SSRI DO NOT STOP WORKING. Valium and consorts (benzodiazepine, tranquilizers) do so after a while, then, yes, people have to increase doses, or get off it, get therapy, switch to something that doesn't stop working, smoke pot, jump off a bridge, join a space-alien-cult, learn painting, or whatever unlucky people do. Or maybe by that time the anxiety disorder or trauma or sleep difficulties for which it had been prescribed are just over, so they can wear it off.
Sertraline (a SSRI) & Co. do not stop working. I took it for a year, experiencing no decrease of the effect whatsoever. Some people take it much longer. That stuff just doesn't lose its effect. That is a very banal fact and not up for discussion, people should really get that right. It doesn't work that way - the brain can't "adapt" to it, like it does with morphine, by decreasing or increasing certain neurotransmitters. SSRI = "selective serotonin re-uptake inhibitors". One has more serotonin available because the used doesn't get removed so quickly. I can't deliver the details for why the brain doesn't adapt to that, but it DOESN'T. The surplus of serotonin is a lasting effect, as long as the drug is taken.
All drugs work differently. They interfere with our natural biochemistry in different ways. Some lose their effects, some do NOT. Even heroin can be taken as an example for what that means: the psychological effects (and others) diminish, so that one has to take more to have the same effect, and for not getting withdrawal symptoms - but the effect of respiratory depression does not diminish, or not that much. So people die of heroin addiction because eventually they suffocate, and because it also causes nausea and vomiting often they die by aspiration of vomit while unconscious. If any and all effects would wear off equally, that wouldn't be the case.
One can probably take Aspirin daily for ten years, and AFAIK it won't "stop working" - but one will get some serious medical problems, yeah.
I'll add a positive Sertraline anecdote, for the Scientologists lurking ... and other haters of medical drugs.
After a major depression, I took a low dose of Sertraline for around half a year. My depression was literally gone in a week, but the brain needs to recuperate, to change certain structures. The depression would have come back if I stopped it. So I took it for the recommended time.
The only physical side effects I had was a dry mouth, and "restless legs" for some nights when I started it. That's all.
Eventually I WANTED to stop it. Not because I felt addicted, or zombified, or giddy, or whatever the 50-100 year old horror tales are that basically all have developed around Valium (tranquilizer) & Haldol (antipsychotic). I just couldn't get the mental mini excesses that are necessary for art (and orgasms by the way). I had all the normal human emotions, but couldn't do certain types of art that previously gave me great satisfaction. I was used to do that art, but now I didn't have the emotional needs that made me do it, yet I still missed it for various reasons. So I became a bit "fed up" with that drug because such a large part of my life was missing; and at that point, the doc anyways said that the minimal time necessary for the brain healing was now over. I got off it without any problems, or feelings of addiction.
The second time I took it, years later, I chose (!) an even lower dose, I had to break these tiny tablets. This time I could even do all the art. I just learned to do it in a bit different way, for another motive, it's an adaptive process.
In short, I see that drug as a very mechanical way to get rid of a depression that has developed in an equally mechanical way for no good reason whatsoever.
One has to stop Sertraline gradually, over some weeks, but that has NOTHING to do with psychological addiction or any "craving", only with physical side effects that would otherwise appear. IIRC, spontaneous stings and twitches, dizziness, and such.
Apart from the seldom cases who get severe side effects for no foreseeable reason, like with pretty much
any drug, there's also that, please consider: some stubborn morons with zero understanding of the biochemistry involved and zero will to listen to their docs stop a high dose instantly because they "feel better", and then they moan that they are "addicted", and/or that they're getting "severe side effects". Bollocks.
http://en.wikipedia.org/wiki/Selective_serotonin_reuptake_inhibitor
Yeah, ya all, have fun with the conspiracy theory that "big pharma" could be secretly supporting CCHR ... because it "could be", and because it makes
some sense. Yeah, could be. So, everybody, listen up, Arnie has pulled something out of his ass that
could be. What an excellent reason to assume the worst case. So much for critical thinking.
Anybody who feels like delving into that, please check all the likely and unlikely
"why" and
"why not", using critical thinking, - that's all I recommend. Look at the "pros"
and "cons". Not only check the "why" and explore all the "pros", no matter how unlikely, just because that's the more
thrilling thing, and keeps producing the more perverse scenarios.
For example: how big is CCHR, what are they doing, what do they achieve, and how could big drug companies secretly support it. Money? People? I'm just saying. Who the fuck has ever heard of CCHR? That obscure bird shit of a Co$ front group, mainly serving as a propaganda producer for Co$-members, should interest big drug companies, to use it for some twisted propaganda scheme? Is that likely? Would that be effective, by any means? Would that make sense for the efficiency-obsessed people running a big drug company? So, what's the reality behind that? Really, if fathoming the details of that is entertaining for somebody, go have fun.
Just try not to lose contact with reality. 
Balance the factors against each other, and take a deep breath from time to time, and ask yourself whether you keep finding correlations
and bits of evidence, or whether you
merely keep spinning colorful tales - even when they could, theoretically, be possible.
Just as the plural of "anecdote" is not "evidence", the plural of "tale" is not "research" but "sequel". So to say.
The bipolar is something else, episodes can come from nowhere, for no obvious reason, and kept getting worse before I ever went on bipolar drugs.
