## 4 Discussion
We used a 60-day HDBR study with an intermittent (iAG) and continuous (cAG) artificial gravity countermeasure [16] to investigate how individual AMS items as well as AMS-SD and AMS-LD changed during and after HDBR relative to pre-HDBR levels. We found significantly elevated AMS scores (indicating greater alertness and mood disturbance) during and after HDBR, with more pronounced elevations during the post-HDBR recovery phase. These elevations were similar across the control and intervention groups during HDBR, and somewhat less pronounced for the iAG group during post-HDBR recovery. The differences between AMS-SD and AMS-LD were negligible, though, which can likely be explained by the fact that those items most strongly affected by HDBR (e.g., health and stress) were considered equally important for short- and long-duration missions by SMEs. The strengths of this study include the use of the PC method for deriving weights for generating AMS summary scores and that SMEs performed both PCs for short- and long-duration missions on a computer platform that guaranteed a randomized but balanced presentation of AMS items. However, this study also has limitations. While the PC analysis was based on 3460 comparisons, it is unclear how representative the pool of 19 SMEs, despite including both sexes and a wide age range, was for all the possible SMEs. Additionally, we only tested AMS scores in a single ground-based study in astronaut surrogate subjects. Thus, it is unclear how the findings translate to astronauts and the spaceflight environment, which should be investigated in future studies. In conclusion, in deriving a weighted summary score for Cognition's AMS survey with the PC method, this study generated a ranking of the individual AMS items in terms of their relevance for astronaut behavioral health, and it also shed some light on differences in relevance for short- and long-duration missions. The AMS summary scores will be a useful tool for monitoring astronaut behavioral health on short- and long-duration space missions with a very brief survey that takes less than two minutes to complete. **Author Contributions:** Conceptualization, M.B. and A.P. ; methodology, M.B. ; software, M.B. ; formal analysis, M.B. and A.P. ; investigation, M.B. and A.P. ; resources, M.B. and A.C.S. ; data curation, M.B. and A.P. ; writing--original draft preparation, M.B., A.P. and Y.G. ; writing--review and editing, M.B., A.P., A.C.S. and Y.G. ; visualization, M.B. ; supervision, M.B. and A.C.S. ; project administration, M.B. and A.C.S. ; funding acquisition, M.B. and A.C.S. All authors have read and agreed to the published version of the manuscript. **Funding:** This study was supported by NASA through 80 NSSC18K0765 and NNJ14 ZSA001N. The Cognition test battery and the Alertness and Mood Survey were developed with funding from the National Space Biomedical Research Institute (NSBRI) through NASA NCC 9-58. **Institutional Review Board Statement:** The AGBRESA study was conducted in accordance with the Declaration of Helsinki, and approved by the local ethics committee (Arztekammer Nordrhein) and by the Institutional Review Board of NASA Johnson Space Center (Pro2508). **Informed Consent Statement:** Subjects provided written informed consent before participation in the AGBRESA study and were allowed to discontinue the study at any time. **Data Availability Statement:** Data from the AGBRESA study can be requested from NASA's Life Science Data Archive ([[https://lsda.jsc.nasa.gov/](https://lsda.jsc.nasa.gov/)]([https://lsda.jsc.nasa.gov/](https://lsda.jsc.nasa.gov/)); accessed on 2 January 2023). Data of the paired comparison analysis will be provided by M.B. upon reasonable request. **Acknowledgments:** We would like to thank the subject matter experts for providing us with their time and expertise. **Conflicts of Interest:** The authors declare no conflict of interest.