Unlike suicide, depression operates ceaselessly at a low hum. A suicide is a loud clap that ripples through disconnected lives: it is known and felt instantly. But the slip into isolation before suicide, into the murk of the disease, rarely gets so much notice. We like to discuss the black, but not the fade. Subsequently, it's hard for friends to know how to interact emotionally with depression, and especially as it spans such a longer time period.

Depression is a thief. It'll rob you of your time, your thoughts, and your sense of self. But before all of that, it'll take your friends.

For me, the combination of bipolar, borderline personality disorder, and depression has manufactured a consistently brilliant cyanide capsule that I clench between my teeth in any and every relationship. Sadly it's almost a guarantee that eventually my friendships all get poisoned.

And I understand. For those around me it's so much easier to cut off a friend who is persistently difficult, self-absorbed, nasty, unpredictable, and decidedly other. And it's even easier to cut off a friend if they cut themselves off first.

I've run this story through my head a million times: one of my best friends—an unnaturally talented writer and a top bloke—slowly began to recede into himself. He cleared all his friends from Facebook, he stopped replying to calls and texts, and then he hauled himself up in his room like a hermit. We all knew what was happening. Friends kept messaging me: "Have you seen X? Is X okay? We should go and see X."

None of us ever went and saw X. That was two years ago and none of us have seen or talked to him since. He is not dead but he is gone. Hauled up in the mountain cabin of his mind. Losing a friend like this was like seeing a ghost pass through the two walls of a hallway—a kind of vanishing that leaves you feeling uncertain.