Tel Aviv University’s Dr Shai Efrati used hyperbaric oxygen therapy (HBOT) to improve the cognitive function and brain tissue of dozens of over-65-year-old volunteers. They received a 60-day course of 2-hours in a pressurized chamber 5 times a week, breathing pure oxygen for some of the time.

https://www.timesofisrael.com/israeli-doctor-claims-to-reverse-aging-with-pure-oxygen-treatment-study/