I say this a lot, but it's true. If someone has a knee injury, or a broken arm, they'll go "This isn't working as it should. Please don't aggravate it". And people will talk to them, offer assistance, and it's normal. For some reason, when it's someone's brain that's gone on the wonk*, they won't talk about it freely (understandable), but if there's a hint of mental illness**, people shy away from talking to them about it. And it shouldn't be so. I'm a firm believer in sharing your shit***, and there shouldn't be as much of a stigma as there is.
*not to minimise it, at all. I have personal and professional experience of all manner of MH issues up to and including several messy suicides, and if I can offer help to one person to prevent them taking that step, I will gladly do so. I will use language that makes it more casual, because it's usually less scary for the person I'm talking to.
**covering the whole gamut, but particularly depression, self-harm and suicide ideation
***as often promoted by Bullshire Constabulary