Radiotherapy is crucial for treating patients with brain tumors, although the adverse events associated with it can be serious, including neuronal loss in adjacent healthy tissue.1,2

This study evaluated whether radiotherapy of the brain affected structural network properties in the brain and whether this treatment modality can cause cortical atrophy. Researchers used mathematical models, such as an approach called graph theory, applied to magnetic resonance imaging (MRI)-derived cortical thickness estimates from images from 54 patients with brain tumors before and after radiotherapy.

Results showed that after radiotherapy, the cortex thinned at a faster rate than it does with Alzheimer’s disease.

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“RT [radiotherapy] is a mainstay of brain tumor treatment,” said first investigator Naeim Bahrami, PhD, a postdoctoral fellow at the Center for Multimodal Imaging and Genetics at the University of California, San Diego School of Medicine.

“Unfortunately, a side effect can be incidental irradiation of normal brain tissue and radiation-induced injury, which have been linked to impairment of brain function. As patient outcomes improve, a major concern is managing long-term complications, including cognitive decline and disability.”

These results demonstrated changes in global and local brain network structure after radiation therapy in brain tumors, characterized by increased separation of brain regions essential for cognition.

Such structural changes could contribute to the delayed cognitive impairments many patients experience after radiotherapy for brain tumors.

“Finding a non-invasive imaging biomarker to better assess cognitive function in the moment and in the future would be very helpful to clinicians,” Dr Bahrami said.


1. Radiation therapy vital to treating brain tumors, but it exacts a toll [news release]. EurekAlert: The Global Source for Science News.–rtv060917.php. Published June 9, 2017. Accessed June 22, 2017.

2. Bahrami N, Seibert TM, Karunamuni R, et al. Altered network topology in patients with primary brain tumors after fractionated radiotherapy. Brain Connect. 2017;7(5):299-308.