Differentially classified methamphetamine-using men who have sex with men: A latent class analysis.

CONTEXT: Substance use interventions for methamphetamine-using men who have sex with men (MSM) are limited by the assumption that they are a uniform group. We hypothesized that an LCA would identify distinct patterns of substance use and demographic and psychosocial variables associated with different substance-using groups would aid in understanding distinctions. Using cross-sectional data from 343 methamphetamine-using MSM, we conducted an LCA to model the patterns of polysubstance use then examined how the classes varied on psychosocial variables defined by the Information-Motivation-Behavioral Skills (IMB) model. FINDINGS: Because we were interested in identifying patterns of polysubstance use (PSU) among our sample, we identified four classes: minimal PSU, marijuana PSU, cocaine/hallucinogens PSU, and designer drugs/heroin PSU. Men in the marijuana PSU class were less likely to have positive attitudes towards methamphetamine than participants in the other three classes. Men in the Cocaine and Hallucinogens PSU class were more likely to have higher PANAS scores (OR = 13.00 [3.25, 52.07]) compared to the other classes, and they were more likely to have higher self-efficacy to enact safer substance use strategies (OR = 10.72 [3.23, 35.47]). MSM in the Designer Drug and Heroin PSU class were more likely to have a diagnosis of Hepatitis B (OR = 4.07 [0.86, 19.36] despite having higher knowledge of sexual health practices (OR = 0.55 [0.36, 0.84]. CONCLUSIONS: Differential classification for methamphetamine-using MSM suggests an opportunity for tailored interventions and secondary prevention programs. By understanding how men vary on illicit substance use, interventionists can routinely screen and link men before they potentially progress to another classification.

Compulsive methamphetamine taking under punishment is associated with greater cue-induced drug seeking in rats.

Methamphetamine (METH) addicts lose control over drug consumption despite suffering multiple adverse medicolegal consequences. To mimic the negative events associated with drug addiction in humans, we recently introduced a rat model of self-administration (SA) with response-contingent punishment on METH intake. These procedures allowed us to distinguish between two addiction-like phenotypes in rats, those that sustained METH taking despite negative consequences (shock-resistant, SR) and rats that significantly reduced their METH intake (shock-sensitive, SS). Here, we further developed our adverse consequence model and examined incubation of METH craving by measuring cue-induced drug seeking in SR and SS rats. Male Sprague-Dawley rats were trained to self-administer METH (0.1mg/kg/injection) or saline intravenously (i.v.) during twenty-two 9-h sessions that consisted of 3 separate 3-h sessions separated by 30min. Subsequently, rats were subjected to incremental footshocks during thirteen additional 9-h METH SA sessions performed in a fashion identical to the training phase. Cue-induced drug craving was then assessed at 2 and 21days after the footshock phase. All rats escalated their intake of METH, with both phenotypes showing similar drug taking patterns during SA training. In addition, rats that continued their METH intake despite negative consequences showed even greater cue-induced drug craving following withdrawal than the rats that reduced METH intake following negative consequences. Taken together, our adverse consequence-based model highlights the possibility of identifying rats by addiction-like phenotypes and subsequent vulnerability to relapse-like behaviors. The use of similar SA models should help in the development of better therapeutic approaches to treat different stages of METH addiction.

Factors associated with initiation of ecstasy use among US adolescents: findings from a national survey.

AIMS: To investigate adolescent pathways to ecstasy use by (1) examining how early onsets of smoking, drinking, and marijuana use are related to a child's risk of initiation of ecstasy use and (2) assessing the influence of other individual and parental factors on ecstasy use initiation. METHODS: Data on 6426 adolescents (12-17 years old at baseline) from the National Survey of Parents and Youth (NSPY), a longitudinal, nationally representative household survey of youth and their parents, were used in the analyses. Information on youth substance use, including ecstasy use, as well as familial and parental characteristics, was available. RESULTS: Initiation of ecstasy use is predicted by an adolescent's early initiation of smoking, drinking, or marijuana use. In particular, early initiation either of marijuana use, or of both smoking and drinking, increases a child's risk for ecstasy use initiation. Among the familial and parental variables, parent drug use emerged as significantly predictive of child initiation of ecstasy use; living with both parents and close parental monitoring, on the other hand, are negatively associated with ecstasy use initiation, and may be protective against it. At the individual level, sensation seeking tendencies and positive attitudes towards substance use, as well as close associations with deviant peers, are predictive of adolescent initiation of ecstasy use. CONCLUSION: Our findings on the risk and protective factors for initiation of ecstasy use, especially with regard to factors that are modifiable, will be useful for prevention programs targeting youth use not only of ecstasy, but also of other drugs.

