To illustrate how horrible it was, being in jail in a wheelchair with four broken limbs after the car accident that prompted me to get sober ... was much, much easier and less painful.

Comedian Rob Delaney’s description of severe depression is enough to stop you in your tracks. How can a mental illness, a disorder of thought and emotion, feel so much worse than the most intense physical discomfort? And yet it’s not unusual to read about metaphorical bouts between illnesses in which the black dog always wins. “It’s a piece of cake in comparison with depression,” said Majella O’Donnell, of breast cancer. Even in the realm of mental anguish, it pummels all competitors into submission. Lewis Wolpert found it “more terrible even than watching my wife die”. A pain worse than fractured bones, cancer and grief. What is this state, which around 10% of us can expect to experience at least once in our lives? Where does it come from, and what can be done about it?

The surprising news is that experts find it hard to agree on a definition. I ask Oliver Robinson, a neuroscientist specialising in psychiatric disorders, to tell me what depression is. “I am asked that quite a lot actually,” he tells me. “The answer I generally give is that I literally have no idea.” How can that be? Robinson points out that depression is unusual among medical conditions in that it’s identified via symptoms alone – a doctor will make a judgment based on criteria such as lack of enjoyment, insomnia or loss of appetite. But hypersomnia (sleeping too much) and overeating can show up as well. Two people with a diagnosis of depression can present very differently.

That’s because, according to Robinson, the causes of their low mood might be very different. “Where a cough is a symptom we don’t diagnose a ‘cough disorder’, right? A cough could be bronchitis, it could be lung cancer, it could be a cold.” This is why drugs that work well for some have little effect on others. “Different underlying mechanisms probably require fundamentally different treatments,” he says. But our understanding of those mechanisms is, in any case, pretty sketchy.



‘One psychiatric textbook urges doctors to look out for ‘a turning downward of the corners of the mouth and … vertical furrowing of the centre of the brow’.’ Untitled (Big Man) by Ron Mueck. Photograph: Oliver Lang/AFP/Getty Images

The role of neurotransmitters, such as serotonin, dopamine and noradrenaline, has been emphasised because medicines that were – accidentally – found to alleviate depression acted on them (the first anti-depressant, Iproniazid, was developed to treat tuberculosis). A more recent focus is the the way different parts of the brain communicate. Illness may occur when these circuits become disrupted. Even then, Robinson says, “whether it’s a result or a cause is entirely up for debate”.

If the precise workings of the depressed brain remain obscure, is it better to ask what depression feels like? Samuel Johnson wrote of the “black dog” of melancholia (a phrase later adopted by Winston Churchill) in the 18th century, and blackness seems to crop up frequently in descriptions of the illness. It is a “black stone in your heart”, a heavy “black cloak”. The association is with darkness, an inability to see beyond the miasma of repeated, terrible thoughts. Heaviness is a common theme too. The term “leaden paralysis” is still used by doctors to refer to the sensation of being weighed down, the sluggishness of a slow-to-respond body.



If limbs feel as though they are in chains, the mind does too. Rumination – a tendency to get stuck the same negative pattern of thinking – is a common symptom. The pattern is often self-reinforcing, as another neuroscientist, Marc Lewis, explains. “Any set of thoughts that is repeated builds synaptic pathways. Thoughts that are repeated over and over build structure into the brain and therefore increase their own likelihood.”

This is the essence of habit formation, and in extreme cases, addiction. In those situations, however, there’s a payoff – whether it’s the satisfaction of completing your daily crossword or the pleasure of an addictive drug. Why should negative thoughts recur? “Because we keep trying to find a way out of them,” says Lewis. “The possibility that I am bad, that nobody likes me, that I’m not doing well enough, the fact that I’ve lost my job and can’t figure out what to do with my life: those kinds of thoughts draw us in. You try to fix [the problem], you try to correct it, you rehearse it.” As time goes on, he says, “you build your prison by continually repeating those particular thoughts. Until that becomes your mental world.”



Melancholy (detail), by Lucas Cranach the Elder, 1472-1553.

