Posted by Adam on November 10, 1999, at 16:40:58
In reply to Re: VERY interesting theory on AD time lag.., posted by Bruce on November 10, 1999, at 12:41:04
Perhaps. My understanding of their theory is that stress (which induces production of the stress hormone cortisol) leads to damage, which leads to depression. If the stress is removed (say, a childhood trauma)
and the depression is releived, why should this process continue? And again, why should relapse occur so quickly?As for their proposition to use SSRIs as a treatment for Alzheimers, I recently attended a conference (mostly on gene therapy, though tissue grafting in that context was discussed). There are lots of people who
are looking to use neural progenitor cells from a variety of possible sources for just such a purpose, as well as other neurodegenerative diseases. It struck me that this approach (as a remedy) might save the patient
but not the person. If the formation of amyloid plaques isn't stopped, then older cells (which, one assumes, are the storage sites of old memories) will keep dying. Even if new cells could be coaxed into the
places where necrosis is occurring (a big if), they won't save what is lost, just replace it with something new. The brain normally has limited plasticity, and some theorize this allows us to retain long-term memory.
I could imagine a patient who, with constant reinforcement, might remember that their spouse is their spouse, but has long forgotten their wedding day, or why they fell in love in the first place. If there is
anything merciful about Alzheimer's, (my grandfather died of it), it's that the sufferer becomes so demented that they are no longer cognizant. To preserve awareness without curing the underlying disorder could be
as much a curse as anything else that might happen. It would at best only be a partial solution.>
> 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.
>
> Bruce
poster:Adam
thread:14806
URL: http://www.dr-bob.org/babble/19991108/msgs/14966.html