The “patient” has an incentive to overestimate the extent of his illness, since he can “get away” with certain things by claiming to be more sick than he is
People around the patient have an incentive to underestimate the extent of illness. They think the person is claiming illness only to extract sympathy and get away with things that would be otherwise not permissible
The second point here leads to internal conflict in the patient, as he can’t express himself fully (since others tend to underestimate). Feelings of self-doubt begin to creep in, and only make the problem worse
There are no laboratory tests in order to detect most kinds of “mental illness”. Diagnosis is “clinical” (eg. if 8 out of following 10 check boxes are ticked, patient suffers from XYZ). This leads to errors in diagnosis
The method of diagnosis also leads to a lot of people in believing that psychiatry is unscientific and some reduce it to quackery. So there is little the medical profession can do to help either the patient or people around him
That diagnosis is subjective means patients have incentive to claim they’re under-diagnosed and people around are incentivized to say they’re over-diagnosed
I don’t think the effect of a lot of medicines to cure mental illness have been studied very rigorously. There are various side effects (some cause you to sleep more, others cause you to sleep less, some cause impotence, others increase your mojo, and so on ), and these medicines are slow to act making it tough to figure out their efficacy.
There is a sort of stigma associated with admitting to mental illness. Even if one were to “come out” to people close to him/her, those people might dissuade the patient from “coming out” to a larger section of people
If you were to be brave and admit to mental illness, people are likely to regard you as a loser, and someone who gives up too soon. That’s the last thing you need! And again, the underestimate-overestimate bias kicks in.
Some recentstudies, though, show a positive correlation between mental illness and leadership and being able to see the big picture. So there is some hope, at least.