Risk of CV death higher in Apollo astronauts, possibly due to deep space radiation

Arguably, astronauts comprise one of the most elite groups of highly educated, well trained, and physically fit individuals. Despite this, astronauts from the Apollo space program may be at a significantly elevated risk of death from cardiovascular disease (CVD), possibly due to the deep space radiation they are exposed to, according to researchers at Florida State University, Tallahassee, FL. Their findings appear in the current issue of the journal Scientific Reports.

Lead author Michael D. Delp, PhD, FSU Dean, College of Human Sciences Astronauts, Florida State University, explained that the astronauts who travel into deep space on lunar missions for the Apollo program, which ran from 1961 to 1972 and included 11 manned flights into space (9 of which were into deep space), are exposed to levels of galactic cosmic radiation not experienced by any other astronauts or cosmonauts.

For this study, the first of its kind, Dr. Delp and colleagues included 24 astronauts from the Apollo lunar missions. Eight men were deceased, and of these, 7 were included in the study.

They found an increase in CVD mortality rates of 43% in Apollo astronauts, a rate that is 4- to 5-fold higher than that in non-flight astronauts and those who have traveled in low Earth orbit.

At the same time, to determine the possible mechanistic reasons behind this increase, they also assessed the long-term effects of space-relevant total-body irradiation and simulated weightlessness on the vascular responsiveness of mice. At the NASA Space Radiation Laboratory, the mice were exposed to a single dose of radiation (1 Gy of 56 FE ions at a dose rate of 10 cGy/min).

After 6 months (20 human years), space-relevant irradiation caused sustained vascular endothelial cell dysfunction, which is known to lead to occlusive artery disease, in the exposed mice.

“What the mouse data show is that deep space radiation is harmful to vascular health,” concluded Dr. Delp, who is currently working with NASA to conduct additional studies on the cardiovascular health of Apollo astronauts.

This research was funded by the National Space and Biomedical Research Institute and the NASA Space Biology Program.