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Post by Amtram on Feb 1, 2014 8:47:51 GMT -5
I just want to throw this out there. We can get to sharing evidence and studies and such as we go. Once again saw ADHD described as a dopamine deficiency. Like it's that easy. To my way of thinking, if it's as simple as that, we should be able to administer an agonist or a reuptake inhibitor for dopamine, and that should take away all the symptoms for everyone. And honest to goodness, I'm not seeing much evidence of that being successfully put into practice.
Even testing for the presence of the DRD4 gene shows that it's not there for everyone with symptoms. Maybe it's there more frequently in the ADHD phenotype, but if it's not there all the time, then is the problem with the broad category of diagnosis? Is it something that we'll figure out by looking at individual symptoms instead of the collection of symptoms that comprise a diagnosis? Is it grasping at straws by researchers? Is it misinterpretation of the findings by the press and laypeople?
IOW, how much is speculation, and how much is hypothesis based on evidence? Where do we think it's going to get us?
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Post by tigger on Feb 13, 2014 14:26:39 GMT -5
Methylphenidate is a dopamine agonist. Unfortunately, while it does attenuate symptoms, it isn't the whole story. Dopamine deficiency is accurate as a description but WAY too simplistic which I believe is your point.
Way to much about what is "known" about ADHD isn't really well "known". I think that researchers out there are trying to both figure out the neurobiology while keeping it all simple enough for the layman to understand. The average person might understand dopamine deficiency but not the significance of DRD4 presence.
I go back and forth with this issue. Something I have seen over the years is that issues that I always believed were simply part and parcel with ADHD are being called out as independent disorders. These include Sensory Processing Disorder and Dyslexia, Dyscalculia, and Dysgraphia. Are they comorbid or elements of the whole?
In order to know what we're looking for, we need to be able to quantify it. Is ADHD accurately described solely as issues of hyperactivity, inattention and impulsivity or do we need to also consider other things that apply?
Then we have Dr. Barkley's contention that ADHD-PI is not ADHD at all but something else. While not yet definitive, his research seems to indicate that the sole presentation of inattentiveness is significantly different to ADHD and follows a different treatment protocol even though the medications for treatment are the same as the medications most effective for ADHD.
To me, we are in a phase of throwing every reasonable hypothesis on the table and then tossing off those that don't prove out. Confusing, perhaps, but a vital phase that hopefully will improve what we know.
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Post by Amtram on Feb 13, 2014 15:01:46 GMT -5
I got to thinking about this again when I was looking at the non-stimulant medications for ADHD, and saw. . .norepinephrine reuptake inhibitors with nearly no affinity for dopamine receptors.
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Post by tigger on Feb 13, 2014 15:24:19 GMT -5
Yep. I believe that the validation is around the balance of neurotransmitters... except that the explanation doesn't hold when the neurotransmitter under discussion is serotonin. While I haven't found a study on this, anecdotal evidence indicates that many ADHDers can't take medications that alter serotonin. I'm one of those. I develop serotonin syndrome with even minuscule doses of SSRIs. I'm also sensitive to SNRIs- Wellbutrin living in that category.
Oddly, I also don't do well on Adderall. The increased anxiety was tortuous. The only thing that has ever worked at all for me is methylphenidate. And nicotine. Nicotine helps a ton. Nicotine is considered to be a dopamine agonist. Go figure. I'll dig out the studies on ADHD and smoking. There are a few.
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Post by dizfriz on Feb 28, 2014 10:36:26 GMT -5
The problem is that nothing about neurobiology is simple, just the opposite. While there is a lot we know about ADHD and neurobiology there is a whole lot more we don't know so in explaining it, it is best sometimes to keep it simple. Discussing ADHD as a dopamine issue is a good example. There is a lot more to it than that but we can sometimes overwhelm with details. I know, it is what happens to me when I try to read deeper into the subject. When I try to watch videos on neuro, sometimes it is too much too fast for my aging brain.
Dizfriz
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Post by Amtram on Feb 28, 2014 11:16:59 GMT -5
I try to learn things a piece at a time. When I've learned enough pieces, I try to think of ways they might fit together, then look for research or commentary from experts who study this stuff to see if I'm putting it together correctly. If I am, then it gives me a better understanding for learning more. If I'm not, then I learn from the experts the way it actually works, and rethink my understanding as necessary. But you're right - it's complex! And the more knowledge we accumulate, the more questions rise up. That's really exciting if you're inclined to curiosity, but most people want a simple, pat answer. (As an example, the "Are you right-brained or left-brained" quiz is making its rounds again on facebook. *headdesk*)
Serotonin is your feel-good chemical. Norepinephrine is your "fight or flight" chemical. Dopamine is your reward chemical. Move along, nothing else to see here. (*snort*)
There are other chemicals being passed along by different synapses, and several of these neurotransmitters can go through chemical processes to become different ones. There are multiple different specific synapses that transmit the same neurochemical, but have a different effect on mood, behavior, and even cognition. The identical synapse in a different area of the brain can produce a completely different effect because it's processing the chemical in a brain area that has a different function.
I happen to think this is friggin' amazing - and at this point, a lot of the stuff that Makes Sense To Me turns out to match up with the science, which makes me do a little happy dance.
I can see where dopamine processing in the frontal lobes, particularly the prefrontal cortex, is a logical place to look for some of the executive function deficits that are part of ADHD. Obviously, though, scientists are looking at other stuff, or we wouldn't have drugs that target norepinephrine reuptake being prescribed for ADHD, n'est-ce pas?
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Post by tigger on Mar 3, 2014 5:35:08 GMT -5
For me, I believe dopamine is my friend. I am highly sensitive to serotonin so I endeavor to block serotonin reuptake inhibitors everywhere possible. NE isn't my friend either- I've been tried on those drugs and the result was determined suicide.
Every SSRI I have ever been prescribed has resulted in Serotonin Crash. Every SNRI was equally damaging.
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Post by Amtram on Mar 3, 2014 11:23:25 GMT -5
Well, here's a video about dopamine pathways that are relevant to antipsychotics for schizophrenia, but there is also information relevant to us because of symptom overlap. Dr. Guzman also covers the essential functions of each of the individual transmission pathways, so it's a good physiology lesson as well.
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