Well, when you do, let me know and we’ll change the world. k? 
Obviously, there is no one reason, but a confluence of factors. And the effective of these factors is not simply additive - 10% unemployment plus 5% increase in divorce equals 15% substance abuse and suicide. In complicated systems, the factors will interact to maintain a fairly stable state, until some tipping point is reached, like a pH buffered solution. Yeah, that makes sense, except major changes typically have some trigger, like the assassination of Archduke Ferdinand …
There’s the changing demographics, the golden children hitting 45;
the changing in the economic structure, the loss of the good blue collar jobs;
the social changes and the improvement in the situation and status of women and non-whites concurrent with the loss of opportunity for white men;
but no, I can’t see that one trigger, the seed of the crystal, to mix my chemistry metaphors.
Unless they just stopped dying of other things. Maybe death by suicide and destructive behavior increased in percentage, because death by stroke and heart attacks and industrial accidents and car crashes decreased so much.