Whilst all these statistics can be disputed, and the magnitudes of increase adjusted accordingly, few psychiatric epidemiologists dispute that this change is real and substantial. Because many more of us admit that we suffer from these problems, it is highly probable that a higher proportion also has low serotonin levels. First identified in the 1940s, serotonin is just one of thousands of chemicals found at the place in the brain where physics and chemistry meet, the synapse. The synapse is a gap between the neurones which electrical impulses pass down. When the electrical current reaches the end of a neurone, it causes a chemical reaction in the synapse.
Many people unconsciously medicate their low serotonin levels using modern 'drugs of solace'.
Alcohol raises levels in the short term, lowering them subsequently. MDMA, the key ingredient in the recreational drug Ecstasy, leads to a temporary flooding of serotonin in the short term but, at least in animals, kills the serotonin receptors, causing permanent damage. Most people imagine that if a chemical is implicated in human behaviour its levels are caused by other chemicals or by genes. But in the case of serotonin, levels in animal and human brains largely reflect what is happening around them, socially and emotionally, now and in the past. If you are feeling lousy today, or in urgent need of a drink or a fix or a fling or a fight, you probably have low serotonin levels caused by the way we live now.