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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 12 of 12. This is the beginning of the thread.
Posted by SLS on January 26, 2009, at 16:58:42
Brain-Derived-Neurotrophic Factor (BDNF) is a substance that is responsible for supporting the viability of neurons and glia in the brain. Brain cells die without it.
Levels of the factor in blood decreases during manic or depressive episodes in proportion to severity. Because BDNF tends to normalize with effective treatment and euthymia, BDNF levels may be a useful tool and biomarker of active bipolar illness.
People with lower BDNF have smaller hippocampii. The hippocampus is responsible for memory (among other things).
Recent studies indicate that BDNF levels in the blood reflect levels in the brain.
Now, it is reported that intravenous administration of BDNF produces antidepressant-like behavioral effects in mice. It also fosters the growth of new neurons in the dentate gyrus of the hippocampus. This suggests the possibility that peripheral BDNF administration might act as an antidepressant and agent for neurogenesis.
It may be that low levels of BDNF are not only the result of affective disorders, but it might also act to help perpetuate the dysregulation producing an episode.
- Scott
Posted by linkadge on January 26, 2009, at 17:56:05
In reply to Blood BDNF reflects brain: Potential Treatment, posted by SLS on January 26, 2009, at 16:58:42
>Levels of the factor in blood decreases during >manic or depressive episodes in proportion to >severity.
I have heard the opposite (that BDNF levels are elevated in mania (and lower in depression)
http://www.journals.elsevierhealth.com/periodicals/ymehy/article/PIIS0306987703002974/abstract
Also see:http://www.accessmylibrary.com/coms2/summary_0286-35145560_ITM
"Lithium significantly decreased BDNF levels in patients with BD and healthy control participants, although BDNF levels remained lower (33%) in the BD group posttreatment. Conclusion: Decreased BDNF may constitute part of the pathophysiologic process of BD in a lithium-responsive subgroup of individuals with this disease."
>Because BDNF tends to normalize with effective >treatment and euthymia, BDNF levels may be a >useful tool and biomarker of active bipolar >illness.I don't necessarily think so. See the above study. There are others like it.
Clozapine and typicals lower BDNF:
Risperidal Lowers BDNF:
http://www.ncbi.nlm.nih.gov/pubmed/10861791?dopt=Abstract
Epival and Phyntoin decrease BDNF:
Ketamine improves depresson but does not increase BDNF:Chronic Stress induces depression in mice without affecting BDNF levels.
Neither desipraminem, prozac or nardil increse hippocampal BDNF levels
etc. etc.>People with lower BDNF have smaller hippocampii. >The hippocampus is responsible for memory (among >other things).
Show me a study which proves this.
Linkadge
Posted by SLS on January 26, 2009, at 19:06:21
In reply to Re: Blood BDNF reflects brain: Potential Treatment, posted by linkadge on January 26, 2009, at 17:56:05
My source of information was just published by the NIMH and bipolar network. Sorry.
- Scott
Posted by SLS on January 26, 2009, at 19:26:41
In reply to Re: Blood BDNF reflects brain: Potential Treatment, posted by linkadge on January 26, 2009, at 17:56:05
This is all you get.
- Scott
Posted by linkadge on January 26, 2009, at 19:29:42
In reply to Re: Blood BDNF reflects brain: Potential Treatment, posted by SLS on January 26, 2009, at 19:06:21
>My source of information was just published by >the NIMH and bipolar network. Sorry.
Its an honest mistake. I can't hold you to it.
Linkadge
Posted by linkadge on January 26, 2009, at 19:35:28
In reply to Re: Blood BDNF reflects brain: Potential Treatment » linkadge, posted by SLS on January 26, 2009, at 19:26:41
It doesn't say that these patients were unmedicated. As the link I posted mentioned, lithium decreased BDNF levels in bipolar patients *and* healthy controlls. Perhaps the significant decrease in BDNF levels in the study you posted was due to pharmachological intervention.
http://www.accessmylibrary.com/coms2/summary_0286-35145560_ITM"Lithium significantly decreased BDNF levels in patients with BD and healthy control participants, although BDNF levels remained lower (33%) in the BD group posttreatment. Conclusion: Decreased BDNF may constitute part of the pathophysiologic process of BD in a lithium-responsive subgroup of individuals with this disease."
Posted by desolationrower on January 26, 2009, at 22:14:40
In reply to Re: Blood BDNF reflects brain: Potential Treatment, posted by linkadge on January 26, 2009, at 19:35:28
BDNF in the striatum i think is associated with post-social defeat anxiety learning. blocking BDNF prevented adverse effects.
