Can radiation exposure contribute to the development of Alzheimer's disease? A new University of Southern Denmark study suggests that it does.

For the study, the researchers induced molecular changes in the hippocampus of mice. That part of the brain is responsible for learning and memory formation, and is known to be negatively affected in Alzheimer's patients.

Two types of chronic low-dose-rate ionizing radiation treatments were used on the mice. They were exposed to cumulative doses of 0.3 Gy or 6.0 Gy given at low dose rates of 1 mGy over 24 hours or 20 mGy over 24 hours for 300 days.
They found that both dose rates are capable of inducing molecular features that resemble those seen in Alzheimer's pathology. The findings were published in the journal, Oncotarget.

More people of all age groups are being exposed to higher levels of ionizing radiation from medical equipment, airplanes, etc. The use of medical imaging has exponentially increased — over 62 million CT scans per year are conducted in the U.S., and about one-third are head exams.

If an individual is exposed to radiation once or a few times in their lifetime, it's not a major concern because the dose is low. However, modern people may be exposed several times that in their lifetime, and the industry doesn't know much about the consequences, according to the researchers.

A head CT exam exposes the patient to between 20 and 100 mGy for about one minute. When someone flies, they are exposed to a dose much smaller than a CT exam.

The mice in the study were exposed to a more than 1,000 times smaller cumulative dose than the dose from a CT scan. Even at such a low dose, changes in the hippocampus were still observed.

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