Marshall - a one-time teammate of Incognito at the Miami Dolphins - has struggled with mental illness in the past, and has called for more players to start talking if there are problems within the locker room.
The 29-year-old told NFL.com: "What's going on in Miami goes on in every locker room. But it's time for us to start talking about this kind of thing.
"Maybe have some group sessions where guys sit down and talk about what's going on off the field or what's going on in the building and not mask everything. Because the longer it goes untreated, the worse it gets."