Implications of chronic methamphetamine use: a literature review

Tripling of methamphetamine/amphetamine use among homeless and marginally housed persons, 1996-2003

Methamphetamine/amphetamine (MA)-related morbidity and mortality has been increasing in the United States. MA use is associated with high-risk sexual behavior and syringe-sharing practices. Homeless and marginalized housed persons (H/M) have high rates of substance use and mental health disorders. Little is known about trends of MA use among the H/M. The objective of this study was to quantify increases in MA use among H/M in San Francisco and to determine which demographic and behavioral subgroups have experienced the greatest increases in MA use. We conducted serial cross-sectional population-based studies in three waves: 1996-1997, 1999-2000, and 2003 and studied 2,348 H/M recruited at shelters and lunch lines. The main outcome was self-reported current (30-day) MA use. We found a tripling of current MA use among H/M persons from 1996 to 2003, with a sevenfold increase in smoked MA use. MA use doubled to tripled in most demographic and behavioral subgroups, whereas it quadrupled in those under age 35, and there was a fivefold increase among HIV-infected persons. The increase in MA use among H/M places a vulnerable population at additional increased risk for HIV infection and MA-use related morbidity and mortality. Among HIV-infected H/M, the increase in MA use has important public health implications for the development and secondary transmission of drug-resistant HIV caused by synergistic neurocognitive decline, poor adherence to HIV medications, and increased sexual risk behavior. Clinicians caring for H/M persons should inquire about MA use, refer interested MA users to MA dependence treatment programs and provide targeted HIV sexual risk reduction counseling. For HIV-infected H/M MA users, clinicians should closely monitor adherence to HIV or other chronic medications, to avoid unnecessary morbidity and mortality. Further research is needed to elucidate the most effective prevention and treatment for MA use and dependence among the H/M.

Experiences and sexual behaviors of HIV-infected MSM who acquired HIV in the context of crystal methamphetamine use

The prevalence of crystal methamphetamine "meth" use among men who have sex with men (MSM) has been shown to be 20 times that of the general population, and it has been linked to increased sexual risk taking in MSM and others. Although previously seen as a "West Coast" phenomenon, clinical and other reports indicate that it is problematic among MSM regardless of geographic location. To assist in future intervention development, we interviewed 20 HIV-infected MSM who believe they seroconverted in the context of using crystal meth. Topics included factors related to continued and previous meth use, HIV risk behavior prior to and after HIV infection, and the consequences of sustained use. Generally, participants openly discussed the highly destructive effects of using crystal meth. Almost every (95%) participant spoke of chronic depression and anxiety following cycles of discontinued use, and participants often claimed an inability to enjoy activities that used to be pleasurable. Almost all (90%) respondents also reported that their social relationships were compromised by their crystal addictions. Many had lost friends, and in some cases, non-drug-using friends distanced themselves because of the addiction. A striking number of participants felt strongly that MSM sexual partner-meeting Web sites represented a major starting point for crystal-influenced sexual "hookups," and that they should likewise be a starting point for interventions. Corroborating previous research in this arena, this study exhibits support for a link between crystal meth use and high-risk sexual behavior among East Coast MSM. The study also draws attention to the need for associated mental health, functional and quality-of life impairments that seem to accompany continued use in individuals with HIV.

Anterior cingulate cortex and benefit of predictive cueing on response inhibition in stimulant dependent individuals

BACKGROUND

Methamphetamine dependence (MD) is associated with impaired response inhibition and with structural abnormalities and functional hypoactivity in the anterior cingulate cortex (ACC). The need to inhibit behavior is often forewarned by cues that do not call for immediate inhibition. We sought to determine whether such cues would engage the ACC and improve inhibition in MD individuals.

METHODS

We used functional MRI to measure ACC activation during performance of a go/nogo response inhibition task in which certain go stimuli (cues) were much more likely than others (noncues) to be followed by nogo trials. Nineteen MD individuals (inpatient treatment, 25-50 days abstinence) were compared with 19 age- and education-matched healthy comparison (HC) subjects.

