Psycho-Babble Medication | about biological treatments | Framed
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Re: VERY interesting theory on AD time lag..

Posted by Bruce on November 10, 1999, at 12:41:04

In reply to Re: VERY interesting theory on AD time lag.., posted by Adam on November 8, 1999, at 23:53:47

> Having said that, I do think it's just plain weird that they would attribute antidepressant action to increased
> neurogenesis, given what is known about such phenomena, which is not a whole lot. The paper showing definitively
> that neuronal stem cells do in fact exist only came out a short time ago. I don't think this new and very exciting
> discovery is all that well understood yet.
> And anyway, it doesn't take a genius to see there are some serious holes in this theory. One real problem it
> took about ten minutes for me to figure out (and I'm sure these guys thought of this) is why, if Prozac makes you
> grow new nerves cells, do the antidepressant effects go away so quickly once you stop taking the drug? They
> hypothesize that congenital defects and/or stress lead to a smaller hypothalmus, and this is an underlying cause
> of depression. Fine. Without even arguing that point, if in six weeks or however long it takes for the latent
> period of antidepressant action to end you have grown back whatever neurons you need to feel better, then why
> should you keep having to take the drug? To prevent further damage? Are they suggesting depression is a neuro-
> degenerative disease like Parkinsons? Neurodegenerative diseases can lead to depression, but it does not follow that
> that is the etiology of all depression, or even a significant fraction of depressive illnesses. Are they suggesting
> that neurogenesis in depressed people occurs at a slower rate than healthy individuals? I don't think anyone has
> demonstrated that. No one has had time to.
> Maybe there's something I'm missing here, but I don't think so. This is too much of a leap too soon for my tastes,
> and I have a hard time understanding how these investigators came so confidently to their conclusions.

I think the researcher's answer would be that, Yes, the new hippocampus cells generally would go away once you stop taking antidepressants. The same forces that helped produced the depression in the first place (cortisol-induced hippocampus shrinkage) would quickly reassert themselves and begin anew at eating away the hippocampus.

Many people need chronic AD treatment. A few months of treatment provides relief for a few months, but a relapse is highly likely once one serious depression has occurred.

You raise some good points. One question that occurred to me was, would another AD type also induce neogenesis? If it is just serotonin, how would this model explain the feact that people get better on norepinehrine or dopamine based drugs? Also, this model doesn't explain why only ~70% of people taking an SSRI get better. Presumably the extra serotonin would spur hippocampus growth even in the non-responders, yet they do not respond...

At any rate, it's a fledgling theory, and seems worthy of further attention. It cannot yet answer all questions put to it. You are probably right, in that there are many paths leading to the same outcome - depression.





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