Rejuvenation clinic

Doc after having removed the prosthetic makeup from his face.

"Sorry for the disguise Marty, but I was afraid you wouldn't recognize me. I went to the rejuvenation clinic and got an all natural overhaul!"

—Doc

A rejuvenation clinic was where a number of years could be added to one's life, up to 30 or even 40 years. Dr. Emmett Brown underwent the process between his departure from 1985 and his later return, possibly in 2015 or even further into the future. Treatments included hair repair, changing the blood, and replacing the spleen and colon. However, Doc thought he looked so youthful that he then added prosthetic makeup before returning to 1985 so that Marty McFly would be able to recognize him. Hair repair was presumably a way to delay or stop male pattern baldness or reverse it, as for unknown reasons Doc chose to keep his white hair (whether he thought this made him look more distinguished is perhaps best left to personal preference) as opposed to coloring it to blond as it had been during 1955.

Behind the scenes

• In reality, Doc tearing off his prosthetic makeup was simply because the filmmakers did not want to go through the process of making Christopher Lloyd look older anymore, nor was Lloyd keen on wearing any more makeup than was necessary. Plus, they didn't want Doc to be old when entering a relationship with Clara Clayton in the third film.

Actuality

• Since there isn't anything close to a rejuvenation clinic in medical technology as we approach 2015 for real, it's possible that what Doc went to was even further in the future. Having access to a time machine, Doc may well have made some investments in the past in order to afford what would likely be an astronomical fee for such an overhaul, or traveled into the future to a date when such services were routine.
• Even within the BTTF universe, there is no indication that major medical procedures like organ replacement were common as of 2015, nor that new organs were available as part of rejuvenation (transplanted organs, from donors, had been available in 1985). Although there had been advancements in plastic surgery, and businesses like Bottoms Up that provided the service, the type of wrinkle removal that Doc had does not appear to have been available; after teenage Jennifer was picked up by Officers Foley and Reese, they were surprised to hear that, according to their identa-pad, she was 47 years old, with Foley commenting "47? That's a hell of a good facelift." In addition, the elderly people seen by Marty in 2015 — Biff, Terry, George and Lorraine — look their ages.
• Finally, Doc simply says that he "went to the rejuvenation clinic", though not necessarily in 2015. The only information that Doc needs to impart to Marty is that (a) Marty needed to be in 2015 to prevent Marty Jr. from committing a crime and (b) there is a reason why Doc looks younger than he did when Marty had seen him last.

Appearances

• Back to the Future Part II (mentioned only)
• Back to the Future Part II novelization (mentioned only)