RESULTS

MD and HC groups had statistically comparable performance, but only MD participants showed an ACC response and lower false alarm rates associated with cues as compared with noncues. Cue-related ACC activity in MD subjects was positively correlated with this cue-related improvement in inhibitory performance.

CONCLUSIONS

The ACC, an area associated with error detection and response conflict, may predict the degree to which advance warning may attenuate MD individuals' difficulty with response inhibition.

Biological treatments for amfetamine dependence : recent progress

Amfetamine abuse has grown into a worldwide epidemic. Methamfetamine, a derivative of amfetamine made from readily accessible chemicals, has plagued the US since the 1960s, with an alarming recent surge in the numbers of those meeting the criteria for amfetamine abuse and dependence. We review this problem using a computerised literature search (PubMed 1964-2007) to summarise knowledge from animal and human studies about treatments for amfetamine dependence, while exploring the potential of pharmacogenetics to help uncover new treatment targets. Several promising therapeutic targets have come from animal models of reward, drug-taking behaviour and withdrawal. Although preclinical and selected clinical results have been promising, clinical studies have yielded inconsistent results. To improve these outcomes, pharmacogenetic studies may be used to identify candidate alleles that predict therapeutic response. Exciting preclinical findings and a steady progression of clinical results offer hope for the development of a treatment for amfetamine dependence.

High ambient temperature increases intravenous methamphetamine self-administration on fixed and progressive ratio schedules in rats

Methamphetamine is a drug that is often consumed at dance parties or nightclubs where the ambient temperature is high. The present study determined whether such high ambient temperatures alter intravenous methamphetamine self-administration in the rat. Male Hooded Wistar rats were trained to self-administer intravenous methamphetamine (0.1 mg/kg/infusion) under a fixed ratio 1 (FR1) or progressive ratio (PR) schedule of reinforcement at an ambient temperature of 23 +/- 1 degrees C. They were then given their daily self-administration session at a raised ambient temperature of 30 +/- 1 degrees C. Methamphetamine self-administration was increased at 30 degrees C under both FR1 and PR reinforcement schedules, with the latter effect indicating that heat enhances the motivation to obtain methamphetamine. High temperatures did not alter self-administration of the D1 receptor agonist SKF 82958 in methamphetamine-experienced rats suggesting some specificity in the methamphetamine effect. When rats were given access to drink isotonic saline solution during methamphetamine self-administration sessions they drank much more solution at 30 degrees C than 23 degrees C. However, availability of isotonic saline to drink did not alter the heat-induced facilitation of methamphetamine self-administration (PR schedule) indicating that the heat effect does not simply reflect increased motivation for intravenous fluids. Hyperthermia was evident in rats self-administering methamphetamine at high ambient temperatures and fluid consumption did not prevent this effect. Heat did not affect blood levels of methamphetamine, or its principal metabolite amphetamine indicating that the facilitatory effect of heat did not reflect altered methamphetamine pharmacokinetics. Overall, these results show that high ambient temperatures increase the reinforcing efficacy of methamphetamine and encourage higher levels of drug intake.

Age-dependent effects of neonatal methamphetamine exposure on spatial learning

Neonatal rats exposed to (+)-methamphetamine (MA) display spatial learning and reference memory deficits in the Morris water maze. In separate experiments the emergence and permanence of these effects were determined. Twenty litters were used in each experiment, and two male/female pairs/litter received saline or MA (5 mg/kg four times a day) on postnatal days (P) 11-20. In experiment 1, one MA and one saline pair from each litter began testing on either P30 or P40, whereas in experiment 2, testing began on P180 or P360. Animals received trials in a straight swimming channel and then in the Morris maze (acquisition, reversal, and reduced platform phases). In both experiments, MA-treated groups showed impaired learning in the platform trials and impaired reference memory in the probe trials, which were largely independent of age. The P30 and P40 MA impairments were seen on acquisition and reduced platform trials but not on reversal. In the probe trials, MA effects were seen during all phases. The P180 and P360 MA-induced deficits were seen in all phases of the platform trials. In probe trials, deficits were only seen during the reversal and reduced platform phases. The results demonstrate that neonatal MA treatment induces spatial learning and reference memory deficits that emerge early and persist until at least 1 year of age, suggesting permanence.

