I know this is a professional pilot forum but bear with me. Just before Christmas 2014 a truck crashed into a crown of Christmas shoppers in Glasgow, Scotland killing 6 and injuring 15. Turned out the driver was suffering blackouts and despite being on medication did not till his employers for fear of loosing his job.
This is a global multi-industry problem it impacts aircrew, train drivers, coach drivers, passenger ship crew and probably a lot of people in other industries.
1 in 4 people will suffer a mental health issue at some stage (not all suicidal) and because the problem is global, it affects all cultures and nationalities, its no good one country bringing in regulations if nobody else follows suite.
So you have to design a system that will not stop the majority of people who now seek help, keeping quiet for fear of their jobs, and it being acceptable to all cultures and nationalities.
We need to change the perception of mental health issues, to employers, employees, governments and regulatory authorities on a global scale.
That is a very very big task, and persoally I cannot see it happening any time soon.
Hope I am wrong and somebody wiser than me comes up with a workable solution quickly.