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Session: Vitamins and Minerals (Oral 9)

(OR09-01-24) Spaceflight Associated Neuro-Ocular Syndrome in a Predisposed Astronaut With B-Vitamin Supplementation as a Potential Countermeasure

Sunday, June 30, 2024
8:00 AM – 8:12 AM CT
Location:  W375A
Objectives: Optic disc edema, one of the pathologic findings of Spaceflight Associated Neuro-ocular Syndrome (SANS) presents in some astronauts on the International Space Station. Astronauts and bed rest subjects with 3–4 risk alleles (G and C alleles from the methionine synthase reductase [MTRR] A66G and serine hydroxymethyltransferase [SHMT1] C1420T) had a greater change in total retinal thickness (ΔTRT) than those with 1–2 risk alleles.

We describe a SANS case of a female astronaut who had two risk factors: small optic cup and one carbon genetic pattern (i.e., 4 of 4 risk alleles). This case challenges several hypothesized risk factors for SANS, including sex, eye-bias, and elevated intracranial pressure. We also document the first attempt to mitigate SANS through B-vitamin supplementation.

Methods: A female astronaut completed a 6-month ISS mission while participating in several IRB approved experiments. Informed consent was provided prior to data acquisition, and the astronaut provided written approval for this report. Eye examinations and fasting blood collections were conducted before, during, and after flight.

Results: Compared to preflight, total retinal thickness (ΔTRT) rapidly increased, peaking at 232 µm (+58%) at flight day (FD) 126. In response, four B-vitamin supplements (vitamins B6 and B12, folate, and riboflavin) were deployed to the ISS and were unpacked on FD153. She consumed them daily through FD169. Coincidentally, CO2 partial pressure decreased from 2.6 to 1.3 mmHg when a vehicle left ISS weeks prior to the FD154 OCT session. ΔTRT was lower than the peak measurement when taken on FD154, and continued to decrease throughout the remainder of the mission.

Conclusions: This individual developed some of the most substantial SANS findings ever detected, regardless of sex or mission duration. Years postflight, the optic disc edema has resolved, and no known long-term health risks remain. This was the first SANS case showing inflight improvement as well as the first inflight attempt to mitigate SANS through B-vitamin supplementation. Whether or not SANS signs would have decreased without B vitamin supplementation and/or the reduction in cabin CO2 is unknown, but these countermeasures are worthy of further consideration as therapeutic options, especially in SANS cases with 4 risk alleles.

Funding Sources: This work was funded by the NASA Human Research Program.