From the NHS to the ISS – brain research project flies to space station aboard Axiom-2 Mission

Mayday Group Medical Director and Neuroscience Clinical Lecturer Dr Jon Sen led an international team of researchers to put ground-breaking research in astronaut brain health aboard the Axiom-2 International Space Station (ISS) mission last May.

A suite of brain-monitoring experiments ranging from the cellular level through to global brain function conceived and designed by Dr Sen, along with collaborators, were selected as payload for the 10-day mission. It is known from previous missions that in microgravity, astronauts can develop neurological and visual symptoms which are thought to be due to body fluid shifts into the head causing brain swelling and increased pressure (spaceflight-associated neuro-ocular syndrome – SANS), but it remains a poorly understood condition.

This research was undertaken to improve our understanding of SANS and also to test new portable monitors that could become standard medical kit for future ventures into space and for future space clinics and hospitals.

Risk-rating and safety measures

With new programmes such as Artemis (the follow-up to the Apollo missions) and the rise in commercial space travel, risk-rating and evidence-based safety measures will be critical to ensuring the viability of space travel, particularly long-duration space flight (LDSF). A further brain research project of Dr Sen’s will be aboard the upcoming SpaceX Polaris Dawn Mission, due to launch during the summer of 2024; this will be a five-day mission into high orbit, the highest any flight has achieved since the Apollo missions, and will again add important data for our understanding and tracking of brain health in space.

One of the key space neuroscience studies on these missions uses pupillary reactivity as a reference for changes in brain pressure (intracranial pressure – ICP). The potential to take ‘pupillometry’ out of the hospital and into extreme environments such as space originated from recognition of its adaptability and capacity to non-invasively and rapidly evaluate brain responses when being introduced into UK neurosurgery and intensive care departments, as well as on UK air ambulance retrievals of neurosurgical patients by Dr Sen, where conventional invasive ICP monitoring is complicated and impractical.

Dr Sen’s team pioneered and tested flight pupillometry with SpaceX and the Polaris Dawn team in conducting the first zero-gravity studies of pupillometry in parabolic flight in 2022, prior to taking it into space. Other studies conducted on Axiom-2 included measurements of blood flow in the brain, EEG to investigate changes in brain waves in space, and ultrasound of the optic nerve to assess how brain swelling in space affects the retina. During the Apollo programme, astronaut Buzz Aldrin described visual disturbances he experienced while on the lunar surface, and other astronauts have reported similar experiences since; these effects may be due to galactic cosmic rays that we are exposed to when flying beyond the Earth’s magnetosphere; the potential effects on the brain are almost completely unknown, but a further project by Dr Sen’s group to send brain tissue on resupply missions to the ISS over the next five years aims to expand our understanding of these effects and explore monitoring and protective mechanisms. These endeavours could go a long way towards creating management protocols and interventions to help protect astronaut brain health in the future.

The Polaris Program

The Polaris Program is a first-of-its-kind effort to advance human spaceflight capabilities, seeking to demonstrate important operational capabilities that will serve as building blocks to help further human space exploration.

SpaceX’s Falcon 9 rocket will launch the Polaris Dawn mission from Launch Complex 39A at Kennedy Space Center in Florida. The crew will carry out a spacewalk using brandnew designed space suits, conduct scientific experiments designed to advance both human health on Earth and our understanding of human health for long-duration spaceflight, and also be the first to test Starlink laser-based communications in space.

From a neurosurgical perspective, there is overlap between SANS and some types of hydrocephalus seen in neurosurgery, which are poorly understood, such as idiopathic intracranial hypertension. In addition, it is now possible to leverage space to conduct experiments, for example with stem cells, where new models of spinal cord injury treatment could be developed with the help of the microgravity environment.

The ISS is also pivotal for analysis of Earth’s climate. It is unquestionably important that we go into space to expand our horizons, and to find solutions to the multitude of problems we face on Earth.