Low-dose radiation and Alzheimer’s disease: Neuronal effects and a potential modality for therapy?

Exposure to low-dose radiation (LDR, mostly less than 100 mGy) may reduce the vulnerability of exposed tissues to subsequent high-dose radiation (HDR)-induced damage, a phenomenon known as adaptive responses, which occurs via mechanisms including anti-inflammation and anti-oxidation. Alzheimer’s disease (AD) is a type of dementia that causes problems with memory, thinking, and behavior. Using the available literature, this review will examine whether there is any effect of LDR on AD. The available evidence shows that although LDR can alter the expression of some genes related to AD such as Apbb1, Lrp1, and Il1α, these alterations do not cause AD-like syndromes in animals, suggesting that LDR may also simultaneously upregulate several protective mechanisms that prevent the eventual development of AD. Furthermore, LDR seems capable of improving the symptoms of AD, as evidenced by the experience of an 81-year-old female AD patient. This patient was diagnosed with AD more than 10 years ago and gradually progressed to advanced AD in 2015, despite routine treatment. The patient then received about 12 computed tomography scans (about 40 mGy each) up until Nov. 2017, which significantly improved her quality of life and reduced several AD symptoms. The improvement in this patient’s medical condition led to a few recent clinical trials investigating the effects of LDR on AD. To date, there is no efficient therapy available for AD; thus whether exposure to LDR at 100 mGy can provide a preventive or therapeutic effect for AD is an important issue. If LDR is a potential treatment for AD, as suggested by this reported case, this non-invasive approach would also bear the merit that it would be unlikely to cause a significant radiation health risk, as the LDR could be delivered locally to the head without any impact on other organs