‘It is a flaw in our cells that becomes a flaw in love’: doctor Siddhartha Mukherjee on the search for a cure for depression

When the oncologist and bestselling author of The Gene found himself drowning in a tide of sadness, he instinctively looked to cells for an explanation. Did the answers lie in the brain?

In the spring of 2017, I was overwhelmed by the most profound wave of depression that I have ever experienced. I use the word wave" deliberately: when it finally burst on me, having crept up slowly for months, I felt as if I were drowning in a tide of sadness I could not swim past or through. Superficially, my life seemed perfectly in control - but inside, I felt drenched in grief. There were days when getting out of bed, or even retrieving the newspaper outside the door, seemed unfathomably difficult. Simple moments of pleasure - my child's funny drawing of a weeping shark (Do the tears go up like bubbles, or just mingle into the saltwater?") - seemed locked away in boxes, with all their keys thrown into the depths of the ocean.

Why? I could not tell. Part of it, perhaps, was coming to terms with my father's death a year before. In the wake of his passing, I had thrown myself manically back to work, neglecting to give myself time and space to grieve. Some of it was confronting the inevitability of ageing. I was at the edge of the last years of my 40s, staring into what seemed like an abyss. My knees hurt and creaked when I ran. An abdominal hernia appeared out of nowhere. The poems I could recite from memory? I would now have to search my brain for words that had gone missing (I heard a Fly buzz - when I died - / The Stillness in the Room / Was like" ... um ... like what?). I was becoming fragmented. It wasn't my skin that had begun to sag, but my brain. I heard a fly buzz.