When we look at the brain of a depressed person, studies show that the hippocampus tends to be much smaller than average…the longer a person has been depressed the smaller the hippocampus becomes. The cells and networks literally deteriorate…Interestingly, many modern drugs, including those which affect serotonin levels, have an indirect effect on the growth of brain cells. This is why serotonin-based drugs seem to help some patients, but not for the reasons we once thought. Instead, they promote the release of other chemicals that ultimately stimulate neurogenesis, the growth of new neurons.