Effect of the head-down tilt on intracranial pressure and cardiovascular control in healthy individuals: perspectives for spaceflights

• Grant number: 19/14877-8
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: December 01, 2020
• End date: February 28, 2025
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Thiago Luiz de Russo
• Grantee: Rafaella Mendes Zambetta
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated scholarship(s): 23/00839-2 - Brain oscillations in Alzheimer's Disease: a resting state EEG analysis, BE.EP.DD

Abstract

Increased Intracranial Pressure (ICP) in microgravity environment may reduce brain compliance and impair Cerebral Blood Flow (CBF). Thus, may decrease global cortical depolarization and affect brain functions, making this phenomenon worrisome to astronauts, especially in interplanetary and long-duration missions. ICP elevation is usually due to fluid displacement from the lower limbs and trunk to the head. Changes in hemodynamic control can also be observed as increase sympathetic autonomic nervous system action, perpetuating this cycle of elevated ICP and decreased brain activation and functions. The gold standard for measuring ICP is invasive, but this method has important disadvantages, and therefore, non-invasive measurement devices have been developed and studied. Objective: to characterize the immediate changes in the ICP waveform morphology during and after microgravity model (head-down tilt); to relate these changes to the autonomic nervous system behavior through the evaluation of Heart Rate Variability (HRV) and Baroreflex Sensitivity (BRS); to identify electric brain activity alterations through electroencephalography (EEG); to verify if P2/P1 ratio from ICP waves can correlate and predict brain activity alterations and cognitive and motor outcomes. Methodology: cross-sectional study with 50 healthy and active individuals, determined by biochemical tests, questionnaires, body composition, clinical examination and Cardiopulmonary Exercise Test (CPET). Five meetings will be held: the first to clarify the nature of the project, to complete the sociodemographic questionnaire and the consent term. In the second one, blood test will be done, and on the third day the Dual energy X-ray Absorptiometry (DXA) and CPET will be done. On the other days, the experimental protocol will be performed, which will consist in the head-down tilt test with -6° and -15°. ICP, ANS function (evaluated by the HRV and BRS) and EEG will be evaluated before, during and after the head-down tilt test, and the subjects will perform cognitive and motors tests before and right after the whole protocol. Statistics: tests of normality (Kolmogorov-Smirnov) and homogeneity (Levene) will be applied. Mixed model analysis will be used to assess whether there is a difference during tilt between the two inclinations (-6 ° and -15 °), using inclination, sensor and acquisition day as fixed factors. To verify the relationship between the postures and the ICP, EEG and cardiovascular variables, the ANOVA tests of repeated measures be performed. To evaluate the performance on the cognitive and motors tests, a paired t-test will be applied, and the Spearman's rank correlation coefficient will be used to determine the magnitude of the relationship between ICP and cognitive and motor tests performance. For all analyzes, will be considered a significance level of 5% and a confidence interval of 95%. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

ZAMBETTA, RAFAELLA MENDES; SIGNINI, ETORE DE FAVARI; CATAI, APARECIDA MARIA; DOS SANTOS, THAINA CRISTINA RAMOS; MICHALISKI, ELOISA SOARES; NAZARIO, ANA KAROLINE; OCAMOTO, GABRIELA NAGAI; FRIGIERI, GUSTAVO; RUSSO, THIAGO LUIZ. Is the ICP pulse waveform P2/P1 ratio during -6° head-down tilt associated with relative VO₂ peak? A non-invasive intracranial compliance monitoring approach. BRAIN AND SPINE, v. 4, p. 6-pg., 2024-08-31. (19/14877-8, 18/25082-3, 23/00839-2, 23/04712-7, 19/25569-2, 23/09582-4)

OCAMOTO, GABRIELA NAGAI; RUSSO, THIAGO LUIZ; ZAMBETTA, RAFAELLA MENDES; FRIGIERI, GUSTAVO; HAYASHI, CINTYA YUKIE; BRASIL, SERGIO; RABELO, NICOLLAS NUNES; SPAVIERI JUNIOR, DEUSDEDIT LINEU. Intracranial Compliance Concepts and Assessment: A Scoping Review. FRONTIERS IN NEUROLOGY, v. 12, p. 10-pg., 2021-10-25. (19/14877-8)

ZAMBETTA, RAFAELLA MENDES; SIGNINI, ETORE DE FAVARI; OCAMOTO, GABRIELA NAGAI; CATAI, APARECIDA MARIA; ULIAM, NICOLY RIBEIRO; SANTARNECCHI, EMILIANO; RUSSO, THIAGO LUIZ. Effects of weightlessness on the cardiovascular system: a systematic review and meta-analysis. FRONTIERS IN PHYSIOLOGY, v. 15, p. 27-pg., 2024-07-26. (19/14877-8, 18/25082-3, 23/00839-2, 23/04712-7, 19/25569-2, 17/22173-5, 23/09582-4)