Posted by Elizabeth on June 4, 2001, at 22:44:43
In reply to Re: tryptophan depletion challenge, posted by Steeler Tookahn on June 4, 2001, at 17:28:29
> One of the researchers explained to me that occasionally the rapid “jolt” of tryptophan that we received seemed to trigger some sort of “braking” mechanism, so the body actually lowered the serum level of tryptophan temporarily. It only lasted about an hour.
That seems likely. There are lots of compensatory mechanisms like this, in the brain and other systems (notably the cardiovascular).
In depressed patients who are treated with sleep deprivation, there is often a relapse the day after, when the patient wakes up (IIRC). Tryptophan depletion can attenuate this -- probably a result of adaptations made to compensate for the TP depletion.
> Unfortunately, I don’t know if the study answered any questions about who might be more susceptible to a reduction in tryptophan –what depressive symptoms might indicate a more severe response and therefore, possibly, be most helped by tryptophan.
Tryptophan doesn't have a great reputation as an AD; however, most clinical trials compared it to imipramine. I don't know of any head-to-head trials of tryptophan vs. fluoxetine. TDC does have some predictive value in that responders seem to be more likely to respond to serotonergic or mixed monoaminergic action ADs than to nonserotonergic ones. My suspicion is that SSRIs are probably more effective than tryptophan in TDC responders. But how to find out without using drug company money (which, IMO, would hopelessly bias such a study)?
> From what I saw, nearly all of the patients suffering from depression had their symptoms exacerbated by the test. A few did not. Medical students were used as a control group to study the effects on a depression-free population. Nearly none of them seemed to be bothered by the test –other than upset stomach and a few headaches.
My guess is that the medical students were screened and those with a history of depression were ruled out.
> One of the students I got to know was quiet the whole day and I finally asked him what was the matter. He said, “I took that test yesterday and it was horrible. Now I know what you people go through”.
These people -- those who haven't been depressed but who respond to TDC -- are, as you surmise, believed to be at risk for or predisposed to depression. I wonder if that guy had a family history of mood or anxiety disorders, alcoholism, etc.
I sort of think it would be neat if all medical students were subjected to this. It wouldn't have an effect on all of them, but it probably would on a lot, and the others would get to witness it firsthand in their classmates. An excellent educational opportunity. (Presumably med students who were on ADs or had a history of depression would be ruled out.)
> It held out a lot of hope that biological markers would soon be found and “types” of depression would be uncovered.
Yeah. There's too little interest in that sort of research now. Today it's all about getting big research grants from drug companies. It seems like the medical research community has given up on finding truly novel treatments or understanding how to predict what treatment will work for whom, and the focus is mostly on developing new drugs that do the same thing with fewer side effects.
There have been a lot of studies like the one you describe. Do you remember the names of any of the researchers, or the research centre (hospital, university, drug company, etc.)?
-elizabeth
poster:Elizabeth
thread:59082
URL: http://www.dr-bob.org/babble/20010530/msgs/65422.html