Neuropsychological effects of cranial radiation: current knowledge and future directions.
Radiation is an invaluable therapeutic tool in the treatment of cancer, with well-established palliative and curative efficacy. As patient survival has improved, attention has focused on long-range treatment side effects. One such adverse effect, neuropsychological impairment, is incompletely understood. Much of the extant research has been directed at childhood leukemia survivors treated with low-dose whole-brain radiation. Less is known about the effects of high-dose focal or whole-brain radiation used in the treatment of brain lesions. This article reviews the scientific literature in this area, with greatest emphasis on methodologically rigorous studies. Research design considerations are discussed. Review findings suggest that low-dose whole-brain radiation (18 to 24 Gy) in children is associated with mild delayed IQ decline, with more substantial deficits occurring in children treated at a young age. A high incidence of learning disabilities and academic failure is observed in this population and may be caused by poor attention and memory rather than low intellectual level. Children who receive higher dose radiation for treatment of brain tumors experience more pronounced cognitive decline. At higher doses, whole-brain radiation, in particular, is linked to deleterious cognitive outcomes. Remarkably little is known about cognitive outcomes in irradiated adults. Preliminary findings indicate that certain cognitive functions, including memory, may be more vulnerable to decline than others. Suggestions for future research are proposed.
Roman
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Department of Physical Medicine, University of Minnesota Hospital and Clinic, Minneapolis.
Sperduto
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D000328:Adult; D001932:Brain Neoplasms / Q000532:radiotherapy*; D018288:Carcinoma, Small Cell / Q000532:radiotherapy; D002648:Child; D016371:Cranial Irradiation / Q000009:adverse effects*; D004521:Educational Measurement; D005544:Forecasting; D006801:Humans; D007360:Intelligence / Q000187:drug effects / Q000528:radiation effects*; D008175:Lung Neoplasms / Q000532:radiotherapy; D008568:Memory / Q000528:radiation effects; D008727:Methotrexate / Q000009:adverse effects; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy / Q000532:radiotherapy*; D011879:Radiotherapy Dosage
D008727:Methotrexate