The finding, made by researchers at Imperial College London, appears published in Biological PsychiatryThrough brain imaging they have found that people with depression have a decreased serotonin response280 million people suffer from depression in the world, according to the WHOPeople with depression have a low capacity to produce serotonin, according to a study carried out by scientists from Imperial College London published in the journal Biological Psychiatry. The so-called ‘happiness hormone’ has traditionally been related to the regulation of our mood, our appetite (also sexual), anxiety, fear or anguish. But now, for the first time, scientific evidence has been compiled through brain imaging that proves that people with depression have a decreased serotonin response. But that’s not to say that decreased serotonin is the underlying cause of depression. “This is the first direct evidence that serotonin release is reduced in the brains of people with depression,” the Guardian told The Guardian. Professor Oliver Howes, a consultant psychiatrist based at Imperial College and King’s College London, and co-author. “People have been debating this question for 60 years, but everything has been based on indirect measures. So this is a really important step.” SSRI drugs The finding also provides a plausible biological explanation for the effectiveness – still relative – of the main drugs used against depression, selective serotonin reuptake inhibitors (SSRIs). The hypothesis that It directly relates serotonin and depression arises after analysis of post-mortem brains and blood tests. The main problem scientists have in accurately measuring the relationship between serotonin and depression is that it is difficult to measure how these transmitters function in the brains of living people. “We can’t put a pipette in there and take a sample. This is as close as we’re likely to get,” Howes says. In their study, the researchers used 17 people with a depressive disorder or depression related to Parkinson’s disease. Along with them, 20 other healthy volunteers were recruited. All of them underwent a positron emission tomography (PET) scan, which uses a radioactive tracer to check how much serotonin reached certain brain receptors. Then, to stimulate the production of the ‘happiness hormone’ were given a dose of amphetamines.Studies showed that depressed people secreted less serotonin.The study published in Biological Psychiatry has aroused skepticism from the scientific community who consider the finding inconclusive. that the study does not provide convincing evidence that a serotonin abnormality is the cause or underlying mechanism of depression, or one of the causes or mechanisms. 280 million people with depression The authors of the study themselves admit that this is a first step that opens a line of research that must be expanded, but that opens a door to more precise treatments. The WHO Action on Mental Health 2013-2030 establishes the steps required to offer appropriate interventions to people with mental disorders, particularly depression.