulties in fatigued survivors are caused by sleep disturbance, anemia, symptoms of depression, or some combination of these factors that frequently co-occur with fatigue.

What should you do if you have cancer brain fog?
If you are experiencing cognitive loss, it’s important to assess the extent of your difficulties. Discuss your concerns with a doctor and, if needed, arrange a consultation with a neurologist or clinical neuropsychologist. These professionals can rule out other causes of cognitive loss and recommend a course of care. Take charge of your cognitive health. Many simple lifestyle changes can preserve and optimize cognitive function.

• Reduce stress. Stress damages brain cells. Practice relaxation techniques, meditation, or deep breathing to manage stress and improve focus.
• Reduce cognitive load. Research shows that multitasking impairs the speed and accuracy of performance. Concentrate on the task at hand.
• Learn something new and complex. Your brain has the ability to grow new cells and make new connections when it is challenged.
• Practice cognitive skills. There are many programs and games that train specific attention and memory skills.
• Exercise. Exercise helps the brain grow new cells and reduces risk of dementia. It also reduces stress and fatigue, and improves depression.
• Eat a balanced diet and get enough sleep. Your brain is part of your body and requires nutritional support and rest to function well.

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