Radiation exposure can increase the risk of stroke, especially as people age, due to its damaging effects on blood vessels and the cardiovascular system. Ionizing radiation, which is used in medical treatments like radiotherapy for cancers, particularly head and neck cancers, can cause injury to the carotid arteries—major vessels supplying blood to the brain. This injury leads to a condition called radiation-induced carotid artery stenosis, where the arteries narrow because of inflammation, damage to the vessel lining, and fibrosis (thickening and scarring of connective tissue). This narrowing restricts blood flow and significantly raises the chance of ischemic stroke, which occurs when the brain’s blood supply is blocked. Studies show that about one in five survivors of head and neck cancer develop this artery narrowing within a few years after radiation treatment, and 5-10% of these patients may experience a stroke or transient ischemic attack (TIA) within 5 to 10 years following radiation exposure.
The process behind this increased stroke risk involves several steps. Radiation causes direct injury to the endothelial cells lining the arteries, triggering inflammation and promoting the buildup of plaques (atherosclerosis). Over time, this leads to stiffening and narrowing of the arteries. Additionally, radiation can damage the nerves that regulate blood pressure through the baroreflex system, which normally helps maintain stable blood pressure by sensing changes in artery wall stretch. Damage to this system can cause labile (unstable) hypertension, which further increases stroke risk.
Age plays a critical role in this relationship. As people get older, their blood vessels naturally become stiffer and more prone to atherosclerosis. When combined with radiation-induced damage, the risk of stroke compounds. Older adults are also more likely to have other stroke risk factors such as hypertension, diabetes, and irregular heart rhythms, which can worsen the effects of radiation on the vascular system. The cumulative effect of aging and radiation exposure accelerates vascular damage and heightens stroke risk.
Beyond cancer survivors, occupational exposure to ionizing radiation—such as in healthcare workers or nuclear industry employees—has also been linked to increased cardiovascular risks, including dyslipidemia (abnormal blood lipid levels) that contribute to atherosclerosis. The longer the duration of radiation exposure, the greater the risk of developing these conditions. Women may be more susceptible than men to radiation’s harmful effects on blood lipids, which indirectly raises stroke risk.
Stroke risk in older adults is influenced by many factors, but radiation exposure adds a significant and often underrecognized component. Radiation-induced vascular injury may remain asymptomatic for years, making regular screening important for those with a history of radiation exposure. Ultrasound imaging of the carotid arteries is commonly used to detect narrowing before symptoms develop. Early detection allows for interventions such as lifestyle changes, medications to control blood pressure and cholesterol, and in some cases, surgical procedures to restore blood flow.
In addition to vascular narrowing, radiation can cause functional impairments in the autonomic nervous system, affecting blood pressure regulation and increasing the likelihood of stroke. This autonomic dysfunction may manifest as labile hypertension, syncope (fainting), headaches, and other symptoms that can complicate stroke risk management.
The relationship between radiation exposure, aging, and stroke risk is complex and multifactorial. Radiation accelerates vascular aging by promoting inflammation, fibrosis, and atherosclerosis, while aging itself predisposes vessels to damage and dysfunction. When combined, these factors create a higher likelihood of stroke, especially ischemic strokes caused by blocked arteries. Preventive care for individuals exposed to radiation, particularly older adults, should include regular cardiovascular monitoring, management of traditional stroke risk factors, and awareness of symptoms that might indicate carotid artery disease or autonomic dysfunction.
In summary, radiation exposure increases stroke risk by damaging blood vessels and disrupting blood pressure regulation, with these effects becoming more pronounced as people age. The combined impact of radiation-induced vascular injury and the natural aging process leads to accelerated
