Cognitive Dysfunction
Causes of Cognitive Dysfunction in Cancer

Advances in the success of treating cancer have been achieved through the combined use of surgery, radiation, cytotoxic drugs (ie. chemotherapy) and immunotherapy. Many cancer treatments are not specific, that is, they affect more parts of your body than just where the tumor is located, and therefore place organs and tissues at risk. The central nervous system, including the brain, is particularly vulnerable to many cancer treatments. Studies estimate that 18% of persons receiving standard dose chemotherapy regimens experience cognitive dysfunction and those receiving high-dose adjuvant (agents used in combination that hasten or enhance the action of the primary agent) therapies have a higher incidence rate. ¹⁵ More than 50% of persons receiving immunotherapy treatment (cytokines such as interferon, interleukin) experience memory, motor, executive functions (functions which allow self-control over our behavior and emotions) and mood alterations. ⁵ Among the treatments for hormonally sensitive cancer (breast, ovarian, testicular, prostate) are surgical or medication manipulation that reduce the amount of circulating sex hormones; there is a high occurrence; there is a cognitive dysfunction and these deficits appear to be directly related to the reduction in sex hormones. ^7,16

Additionally, many medications used to manage medical complications may cause side effects of cognitive impairment (immunosuppressive agents used in bone marrow transplant, antibiotics, steroids, drugs used to manage pain, nausea/vomiting, and other cancer-related symptoms).

Infections and low red blood cell counts (anemia) are common in people with cancer and may result in cognitive dysfunction. People undergoing active treatment are particularly susceptible to infections and anemia.

Some cancers themselves produce hormones or neurochemicals that alter the brain's function (small cell lung cancer, acute leukemia are two examples). Also, decreased production of thyroid hormones, produced by the thyroid gland in the neck, may reduce acuity of thinking and may be associated with low mood states. Dysfunction of the liver or kidneys may cloud mental functioning due to the accumulation of toxins within the blood that are normally excreted.

Deficiencies in iron, vitamin B and folic acid may cause a decline in attention, perceptual-motor speed, memory, and verbal fluency.

Tumors located in the central nervous system cause a predictable and progressive decline in mental functioning. In addition, the spread of cancer to the central nervous system can lead to cognitive dysfunction.

Addressing cognitive impairment as a symptom of cancer is important in restoring optimal quality living.