Inflamed Bodies, Depressed Minds
The mysterious connection between the immune system and the brain
We all know depression. It touches every family on the planet. Yet we understand surprisingly little about it.
This dawned on me in an acutely embarrassing way one day in my first few years of training as a psychiatrist, when I was interviewing a man in the outpatient clinic at the Maudsley Hospital in London. In response to my textbook-drilled questioning, he told me that his mood was low, he wasn’t finding any pleasure in life, he was waking up in the small hours and unable to get back to sleep, he wasn’t eating well and had lost a bit of weight, he was guilty about the past and pessimistic about the future. “I think you’re depressed,” I told him. “I already know that,” the patient told me, patiently. “That’s why I asked my GP to refer me to this clinic. What I want to know is why am I depressed and what can you do about it?”
I tried to explain about anti-depressant drugs, like selective serotonin reuptake inhibitors (SSRIs) and how they worked. I found myself burbling about serotonin and the idea that depression was caused by a lack of it. “Imbalance” was the word I had heard more-experienced psychiatrists deploy with aplomb on these occasions. “Your symptoms are probably caused by an imbalance of serotonin in your brain, and the SSRIs will restore the balance to normal,” I said, waving my hands around to show how an imbalanced thing could be rebalanced, how his wonky mood would be restored to equilibrium. “How do you know that?” he asked. I started to repeat all the stuff I had just learned from the textbooks about the serotonin theory of depression, before he interrupted: “No, I mean how do you know that about me? How do you know that the level of serotonin is imbalanced in my brain?” The truth is that I didn’t.
That was about 25 years ago, and we still don’t have confident or consistent answers to these and many other questions about where depression comes from or what to do about it. Is depression all in the mind? Is my depression “just” the way I am thinking about things? But then why is it so often treated with drugs that work on nerve cells? Is it “really” all in the brain? To our friends and family who are depressed, we may not know what to say. If we are depressed…