Hair analysis of 21 people who requested only ecstasy from their supplier found that 19 had MDMA in their hair, but 8 also had amphetamine or methamphetamine, and 7 had levels of the MDMA metabolite MDA equal to or greater than MDMA itself, indicating use of MDA in addition to MDMA. These additional amphetamine derivatives may be included by clandestine laboratories to enhance effects or because MDA synthesis is perceived as simpler. Drug users and researchers studying possible brain neurotoxic effects of MDMA must consider that ecstasy tablets can contain MDA and methamphetamine despite no demand for those drugs.
A post-mortem analysis of a high-dose MDMA user's brain found that protein levels of the serotonin transporter (SERT) were markedly reduced in the striatum and occipital cortex (by 48–58%) and less affected in frontal and temporal cortices (by 25%), while tryptophan hydroxylase (TPH), the enzyme that synthesizes serotonin, was severely decreased in the caudate and putamen (by 68% and 95%, respectively). The reduction in striatal SERT protein was larger than the binding decreases typically reported in imaging studies. These results suggest high-dose MDMA exposure may cause loss of two key protein markers of serotonin neurons, possibly indicating physical damage or downregulation of neuronal components.