Do you have sources for that comparison of Opioides with MDMA?
I also couldn't find much studies on MDMA itself, as most such studies refer to some sort of pills, which are usually mixed with other drugs (e.g. Speed).
The Wikipedia article has a tonne of links to studies that link amphetamines to addiction, which is also a primary trait of opiates. Opiates also have negative side-effects with abuse, just like amphetamines.
They have many similarities.
> and extended use can also lead to addiction, memory problems, paranoia and difficulty sleeping
They have many similarities.
> and extended use can also lead to addiction, memory problems, paranoia and difficulty sleeping
Etc.