Underreporting of ecstasy use among high school seniors in the US.

BACKGROUND: National surveys suggest ecstasy (3,4-methylenedioxymethamphetamine [MDMA]) use has decreased substantially among adolescents in the US since 2001; however, the recent phenomenon of "Molly" (ecstasy marketed as "pure MDMA") may be leading to underreporting of use as not all users are aware that "Molly" is a form of ecstasy.

METHODS: We examined 2014 data from Monitoring the Future, a nationally representative survey of high school seniors in the US (N=6250, modal age: 18). Three randomly distributed survey forms asked about ecstasy use, and one included "Molly" in the definition. Self-reported lifetime, 12-month, and 30-day ecstasy use were compared to determine whether including "Molly" in the definition was associated with higher prevalence or frequency of use.

RESULTS: The form including "Molly" in the definition had significantly higher prevalence than the two (combined) forms that did not. Lifetime use (8.0% vs. 5.5%) and 12-month use (5.1% vs. 3.6%) were significantly higher with "Molly" in the definition. Lifetime prevalence remained higher with "Molly" in the definition when controlling for correlates of ecstasy use; however, 12-month use did not. Differences in prevalence were associated with lifetime occasions of use, with lower concordance between forms at lower levels of lifetime occasions (e.g., 1-2 times). Survey form was not related to number of times used among more frequent users.

CONCLUSIONS: Prevalence of ecstasy use appears to be underestimated when "Molly" is not included in the definition of ecstasy/MDMA. Surveys should include "Molly" in the definition of ecstasy to more adequately assess prevalence of use.