Is eternal youth worth having? A tech millionaire is taking blood from his own son to try and be young again. But what is so bad about growing old?
The man spending millions to be 18 again
Price of youth: Johnson spends millions every year on experimental treatments to de-age his organs. Glossary
Organs - Parts of the body that do a specific job, such as the heart or lungs.
Disease - An illness or sickness.
Eternal - Lasting forever.