In Tierra del Fuego local people tried to explain to Darwin that the captain of the boat was feeling sad by pulling down their cheeks with both hands to make the face as long as possible. Darwin went to great lengths to explain another feature of the expression of sadness which he called ‘obliquity of the eyebrows’. The ends of the eyebrows nearest the nose are raised, causing the brow to furrow slightly. He calls this the grief muscle and notes that although it is contracted when we feel sad, only some people can move it voluntarily, an ability which seems to be inherited. The world-renowned expert on facial expressions, Paul Ekman, has studied identical twins who were raised apart and discovered that if one twin is able to flex this muscle, so can the other.
Along with general posture and tone of voice, facial expressions help us to spot emotions in others, but while some people are excellent at reading these signals and working out how another person is feeling, others won’t even notice. In fact the emotions we are best at observing in others are the same emotions we are experiencing ourselves. Therefore, although one might expect a depressed person to be too unhappy and concerned with their own misery to notice how someone else is feeling, in fact it’s the reverse. Depressed people are the fastest to spot depression in others, while happy people are best at noticing the emotions of other happy people. It’s almost as though the feelings we are currently experiencing ourselves are so strong in our consciousness that we find ourselves drawn to that feeling in others.
the sad mind and the sad body
Three years ago Julia wheeled her trolley past an empty customs desk. Her trip to Vietnam had been fantastic and as usual when she was tanned and rested, she felt great. Wouldn’t it be nice if someone had come to meet her? To her surprise she saw that someone had. Her sister’s boyfriend was leaning grimly on the barrier, but it wasn’t nice at all. Why was he here? What had gone wrong? Had her mother’s cancer come back? No, it wasn’t that. He told her that everyone was safe, but that her parents’ thatched cottage in Suffolk had burnt down. Julia was devastated. ‘It was a 400-year-old cottage and my dad had lived there since he was ten. When I got back to my sister’s house she showed me the front page of the local paper and there was a picture of my dad who’s an artist, holding one of his pictures with the headline, “Artist Loses Life’s Work” and he was crying. It felt as though I were looking at a newspaper that had been used as a prop in a film. I kept thinking that my kids will never see the house where I grew up. I think when sadness is at its worst you wake up and for five seconds you think everything’s OK and then you have this sudden shock that something’s happened. It’s almost like someone’s pressing an iron bar down on your chest. True sadness to me is like a physical pain. My heart actually hurt for weeks and weeks.’
It is true that sadness has physical effects on the body. Skin conductance, associated with sweating, increases and even intestinal processes can change. A patient called Tom, from a case study in 1943, had a stomach which became pale whenever he was depressed and, back in the 1920s, it was found during other research that depressed patients secreted less gastric acid into their stomachs than usual. There are also hormonal differences between the depressed and the non-depressed. About half of those with depression seem to have abnormally high blood levels of the hormone Cortisol which is released during times of stress under the control of a brain system called the HPA axis. This causes a cascade of chemical reactions. A small area of the brain called the hypothalamus (H) organises activities such as sex-drive and the control of body temperature. It releases a hormone which affects the pituitary gland (P) which in turn causes the adrenal glands (A) above the kidneys, to produce the stress hormone Cortisol, hence the name HPA axis. Crucially, for some people this control system doesn’t seem to work, resulting in an excess of Cortisol.
Naturally the main organ affected by sadness is the brain. There are changes in the levels of neurotransmitters or chemical messengers which communicate between the millions of neurons in the brain in a kind of relay race. One of the most important is serotonin which is ejected in a burst every millisecond and seems to have an involvement in almost everything that happens in the brain, without having the sole responsibility for any single function. When we feel depressed serotonin levels are lower. This is the basis on which anti-depressants like Prozac work. Prozac is an SSRI or selective serotonin reuptake inhibitor. Normally when serotonin is squirted out of the nerve ending it acts on receptors in the brain and if too much is released it’s taken back up into the nerve endings so that it can be recycled. The idea of drugs like SSRIs is to block this process, so that instead of being taken back up, the serotonin can spend longer in contact with the receptor and have more of an effect on mood. The effect, however, is far from immediate. When Julia took Prozac when she was depressed it was a few weeks before she noticed a difference. ‘You take it for a few days and you wonder why you’re bothering because you still feel terrible. Then very gradually it starts to work. It’s not as though you suddenly feel high or happy; it’s more as though your real self has been covered up and something in the tablets uncovers it and lets you be yourself again.’
If SSRIs can increase the amount of serotonin which is active in the brain and serotonin can make you feel happier, then it should follow that we could all feel more cheerful if we took an SSRI. However, in a non-depressed person these drugs have no effect on mood because of the way that serotonin operates in the brain. It’s not like dopamine, the neurotransmitter which causes us to feel joyful. If you are not depressed then SSRIs make no difference to the way you feel. In fact, even lowering your levels of serotonin artificially leaves your mood constant if there is no history of depression in yourself or your family, suggesting that a vulnerability to depression is the key. If you have had depression before and your serotonin levels are lowered medically then you will feel depressed once again. For some reason studies have found that women’s serotonin levels are easier to lower artificially, while men’s brains appear to be better able to compensate for these chemical changes induced in a lab. Phil Cowen, a psychopharmacology professor at Oxford University who has worked on SSRIs for several years, described this phenomenon as a little like a scar. Once you’ve had depression the scar remains. Somehow those pathways in the brain have been disrupted. It’s also complicated by a natural variation in the number of receptors for serotonin that each person has. It can only have an effect if there are receptors to receive it.
a diagnosis of depression
The distinction between depression and sadness could be classified as a differentiation created by society. Extreme, prolonged sadness can reach a point where friends and family are unable to help. At that point, as with Chloe, they entreat the person to seek professional help and the symptoms are labelled as an illness – clinical depression. This diagnosis came as a great relief to Chloe, providing her with an explanation for her feelings whilst absolving others of any blame.
Symptoms of clinical depression fall into four categories, but a person doesn’t have to experience all of them for a diagnosis of depression. The most obvious are the emotional symptoms. People are often saddest and most tearful in the mornings, using words like ‘blue’, ‘hopeless’ and ‘lonely’ to describe their mood. It can be accompanied by anxiety and a lack of pleasure in normally enjoyable activities such as eating tasty food or seeing friends. Then there are the physical changes – waking very early in the morning, loss of appetite and loss of interest in sex. The third type of symptom