From the research that I've seen--most notably (1) dosing up rhesus monkeys with extremely high concentrations (20mg/kg) (2) an autopsy performed on a heavy ecstasy user (4000 pills over 6 years, frequent high doses)--no evidence whatsoever has been found of dopamine neuron degeneration. Even with the amount of meth that is possibly contained in an ecstasy pill, no such effect of dopaminergic evidence has surfaced in physiological or psychological investigations. My inclinations would lead to me to agree with bben on this one.
As for frying SERT, be careful, although the verdict isn't out on the reversibility of suggested axonal degeneration. From what I can tell, SERT levels eventually normalize while axonal innervation patterns change. While the hippocampus/frontal cortex show lasting deinnervation (loss of axonal terminals connecting neural cells), other areas like the amygdala and hypothalamus show hyperinnervation (increase of axonal terminals connecting to neural cells). Thus synaptic conductivity is maintained while innervation patterns change. The permanency of this change is equivocal, as well as the extent and influence on psychological and cognitive functioning.
A recent study, "Cognition in Novice Ecstasy Users with Exposure to Other Drugs" (Schilt 2007), showed a decrease in verbal memory but not any other cognitive functions after 1-30 uses in a 1 year period. It is the only prospective study on mdma--all others being retrospective--and in this regard the possibility of confounding factors (other substances, morbidity...) is greatly reduced. Subjects were tested on a variety of cognitive and psychological measures before ecstasy use, and those deemed most likely to use ecstasy were closely followed and re-examined a year later, matched with the initial controls.
Schilt quotes "The main underlying factor seems to be a depletion in serotonin among ecstasy users, a depletion that might be reversible. Serotonin is involved in several cognitive functions, but might be especially relevant in learning and memory. Serotonergic depletion seems to result in impaired consolidation, leaving attention unnaffected."
All in all, given that anxiety and depression deplete serotonin through the medium of cortisol, it would seem that reduced serotonin levels following ecstasy use could likely result in these moods. Cognitive functioning may also be compromised as a result of lowered SERT. What isn't established is the efficacy of mood-enhancing regimens such as consistent exercise, proper diet (tryptophan-rich, omega 3...), and various other stress-reduction measures (e.g., meditation, relaxation). Something to consider...
