The “mental fog” called chemo brain is very real. It can actually be seen in imaging studies.

Highlights As many as 25-30% of patients have chemo brain that is not a byproduct of other chemotherapy side effects such as anemia and fatigue. For a thumbnail summary of chemo brain symptoms, click here. If you experience any symptoms of chemo brain, alert your health care team.

In our last issue of New Connections, in the first of a 3-part series on chemo brain, we discussed what chemo-brain is and what may cause it. Click here to review that article. In this issue, we discuss what imaging studies show and  report on some of the research currently underway on chemo brain.

Seeing is believing.

One of the biggest hurdles in solving the chemo brain puzzle has already been overcome: the scientific and medical communities now recognize chemo brain as a side effect of cancer treatment. This recognition came in large part from imaging studies of the brains of people who had experienced chemo brain. These studies showed smaller size in the areas of the brain that are part of memory, planning, putting thoughts into action, monitoring thought processes and behavior, and inhibition.

Other imaging studies have shown changes in the brains of cancer survivors treated with chemotherapy that did not appear in latter survivors who did not get chemotherapy.

The picture is clear: Although the brain usually recovers over time, it can be impacted by chemotherapy, proving that the condition known as chemo brain is very real. Recognizing chemo brain as a treatment side effect was the first step. Now studies are being done to learn more about the condition.

What is being done about chemo brain?

There is heightened concern about chemo brain now because recent treatment studies favor the use of more aggressive and high-dose drug schedules.

Experts are trying to learn more about the condition, find ways to prevent chemo brain, and help people cope if they have it.

 There are studies underway to:

• Look at which chemotherapy drugs are most likely to cause chemo brain and in what doses.
• Determine which patients are most likely to develop chemo brain. To do this, people’s mental abilities are measured before treatment, then after treatment, and then compared.
• Investigate ways to protect the brain from chemo side effects, such as with more specific, targeted drugs that focus on the cancer cells and spare normal, healthy cells.
• Look at medications for depression, attention-deficit hyperactivity disorder (ADHD), and dementia as possible medications for chemo brain.
• Look at genetic differences that may make some people more likely than others to experience chemo brain. One particular gene, called APOE, is being examined more closely. Research has shown that one version of this gene, E4, is associated with Alzheimer's disease and increases the chance for cognitive problems after traumatic brain injury. Studies are trying to find out whether carriers of the E4 gene who get chemotherapy may have a higher risk of developing long-term chemo brain.
• Investigate whether certain hormonal factors may make some people more susceptible to mental effects from chemotherapy. Estrogen is one target of investigation.
• Further examine the effects of chemotherapy drugs on nerve and brain cells. Recent studies have already shown clear evidence of nerve damage from at least some forms of chemotherapy. Identifying which nerve or brain cells are most at risk is critical to developing ways to reduce the damage.
• Look into the possibility that chemicals produced by the body in response to invasive cancer (cytokines) may be partly responsible for changes in brain function.

If you have problems with thinking that interfere with daily life, simply being aware that these are not uncommon can help you feel better. And in the next issue, we’ll suggest some programs and tips for managing chemo brain that may help you cope.

The American Cancer Society is in your corner around the clock to guide you through every step of the cancer experience. Whether it’s the middle of the day or the middle of the night, call us at 1-800-227-2345 or visit us at cancer.org.