Research by a team at the Rochester Medical Center suggests that exposure to the radiation of outer space could accelerate the onset of Alzheimer's disease in astronauts. 'Galactic cosmic radiation poses a significant threat to future astronauts... Exposure to cosmic radiation equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer's disease' says M. Kerry O'Banion. Researchers exposed mice with known timeframes for developing Alzheimer's to the type of low-level radiation that astronauts would be exposed to over time on a long space journey. The mice were then put through tests that measured their memory and cognitive ability and the mice exposed to radiation showed significant cognitive impairment. It's not going to be an easy problem to solve, either. The radiation the researchers used in their testing is composed of highly charged iron particles, which are relatively common in space. 'Because iron particles pack a bigger wallop it is extremely difficult from an engineering perspective to effectively shield against them,' says O'Banion. 'One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete.'