Emotional Rollercoaster: A Journey Through the Science of Feelings. Claudia Hammond

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СКАЧАТЬ 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 concerns motivation. Depressed people usually find it very hard to get started on projects, or to make decisions.

      Finally and most intriguingly there are the cognitive symptoms – those associated with thoughts. Even feeling slightly sad can affect the way a person thinks. This can be illustrated by a simple word experiment: participants listen to either happy or sad music through headphones. Afterwards they sit in front of a computer and letters are flashed up on the screen. This is a standard psychological test called a lexical decision task, where the letters on the screen sometimes form a word and sometimes don’t. The task is to identify the real words as quickly as possible. Those who had been listening to happy music were faster at spotting the words associated with happiness like ‘delight’, while the people who heard sad music identified the sad words like ‘weep’ the fastest. If the way the brain processes words is affected by a temporary music-induced mood then for a clinically depressed person these changes will last much longer. Unfortunately these shifts in thinking can help to maintain a person’s depression.

      Depressed people often perceive themselves to be useless and begin to believe that anything that goes wrong must be their fault. Imagine what you would think after you’d accidentally dropped a glass and broken it. If you’re not depressed you might be briefly annoyed with yourself, but as you cleared up the fragments of glass, you would probably console yourself with the fact that it was an accident and that these things happen. A depressed person is more likely to blame themselves, to see it as further proof that everything always goes wrong for them and that it always will. The depressed person looks round for evidence to support their view that everything’s hopeless, while dismissing any good fortune as pure chance. Addressing these sorts of thoughts provides the basis for cognitive therapy for depression.

      Chloe found that her depression forced her to stop and take stock of her life. She felt that she had been so happy previously that she hadn’t been sufficiently self-analytical. A tragedy in her life also provided something of a turning point. A few months after starting on Prozac she was feeling slightly better and went to Australia to visit a friend, but became very depressed once more. Then on 12th September 2001 she heard that a friend of hers was missing after the destruction of the twin towers in New York. She flew to New York to help his wife in her search, but he had been killed. For the first time in years, Chloe found that someone else needed her help and she couldn’t be the sad person anymore. After five weeks in New York, helping her friend to arrange a memorial service, she realised that she was able to deal with practicalities and, despite her grief, she found that she could do something she had not done for a long time – laugh.

      why do only some people become depressed?

      Traditionally, an expert’s answer to this question depends on the theoretical background in which they are working. One of the most plausible explanations and one that we can all relate to, is that social factors play a large part. It wouldn’t be surprising for depression to be present in a tough life where lots of things go wrong. A landmark study conducted in the seventies by two British sociologists George W. Brown and Tirril Harris, found that the biggest risk factors for depression in women were caring for three children under the age of five, with no family or friends in whom to confide, and having lost a mother before the age of eleven.

      However, your chances of getting depressed might have been set in stone long before adulthood, even before birth. If one of your parents or siblings suffers from clinical depression it makes the likelihood of you becoming depressed between one-and-a-half and three times more likely. This doesn’t prove that depression is simply a genetic condition. Instead you might learn from a parent or sibling that depression is the best way to respond when things are going badly. A different person might turn to violence or alcohol abuse instead. Twin studies are the standard way of separating the influence of genetics from the effect of life experiences – in other words nature and nurture. The theory is that if identical twins are brought up separately then any differences between them must be down to the environment rather than genetics, because both twins have the same genes. If one identical twin develops depression there’s almost a fifty-fifty chance that the other twin will too, indicating a role for both genetics and life experiences. However, it’s not simply the case that there is one gene which predisposes you to depression, or not as far as we know. For some reason various genes seem to be implicated.

      Other researchers believe that to get to the root of depression we should study chemical changes in the brain. However, this need not rule out the influence of the environment. The work on serotonin is a good example of how all these factors can work together. Studies of monkeys in the early 1990s demonstrated that the dominant members of the group had higher serotonin levels, but that these levels weren’t permanent. If a monkey was removed from the group by the experimenters its serotonin levels fell. The same СКАЧАТЬ