Purpose of Review <p>Ionizing radiation exposure has increased substantially in older adults due to widespread use of diagnostic imaging and radiotherapy. While carcinogenic risks are well recognized, growing evidence suggests that ionizing radiation may also contribute to neurodegenerative processes in aging populations. This review examines current evidence linking medical and occupational radiation exposure to dementia and Parkinson’s disease in the elderly.</p> Recent Findings <p>Epidemiological studies and meta-analyses report modest but consistent associations between cumulative radiation exposure and increased risks of dementia and Parkinson’s disease, with relative risks of approximately 1.1 per 100 mSv. Experimental studies demonstrate that ionizing radiation accelerates oxidative stress, neuroinflammation, microvascular injury, and impaired DNA repair—mechanisms already compromised in the aging brain. Clinical evidence indicates high rates of cognitive decline following cranial radiotherapy, particularly in patients over 65 years of age.</p> Summary <p>Ionizing radiation may act as an underrecognized contributor to neurodegeneration in older adults. Although absolute risks are modest, their population impact is relevant given widespread exposure. Personalized risk–benefit assessment, strict adherence to radiation protection principles, and increased use of non-ionizing imaging alternatives are essential to preserve neurological health in aging populations.</p>