Cognitive side effects to chemotherapy, often called “chemobrain” or “chemofog”, are a growing concern among cancer survivors. Symptoms such as a decline in memory, concentration and executive functions (such as organization or attention) are often described. Cognitive changes can cause significant distress and prevent a return to the quality of life experienced before treatment.
Recent studies have started to unravel the way chemotherapy agents affect the brain. Imaging of patients after chemotherapy show that treatments produce structural and functional changes in the brain. A number of explanations have been suggested for these changes after chemotherapy. Inflammatory changes in the brain, low hormone levels, or toxic destruction of nerve cells are a few examples.
Currently, there is no recognized treatment for cognitive dysfunction following chemotherapy. A greater understanding of the causes for cognitive decline will be key to finding ways of preventing or treating the effects of chemobrain.
Some studies have focused on the ability of the hippocampal region of the brain to form new nerve cells (called neurogenesis). Several cognitive and mood disorders, such as memory decline, fatigue and depression, have been linked to problems with neurogenesis.
Two recent studies investigating breast cancer patients focused specifically on the hippocampus. In one study, breast cancer survivors showed an average reduction of 8% in hippocampal size compared with healthy controls. Hippocampal shrinkage in this study was associated with the ability to retrieve facts from memory. Similarly, a second study found that the size of the hippocampus on the left side of the brain was reduced by nearly 7% in chemotherapy-exposed patients compared with healthy controls. Left hippocampal size was associated in this study with verbal memory performance (such as remembering words). Additional studies have also linked reduced hippocampus size in chemotherapy-exposed patients with deficits in figural and visual memory.
Only a few studies have reported chemotherapy-related effects on hippocampal function (rather than size). In all of these studies, activation of the hippocampus was less effecient and less functional in patients treated with chemotherapy.
Taken together, an increasing number of studies suggest that cognitive dysfunction following chemotherapy is associated with changes in the hippocampal region of the brain. Impaired hippocampal neurogenesis may be a contributing factor to cognitive decline, and key to preventing or treating chemobrain.
Published By :
Neuroscience
Date :
Nov 19, 2015
