Radiation and Alzheimer's Disease (AD)

Abstract

radiation suggested that ionizing radiation was a risk factor for AD. Intranasal inhalation of radon gas could subject the rhinencephalon and hippocampus to damaging radiation that initiated AD [8]. The Alzheimer neurofibrillary tangle is composed of tau, which is one of the most common pathological hallmarks of AD and tau aggregation pathology at Braak stage 1 1 (out of 6 Braak stages) or beyond affects 50% of the population over the age of 45 [9][10][11]. Our recent review of the effect of the pre-and post-natal irradiation on animal models and human studies indicated many similarities in hippocampal neuropathology, cognitive impairment and relevant molecular mechanisms between Alzheimer's disease and early life radiation exposure-induced neuropsychological disorders [12][13][14][15][16]. It suggests that irradiation of the brain in early human life may set abnormal developmental events into motion that starts from tau aggregation at the ages of 40s and 50s, leading to the development of Alzheimer's Disease at the late stages of human life. Alzheimer's disease (AD) is the most common form of dementia, and accounts for 60 to 80 percent of dementia cases. While about onethird of all people age 85 and older may have Alzheimer's disease, and the number of people with the disease doubles every 5 years beyond age 65, its early onset may start from the ages of 40s and 50s. Old age and genetic factor are two most important factors for the development of Alzheimer's disease. Epidemiological studies have suggested that excessive alcohol consumption, smoking, environmental toxin such as pesticides (Dichlorodiphenyltrichloroethane or DDT), food additives (such as nitrogen-based chemicals which are converted to toxic nitrosamines during cooking), contamination ( mussels contaminated with demonic acid), food components (two amino acids in seeds of certain legumes which enhance the action of the neurotransmitter glutamate), air pollution (such as aerosolized nickel nanoparticles, a component of air pollution) may also play important roles in the development of the disease [1]. Serious head injury, heart disease, diabetes, stroke, high blood pressure and high cholesterol which damage the heart and blood vessels may be indirectly related to the development of AD due to the increase of β-amyloid (Aβ).Recent systematic review of bibliographic databases from PubMed, EMBASE, Cochrane Library and Web of Science suggests that occupational exposure to extremely low frequency magnetic fields (ELF-MF) to welders, electric utility workers, train drivers and sewing machine operators may increase the risk of AD [2,3]. Experimental studies indicated that low-dose radiation exposures (10 cGy) induced genes not affected by high-dose radiation (2 Gy) and that low-dose genes were associated with unique pathways and functions. Nine neural signaling pathways had a high degree of concordance in their transcriptional response in mouse brain tissue after low-dose irradiation, in the aging human brain (unirradiated) and in brain tissue from patients...