Originally Posted by
ScottFromWI 
And from what I've read, an SSRI is much more effective against depression than anxiety ( which is why I assume they call them anti-depressants ).
Here's how they work, just an fyi in layman's terms.
1) Serotonin is one of many brain chemicals. It is often responsible for regulating mood.
2) Brain cells (neurons) are not connected. They don't actually touch each other. Instead, there is a small gap between them. Brain chemicals enter that gap and land on the receiving neuron which changes it's permeability and allows positivly charged ions into the cell which creates an electrical impulse or "firing" of the neuron.
3) SSRI's (selective serotonin reuptake inhibitors) in short, increase the amount of serotonin in the brain. When serotonin is released into the gap, it lands on "landing sites" of the receiving neuron, causing it to fire. There are also landing sites on the sending neuron. When enough serotonin lands on these sending neuron landing sites, it signals the sending neuron to stop releasing serotonin. It's like an "auto" shut off which basically tells the cell, "OK, the gap is full of serotonin. You can shut off now"
4) What SSRI's do is land on those sending neuron sites and block them. This way, the sending neuron never gets the message to stop releasing serotonin. The end result, more serotonin is released into your system.
SSRI's are not the first type of anti-depressant. But they are the newest and have shown to have much less side effects from older MAOI's or Tricyclic antidepressants.
Hope this helps!