Risk of Adverse Cognitive or Behavioral Changes and Psychiatric Disorders Leading to In-Mission Health and Performance and Long-Term Health Effects

The exploration spaceflight environment poses unique stressors to human health and performance. These challenges pose a significant and still unknown risk to astronauts’ behavioral health and performance (BHP). Even with excellent astronaut selection methods, a possibility remains that crewmembers could sustain behavioral health problems that may threaten mission success. The Risk of Adverse Cognitive or Behavioral Changes and Psychiatric Disorders Leading to In-Mission Health and Performance and Long-Term Health Effects (Behavioral Health) emphasizes the need to characterize cognitive and behavioral outcomes, develop tools to monitor behavioral health, and ultimately implement countermeasures to prevent, mitigate, or treat adverse cognitive and behavioral changes that may lead to significant adverse in-mission BHP or long-term health effects. Since the last publication of this evidence book, the Behavioral Health risk knowledge base characterizing cognitive and psychological outcomes in both spaceflight and ground analog environments has significantly increased, and initiated interdisciplinary collaboration to integrate research topics across 3 high-impact spaceflight hazard exposures—space radiation, isolation, and altered gravity—has been implemented, and integrated animal studies reviewing radiation induced behavioral effects have been conducted.

Evidence from spaceflight and from studies in environments analogous to spaceflight suggest that the average incidence rate of an adverse behavioral health event occurring during a space mission is relatively low for current missions of up to 6 months in low Earth orbit (LEO). Although subclinical mood and anxiety disturbances have occurred, no behavioral emergencies have been reported to date during spaceflight. However, anecdotal evidence, subject matter expert consensus and empirical evidence all indicate that the likelihood of an adverse cognitive or behavioral change or a psychiatric disorder occurring rises with increases with mission duration, distance from Earth, and greater exposure to spaceflight hazards. Three high-impact spaceflight hazards—radiation exposure outside of LEO, isolation and confinement, and altered gravity—are expected to exert combined effects on the central nervous system (CNS), and subsequently crew cognition, behavior, and performance. Thus, interdisciplinary research efforts are underway to fully characterize multiple pathways by which behavioral health may be impacted and thus mitigated. This includes efforts to develop animal and cell models to elucidate radiation induced behavioral and pathophysiological effects and to establish approaches to extrapolate risk to humans. Taken together these studies have documented increases in anxiety and depression-like behaviors and decrements on specific tasks of cognitive functions in rodents after exposure to mission relevant doses, such as those of near-term long-duration lunar missions.