Heterogeneity of stimulant dependence: a national drug abuse treatment clinical trials network study.

We investigated the presence of DSM-IV subtyping for dependence on cocaine and amphetamines (with versus without physical dependence) among outpatient stimulant users enrolled in a multisite study of the Clinical Trials Network (CTN). Three mutually exclusive groups were identified: primary cocaine users (n = 287), primary amphetamine users (n = 99), and dual users (cocaine and amphetamines; n = 29). Distinct subtypes were examined with latent class and logistic regression procedures. Cocaine users were distinct from amphetamine users in age and race/ethnicity. There were four distinct classes of primary cocaine users: non-dependence (15%), compulsive use (14%), tolerance and compulsive use (15%), and physiological dependence (tolerance, withdrawal, and compulsive use; 56%). Three distinct classes of primary amphetamine users were identified: non-dependence (11%), intermediate physiological dependence (31%), and physiological dependence (58%). Regardless of stimulants used, most female users were in the most severe or the physiological dependence group. These results lend support for subtyping dependence in the emerging DSM-V.

The clinical characteristics of adolescents reporting methamphetamine as their primary drug of choice: an examination of youth admitted to inpatient substance-abuse treatment in northern British Columbia, Canada, 2001-2005.

We conducted a 5-year medical-chart review of all admissions to an inpatient adolescent substance-abuse program. Youth indicating methamphetamine as their primary drug of choice did not have worse dropout rates or a more severe baseline profile on 4 Addiction Severity Index subscales (Family/Social Conflict, Legal, Psychological, and Medical), compared to adolescents reporting another drug of choice.

DAT polymorphism and diverse clinical manifestations in methamphetamine abusers.

The clinical outcome for methamphetamine (MAP) abusers is variable. MAP exerts its biological activity through rapid conversion to amphetamine (AP) and MAP itself. The dopamine transporter (DAT) is the main modulator of MAP/AP-induced dopamine release and dopamine neurotoxicity, and is also the major regulator of dopamine level in the brain. We tested for an association between a DAT-gene polymorphism and clinical variations in MAP abusers. A total of 146 MAP abusers were enrolled in the study and classified into three clinically distinct groups: MAP dependence (n = 30), MAP psychosis (n = 88) and chronic MAP psychosis (n = 28). Patients with schizophrenia (n = 79) and healthy controls (n = 72) were also recruited for the study. The 40 base pair variable number tandem repeat polymorphism in the 3'-untranslated region of the DAT was the focus of the investigation. The subjects were all Chinese residents of Taiwan. The respective allelic frequencies for DAT repeats 11, 10 and 9 were 0.067, 0.833 and 0.083 for the MAP-dependence group, 0.006, 0.864 and 0.119 for the MAP psychosis group, 0.018, 0.893 and 0.089 for the chronic MAP psychosis group, 0.019, 0.911 and 0.07 for the schizophrenic controls, and 0.021, 0.889 and 0.083 for the healthy controls. No significant associations were demonstrated between this DAT polymorphism in genotype and allele frequency and the clinical outcome of MAP abusers. The biological relevance of the variable number tandem repeat polymorphism in the 3'-untranslated region of DAT in MAP abusers was not demonstrated in this study.

Increasing popularity of injection as the route of administration of amphetamine in Edinburgh.

Six hundred and thirty four interviews of injecting drug users were performed between 1992 and 1994 as part of a study of injecting drug use and HIV prevalence in Edinburgh, Scotland. Amphetamine was injected by more subjects (44%) than any other drug. Preference for injection as the route of administration of amphetamine increased over the period despite no change in the popularity of the drug generally. Simultaneously, heroin use and injection declined. Analyses indicated that amphetamine injectors comprised two distinct sub-groups. The majority were polydrug injectors who injected frequently, had a longer injecting history and were more likely to share injection equipment. About one-fifth were stimulant-only injectors who injected infrequently, were relatively recent initiates to injecting and whose numbers increased over the 3 years. Drug treatment and prevention services may need to explore alternative methods to respond effectively to these emerging trends.