In Saving Private Ryan does Captain Miller (Tom Hanks) is having early Parkinson's? It usually starts with main hand hangers and then arm...

I have looked for this on the net and there are claims that it is PTSD (Post Traumatic Stress Disorder), and not Parkinson's, but I couldn't find anything like shaky hands being caused by PTSD.

Is Captain Miller having early Parkinson's disease?