Chemotherapy effects on brain may be a myth
 

"Chemofog" - impairments in memory and in thinking, or "cognition,"that have been attributed to chemotherapy -- was not seen in twostudies of women being treated for breast cancer, according to apresentation at the 60th annual meeting of the American Academy ofNeurology in Chicago..

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Chemo Brain in the Chemo
 

There are a number of theories as to why chemobrain may occur. One is that some types of chemotherapy can cross the blood/brain barrier. Another is that the cognitive problems are created by free radicals, the toxic elements that many types of chemotherapy produce. And yet another is that some people have a genetic (epigenetic) background that makes them more susceptible to the effects of chemotherapy. Most likely it is not just one factor but many factors that combine to set the stage for chemobrain to occur.

According to studies by Dartmouth-Hitchcock Medical Center, even standard-dose chemotherapy can negatively impact the cognitive functioning of cancer survivors up to 10 years after treatment. Reports of depression, anxiety, and fatigue, all of which can affect cognitive functioning, suggests that the differences in performance on cognitive tests were due to the chemotherapy itself, not to greater levels of depression, anxiety, and fatigue in patients who received chemotherapy.

Leukoencephalopathy syndrome is a disorder that results from structural alterations of cerebral white matter, is characterized by cerebral edema, and can occur in patients of any age. It is the destruction of the myelin sheaths which cover nerve fibers. These sheaths, composed of lipoprotein layers, promote the transmission of a neural impulse along an axon.

Certain chemotherapy agents, especially those used in high-dose protocols, are causal agents. Because this syndrome alters neurobehavioral function, patients may present in a confused state, which can progress quickly to irreversible dementia, coma, or death, depending on its severity.

Necrotizing Leukoencephalopathy is a form of diffuse white matter injury that can follow chemotherapy. The chemotherapy drugs that most likely cause it are the vinca alkaloids (vincristine, vindesine and vinblastine), platin drugs (cisplatin, carboplatin), and the taxanes (taxol, taxotere). These drugs have the potential of interfering with nerve function.

Filley & Kleinschmidt-DeMasters, 2001
Journal of Clinical Oncology, January 15, 2002
Cossaart, SantaCruz, Preston, Johnson, & Skikne, 2003