SSRIs are small molecule chemical structures that are able to enter the brain and the cerebral spinal fluid. These drugs alter what occurs at the synapse-- the connection between two nerves where everything in the brain happens. The SSRI disables the serotonin re-uptake pump, a structure that sucks the serotonin back in to be recycled; nearly 100% of serotonin is recycled.
There are 15 known types of serotonin receptors that are grouped into 3 families. The receptors are known as 5-HT receptors, after the chemical name for serotonin, 5-hydroxytryptamine.
Initially the receiving nerve in the synapse gets more serotonin and you feel better for a while. But since the drug prevents serotonin from being re-cycled, eventually the serotonin becomes depleted, and you become serotonin-deficient. As receptor sites are being shut down, many of them are damaged and permanently disabled. When the dosage is increased, some relief is realized but that too is temporary, and more damage is being done at the higher dosage.
This physical alteration of the brain is troubling to say the least.
After a while there are fewer receptor sites, serotonin is depleted, and since serotonin can only be produced from an appropriate diet, these drugs all "poop-out"; the dosage needs to be continually raised. The only way to elevate serotonin levels in the brain is to consume food (or supplements) that contain tryptophan, which is an amino acid (a protein) that is necessary for the production of serotonin.
We must acknowledge that this bizarre antidepressant society of which we are part is much too recent to propose a prognosis that is meaningful. A vast landscape strewn with tortured, twitching and lurching bodies is probably a vision of the future that is too pessimistic. But to think everything will go back to normal is wishful thinking. We simply have to make the best of it, be pro-active, and be unrelentingly compassionate toward ourselves and toward all who are struggling to find their way through this mess.
Hang in there and just keep talking about it!