Is eternal youth worth having? A middle-aged tech millionaire seeks the secret to never-ending adolescence for the affordable price of $2m (£1.6m) per year. But is never growing old all it is cracked up to be?
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
Eternal - Lasting forever.
Cryonics - The practice of freezing the bodies of people who have just died in the hope that future medical treatments will be able to save them.
Hubristic - Overly proud or self-confident.
Dementia - A syndrome associated with memory loss and other declining brain functions.
Dorian Gray - The character created by Oscar Wilde whose wish to stay young and beautiful is granted.
Aesthetic - Concerned with an artwork’s beauty. Aesthetics is the branch of philosopher that explores art, beauty and taste.