For millions of cancer survivors, the end of chemotherapy does not always bring full relief. The lingering fog, forgetfulness, and mental fatigue known as “chemo brain” can persist for years, baffling both patients and doctors. Now, a new study in Communications Biology offers a biological explanation hidden deep within the brain’s waste removal system.
Researchers at Virginia Tech’s Fralin Biomedical Research Institute have found that chemotherapy drugs may damage or shrink the brain’s lymphatic vessels, impairing drainage and potentially leading to the cognitive symptoms long reported by cancer patients. The findings, published October 13, 2025, introduce the first human tissue-engineered model to study these lymphatic effects and could shift how scientists think about post-cancer care.
The Brain’s Hidden Plumbing System
The brain’s lymphatic network, tucked within the meninges, is responsible for clearing waste and transporting immune cells. When these vessels become clogged or atrophied, toxins can accumulate and interfere with normal brain function. According to senior author Jennifer Munson, director of the Fralin Biomedical Research Institute’s Cancer Research Center, chemotherapy may trigger just that.
“What we see is a shrinking of the lymphatic vessels, and fewer loops or branches in the vessels,” said Munson. “These are signs of reduced growth that indicate the lymphatics are changing, or not regenerating in beneficial ways.”
Using a combination of mouse experiments, ex vivo tissue analysis, and a custom-built in vitro lymphatic model, Munson’s team tested two common cancer drugs: docetaxel and carboplatin. Both disrupted lymphatic growth, but docetaxel caused the most dramatic changes. In mice, this drug reduced lymphatic drainage and led to measurable memory deficits in cognitive tests.
Brain imaging confirmed that treated mice showed slower fluid flow through the lymphatic system. The pattern, the researchers note, parallels findings in Alzheimer’s and traumatic brain injury, suggesting a shared mechanism of cognitive decline.
A Gendered Burden And A Path Forward
The study also found that chemo brain disproportionately affects women, particularly those receiving breast cancer therapies. That difference, Munson said, may reflect broader sex-based disparities in lymphatic diseases and immune regulation.
“Women are affected by chemo brain, or brain fog, much more than men when treated by very common chemotherapies,” said Munson. “We are extremely interested in trying to understand that difference and why that difference might exist.”
Her co-author, biomedical engineer Monet Roberts, said the work underscores the need to treat cognitive health as part of cancer recovery. Their new three-tiered model, which integrates cell cultures with animal and tissue systems, allows precise study of how drugs alter the brain’s plumbing and opens doors to interventions that could protect it.
Future research will explore whether pharmaceutical or lifestyle strategies could restore lymphatic drainage after treatment. Munson points to evidence that sleep and exercise can enhance fluid flow in the brain, raising hope that similar tactics might help cancer survivors regain mental clarity.
While more research is needed to translate the findings into therapies, the results provide one of the clearest biological links yet between chemotherapy and long-term cognitive side effects. The study also expands a growing field of research that connects brain lymphatics to memory, inflammation, and neurodegeneration.
“Ultimately, this work underscores the need to consider not only survival, but also the long-term, often overlooked neurological side effects of cancer treatment on cognitive well-being and quality of life,” Roberts said.
Communications Biology: 10.1038/s42003-025-08784-4
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