The use of ecstasy or MDMA (3,4–methylenedioxymethamphetamine) constitutes an important public health concern.1
Recreational ecstasy use is associated with a long list of adverse effects, such as impaired driving, aggression, liver and heart damage, memory and other cognitive deficits, impaired immune competence, psychiatric distress and disorders, hormonal changes, and mortality.1,2
Ecstasy is also one of the most compromising and controversial illicit drugs due to its potential for serotonergic neurotoxicity and behavioral disturbances.1–4
Polysubstance use is often cited as a confounder in research on ecstasy’s neurotoxic effects, which not only creates challenges in attributing adverse consequences in drug users to any given drug, but also enhances the likelihood of neurotoxic and other adverse effects in ecstasy users.5–7
In this study, we capitalize on data from a nationally representative study of psychiatric comorbidity to understand the heterogeneity of ecstasy users in regards to substance use and psychiatric disorders. An understanding of the nature of these different subtypes is critical to etiological and prevention research.
Ecstasy comprises properties of both stimulants and hallucinogens and is classified as a hallucinogen.8
It is commonly known as one of several “club drugs” (eg, MDMA, methamphetamine, and d–lysergic acid diethylamide or LSD) that are used to maintain the high energy levels required for extended periods of dancing or to generate an altered state of consciousness.9
In the United States, ecstasy use reportedly increased significantly during the 1990s and early 2000s.9,10
When this trend was first noticed, the drug appeared to be used predominantly by whites and party or club participants, but it spread later to nonwhite groups (eg, Hispanics and blacks) and non-club settings.9,10
National treatment-related data have also revealed a significant increase in ecstasy/MDMA-related mortality and admissions to emergency departments from 1994 and 2001.11,12
Since 2002, national surveys of American students and the general population have shown a decline in ecstasy use.13,14
However, recent results from both Monitoring the Future Surveys13,15
and the National Survey on Drug Use and Health14
suggest that ecstasy use increased from 2006–2007 and remained stable in 2008. Nationally, the estimated number of new past-year ecstasy users decreased from 1.2 million in 2002 to 642,000 in 2003 and then rose to 860,000 in 2006, which was similar to the estimate in 2007.14
The vast majority (61–70%) of new ecstasy users in the United States are adults.14
Several studies have found that many ecstasy users also use alcohol, marijuana, and other stimulants such as cocaine and amphetamines.7,16–19
It has been suggested that stimulants are consumed to enhance ecstasy’s effects, while marijuana is often used to alleviate the discomfort and adverse mood states associated with the period following ecstasy use.17,20
Polydrug use, however, is likely to have particularly adverse neuropsychobiological effects.4,7
For example, because stimulants are also neurotoxic upon serotonergic and dopamine neurons, they may interact with ecstasy to enhance its adverse effects on users.5,7
Ecstasy’s reported associations with polysubstance use, as well as its negative effects, have important implications for prevention and intervention. As of now, there is limited information available concerning what particular subgroups may be at high risk for exhibiting substance use disorders (SUDs) and that should thus receive tailored or intense interventions. Little is also known about the extent to which ecstasy users are characterized by a severe pattern of psychiatric disorders, and whether early case finding and intervention within this population is warranted. Given the recent increase in ecstasy use among adults,14
we need to characterize better various types of users who constitute this population in order to identify vulnerable subgroups for tailored interventions.
Latent class analysis (LCA) is a particularly suitable method for investigating whether distinct subtypes or classes of drug users exist within a diverse sample of study participants.21,22
LCA’s unique strength lies in its capability to specify “unobserved” or “latent” subgroups of individuals. It has already been used to enhance the field’s understanding of variability in polysubstance use patterns.16
In LCA, observed variables are viewed as imperfect indicators of an underlying and unobserved construct, and a finite number of mutually exclusive classes are empirically derived from the analysis of co-occurring patterns of dichotomous variables. LCA thus can help elucidate whether there are discrete sets of ecstasy users by classifying them empirically into a few subgroups according to their reported use patterns of a variety of drugs. In this study, we apply LCA to investigate the existence of subtypes of ecstasy users. Study data are drawn from the 2001–2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), which is the largest national study of psychiatric comorbidity among American adults.23
NESARC also includes the most comprehensive assessment of psychiatric disorders presently available. Data concerning participants’ history of substance abuse treatment and familial substance abuse—a potentially robust indicator of severe substance abuse24,25
—also help to determine their differential associations with various subtypes.
Recently, Keyes et al.26
examined the association of ecstasy use with mental and alcohol use disorders among young adults aged 18–29 years in the 2001–2002 NESARC. They found that both past-year and former ecstasy users as compared to non-drug users had increased odds of exhibiting alcohol use disorders, panic disorder, dysthymia, and antisocial personality disorder in their lifetime. Additionally, a history of bipolar and social phobia was associated with former ecstasy use, while a history of specific phobia was associated with past-year ecstasy use. Similarly, non-ecstasy drug users had greater odds of exhibiting all these lifetime disorders than non-drug users. Direct comparisons in psychiatric disorders between ecstasy users and non-drug users, however, are not reported by Keyes et al.26
Specific drug use disorders and nicotine dependence also are not examined by Keyes et al.26
In this paper, we extend from prior research26
by examining each of all SUDs among adult ecstasy users aged 18 and older and by applying LCA to enhance our investigation of subtypes of ecstasy users and their distinct profiles in demographics, history of substance abuse treatment and familiar substance abuse, specific SUD, and metal disorders. For ease of interpretations, we also examine prevalence rates and corresponding 95% confidence intervals of all disorders for non-ecstasy drug users. Two main questions are examined: 1) Are there subtypes of ecstasy users that are distinguished by their patterns of drug use? 2) If so, are various subtypes of ecstasy users associated with distinct socioeconomic characteristics, patterns of substance use and related disorders, history of substance abuse treatment and familial substance abuse, and mental disorders?