The finding gives clues to what causes depression in people, how drugs like Prozac relieve it and why the effect takes so long to kick in. Just over a year ago, researchers showed that people grow new neurons all the time. This overturned a long-held belief that brain cells, unlike cells in other parts of the body, are not replaced when they die. Barry Jacobs and Casimir Fornal at Princeton University put together findings from several different brain studies. They also knew that chronic stress can slow neuron birth, or neurogenesis, in the brains of rodents.
Stress is thought to contribute to depression.
It just occurred to me that maybe this is what depression is all about. Jacobs and Fornal went on to show that activating one type of receptor for the neurotransmitter serotonin in rats' brains increased the birth of neurons. SSRIs prevent serotonin from being mopped up, leaving more of it around to transmit messages. The team gave daily injections of Prozac to five rats for 21 days. Five control rats were injected with saline.