For Louise John, who first experienced depression at university, the illness was like “a giant black cloud that will suck any kind of personality or positivity out of somebody. You are just left a shell,” she tells me. “There’s no desire or care to do anything, with no obvious way out.” Rather than losing her appetite, Louise ate a lot, and put on weight. Nevertheless, she was obviously unwell. “When I look back on pictures now, I just look grey. I just look ill.”

A truly scientific definition may still elude us, but professionals tend to agree that you usually know a depressed person when you see one. This may be because it shows even in the way you carry yourself. A 2009 study found that “gait patterns associated with sadness and depression are characterised by reduced walking speed, arm swing, and vertical head movements”. One psychiatric textbook urges doctors to look out for “a turning downward of the corners of the mouth and … vertical furrowing of the centre of the brow” while noting that “some patients maintain a smiling exterior despite deep feelings of depression”.

Descriptions of “clinical signs” form part of an long tradition. According to 17th century scholar Robert Burton, Hippocrates reckoned that the outward signs of melancholy included looking “hollow-eyed … old, wrinkled, harsh, much troubled with wind, and a griping in their bellies, or bellyache … dry bellies and hard, dejected looks, flaggy beards”. Burton himself wrote that melancholy caused people to become “lean … uncheerful in countenance, withered, and not so pleasant to behold, by reason of those continual fears, griefs, and vexations”.

Burton’s earthy language calls to mind some of the more unpleasant afflictions of early modern life: scurvy, the plague, or worms. And yet we’re obviously dealing with an entirely different kind of disease. It’s doesn’t arise because of the absence of some vital nutrient. It can’t be caught, like an infection. It’s not a parasite that can be swiftly dispatched with a short course of the right drug. The mysterious nature of depression has led some to argue that it has its basis in the normal functioning of the human mind and body – a functioning that is somehow disrupted and made malignant. It’s even been suggested that depression emerged because it helps us survive. In other words, it evolved because it is adaptive.

Melencolia, by Albrecht Durer, 1471-1528.

It’s hard to imagine that depression could ever be useful. But picture our distant ancestors: they lived cooperatively, though there was always an element of competition. In one scenario, an individual is faced with a difficult social problem, like the loss of status due to an injury or an inability to find a mate. In becoming depressed they forget about trivialities and concentrate intensely on the issue at hand – they ruminate. As a result, it’s said, they’re more likely to find a solution. Here, depression is a way of focusing mental resources in order to figure a way out of a tricky situation. In another, falling into despair and becoming incapable of looking after yourself forces others members of the group to take greater care of you. Depression is, in other words, “a strategy for extorting investment” from your peers.

In his review of the literature, behavioural scientist Daniel Nettle gives these theories short shrift. In contrast to genuine evolutionary adaptations, such as colour vision, those who don’t experience depression aren’t put at a disadvantage. Also, the illness frequently returns regardless of social context: in the adaptationist model, it should disappear once the problem is solved and only reemerge in response to another, similar, difficulty. Not only that, but, left untreated, it can damage relationships rather than strengthening them.

So if it’s a disadvantage, how come it hasn’t been evolved away? Nettle argues that depression could be the result of a complex trade-off. He uses the example of height: reproductive fitness increases the taller you are, up to a point, when the problems outweigh the benefits – very big babies, for example, are more likely to die in childbirth. But height is determined by a large number of genes that also play other roles – so the possibility of being too tall or too short simply can’t be eliminated by natural selection.



It’s the same with “emotional reactivity”. Increased reactivity (otherwise known as neuroticism) brings some benefits: an obsessive striving after goals and a tendency to avoid risks. Beyond a certain point, however, it increases the likelihood of mental ill-health. In other words, depression is a spectre that will always accompany the human race, even as it continues to adapt better to its environment.



People are resistant to drugs. 'Oh it’ll mess with my brain.' I say ‘but you have half a bottle of wine every night!’

We’ve spoken of brain circuitry, the black dog, repeated thoughts that build a prison, competing evolutionary pressures. And yet the explanations are not exhausted.



