To cut a long story short, I’m working on a speculative fiction story (although, for a change of pace, it’s for an indie game, not a book ¬_¬) and one of the characters has an implant in their brain which was intended to release a series of neurotransmitters and psychoactive drugs as they grew up to prevent brain damage from being born prematurely (in-universe it’s ambiguous as to whether it did anything, so this doesn’t need to be plausible science. I’d still be interested if anyone had any thoughts on it though…particularly if you have any idea where it might be implanted).
I was planning (just to make their design a bit more interesting and easier to draw/recognise in sprite form) to have the character in question have naturally brown or dark hair that has blond or red sections.
Does anyone with a better knowledge of such things know if it’s scientifically plausible that drugs would cause hair to change colour?
Certainly not neurotransmitters, but I dare say that there could be drugs that could affect the color of hair as it grows. It would not change the color of already grown hair, because that is, to all intents and purposes, dead, and chemicals such as drugs in the bloodstream cannot reach it, but a drug could affect the color of new hair as it is created at the hair follicle.
Just recently I saw a story on line about people (in Germany, I think) whose hair was taking on a greenish tinge because of copper pollution in their water supply. (I may not have all those details right, but it definitely involved hair getting turned green.) On a loose definition of drug, you have a case of a drug changing someones hair color right there.
My dear bride, when she was on chemotherapy for CML, experienced a significant change in her hair texture and color. It became curly and reverted to her natural brown (which had turned grey before she was 25). So, yes, some chemicals can do this. Neurotransmitters? Probably not.