Neurological difficulties induced by some cancer treatments might stem from nervous-system cells called microglia, which promote inflammation.
Some chemotherapies cause a lasting condition known as ‘chemobrain’, which is marked by deficiencies in attention, information processing and fine motor skills. Michelle Monje at Stanford University in California, and her colleagues found that children and young adults treated with a chemotherapy called methotrexate had fewer oligodendrocyte-lineage cells — cells that help to form the crucial insulation around neurons — in their brains than those who had not been exposed to the drug.
Similarly, mice exposed to methotrexate had fewer of these cells than untreated controls. Six months after methotrexate treatment, these mice struggled to distinguish between novel and familiar objects. They also had increased numbers of active microglia.
After exposing the mice to chemotherapy, researchers gave the animals a drug that reduced the numbers of their microglia. This reversed methotrexate’s negative effects on both oligodendrocyte-lineage cells and the animals’ ability to discriminate between novel and familiar objects.