Posted by Shawn. T. on March 3, 2003, at 22:28:39
In reply to Anti-depressants do not fix a chemical imbalance., posted by Caleb462 on March 1, 2003, at 14:03:46
I think that it's obviously important to separate the issue of whether or not antidepressants actually help people from the issue of how they affect "chemical imbalances." I think that antidepressants may correct the dysregulation of neurotransmitters/neuromodulators, but the antidepressant used and the person in question make all the difference.
Selective serotonin reuptake inhibitors (SSRI's) increase extracellular levels of serotonin. So if you want to make the claim that SSRI's are directly correcting an imbalance in serotonin levels, you have to show that depressed people taking them exhibit low serotonin activity without these drugs. Studies have shown that from 29% to 35% of people with depression fall in the low serotonin activity subgroup. Note that dopamine turnover may also be decreased in a portion of this subgroup. So, if the dopamine correlation is ignored, roughly 29% to 35% of people with depression who are taking an SSRI are directly correcting a chemical imbalance.
What about drugs that solely inhibit the reuptake of norepinephrine (like reboxetine or Strattera) or drugs that inhibit the reuptake of both norepinephrine and serotonin (like Effexor or duloxetine)? I have no data on the percentage of people with unipolar depression that exhibit high or low norepinephrine activity, but all of the data that is available points to a trend toward higher norepinephrine activity in a subgroup of patients. Information on the interaction between this subgroup and selective norepinephrine reuptake inhibitors is unavailable, so I'm not quite sure how these drugs would affect someone with high norepinephrine activity. TCA's that inhibit the reuptake of both norepinephrine and serotonin do decrease norepinephrine turnover in responders with previously high norepinephrine activity, but this is a trend seen with serotonin reuptake inhibitors in general.
If SSRI's decrease norepinephrine turnover in people with high norepinephrine activity coupled with normal serotonin activity, do they not still correct an imbalance? The argument here clearly must involve the question of whether or not the imbalance in serotonin activity that is created as a result of correcting norepinephrine dysregulation is justified. Increased serotonin activity can certainly lead to side effects, so the answer to this question will remain up to the experiences of the individual taking the drug.
I won't delve into dopamine, but rest assured that dopamine dysregulation occurs in a subgroup of people with unipolar depression. Again, the real answer to the question of "chemical imbalance" depends on the drug and the person taking the drug. If you desire references, see http://www.neurotransmitter.net/serotonindepression.html or
http://www.neurotransmitter.net/nedepression.html
Shawn
poster:Shawn. T.
thread:205038
URL: http://www.dr-bob.org/babble/20030301/msgs/205680.html