Some scientists speculate that we will spot one of Earth's true twins next year. Others predict that multigenerational space travel is just a matter of time. In fact, space travel does seem imminent. But what effect will space travel have on our health? What effect does space travel have on NASA astronauts' health right now? Researchers from the University of Rochester Medical Center have found that space travel may speed up the progression of Alzheimer's disease.

Space is filled with radiation, although the Earth's magnetic field protects humans from most of it. However, that protection evaporates once a person is launched into space. That means that astronauts and other space travelers are subjected to a constant barrage of radiation once they leave Earth's magnetic field. Though astronauts have the capacity to shield themselves from radiation from events like solar flares, other forms of cosmic radiation cannot be blocked. Also, the longer period of time a person spends in space, the greater exposure the person has. That exposure has been linked to an increased risk of a variety of ailments: cancer, cardiovascular problems, and musculoskeletal issues.

Psych Central reports that Dr. M. Kerry O' Banion and his team studied the effect that high-mass, high-charge particles might have on the central nervous system. In his study, he used iron particles since they are large and it would be difficult for engineers to create a barrier against them. The study exposed mice to radiation at levels comparable to what astronauts would experience on a trip to Mars. Then the mice underwent experiments in which they had to remember the placement of objects in certain locations.

O' Banion and his colleagues found that mice exposed to radiation were more likely to fail at these tasks than their counterparts. These mice were much younger than when symptoms typically appear. The mice's brains also displayed vascular alterations and buildup of beta amyloid, a protein that is the harbinger of the disease.

However, while this information is bad news for NASA astronauts, it may not be something that the rest of us need to fear. While researchers certainly believe that multigenerational space travel is imminent, Cameron Smith from Portland State University said to Space.com that he believes that evolution and natural selection will continue. Perhaps in the future Alzheimer's disease will be a thing of the past.