For Sally Willis, a psychoanalyst of 30 years experience, depression is a way of defending yourself against overwhelming thoughts and emotions, usually generated by childhood trauma. Anything can be a defence, she says: drinking too much, getting into abusive relationships, anger, mania, getting very stressed. Depression is brought to bear when there’s nothing else left in your armoury. “It’s like a blanket over feelings that are unacceptable to the conscious mind. It absolves you of all responsibility to say ‘I have these feelings and I need to attend to them’. But it’s a very unpleasant way to opt out. It’s agony really. I’ve suffered from depression myself. It’s physical, it’s emotional, and it’s too much.”

I’m surprised to find how relaxed Willis, who describes herself as a “modern Freudian” is about drug treatment. Some psychoanalysts believe that pills only hold symptoms at bay and interfere with the process of “working through” – gradually bringing the unacceptable feelings into consciousness and engaging with them. In fact, she says, “a good psychiatrist is like a wizard. It’s extremely interesting to me how many people are resistant to drugs. They think – oh it’s going to mess with my brain. And I say to them ‘but you have half a bottle of wine every night!’ And that’s far more dangerous than these drugs which are nowadays so specific and so targeted.”

Willis believes that when a patient is seriously ill, psychiatry is a vital means of addressing the disrupted brain chemistry. Psychoanalytic treatment can then be used to treat relational aspects of the illness – the dynamics that exist between the self and others. I ask what aspect of Freud’s theory of depression, formulated nearly a century ago, well before anti-depressants and brain scans, she sets most store by. “He brilliantly said – he used the word ‘compelled’ but I often use the word ‘doomed’ – we’re compelled to repeat what we haven’t worked through.” In the technical jargon, this is known as repetition compulsion, a drive to replicate an early trauma, to set up situations in which it gets played out over and over, albeit with different people. “I see it again and again. People are compelled to repeat what they haven’t worked through.”

Which, interestingly enough, brings us back to contemporary neuroscience, and Marc Lewis’s view of the brain stuck in a rut. Borrowing from complex systems theory, Lewis calls depression “a very strong psychological attractor”. The dictionary definition of an attractor is “a value or set of values toward which variables in a dynamical system tend to evolve”. That’s not so easy to grasp – but think of it as a sort of sinkhole, a point to which a rolling ball in a landscape will start to move once you’ve given it a push. “Depression is a place to which mental processes converge when they’re perturbed from different starting points. Once the attractor grows in power it becomes a more and more likely outcome for any given stream of thoughts,” he says.

Complicated as it, this is the best definition of depression is that I’ve come across. For those with a genetic disposition, it exerts a gravitational pull. Very often that pull can be resisted, but sometimes, given a knock, you can’t help but roll towards it. Is there a way to break out of its orbit? We are very lucky to live in an age when psychiatrists can be described as “wizards” rather than jailers. But pills seem to work best when you take them on the couch.

Lewis, who was once addicted to heroin and speed (and wrote a brilliant memoir about it), told me this: “Around the time I quit drugs, I was 30, 32. I got into psychotherapy for a while and I had a pretty good therapist. And I felt real pure sadness for the first time in many years.

“It was amazing. I was like, ‘Oh, this is what sadness feels like, this is what I’ve been fighting all this time, or denying or resisting.’ And I think with depression you have sadness, but you keep fighting it … it’s sadness plus anxiety. When you have pure sadness – that can be kind of a relief.”

He also believes the practice of mindfulness can help. But what does mindfulness actually do? According to Lewis, it builds a capacity for self-acceptance. “To forgive yourself you have to first just be with yourself, to just sit here and say OK, this is who I am, this is what I’ve got, this is not evil, I’m not Adolf Hitler. You know – it’s not perfect, but this is who I am. And once you stay there for a little while, I think you can start to accept and forgive. That’s pretty fundamental.”

Useful websites: depressionalliance.org (UK) samaritans.org (UK) adaa.org (US) suicidepreventionlifeline.org (US) www.sane.org (Aus) lifeline.org.au (Aus)