The vast majority of my feelings not only can I not describe to neurotypicals, but I probably couldn't even described to my fellow world inmates. Even my resting state is basically "acidic low-level buzzing pain". This not only has no word in the English language, but is extremely hard to imagine well, if at all. And I am making quite a leap of faith in this instance that the same is the case for those who have other mental illnesses. But I'm not sure that it's quite that big a leap of faith, simply because ordinary people DEFINITELY do not know what a hallucination is like (unless they have partied particularly hardy) or the calm foreboding feeling before a bad episode comes into full bloom. And this is part of the reason, I've said before, that mental illness is completely non-intuitive to neurotypicals, making it harder to understand, harder to empathise with, and harder to even believe that it exists. But things don't need to be that way. The non-intuitiveness gap CAN be crossed, even if not everything can be explained.
Do Mental Health Awareness campaigns do enough to make people understand mental illness, if even to a limited extent? Probably. I don't really know, as I don't know the ins and outs of these things, but as it stands what I do know is that whatever they have tried hasn't worked yet. Do these campaigns tend to describe mental illnesses as simply as possible - as ABSOLUTELY simply as possible? The easiest way, I think, to bridge the non-intuitiveness gap is simply to come up with lots of little abstractions; hypothetical situations that don't describe mental illness in a clinical, detached manner (which might allow a reader to pretend it's just words and not a possibility). So instead of:
'Major depressive disorder (MDD) (also known as recurrent depressive disorder, clinical depression, major depression, unipolar depression, or unipolar disorder) is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities.', let's try 'Imagine a world in which everything you try is shot to pieces. Your energy has been stolen away. Every step provides a 200mg dose of pain delivered straight into your bloodstream. Nothing can hold your attention for long, because nothing gets rid of the pain. You doubt the world's sanctity. You doubt your sanity, and you doubt even yourself. You cannot escape the pain and hence you feel worthless. The future looks grim.'.
My description may not entirely cover all everything in a depression, and may not exactly be true to every depression, but I'd like to think at least, that it forces any reader to place themselves into the position of a person with mental illness, instead of allowing them to simply skim over the symptoms and say "Wow mental disorders are so totally fake. Look at these requirements! I could even have them! It's obviously the government trying to scam us again.". Clinical specifications are sometimes so unnecessarily broad and lacking an emotional outlook that people can easily be tricked into believing that they are ill when they are not, or that no one is ill because of the lack of description of the suffering involved. There is never a disclaimer saying: "If you are not suffering to quite some extent, or if your experience of life is not vastly different to everyone around you, then you probably do not have a mental disorder - and if you do, it is most likely mild enough not to impair you significantly."
But we shouldn't get rid of scientific description entirely. We should simply place side-by-side descriptions of worst case scenarios beside them, to make sure that people drop their prejudiced attitudes and show a bit of sympathy.
(Of course, I don't know if Mental Health Awareness campaigns actually do this or not. But I've never really seen a description that adequately expressed to me how horrible mental illness is. In any case, it's at least important, even if it's done already, to bridge the non-intuitiveness gap and tell people what mental illness is like, rather than bombarding them with detached words and nicey-nicey language. It's awful. Don't tone it down and make it seem trivial - I actually have seen this in some leaflets.)
*Really sorry I keep talking about depression. I feel if I started trying to describe other mental illnesses I'd somehow characterise them wrongly having not experience them myself. Not that I have run-of-the-mill depression, I mean, I get delusions and hypomania (on a rare occasion) and somewhat psychotic episodes where imaginary people talk to me. But despite not being diagnosed with anything in particular, it's not like I can suddenly pretend I understand what other people are going through. I don't, and I'm not going to pretend that I do. But since I've been depressed for the vast majority of my life, I think to some extent I should be able to help other people understand it.