A new study from the University of Southern Denmark suggests that radiation may be a confounding factor in Alzheimer’s disease.
The leading cause of dementia in the elderly is Alzheimer’s. It is expected to affect up to 80 million patients by 2040. Humans are exposed to radiation on a nearly constant level from many different sources, such as medical devices, airplanes, etc. This radiation could have a connection to Alzheimer’s. That’s what postdoc Stefan J Kempf and an international consortia involving colleagues from Italy, Japan, Germany, and Denmark, have set out to discover.
“It is crucial that we investigate the potential factors behind this disease,” Dr. Kempf said. The study was published in Oncotarget. It has shown that low doses of ionizing radiation induce molecular changes in the brain that resemble the pathologies of Alzheimer’s.
Ionizing radiation is being exposed to more age groups than ever before. The reason being use of medical diagnostics and therapeutic radiology has increased quite a bit. 62 million CT scans per year are currently carried out in the USA, and approximately one-third of all diagnostic CT examinations are scans of the head region.
Dr. Kempf added that “All these kinds of exposures are low dose and as long as we talk about one or a few exposures in a lifetime I do not see cause for concern. What concerns me is that modern people may be exposed several times in their lifetime and that we don’t know enough about the consequences of accumulated doses.”
The study suggests that even relatively low radiation doses similar to those received from a few CT scans could trigger molecular changes associated with cognitive dysfunction. The researchers are working with the hippocampus of mice. The hippocampus is an important brain region responsible for learning and memory formation that is usually affected by Alzheimer’s. Elucidating molecular alterations in the hippocampus, they induced changes by two kinds of chronic low-dose-rate ionizing radiation treatments. They exposed the mice 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. The researchers concluded that “both dose rates are capable of inducing molecular features that are reminiscent of those found in the Alzheimer’s disease neuropathology,” said Dr. Kempf.
The dose varies from 20 to 100 mGy and lasts for around one minute during one head scan. When a person flies, they will also receive ionizing radiation but the rates are much smaller than a CT scan.
The exposed mice were subjected to a more than 1000 times smaller cumulative dose than what a patient gets from a single CT scan in the same time frame. According to Dr. Kempf, even then the researchers could see changes in the synapses within the hippocampus that resemble Alzheimer’s pathology. He says that the data indicates that chronic low-dose-rate radiation targets the integration of newborn neurons in existing synaptic wires.