Earlier quoted context omitted.
>> They also mentioned that it _might_ work by affecting serotonin in the brain, but no one actually knows yet; I don't even think we know with regards to any substance, i.e even why SSRI work - I think we have some good hypothesis, but nothing conclusive. I've even seen an ad on CNN for tardive dyskinesia that says 'the is thought to do something to dopamine' - Doesn't exactly inspire confidence but having suffered…
As you mention, most SSRI ads specifically note that it is thought to work by inhibiting serotonin reuptake...maybe. There isn't even strong proof that serotonin plays the part popularly believed. But SSRIs work for many people, and do seem to have an effect, so the theoretical is good enough for now.
Serotonin itself has little to do with depression at the synaptic level