What is chemo brain?

Chemo brain refers to problems with attention, memory, and thinking during cancer treatment. Other names include chemo fog, chemotherapy-induced cognitive impairment, and cancer treatment-related cognitive impairment.

People often think of cognitive impairment (trouble thinking clearly) as a symptom of chemotherapy. But it can develop before, during, or after any cancer treatment. In some people, it is brief. Others experience it for years.

Common signs of chemo brain include:

  • Confusion or mental fogginess
  • Finding it harder to multitask (do more than one activity at a time)
  • Forgetfulness or short attention span
  • Trouble recalling common words or details such as names and dates
  • Difficulty in making decisions quickly
  • Decreased motor skills

What causes chemo brain?

Doctors do not always know what causes chemo brain. It can be a side effect of chemotherapy, as some chemotherapy drugs are able to get through the blood-brain barrier. But different issues related to cancer and its treatment may also lead to this symptom.

People may develop chemo brain because of:

  • Cancer treatments other than chemotherapy, such as hormone therapy, and surgery
  • Problems with sleep and nutrition due to cancer treatment, leading to conditions such as anemia and/or sleep apnea
  • Fatigue (extreme tiredness)
  • Stress, depression and anxiety related to a cancer diagnosis
  • The loss of protection provided by the hormones estrogen, progesterone or testosterone when people with breast cancer and prostate cancer are treated with certain hormonal treatments
  • Oxidative stress caused by higher levels of free radicals and damage to DNA
  • Changes to the immune system

Are there risk factors for chemo brain?

There may be risk factors for chemo brain, including:

  • A genetic variation that might make some people more likely to develop chemo brain
  • Age
  • Chemotherapy dosage levels
  • Chemotherapy agent combinations
  • Additional treatments, such as hormone therapy or radiation
  • Other medical conditions such as diabetes and cardiovascular disease

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