Instead, depression has more to do with brain cell activity, and especially excitatory connections. Normal activity is reduced in the depressed person, and it affects the ability to concentrate, remember and make decisions, says Prof Scott M Thompson from the University of Maryland School of Medicine.
Because serotonin can strengthen the communication between brain cells, researchers wrongly believed that its lack was a direct cause of depression. Although the theory was never proven, it launched the SSRI (selective serotonin reuptake inhibitor) drugs industry, which includes major brands such as Prozac, Zoloft and Celexa.
Instead of developing drugs that promote serotonin levels, the pharmaceutical industry should instead be focussing on promoting better communication between brain cells, says Prof Thompson.
(Source: Nature Neuroscience, 2013; doi: 10.1038/nn.3355).