-How much would someone's handwriting change in four years? I want it to be similar enough to Character A's old handwriting so that the recipient, Character B, is surprised to see it, but dissimilar enough for B to eventually dismiss it as someone else's writing. If that makes sense.
Things I got from google- Alcohol. Obviously that would change how you write, but I'd rather not have A get drunk to write the letter. It's meant to be a heartful apology.
Changing it on purpose- Not really what I'm looking for but I could work with it.
Partial blindness- A had an accident and is mostly blind in one eye. I'm sure this would affect handwriting but I got nothing except lots of stat tables and unhelpful sites.
Thanks in advance.
ETA: Thanks everyone, I have my answer now. :)