Dataset Information

The Impact of 6 and 12 Months in Space on Human Brain Structure and Intracranial Fluid Shifts.

ABSTRACT: As plans develop for Mars missions, it is important to understand how long-duration spaceflight impacts brain health. Here we report how 12-month (n = 2 astronauts) versus 6-month (n = 10 astronauts) missions impact brain structure and fluid shifts. We collected MRI scans once before flight and four times after flight. Astronauts served as their own controls; we evaluated pre- to postflight changes and return toward preflight levels across the 4 postflight points. We also provide data to illustrate typical brain changes over 7 years in a reference dataset. Twelve months in space generally resulted in larger changes across multiple brain areas compared with 6-month missions and aging, particularly for fluid shifts. The majority of changes returned to preflight levels by 6 months after flight. Ventricular volume substantially increased for 1 of the 12-month astronauts (left: +25%, right: +23%) and the 6-month astronauts (left: 17 ± 12%, right: 24 ± 6%) and exhibited little recovery at 6 months. Several changes correlated with past flight experience; those with less time between subsequent missions had larger preflight ventricles and smaller ventricular volume increases with flight. This suggests that spaceflight-induced ventricular changes may endure for long periods after flight. These results provide insight into brain changes that occur with long-duration spaceflight and demonstrate the need for closer study of fluid shifts.

SUBMITTER: Hupfeld KE

PROVIDER: S-EPMC7446230 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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The Impact of 6 and 12 Months in Space on Human Brain Structure and Intracranial Fluid Shifts.

Hupfeld Kathleen E KE McGregor Heather R HR Lee Jessica K JK Beltran Nichole E NE Kofman Igor S IS De Dios Yiri E YE Reuter-Lorenz Patti A PA Riascos Roy F RF Pasternak Ofer O Wood Scott J SJ Bloomberg Jacob J JJ Mulavara Ajitkumar P AP Seidler Rachael D RD

Cerebral cortex communications 20200615 1

As plans develop for Mars missions, it is important to understand how long-duration spaceflight impacts brain health. Here we report how 12-month (<i>n</i> = 2 astronauts) versus 6-month (<i>n</i> = 10 astronauts) missions impact brain structure and fluid shifts. We collected MRI scans once before flight and four times after flight. Astronauts served as their own controls; we evaluated pre- to postflight changes and return toward preflight levels across the 4 postflight points. We also provide d ...[more]

PMID: 32864615

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Project description:OBJECTIVE:Implanting subdural and penetrating electrodes in the brain causes acute trauma and inflammation that affect intracranial electroencephalographic (iEEG) recordings. This behavior and its potential impact on clinical decision-making and algorithms for implanted devices have not been assessed in detail. In this study we aim to characterize the temporal and spatial variability of continuous, prolonged human iEEG recordings. APPROACH:Intracranial electroencephalography from 15 patients with drug-refractory epilepsy, each implanted with 16 subdural electrodes and continuously monitored for an average of 18 months, was included in this study. Time and spectral domain features were computed each day for each channel for the duration of each patient's recording. Metrics to capture post-implantation feature changes and inflexion points were computed on group and individual levels. A linear mixed model was used to characterize transient group-level changes in feature values post-implantation and independent linear models were used to describe individual variability. MAIN RESULTS:A significant decline in features important to seizure detection and prediction algorithms (mean line length, energy, and half-wave), as well as mean power in the Berger and high gamma bands, was observed in many patients over 100 d following implantation. In addition, spatial variability across electrodes declines post-implantation following a similar timeframe. All selected features decreased by 14-50% in the initial 75 d of recording on the group level, and at least one feature demonstrated this pattern in 13 of the 15 patients. Our findings indicate that iEEG signal features demonstrate increased variability following implantation, most notably in the weeks immediately post-implant. SIGNIFICANCE:These findings suggest that conclusions drawn from iEEG, both clinically and for research, should account for spatiotemporal signal variability and that properly assessing the iEEG in patients, depending upon the application, may require extended monitoring.

Project description:ImportanceSpaceflight results in transient balance declines and brain morphologic changes; to our knowledge, the effect on brain white matter as measured by diffusion magnetic resonance imaging (dMRI), after correcting for extracellular fluid shifts, has not been examined.ObjectiveTo map spaceflight-induced intracranial extracellular free water (FW) shifts and to evaluate changes in brain white matter diffusion measures in astronauts.Design, setting and participantsWe performed retrospective, longitudinal analyses on dMRI data collected between 2010 and 2015. Of the 26 astronauts' dMRI scans released by the National Aeronautics and Space Administration Lifetime Surveillance of Astronaut Health, 15 had both preflight and postflight dMRI scans and were included in the final analyses. Data were analyzed between 2015 and 2018.Interventions or exposuresSeven astronauts completed a space shuttle mission (≤30 days) and 8 completed a long-duration International Space Station mission (≤200 days).Main outcomes and measuresThe dMRI scans were acquired for clinical monitoring; in this retrospective analysis, we analyzed brain FW and white matter diffusion metrics corrected for FW. We also obtained scores from computerized dynamic posturography tests of balance to assess brain-behavior associations.ResultsOf the 15 astronauts included, the median (SD) age was 47.2 (1.5) years; 12 were men, and 3 were women. We found a significant, widespread increase in FW volume in the frontal, temporal, and occipital lobes from before spaceflight to after spaceflight. There was also a significant decrease in FW in the posterior aspect of the vertex. All FW changes were significant and ranged from approximately 2.5% to 4.0% across brain regions. We observed white matter changes in the right superior and inferior longitudinal fasciculi, the corticospinal tract, and cerebellar peduncles. All white matter changes were significant and ranged from approximately 0.75% to 1.25%. Spaceflight mission duration was associated with cerebellar white matter change, and white matter changes in the superior longitudinal fasciculus were associated with the balance changes seen in the astronauts from before spaceflight to after spaceflight.Conclusions and relevanceFree water redistribution with spaceflight likely reflects headward fluid shifts occurring in microgravity as well as an upward shift of the brain within the skull. White matter changes were of a greater magnitude than those typically seen during the same period with healthy aging. Future, prospective assessments are required to better understand the recovery time and behavioral consequences of these brain changes.

Dataset Information

The Impact of 6 and 12 Months in Space on Human Brain Structure and Intracranial Fluid Shifts.

Publications

The Impact of 6 and 12 Months in Space on Human Brain Structure and Intracranial Fluid Shifts.

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