Yes, they have, and cortisol spikes 800% in some users -- and post use 3 month hair samples show that at some point during those 3 months, cortisol was up to 400% higher than controls.
I have still not seen any conclusive data regarding significant serotonin deficits persisting longer than a few days. TPH rebounds quickly, and is never 100% inhibited at doses human use. Serotonin synthesis actually never stops. (unless one is on a tryptophan deficient diet, and even then it only drops by 90% ) -- at normal rates of serotonin synthesis the entire storage of serotonin in the synaptic vesicles in the brain can be replaced in a few hours, actually minutes in some cases. - if you are really interested I can try and dig up the citation
No study actually shows any detrimental effects of the (possible) MDMA caused downregulation of SERT binding and 5HT expression in long term abstinent users. Memory deficit can be laid at the feet of cannabis and poly drug use, and there is simply no data identifying what the actual mean and SD of SERT binding IS in humans.
Furthermore, even with the proposed MDMA cause serotonergic deficits, the MDMA users were more well adjusted and less anxious/depressed than the controls.
The hypervigilant, pins and needles, insomniac, anxious, panicky, DP/DR symptoms are hallmarks of GABA/Glutamate imbalance.
That does not mean that the serotonin flood was not the genesis for the HPA dysregulation, as serotonin mediates GABA and glutamate release and metabolism.
If it is a serotonin deficit issue, then SSRI administration will resolve the symptoms; so that should be the first course of action. If SSRI administration does not resolve the symptoms, one can safely conclude it is either
1. Not serotonergic issues
or
2. not simply serotonergic, but also some other NT
My personal opinion is that the experience has caused the person to conflate the pleasure of a serotonin/dopamine/nor-epinephrine surge -- with the stress response. So every rise is seen as a fight/flight situation, resulting in HPA axis dysregulation and associated NT dysfunction. This conflation may be entirely biologically mechanistic - and not conscious at all.