-d/r
Posted by Phillipa on January 27, 2009, at 0:23:24
In reply to Re: Blood BDNF reflects brain: Potential Treatment, posted by desolationrower on January 26, 2009, at 22:14:40
Okay if I follow? Don't know what BDNF is and too late to read now. Phillipa
Posted by SLS on January 27, 2009, at 7:17:40
In reply to Re: Blood BDNF reflects brain: Potential Treatment, posted by desolationrower on January 26, 2009, at 22:14:40
> BDNF in the striatum i think is associated with post-social defeat anxiety learning. blocking BDNF prevented adverse effects.
This is all very nice, but what does that have to do with my first post? Nothing.
What adverse effects? It is a "no brainer" that the lack of BNDF or its receptor prevents LEARNING. What you describe, post-social defeat learning, is exactly that. Cut off BDNF, and nobody learns nuttin', even the most uncomfortable and counterproductive of lessons.
Apparantly BDNF is not by itself a cause for depression and mania, but is associated with different mood states and is necessary for antidepressants to do their work. There is a dichotomy of functions of BDNF on stress and reward systems, as proBDNF and BDNF oppose each other. Again, though, this in no way refutes the observations and conclusions of those investigators who contributed to the work I wrote about in my first post.
I sure don't know everything there is to know about BDNF, however, I hope my brain levels of it increase so that I can come closer to doing so.
- Scott
Posted by SLS on January 27, 2009, at 7:32:22
In reply to Re: Blood BDNF reflects brain: Potential Treatment » desolationrower, posted by SLS on January 27, 2009, at 7:17:40
> I sure don't know everything there is to know about BDNF, however, I hope my brain levels of it increase so that I can come closer to doing so.
Actually, I doubt that I am going to spend very much more time studying this stuff. Now that I am functioning well, my focus will be in other areas of life.
We'll see.
- Scott
Posted by linkadge on January 27, 2009, at 9:54:20
In reply to Re: Blood BDNF reflects brain: Potential Treatment » desolationrower, posted by SLS on January 27, 2009, at 7:17:40
>Apparantly BDNF is not by itself a cause for >depression and mania, but is associated with >different mood states and is necessary for >antidepressants to do their work.
I disagree. There is no proff that BDNF is necessary for antidepressants to work. There are sevral studies which demonstrate that oftentimes clinically effective antdepressants work in the absence of any form of BDNF modulation. A quick search on pubmed also reveals severals studies of novel antidepressant compounds which do not modulate BDNF. If you expanded that claim to suggest it is the modulation of "growth factors" that is the target of antidepresants, this might be harder to refute. It has recently been demonstrated, for instance, that the growth factor VEGF appears to have some sort of antidepressant effects.
But, many studies are arising which are countering the notion that BDNF increase is a class effect of antidepressants.
>I sure don't know everything there is to know >about BDNF, however, I hope my brain levels of >it increase so that I can come closer to doing >so.
Excessive levels of BDNF can have negative effects on mental health. For instance, certain models of epilepsy are associated with really high BDNF levels. As well, boosing BDNF in certain brain regions appears to cause sensorimotor gating deficits as seen in schizophrenia.
Linkadge
Posted by bleauberry on January 28, 2009, at 17:30:49
In reply to Blood BDNF reflects brain: Potential Treatment, posted by SLS on January 26, 2009, at 16:58:42
I don't know about the BDNF stuff at all so I can't comment on that.
But I did want to comment on studies done on rats or mice.
Rat brains are not human brains. For example, studies that show that the drug DMSA removes mercury from brain tissues were done on rats. The brain barrier of rats is much more permeable than the human blood brain barrier. There is solid evidence DMSA removes rat brain mercury, but zero evidence it removes human brain mercury. And with this particular example, we are only talking about the brain barrier. We haven't even got to the brain yet. It is wrong to conclude that what happens with a rat is predictive of what happens to a human.
I could go on for a long time picking apart the flawed methods of study done with rats. In short, all of it is based on human assumption. We assume a particular behavior implies a certain thing. Studies that measure actual chemicals in blood or brain of rats, well, again, that does not mean it happens that way in humans. It might or it might not. Since we aren't going to do a biopsy of a live human brain, we can only go by assumption, which again, is not something to place all your bets on.
Whatever BDNF does in rats is in my opinion not reliable to predict what it does in humans. Rats are not humans. Similar, but no cigar. Even apes or monkeys are not a good substitute.
Whenever I see a study that involved rats or mice, I click the X in the corner and move on to the next study. Using a mouse of course. :-)
The human physiology is inherently unique from any other organism on the planet.
This is the end of the thread.
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