Chemotherapy found to stop new brain cells from growing, worsening depression in brain cancer patients

Chemotherapy is depressing enough, but a drug used in the procedure may heighten it and make it worse, according to a study by researchers from King’s College London.

Depression is considered one of the least recognizable symptoms of cancer since the condition is commonly attributed to the shock of the patient upon hearing the news. The results of a new study, however, bring new light to the condition being an actual symptom of the disease rather than psychological distress stemming from receiving a cancer diagnosis.

Research has demonstrated that depression is prevalent in sufferers of brain cancer. According to studies, an estimated 30 percent of patients with brain cancer deal with it. However, this symptom is under-diagnosed; only less than 10 percent report experiencing symptoms of depression and 20 percent of patients are classified to have clinical depression.

Chemotherapy is a treatment that brings side effects of its own – most famous of which is hair loss.

Using data from animal studies, researchers were able to determine the chemotherapy may also affect neurogenesis or the growth of new brain cells. In this study, researchers questioned whether the effects of chemotherapy on neurogenesis significantly disrupted biological brain mechanism and if these changes increased a patient’s vulnerability to depression.

For this study, researchers gave healthy mice a chemotherapy drug known as temozolomide (TMZ), which is commonly used in treating brain cancer for humans. After the mice were administered with TMZ, researchers saw a decline in the production of new neurons in the hippocampus – the part of the brain that is related to emotion and memory. Results also indicated a direct link between neurogenesis and stress, with neurogenesis declining in direct response to the increased production of stress hormones.

This meant that people undergoing chemotherapy not only have lesser brain cells but have a greater level of stress when exposed to it. (Related: Radiation therapy for brain cancer found to cause significant damage to the brain.)

Researchers also observed substantial changes in the behavior of mice who had undergone chemotherapy, most notable of which is the lack of pleasure seeking or behavioral despair. The changes mimic behavior observed in people who experience depression, such as a lack of motivation and resignation.

The results may be based on mice and may not accurately represent what is actually happening to patients who have depression, but researchers believe that these findings could help improve patient care.

“Our results suggest that chemotherapy may stunt the growth of new brain cells, which has biological and behavioral consequences that may leave people less able to cope with the stress of having cancer,” Martin Egeland, a co-author of the study, explained. “Understanding the specific effects of chemotherapy on mood could lead to improved treatments and increase the quality of life for those affected by cancer.”

While there is no way to test these findings in humans, further studies that would be undertaken for the study include the effect of intervention methods, such as cognitive training, for patients and how it can protect them from depression.

“We will have to determine when is the best time to intervene and how much time we have. Treating the cancer is the priority of course,” according to senior author Sandrine Thuret. “However, if we can improve the quality of life of the patient, it can also be a step forward and may reduce their vulnerability to mental health problems.”

The National Cancer Institute lists depression as a symptom of cancer. While there are many risk factors for developing depression, the agency notes that going to counseling programs can be a way to deal with depression. Developing relaxation skills and stress-reduction exercises are also other ways to combat it.

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