People may isolate themselves even more than usual or withdraw from favorite activities. Or the opposite may be true. A lot of times, people will try harder, will do more. They'll spend longer hours doing something involved with the farming (thinking) if I just try harder, it's going to turn out OK, ... One risk we run when people work longer hours is a greater chance of injury, maybe taking risks they shouldn't take.
If people are seriously depressed, suicide can come up. People may say the whole world would be better off without me. That may not sound like a big deal at the time, but that can be a signal that something serious is going on here. Suicide is very, very preventable. Part of it is just being observant, listening to what people have to say and not pooh-poohing what's going on with them.