Table 1.
Astronaut and control group demographics and flight experience.
| Astronauts | Controlse | |||||||
|---|---|---|---|---|---|---|---|---|
| All Astronauts | Novice | Experienced | t or χ2 | p | All Controls | t or χ2 | p | |
| Demographics | ||||||||
| n | 15 | 9 | 6 | – | – | 11 | – | – |
| Age (years)a | 47.46 (6.28) | 43.98 (4.90) | 52.67 (4.18) | 3.68 | 0.003** | 42.28 (10.60) | 1.44 | 0.169 |
| Sex | 27% F | 33% F | 17% F | 0.51 | 0.475 | 27% F | 0.001 | 0.973 |
| Current mission | ||||||||
| Mission duration (days) | 190.67 (57.36) | 166.78 (31.37) | 226.50 (71.21) | 1.93 | 0.099 | – | – | – |
| Time elapsed between landing and return + 4 days MRI scan | 4.53 (1.13) | 4.83 (0.41) | 4.33 (1.41) | 1.00 | 0.341 | – | – | – |
| Experienced astronauts (n = 6)b | ||||||||
| Number of previous missions | – | – | 2.00 (0.89) | – | – | – | – | – |
| Past flight days (days)c | – | – | 187.50 (151.67) | – | – | – | – | – |
| Time elapsed since last flight (years)d | – | – | 5.77 (1.60) | – | – | – | – | – |
**p < 0.01. For each metric, we report the mean (standard deviation) for the whole astronaut cohort, the novice and experienced subgroups, and the whole control group. We also report the results of two-sample t-tests to characterize differences in demographic variables between the novice and experienced astronaut groups, and between the whole astronaut cohort and the whole control group. For sex, we report the percentage of females included in each group and the result of a Pearson’s Chi-square test for differences in the sex distribution within each group.
aAge represents age, in years, at the date of launch for the astronauts and age at the first MRI scan for the controls.
bHere, we report further details regarding previous spaceflight experience for n = 6 of 15 astronauts who completed at least one flight before the current ISS mission.
cPast flight days indicates the total number of previous days spent in flight, not including the current mission.
dTime elapsed since the last flight is the time from the landing day of the most recent flight to the launch of the current mission.
eHere we include only those control group participants with complete MRI datasets (n = 11). See “Methods” for further details.
Significant values are in bold.