Open-label study of a proprietary treatment program targeting type A gamma-aminobutyric acid receptor dysregulation in methamphetamine dependence

OBJECTIVE

To evaluate the safety and efficacy of the pharmacological component of a proprietary medical treatment program targeting type A gamma-aminobutyric acid receptor dysregulation in adults who met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria for methamphetamine dependence.

PARTICIPANTS AND METHODS

A prospective, open-label, single-group study of the medication portion of a proprietary treatment program for methamphetamine dependence was conducted from July 1, 2005, to May 10, 2006, at Research Across America, an outpatient private, for-profit, clinical research company in Dallas, TX. In the study, flumazenil, hydroxyzine, and gabapentin, all of which were approved by the US Food and Drug Administration for indications other than drug dependence, were used off-label for the treatment of methamphetamine dependence. Fifty persons who had used methamphetamine within 7 days of study entry were enrolled and received the treatment. Treatment lasted 4 weeks, followed by 8 weeks of weekly follow-up visits to monitor for methamphetamine use via urine drug tests and self-reporting.

RESULTS

Participant retention was higher than expected, with 85% of participants completing the program. Significant decrease in methamphetamine use (P<.001) was noted at 84 days after vs 90 days before treatment. If missing data are counted as days of methamphetamine use, a 47% reduction in use was observed for the entire sample (P<.001) and a 65% reduction for the 36 who completed the 8-week evaluation phase (P<.001). Urine test results and self-reported use were positively correlated (Pearson r=0.72, P<.001). The frequency of cravings was reduced on average by 66% (P<.001), with 30 of 31 (97%) of the 36 who completed the study reporting reduction in cravings.

CONCLUSION

Substantial reductions in methamphetamine cravings and use were observed in all phases of treatment, and the retention rate of participants was high. These findings suggest that the efficacy of the medications and of the entire program in treating methamphetamine dependence should be examined in controlled trials.

Neurocognitive Effects of Methamphetamine: A Critical Review and Meta-analysis

This review provides a critical analysis of the central nervous system effects of acute and chronic methamphetamine (MA) use, which is linked to numerous adverse psychosocial, neuropsychiatric, and medical problems. A meta-analysis of the neuropsychological effects of MA abuse/dependence revealed broadly medium effect sizes, showing deficits in episodic memory, executive functions, information processing speed, motor skills, language, and visuoconstructional abilities. The neuropsychological deficits associated with MA abuse/dependence are interpreted with regard to their possible neural mechanisms, most notably MA-associated frontostriatal neurotoxicity. In addition, potential explanatory factors are considered, including demographics (e.g., gender), MA use characteristics (e.g., duration of abstinence), and the influence of common psychiatric (e.g., other substance-related disorders) and neuromedical (e.g., HIV infection) comorbidities. Finally, these findings are discussed with respect to their potential contribution to the clinical management of persons with MA abuse/dependence.

Misuse of methamphetamine and prescription stimulants among youths and young adults in the community

BACKGROUND

Gender differences in the prevalence and characteristics of misuse of methamphetamine (meth) and prescription stimulants were examined in a representative US sample of youths and young adults aged 16-25 (N=24,409).

METHODS

Stimulant misusers were categorized into three mutually exclusive subgroups: meth users only, meth and prescription stimulant users, and prescription stimulant users only (e.g., Benzedrine, Ritalin, or Dexedrine). Multinominal logistic regression analyses identified the characteristics associated with misuse of meth and prescription stimulants.

RESULTS

About 1 in 10 youths reported any misuse of stimulants in their lifetime. Prescription stimulant misuse occurred earlier and was more frequent than meth misuse. About 47% of meth misusers also reported prescription stimulant misuse. Among misusers of meth and prescription stimulants, males were more likely than females to misuse methylphenidate (82% versus 65%) but were less likely to misuse diet pills or amphetamines (37% versus 49%). Multinominal logistic regression analyses indicated that all subgroups of lifetime stimulant misuse were associated with past year substance abuse. The characteristics of meth misusers differed slightly from prescription stimulants misusers.

