Can the Severity of Dependence Scale Be Usefully Applied to 'Ecstasy'?

Background/Aims: Although use of 'ecstasy' (drugs sold as containing 3,4-methylenedioxymethamphetamine) is prevalent, it is typically infrequent, and treatment presentations involving ecstasy as a principal problem drug are relatively rare. Human case reports and animal literature suggest dependence potential, although there may be some unique aspects to this syndrome for ecstasy in comparison to other substances. The Severity of Dependence Scale (SDS) was examined to determine whether this could usefully identify 'dependent' ecstasy consumers. Methods: We conducted a cross-sectional survey of 1,658 frequent (at least monthly) ecstasy consumers across Australia, assessing drug use, associated harms and risk behaviours. Dependence was evaluated with the SDS, using a cut-off of 4 to identify potential 'dependence'. Results: One fifth of the participants were screened as potentially dependent. These individuals used ecstasy more frequently, in greater amounts, engaged more extensively in risk behaviours and reported greater role interference than other participants. These findings were independent of methamphetamine use or dependence. The underlying structure of the ecstasy SDS was bifactorial. Conclusions: The SDS has demonstrated construct validity as a screening tool to identify ecstasy users at elevated risk of experiencing adverse consequences, including features of dependence. The underlying structure of dependence symptoms differs for ecstasy compared to other drug classes, and some dependent consumers use the drug infrequently. The unique neurotoxic potential and entactogenic effects of ecstasy may require a distinct nosological classification for the experience of dependence associated with the drug.