Cognitive Decline Secondary to Therapeutic Brain Radiation—Similarities and Differences to Traumatic Brain Injury

Abstract

Traumatic brain injury (TBI) resulting from forceful impacts on the torso and head has been of major interest because of the prevalence of such injuries in military personnel, contact sports and the elderly. Cognitive and behavioral changes associated with TBI are also seen following whole brain radiation treatment for cancer and chemotherapy for disseminated tumors. The biological mechanisms involved in the initiation of TBI from impact, radiation, and chemotherapy to loss of cognitive function have several shared characteristics including increases in blood brain barrier permeability, blood vessel density, increases in inflammatory and autoimmune responses, alterations in NMDA and glutamate receptor levels and release of proteins normally sequestered in the brain into the blood and spinal fluid. The development of therapeutic agents that mitigate the loss of cognition and development of behavioral disorders in patients experiencing radiation-induced injury may provide benefit to those with TBI when similar processes are involved on a cellular or molecular level. Increased collaborative efforts between the radiation oncology and the neurology and psychiatry communities may be of major benefit for the management of brain injury from varied environmental insults.

Risk of Developing Non-Cancerous Central Nervous System Diseases Due to Ionizing Radiation Exposure during Adulthood: Systematic Review and Meta-Analyses

“…The adverse health effects following exposure to IR have been the subject of a large amount of scientific research, mainly focusing on carcinogenic risks [ 3 ]. However, several epidemiological studies have highlighted the non-cancerous detrimental impact of high or moderate IR doses on the central nervous system (CNS) [ 4 , 5 , 6 ], and radiation-induced cognitive injury is becoming an increasingly important research subject [ 7 , 8 ]. Non-cancerous CNS disorders are a large and complex group of diseases, including mental and behavioral disorders, diseases of the CNS, and trauma, and they have multifactorial origins.…”

Sensory sensitivity after acquired brain injury: A systematic review

“…We only included articles that discussed sensory sensitivity after cerebral damage and excluded articles that related atypical sensory sensitivity to peripheral injury (i.e. ocular damage), meningitis, encephalitis (due to the possibility of comorbid peripheral nervous system damage) (Bogovic, 2015) and brain tumours (since we could not specify whether changes in sensory sensitivity are a result of the brain injury or the cancer treatment) (Huang et al, 2019; Raffa et al, 2006). We also excluded articles on toxic encephalopathy due to long‐term solvent exposure since solvent exposure (in the absence of encephalopathy) can result in abnormal sensitivity to olfactory stimuli (Zibrowski & Robertson, 2006).…”

The psychological consequences of (perceived) ionizing radiation exposure: a review on its role in radiation-induced cognitive dysfunction

“…Although the adult brain is considered more resilient in comparison to the developing brain, recent evidence from cranial radiotherapy patients highlights the impact of highdose exposure on brain morphology and network functionality/connectivity (Ma et al 2017;Jacob et al 2018;Qiu et al 2018;Cramer et al 2019;Huang et al 2019). Further, there is growing evidence that exposure of the adult brain to moderate doses may be detrimental to cognitive functioning.…”