CONCLUSIONS

Multidrug use is common among stimulant misusers. Parents should be informed about the risk of prescription stimulant misuse by their youths.

Amphetamine-related presentations to an inner-city tertiary emergency department: a prospective evaluation

OBJECTIVE

To describe the prevalence, characteristics and outcomes of amphetamine-related presentations to a tertiary hospital emergency department (ED).

DESIGN, SETTING AND PARTICIPANTS

Prospective observational study of amphetamine-related presentations to the ED of the Royal Perth Hospital (RPH), an adult, inner-city, tertiary referral hospital, between 3 August and 2 November 2005. For all patients presenting to the ED, the treating doctors were automatically prompted by the computerised data entry system to consider amphetamine use.

MAIN OUTCOME MEASURES

Proportion of ED presentations related to amphetamine use; demographic features and usage practices of amphetamine users; characteristics of presentations and admissions; associated psychiatric illnesses and use of other drugs.

RESULTS

Over the study period, there were 13 125 presentations, of which 156 (1.2%) were judged to be causally related to amphetamine use. Of those 156 patients, over half were habitual drug users (89 [57.1%] used amphetamines at least weekly), and the majority were men (111 [71.2%]). The mean age was 28 years (range, 16-55 years). Presentations were of high acuity: 104 patients [66.7%] were rated 1, 2 or 3 on the Australasian Triage Scale; 50 (32.1%) arrived by ambulance; and 25 (16.0%) arrived with police. The mean time spent in the ED was 6 h (range, 0.5-24 h). Fifty patients (32.1%) required sedation, and the likelihood of requiring sedation increased almost threefold if the heart rate was over 100 beats/min on presentation. Sixty-two patients (39.7%) were admitted and 58 (37.2%) required psychiatric evaluation. Repeat attendance was common, with 71 patients (45.5%) having previous amphetamine-related presentations to the RPH ED.

CONCLUSIONS

Amphetamine-related presentations comprise 1.2% of all ED attendances and have a major impact on hospital EDs. Patients are often agitated and aggressive, require extensive resources, and frequently re-attend. The burden of amphetamine-related illnesses on EDs is likely to increase in the future.

Methamphetamine blood concentrations in human abusers: application to pharmacokinetic modeling

Characterization of methamphetamine's (METH) dose-dependent effects on brain neurochemistry may represent a critical component for better understanding the range of resultant behavioral pathologies. Most human studies, however, have assessed only the effects of long term, high dose METH abuse (e.g., greater than 1000 mg/day) in individuals meeting DSM-IV criteria for METH dependence. Yet, for the majority of METH abusers, their patterns of METH exposure that consist of lower doses remain less well-characterized. In this study, blood samples were obtained from 105 individuals detained by police for possible criminal activity and testing positive for stimulants by EMIT assay. METH blood concentrations were subsequently quantified by GC-MS and were predominantly in the low micromolar range (0.1-11.1 microM), with median and mean values of 1.3 microM (0.19 mg/l) and 2 microM (0.3 mg/l), respectively. Pharmacokinetic calculations based on these measured values were used to estimate initial METH body burdens, the median value being 52 mg. Modeling a 52 mg dose for a 4 day-METH maintenance exposure pattern of 4 doses/day at 4 h intervals showed that blood concentrations remained between 1 and 4 microM during this period. Collectively, these data present evidence for a METH exposure pattern distinct from high dose-METH abuse and provide the rationale for assessing potential brain pathology associated with such lower dose-METH exposure.

'Tweaking 12-Step': the potential role of 12-Step self-help group involvement in methamphetamine recovery

AIMS

To determine from a review of the available literature the extent to which involvement in 12-Step mutual support groups could play a role in the recovery process for individuals abusing or dependent on methamphetamine.

METHOD

Review of the literature on outcomes associated with 12-Step meeting attendance and involvement in 12-Step activities among substance abusers, particularly those who abuse stimulants.

