There are many people around the world who struggle with mental health problems. To get out of heavy periods of dark thoughts, help often comes in the form of a pill. The small doses should ensure a form of balance in the brain. And there is one substance in particular that has long been closely linked to depression – namely serotonin. The Norwegian artist “Girl in red” has even written a song about the topic. The song starts like this: I’m running low on serotonin.Chemical imbalance got me twisting thingsStabilize with medicine But now researchers cast doubt on the link between serotonin and depression. They have reviewed research from several decades back in time, and find no clear connection. Can’t find good evidence Joanna Moncrieff is a psychiatrist and staff member at University College London. She has led the new study, which is published in Molecular Psychiatry. – I think we can safely say that there is no good evidence that depression comes as a result of deviations in levels of serotonin, she says in a press release. Together with other researchers, she has looked at 17 previous studies of various sizes. And the results show that serotonin’s role in depression is weak at best, the authors write. – This is important Bjørnar Hassel is a professor at the University of Oslo. Among other things, he has written professional articles in Store norske lexikon about serotonin. Hassel believes that one can agree with much of what the researchers in the new study write. He nevertheless has some reservations. – When they find no connection between depression and serotonin in the blood, it cannot be surprising. The blood levels of these substances do not say anything about the levels in the brain. At the very least, one should measure in spinal fluid (CSF), and even that does not give a perfect picture of the situation in the brain. But the professor thinks the study is important. – How one understands depression biochemically has something to do with how we see ourselves. How we understand illness and mental function. If we misunderstand, we get the wrong impression of how the brain works, he says to news. Facts about depression Photo: Henrik Bøe Depression is a condition characterized by lowered mood, lack of interest and joy and loss of energy or increased fatigue. About one in ten Norwegians will develop a depressive disorder within a year. Depression is an important cause of disability worldwide, partly because people live so long with the disease, often without good treatment. Worldwide, 264 million people suffered from depression in 2020. Depression returns in about a third of patients within 1 year of ending treatment and in more than 50 percent of patients during their lifetime. In severe depression, 75-85 percent have recurrent episodes. Calculations show that patients with depression will, on average, experience 4 periods of depression during their lifetime. Source: nhi.no Started in the middle of the 20th century The fact that disturbances in our mood arise from a chemical imbalance in the brain first became a theory in the middle of the 20th century. And it has to do with monoamines. Monoamines are a group of chemical substances in our body. These include dopamine, norepinephrine and serotonin, among others. Several of them play an important role as signaling substances in the brain. Early on, it was suggested that the neurotransmitter norepinephrine was out of whack in people with depression. Not long after, they also found a link between serotonin and people with mental health problems. As a result, a hypothesis called the “monoamine hypothesis” was developed in 1965. In the 80s, the sale of antidepressants began. These contained what is called selective serotonin reuptake inhibitors (SSRIs). The drugs increase the effect of serotonin in the brain. Since then, the link between depression and serotonin has been valid. However, this medication does not work equally well on everyone. About one in five say it has an effect Use of antidepressants has increased sharply since the 1990s. Research shows that only about one in five people find that the medicine works as a reliever. The researchers of the new study believe it is not difficult to see why the old hypothesis is well accepted among people. – Many people take such drugs because they believe that the depression has a biochemical cause. But this research suggests that this belief is not based on evidence, says Moncrieff. Nevertheless, she emphasizes that they do not encourage people to stop their treatments. It may be that serotonin works on other mechanisms, about which not enough is yet known. – But since so many people are addicted to these substances, it is important to find out what is really happening, says the psychiatrist. The researchers say their findings are important because studies show that as many as 85-90 percent of the population believe depression is caused by low serotonin levels or a chemical imbalance. Photo: Terje Pedersen / NTB Think genetics can be the answer Professor Bjørnar Hassel supports this. – Another point is that these medicines can work well against both anxiety and obsessive-compulsive behavior (OCD). Anxiety often accompanies depression, and these medications can therefore have a place in the treatment of depression by reducing this additional disorder. But all in all, the Norwegian expert believes that the connection between serotonin and depression is not very strong. He also does not think antidepressants with SSRIs work for mild depression. First of all, the serious kind. – There are a lot of different hypotheses for mental illness. The elders take the effect of one medicine as a starting point. More modern hypotheses are based on more recent knowledge – often genetics. Hassel believes that genetics will provide more answers to what lies behind depression in the future. – By, among other things, looking at the combined effect of many genes, all of which give a certain vulnerability to developing the disease.
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