Key result
The intrinsic cardiovascular regulatory system (β), which initially declined after 1 month in space, significantly improved after 11 months of a 1-year spaceflight (P = 0.0167), suggesting adaptation to microgravity.
Why the study?
The intrinsic cardiovascular regulatory system did not adapt to microgravity after a 6-month spaceflight, prompting investigation into cardiovascular adaptation during a 12-month-long mission.
Does a 12-month spaceflight alter heart rate variability and intrinsic cardiovascular regulation in a healthy astronaut?
Observational (n=1)
Does a 12-month spaceflight alter heart rate variability and intrinsic cardiovascular regulation in a healthy astronaut?
Absolute Event Rate: 0.789% vs 0.638%
p-value: p=0.0167
A 12-month spaceflight initially impairs intrinsic cardiovascular regulation, but adaptation occurs by 11 months, potentially mediated by unconscious activation of the brain's default mode network.
Should not yet change practice; leaves open confirmation of delayed HRV adaptation beyond 6 months in long-duration spaceflight.
The intrinsic cardiovascular regulatory system (β, 0.00013-0.02 Hz) did not adapt to microgravity after a 6-month spaceflight. The infraslow oscillation (ISO, 0.01-0.10 Hz) coordinating brain dynamics via thalamic astrocytes plays a key role in the adaptation to novel environments. We investigate the adaptive process of a healthy astronaut during a 12-month-long spaceflight by analyzing heart rate variability (HRV) in the LF (0.01-0.05 Hz) and MF1 (0.05-0.10 Hz) bands for two consecutive days on four occasions: before launch, at 1-month (ISS01) and 11-month (ISS02) in space, and after return to Earth. Alteration of β during ISS01 improved during ISS02 (P = 0.0167). During ISS01, LF and MF1 bands, reflecting default mode network (DMN) activity, started to increase at night (by 43.1% and 32.0%, respectively), when suprachiasmatic astrocytes are most active, followed by a 25.9% increase in MF1-band throughout the entire day during ISS02, larger at night (47.4%) than during daytime. Magnetic declination correlated positively with β during ISS01 (r = 0.6706, P < 0.0001) and ISS02 (r = 0.3958, P = 0.0095). Magnetic fluctuations may affect suprachiasmatic astrocytes, and the DMN involving ISOs and thalamic astrocytes may then be activated, first at night, then during the entire day, a mechanism that could perhaps promote an anti-aging effect noted in other investigations.
No takes yet. Share an insight, caveat, or question.
Otsuka et al. (2022) conducted an observational in Healthy (adaptation to microgravity) (n=1). Long-duration spaceflight (microgravity) vs. Pre-flight baseline and early flight (1 month) was evaluated on Intrinsic cardiovascular regulatory system (β, 0.00013–0.02 Hz) (p=0.0167). The intrinsic cardiovascular regulatory system (β), which initially declined after 1 month in space, significantly improved after 11 months of a 1-year spaceflight (P = 0.0167), suggesting adaptation to microgravity.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: