Scientists Discover Dark Side of 'Happy Hormone'

                It is known as one of the “happy hormones” and its discovery led to the development of what were hailed as depression “wonder drugs” like Prozac. But, despite being prescribed as a treatment for anxiety, these “SSRI” drugs designed to boost levels of serotonin (a happy hormone) in the brain had a strange and mysterious side-effect. In some cases, they initially made people feel more anxious or even suicidal. Now, a new study, has found that contrary to the popular view serotonin only promotes good feelings, it also has a darker side. US researchers delivered a mild shock to the paws of mice and found this activated neurons that produce serotonin in an area of the brain known to be involved in mood and depression. Increasing these neurons’ activity appeared to make the mice anxious. Using sophisticated equipment to monitor the mice’s brain then mapped what they described as an “essential” serotonin-driven circuit “governing fear and anxiety”.

The hope is that researchers will be able to identify a drug that inhibits this circuit and that people could takes for just the first few weeks of SSRI use to get over that hump. SSRI are usually the first choice medication for depression because they have fewer side effects. It says the common side effects of the drugs can include, feeling agitated, shaky or anxious, feeling or being sick, dizziness, blurred vision and low sex drive. The researchers said the next step was to find out whether the same serotonin brain circuitry exists in humans. It’s logical that it would since we know SSRIs can induce anxiety in people, and the pathways in these brain regions tend to be very similar in mice and humans. They suggested that existing drugs might be capable of blocking the anxiety inducing effects of serotonin. Researchers are hoping to identify a receptor in the brain that is already targeted by established drugs.