Here's "Four Horsemen" of another type of apocalypse: alcoholism. They are bone-chilling, indeed!
Excerpt found in the Big Book of Alcoholics Anonymous. (3rd edition)
Chapter 11 "A Vision for You" (pg 151)
"The less people tolerated us, the more we withdrew from society, from life itself. As we became subjects of King Alcohol, shivering denizens of his mad realm, the chilling vapor that is loneliness settled down. It thickened, ever becoming blacker. Some of us sought out sordid places, hoping to find understanding companionship and approval. Momentarily we did -- then would come oblivion and the awful awakening to face the hideous Four Horsemen -- Terror, Bewilderment, Frustration, Despair. Unhappy drinkers who read this page will understand!"

Of course, this description is not exclusive only to people suffering from addictions. Any seemingly incomprehensible situation could qualify. Some prime examples would be: severe mental illness, incurable disease, initial loss of a loved one...