RESULTS

There are few if any data available on methamphetamine abusers and their use of 12-Step approaches. Evidence derived from work with alcohol- and cocaine-dependent individuals indicates that involvement in 12-Step self-help groups, both attending meetings and engaging in 12-Step activities, is associated with reduced substance use and improved outcomes. Although involvement in 12-Step fellowship improves outcome, many individuals do not engage on their own in 12-Step activities, and there are high rates of dropout from such groups. There are a number of evidence-based therapies available to assist clinicians in facilitating 12-Step involvement; however, these have not been used with methamphetamine abusers. While there are some potential barriers to adopting manualized treatment interventions into clinical practice, the familiarity, in community-based practice, of the 12-Step approach may make this easier.

CONCLUSION

More actively integrating 12-Step approaches into the treatment process may provide low- or no-cost options for methamphetamine abusers and increase the capacity for providing treatment. Further research and evaluation are necessary to determine the extent to which methamphetamine abusers do engage in 12-Step self-help programs, whether they prefer more general (e.g. Alcoholics Anonymous, Narcotics Anonymous, Cocaine Anonymous) or drug-specific (e.g. Crystal Meth Anonymous) meetings, the rate of dropout and the outcomes associated with their involvement. Further, the efficacy of efforts to facilitate involvement of methamphetamine abusers in such 12-Step groups needs to be determined.

Contingency management: an evidence-based component of methamphetamine use disorder treatments

AIMS

To review briefly some of the available evidence regarding the utility of contingency management in treating methamphetamine use disorders.

DESIGN

A literature review was conducted to locate relevant studies for the review.

FINDINGS

The review suggests that contingency management is likely to be a useful component of treatment strategies designed to address methamphetamine use disorders. Results suggest that contingency management can increase the likelihood of providing methamphetamine-free urine samples during treatment.

CONCLUSIONS

Evidence suggests that contingency management is a good candidate for inclusion in treatment strategies for methamphetamine addiction.

The role of the plasmalemmal dopamine and vesicular monoamine transporters in methamphetamine‐induced dopaminergic deficits

Amphetamine (AMPH) and methamphetamine (METH) are members of a collection of phenethylamine psychostimulants that are commonly referred to collectively as "amphetamines." Amphetamines exert their effects, in part, by affecting neuronal dopamine transport. This review thus focuses on the effects of AMPH and METH on the plasmalemmal dopamine transporter and the vesicular monoamine transporter-2 in animal models with a particular emphasis on how these effects, which may vary for the different stereoisomers, contribute to persistent dopaminergic deficits.

Long-term effects of a single adult methamphetamine challenge: minor impact on dopamine fibre density in limbic brain areas of gerbils

BACKGROUND

The aim of the study was to test long-term effects of (+)-methamphetamine (MA) on the dopamine (DA) innervation in limbo-cortical regions of adult gerbils, in order to understand better the repair and neuroplasticity in disturbed limbic networks.

METHODS

Male gerbils received a single high dose of either MA (25 mg/kg i.p.) or saline on postnatal day 180. On postnatal day 340 the density of immunoreactive DA fibres and calbindin and parvalbumin cells was quantified in the right hemisphere.

RESULTS

No effects were found in the prefrontal cortex, olfactory tubercle and amygdala, whereas the pharmacological impact induced a slight but significant DA hyperinnervation in the nucleus accumbens. The cell densities of calbindin (CB) and parvalbumin (PV) positive neurons were additionally tested in the nucleus accumbens, but no significant effects were found. The present results contrast with the previously published long-term effects of early postnatal MA treatment that lead to a restraint of the maturation of DA fibres in the nucleus accumbens and prefrontal cortex and a concomitant overshoot innervation in the amygdala.

CONCLUSION

We conclude that the morphogenetic properties of MA change during maturation and aging of gerbils, which may be due to physiological alterations of maturing vs. mature DA neurons innervating subcortical and cortical limbic areas. Our findings, together with results from other long-term studies, suggest that immature limbic structures are more vulnerable to persistent effects of a single MA intoxication; this might be relevant for the assessment of drug experience in adults vs. adolescents, and drug prevention programs.