The Mean Girls star has endured a turbulent summer (10) which has seen her jailed twice and sent to court-ordered rehab.
Marshall was rumoured to have fallen out with Lohan on the set of Georgia Rule in 2006, after a studio executive reprimanded the actress at the director's request. The letter, which was leaked online, blamed "all-night heavy partying" for Lohan's "irresponsible and unprofessional" behaviour.
But Marshall appears to have put the past behind him, by insisting Lohan has a "great heart" and a bright future in Hollywood.
He tells Access Hollywood, "I feel bad that she's going through all this and I hope she gets it together. She's gotta go through the process... She said she thought she was good, she slipped, she's back and forth, but you know, she's got a great heart, and as soon as she gets situated where she can change, this is what we need.
"I am not a psychiatrist, I'm a film director - which is part psychiatrist, mind you! I got to know her - she's young and going through the Hollywood process of being in front of everybody and all the media, and that affects you.
"I hope she can come out of it, because she's really, really talented. (She's) really a good actress. So I hope she doesn't waste this gift that she was given."