LETTERS Comments on “Prolonged Microgravity Affects Human Brain Structure and Function” his letter addresses the article, “Prolonged Microgravity bly affected the validity of the findings of the study conducted by 1 1 TAffects Human Brain Structure and Function.” To investigate Roberts et al. whether brain structural changes(whichcan be observed after long-term space missions) are associated with alterations in motor Disclosures: James Welsh—UNRELATED: Grant: I have a Small Business Innovation Research grant from the National Institutes of Health, but it is related to proton or cognitive function, Roberts et al retrospectively analyzed brain radiography and proton beam CT scanning; Consulting Fee or Honorarium:I am MR images of National Aeronautics and Space Administration an advisor to TAE Life Sciences for boron neutron capture therapy.* astronauts to quantify pre- to postflight alterations in brain struc- Membership: Coqui Pharma, Comments:Ihave received no ﬁnancial remuner- ation; Employment: Department of Veterans Affairs, Comments:Thisis my ture. They showed that brain structural changes were linked to primary employer; Patents (Planned, Pending or Issued):Ihold apatentfor a changes in cognitive and motor test scores as well as the develop- method to reduce adverse effects of reirradiation by adjusting the effective ment of spaceflight-associated neuro-optic syndrome. However, dose rate.So far,Ihave received no ﬁnancial beneﬁt; Royalties:Prometheus Books, Comments:Iam theauthorof Sharks Get Cancer, Mole Rats Don’t: duetothe smallsample sizeand number of comparisons, they sug- How Animals Might Hold the Key to Cancer Immunity.Thiswas published in gested that their findings shouldbeinterpreted with cautioun. 2016. *Money paid to the institution. Although this article has certain strengths, it has at least 1 REFERENCES major shortcoming that stems from ignoring the key point that in 1. Roberts DR, Brown TR, Nietert PJ, et al. Prolonged microgravity long-duration deep space missions, astronauts are exposed to affects human brain structure and function. AJNR Am J Neuroradiol multiple stressors ranging from psychological stress due to the 2019;40:1878–85 CrossRef Medline confined environment to ionizing radiation and gravitational 2. Parihar VK, Allen BD, Caressi C, et al. Cosmic radiation exposure changes. It is not well-understood whether these stressors impact and persistent cognitive dysfunction. Sci Rep 2016;6:34774 CrossRef the central nervous system only individually or in combination Medline (ie, synergistically). However, what we are fully aware of is the key 3. Cucinotta FA, Alp M, Sulzman FM, et al. Space radiation risks to the role of space radiation on human brain function, according to central nervous system. Life Sciences in Space Research 2014;2:54–69 CrossRef Parihar et al, “The Mars mission will result in an inevitable expo- 4. Krukowski K, Feng X, Paladini MS, et al. Temporary microglia-deple- sure to cosmic radiation that has been shown to cause cognitive tion after cosmic radiation modifies phagocytic activity and pre- impairments in rodent models, and possibly in astronauts engaged vents cognitive deficits. Sci Rep 2018;8:7857 CrossRef Medline in deep space travel.” Cucinotta et al have also confirmed galactic cosmic ray (GCR)-induced alterations in astronauts’ cognitive J.J. Bevelacqua function, “Galactic cosmic rays may alter astronauts, cognition Bevelacqua Resources during space missions.” Cucinotta et al also reported that expo- Richland, Washington sure to GCRs can be associated with increased risk of CNS disor- J. Welsh ders, “GCR[s] may increase central nervous system risks Department of Radiation Oncology including Alzheimer disease.” Most important, Krukowski et al Edward Hines Jr VA Hospital reported that novel pharmaceutical agents are being explored for Hines, Illinois their ability to protect memory function in rodents exposed to S.M.J. Mortazavi simulated cosmic radiation, “Now neuroscientists have identified Diagnostic Imaging Department a potential treatment for the brain damage caused by cosmic rays, Fox Chase Cancer Center a drug that prevents memory impairment in mice exposed to Philadelphia, Pennsylvania simulated space radiation.” In summary, this omission has possi- Medical Physics Department School of Medicine http://dx.doi.org/10.3174/ajnr.A6387 Shiraz, Iran AJNR Am J Neuroradiol 41:E7 Feb 2020 www.ajnr.org E7
American Journal of Neuroradiology – American Journal of Neuroradiology
Published: Feb 1, 2020
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