Space travel may have harmful effects on astronauts' brains as exposure to galactic cosmic radiation could trigger Alzheimer's, reports citing a new study said.

With the race for space tourism hotting up, new obstacles to inter-galactic travel have come to the fore as research for the first time showed that radiation exposure in space could lead to cognitive problems, the report said.

People on earth are generally protected against cosmic radiation by the earth's magnetic field but once astronauts left orbit they were exposed to constant shower of various radioactive particles, the 'Daily Mail' reported.

According to senior author of the study, professor Kerry O'Banion from the University of Rochester Medical Centre (URMC) Department of Neurobiology and Anatomy, galactic cosmic radiation posed a significant threat to future astronauts. The possibility that radiation exposure in space may give rise to health problems such as cancer had long been recognized, he added.

The study, however, showed for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain associated with Alzheimer's disease.

Studies on mice have shown that after they were exposed to various doses of radiation, including levels comparable to what astronauts would experience during a mission to Mars, they were far more likely to fail certain tasks - suggesting neurological impairment.

NASA has, for the last 25 years, funded research to determine the potential health hazards of space travel in order to develop countermeasures as also to determine whether or not the risks warranted sending men and women on extended missions in deep space.

Over the period, several studies have demonstrated the potential cancer, cardiovascular, and musculoskeletal impact of galactic cosmic radiation.

The results of the study announced today for the first time showed the potential impact of space radiation on neurodegeneration, particularly the biological processes in the brain that contributed to the development of Alzheimer's disease. O'Banion and his team who have focused on the effects of radiation on the central nervous system have been working with NASA for over eight years.

The study focused on the effect of high-mass, high-charged (HZE) particles, which are propelled through space at very high speeds by the force of exploding stars and come in many different forms.

Unlike hydrogen protons that are produced by solar flares, the mass of HZE particles like iron, combined with their speed, enable them to penetrate solid objects such as the wall and protective shielding of a spacecraft.

O'Banion said because iron particles packed a bigger wallop, it was extremely difficult from an engineering perspective to effectively shield against them. One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete, he added.