Underreporting of ecstasy use among high school seniors in the US.
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. We examined 2014 data from Monitoring the Future, a nationally representative survey of high school seniors in the US (N6250, 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. 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. Prevalence of ecstasy use appears to be underestimated when Molly is not included in the definition of ecstasyMDMA. Surveys should include Molly in the definition of ecstasy to more adequately assess prevalence of use.