Environmental Enrichment and Cortical Changes among Brain Tumor Survivors

Abstract

Though rare compared to other types of cancer, brain tumors can leave an individual with devastating neurological disabilities that impact cognition, function, independence, and overall quality of life. Glioma, those histologically classified as oligodendroglioma or astrocytoma with World Health Organization (WHO) 2 or 3 are brain tumors that commonly affect adults, with a mean age at diagnosis of 41 years old. The multimodal treatment approach of surgery, chemotherapy, and radiation has extended overall median survival, yet, minimal evidence exists to guide the management of chronic complications that arise from such life-saving measures. Brain radiation therapy (RT) is closely associated with accelerated brain aging, as evidenced by increased global cortical atrophy rate and progressive cognitive decline. Multiple domains of cognition, such as impairment in processing speed, attention, executive function, and memory, are commonly observed. Despite the potential cognitive preservation associated with the use of proton-beam radiation (PBRT), conventional photon RT (XRT) may be the only type of RT available and accessible to an individual. Studies indicate social support, physical activity, economic stability, and employment status, comprehensively known as environmental enrichment (EE), have associated health benefits on the well-being and quality of life in the general cancer survivor population. However, the effects of EE on cognitive impairment, healthy brain aging, functioning, and symptom burden have not been studied among brain tumor survivors. Thus, the overall purpose of this dissertation is to examine the role of EE in promoting cognitive function, healthy brain aging, functionality, and reducing symptoms after treatment. Specifically, this dissertation has the following aims: 1) Conduct a literature review of the neuroimaging measures that can be employed by nurse scientists to assess the association between brain and cognitive changes; 2) Examine the association between EE and health outcomes (cognitive function, cortical changes, functional status, and symptoms) at five years in a cohort of BT survivors diagnosed with glioma treated with RT; and 3) Describe the health outcomes (cognitive function, cortical changes, functional status, and symptoms) in patients who received conventional photon radiation and those that received proton-beam radiation in relation to levels of EE among patients diagnosed with glioma five years from the time of diagnosis. The 39 individuals we recruited experienced varying levels of EE. We observed distinct increasing patterns in estimates and Odds Ratio of improved health outcomes in multiple measures (Montreal Cognitive Assessment [MoCA], Symbol Digit Modality Test, and Karnofsky Performance Status) with increasing levels of EE. We also noted higher MoCA scores, lower brain atrophy, and lower symptom burden) with in the High EE category. Comprehensively understanding the relationship between environmental, behavioral, and social factors with health outcomes is necessary to advance the paucity of research among BT survivors. Future research is necessary to examine the potential mechanism by which EE improves cognitive function and functional status, thereby promoting healthy brain aging, and reducing symptom burden after brain RT.