Cognitive disorders and delirium may be complications of cancer and cancer treatment, especially in people with advanced cancer.

In patients with cancer, cognitive disorders and delirium may be due to the direct effects that cancer has on the brain, such as the pressure of a growing tumor. Cognitive disorders and delirium may also be caused by indirect effects of cancer or its treatment, including the following:

• Organ failure.
• Electrolyte imbalances: Electrolytes are important minerals (including salt, potassium, calcium, and phosphorous) that are needed to keep the heart, kidneys, nerves, and muscles working correctly.
• Infection.
• Symptoms caused by the cancer but that occur apart from the local or distant spread of the tumor (paraneoplastic syndromes), such as inflammation of the brain.
• Medication side effects: Patients with cancer usually take many medications. Some drugs have side effects that include delirium and confusion. The effects of these drugs usually go away after the drug is stopped.
• Withdrawal from drugs that depress (slow down) the central nervous system (brain and spinal cord).

Risk factors for delirium include having a serious disease and having more than one disease.

Other conditions besides having cancer may place a patient at risk for developing delirium. Risk factors include the following:

• Advanced cancer or other serious illness.
• Having more than one disease.
• Older age.
• Previous mental disorder, such as dementia.
• Low levels of albumin (protein) in the blood.
• Infection.
• Taking medications that affect the mind or behavior.
• Taking high doses of pain medication.

Early identification of risk factors may help prevent the onset of delirium or may reduce the length of time it takes to correct it.

Glossary Terms

Cancer that has spread to other places in the body and usually cannot be cured or controlled with treatment.

A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.

A mineral needed for healthy teeth, bones, and other body tissues. It is the most common mineral in the body. A deposit of calcium in body tissues, such as breast tissue, may be a sign of disease.

A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is a cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is a cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is a cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord. Also called malignancy.

The brain and spinal cord. Also called CNS.

The mental process of thinking, learning, remembering, being aware of surroundings, and using judgment.

A mental state in which one is not thinking clearly.

A mental state in which a person is confused, disoriented, and not able to think or remember clearly. The person may also be agitated and have hallucinations, and extreme excitement.

A condition in which a person loses the ability to think, remember, learn, make decisions, and solve problems. Symptoms may also include personality changes and emotional problems. There are many causes of dementia, including Alzheimer disease, brain cancer, and brain injury. Dementia usually gets worse over time.

In medicine, a disturbance of normal functioning of the mind or body. Disorders may be caused by genetic factors, disease, or trauma.

Refers to cancer that has spread from the original (primary) tumor to distant organs or distant lymph nodes. Also known as distant metastasis.

The amount of medicine taken, or radiation given, at one time.

Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic.

A substance that breaks up into ions (particles with electrical charges) when it is dissolved in water or body fluids. Some examples of ions are sodium, potassium, calcium, chloride, and phosphate. These ions help move nutrients into cells, help move waste out of cells, and help nerves, muscles, the heart, and the brain work the way they should.

Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body’s natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.

Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.

One of a pair of organs in the abdomen. Kidneys remove waste from the blood (as urine), produce erythropoietin (a substance that stimulates red blood cell production), and play a role in blood pressure regulation.

An invasive malignant cancer confined entirely to the organ where the cancer began.

A legal drug that is used to prevent, treat, or relieve symptoms of a disease or abnormal condition.

In medicine, a mineral is a nutrient that is needed in small amounts to keep the body healthy. Mineral nutrients include the elements calcium, magnesium, and iron.

A bundle of fibers that receives and sends messages between the body and the brain. The messages are sent by chemical and electrical changes in the cells that make up the nerves.

A part of the body that performs a specific function. For example, the heart is an organ.

A group of symptoms that may develop when substances released by some cancer cells disrupt the normal function of surrounding cells and tissue.

Having to do with or containing the element phosphorus.

A metallic element that is important in body functions such as regulation of blood pressure and of water content in cells, transmission of nerve impulses, digestion, muscle contraction, and heartbeat.

In medicine, action taken to decrease the chance of getting a disease or condition. For example, cancer prevention includes avoiding risk factors (such as smoking, obesity, lack of exercise, and radiation exposure) and increasing protective factors (such as getting regular physical activity, staying at a healthy weight, and having a healthy diet).

A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin and hair and of substances such as enzymes, cytokines, and antibodies.

Something that increases the chance of developing a disease. Some examples of risk factors for cancer are age, a family history of certain cancers, use of tobacco products, being exposed to radiation or certain chemicals, infection with certain viruses or bacteria, and certain genetic changes.

A problem that occurs when treatment affects healthy tissues or organs. Some common side effects of cancer treatment are fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss, and mouth sores.

A column of nerve tissue that runs from the base of the skull down the back. It is surrounded by three protective membranes, and is enclosed within the vertebrae (back bones). The spinal cord and the brain make up the central nervous system, and spinal cord nerves carry most messages between the brain and the rest of the body.

An indication that a person has a condition or disease. Some examples of symptoms are headache, fever, fatigue, nausea, vomiting, and pain.

An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancer), or malignant (cancer). Also called neoplasm.