Cognitive changes can happen suddenly (acute onset) or slowly over time (gradual onset). These types of changes can be different in adults and children. We’ll focus here on cognitive changes in adults with cancer. Talk with your health care team if you have questions related to children who experience cognitive changes.
Higher risks of cognitive changes:
- Tumor located in the central nervous system (CNS) which includes the brain and spinal cord.
- Treatments administered directly to the CNS.
- Treatments administered when extremely ill.
- Chemotherapy and radiation given to the brain at the same time.
- Chemotherapy given into the spinal fluid after radiation.
Cognitive changes are sometimes related to higher dose chemotherapy and the use of immunotherapy to boost the immune system. Those who have cancer involving the brain may also experience cognitive changes as a result of the tumor or the treatment of the tumor. While cognitive changes associated with brain surgery often occur immediately, changes associated with radiation and chemotherapy can develop more gradually over time.
Some changes after cancer are very minor and will go away. Other cognitive changes may be more noticeable and may not be reversible. Discuss any signs or symptoms with your health care team.
Types and Symptoms of Cognitive Changes
Discuss all of these possible causes of cognitive problems with your health care team. This will help you receive the correct diagnosis and treatment.
Mild cognitive changes ("Chemo-brain")
Sometimes survivors experience changes in their ability to remember or concentrate after they have chemotherapy. This typically mild form of cognitive change is sometimes called "chemo-brain." Even these typically mild cognitive changes can disrupt daily living and the ability work. Symptoms include:
- Difficulty concentrating and multi-tasking.
- Difficulty remembering things that occurred recently.
- Difficulty completing tasks.
- Slowed thinking speed.
- Inability to think clearly.
Neurocognitive effect of tumors
A tumor or cancer cells in the brain can injure healthy cells and can cause cognitive changes. Chemotherapy, radiation and surgery are treatments that are used to remove or destroy cancer cells. However, they can also damage some of the surrounding healthy cells either by direct administration or by impacting the brain indirectly. Depending on how much damage occurs, there could be noticeable symptoms such as with thinking, memory, speech, visual-spatial problems and behavior changes.
Acute onset cognitive changes (delirium)
Acute onset cognitive changes are those that occur suddenly. Some acute changes, such as delirium, come and go with no real pattern. This can happen during treatment with certain medications and chemotherapy agents, and may be reversible. Symptoms include:
- Fluctuating alertness and orientation.
- Difficulty concentrating.
- Reduced level of consciousness or the person seems “out of it”.
- Person does not understand what is going on around him or her.
- Unusual sleep patterns, such as awake at night and asleep during the day.
- Memory loss.
- Loud, aggressive behavior.
- Hallucinations or seeing things that are not really there.
- Disorientation or the person doesn’t know where s/he is.
- Quiet, inactive behavior, including sedation or confusion.
Gradual onset cognitive changes (dementia)
Dementia is a term used in this document to describe cognitive changes due to medical conditions other than Alzheimer's disease. Gradual onset cognitive changes come about slowly over time and may be long lasting. Symptoms of dementia might not appear until active treatment for cancer is finished. Symptoms include:
- Poor memory.
- Difficulty with abstract thinking and/or multi-tasking.
- Poor judgment (makes unsafe decisions).
- Poor decision making.
- Changes in personality (may become moody or upset without a noticeable cause).
- Difficulty with problem solving and following directions.
- Disorientation (not knowing where s/he is).
- Changes in cognition and behavior negatively affect professional or social life and degree of independence.
Other cognitive changes in cancer survivors
Chemotherapy may cause fatigue and anemia, which may also lead to cognitive problems, particularly with the ability to pay attention. In addition, a survivor can experience other conditions that cause cognitive changes that may or may not be related to cancer or treatment. Some of these conditions are reversible—some are not. Conditions include:
- Electrolyte derangements.
- Hypoxemia (low oxygen levels).
- Other diseases of the brain such as Alzheimer's disease or Parkinson's disease.
- Thyroid problems.
- Severe nutrition problems.
When Do Cognitive Changes Occur?
Cognitive changes can occur at any point during your experience with cancer. Sometimes they are the first sign of a brain tumor. These changes may also happen after completing cancer treatment or after taking certain medications.
- Chemo brain can occur during or after chemotherapy treatment.
- Delirium may occur suddenly during treatment. Delirium usually happens after an identified cause, such as chemotherapy, and it is often reversible.
- Dementia due to cancer treatment comes on gradually over time and usually after treatment is completed. It may be harder to identify than delirium, and it may not have one identifiable cause. Dementia can develop as early as three months after radiotherapy to the brain. It can also occur 48 months or longer after completion of radiation therapy.
- Symptoms of dementia (such as memory loss) can also occur after surgery to remove a brain tumor.
Living with Cognitive Changes
How to Manage Cognitive Changes
- Take prescribed medication as prescribed by writing down the time and date when you take the medication, taking the medication at the same time every day, using a medication reminder or pill dispenser or asking someone to help you keep track, if necessary.
- Avoid dangerous activities if you are alone, such as cooking, using tools that could cause injury, driving and traveling to unfamiliar places.
- Ask your family to watch for safety issues.
- Get plenty of rest and sleep.
- Use a health journal to communicate symptoms and side effects of medicine with your health care team.
- Talk with your family and an attorney about legal documents you may need.
Whether cognitive changes will improve or be permanent depends on their cause. Acute cognitive changes (delirium) that occur because of certain medicines often improve when you stop taking the medicine. Chronic changes (dementia) are often not reversible. However, some medications may enhance cognitive function, or there may be some improvement if the cause of the problems can be corrected.
If you notice changes in your thinking, memory or behavior, keep a record of the problems that you experience. Ask your family or friends to also watch for changes. Talk to your health care team about these symptoms as soon as possible. Request a neuropsychological evaluation with a neuropsychologist to help diagnose the nature, severity and possible causes of your cognitive changes. A neuropsychologist may suggest interventions to improve your functioning. Treating the underlying condition often lessens or eliminates the cognitive problems.
Correa, D.D. (2010). Neurocognitive function in brain tumors. Curr Neurol Neurosci Rep (10)3; 232-239.
Calabrese, P., & Schlegel, U. (2009). Neurotoxicity of treatment. Resent Results in Cancer Research, 171: 165-174.