Mars-bound astronauts could develop dementia and an uncontrollable sense of dread – dubbed “space brain” – during the journey, scientists have warned.

Researchers studied the effects of cosmic rays that would bombard astronauts and their results pose a significant problem for those wishing to establish a colony on the distant planet.

Nasa is actively studying how to send humans to Mars, which is nearly 34 million miles away, and the Netherlands-based Mars One group plans to send people there by 2027. US entrepreneur Elon Musk has also talked about sending people by 2022.

However Professor Charles Limoli, an expert in radiation oncology at University of California, Irvine, and colleagues found highly charge particles in cosmic rays caused significant long-term brain damage in test rodents, resulting in cognitive impairments and dementia.

And it also interfered with the “fear extinction” process, which helps people get over scary or stressful incidents so they can, for example, go swimming again after nearly drowning, he reported in the journal Scientific Reports.

“This is not positive news for astronauts deployed on a two- to three-year round trip to Mars,” Professor Limoli said.

“The space environment poses unique hazards to astronauts. Exposure to these particles can lead to a range of potential central nervous system complications that can occur during and persist long after actual space travel – such as various performance decrements, memory deficits, anxiety, depression and impaired decision-making.

“Many of these adverse consequences to cognition may continue and progress throughout life.”

Alarmingly, the first Martian explorers could also become paranoid during the flight because of the effects on the brain’s normal process of dealing with stressful events. “Deficits in fear extinction could make you prone to anxiety, which could become problematic over the course of a three-year trip to and from Mars,” Professor Limoli said.

While astronauts have lived on the International Space Station for more than a year, they have not faced the same level of cosmic rays because it orbits the Earth inside the planet’s protective magnetosphere.

Nasa finds flowing water on Mars - in pictures Show all 7 1 /7 Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures The MAVEN spacecraft orbiting Mars EPA Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures In this handout illustration provided by NASA/JPL, an artist's conception of the Phoenix Mars Lander on the Red Planet. Phoenix is slated to land on Mars on May 25, 2008.

Areas of the spacecraft could be fitted with extra shielding but it is currently not possible to fully protect the astronauts in this way. There is “really no escaping” the cosmic rays, Professor Limoli said.