Alzheimer’s added to dangers faced by deep space astronauts

Psychiatrists involved with the early days of NASA’s space program were concerned astronauts might succumb to “space madness” as a result of experiencing prolonged periods of microgravity and claustrophobic isolation. While their fears turned out to be unfounded, a new study has found cause for concern for the mental faculties of astronauts on planned future deep space missions. The study shows that the levels of radiation an astronaut would be exposed to on a mission to Mars could cause cognitive problems and accelerate the onset of Alzheimer’s disease.

With astronauts exposed to a continuous stream of various radioactive particles, which we on terra firma are largely protected from by the earth’s magnetic field, NASA has been funding research to determine the potential health risks of such exposure on space travelers for over 25 years. In that time, numerous studies have shown that galactic cosmic radiation can poses a cancer risk and has a negative impact on cardiovascular and musculoskeletal systems. Now neurodegeneration can be added to the list of potential dangers.

A team from the University of Rochester Medical Center (URMC) Department of Neurobiology and Anatomy, led by M. Kerry O’Banion, M.D., Ph.D., which has been working with NASA for over eight years, focused on the impact of high-mass, high-charged (HZE) particles. Unlike hydrogen protons that are produced by solar flares and which astronauts can take precautions against with appropriate warning, HZE particles are propelled through space at very high speeds from the force of exploding stars. They come in various forms, including iron particles, which is the one the researchers chose to examine.

“Because iron particles pack a bigger wallop it is extremely difficult from an engineering perspective to effectively shield against them,” said O’Banion. “One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete.”

With the specific aim of examining whether or not radiation exposure had the potential to accelerate the biological and cognitive indicators of Alzheimer’s disease, particularly in those with a predisposition to developing it, the researchers used animal models – namely mice – for which the precise timeframe of the disease’s progression has been extensively studied and is understood.

The animals were exposed to various doses of radiation – including comparable levels to what astronauts would experience on a trip to Mars – created by smashing matter together at very high speeds using the NASA Space Radiation Laboratory at Brookhaven National Laboratory.

In a series of experiments in which the mice had to recall objects or specific locations, the researchers observed a higher rate of failure amongst those that were exposed to radiation. The brains of the mice also showed signs of vascular alterations and a greater than normal accumulation of the protein “plaque” beta amyloid, the accumulation of which is a hallmark of Alzheimer’s disease.

“These findings clearly suggest that exposure to radiation in space has the potential to accelerate the development of Alzheimer’s disease,” said O’Banion. “This is yet another factor that NASA, which is clearly concerned about the health risks to its astronauts, will need to take into account as it plans future missions.”

The results of the study will be of obvious concern to NASA, which is planning manned missions to an asteroid in the next decade, and to Mars in 2035.

The team’s study appears in the journal PLOS ONE.

Source: University of Rochester Medical Center