View clinical trials related to Stimulant Use.
Filter by:The relapsing nature of substance use disorder is a major obstacle to successful treatment. About 70% of those entering treatment will relapse within one year. To improve treatment outcome, new interventions targeting the underlying brain biomarkers of relapse vulnerability hold significant promise in reducing this critical public health problem. This study is testing a new intervention, namely tDCS-Augmented Cognitive Training, to engage these brain biomarkers to improve cognition and improve treatment outcomes.
In Hong Kong, methamphetamine use is common and cocaine use has increased steadily over the past few years. While the use of ketamine decreased from 35.8% in 2015 to 13.9% in 2017, methamphetamine and cocaine have become the most commonly used psychotropic substances and account for more than 50% of drug abuses cases in 2017. Among all stimulants, methamphetamine is most commonly used because it releases three times more dopamine than cocaine and the effects can last from eight to twelve hours, compared to two hours for cocaine. On top of its extreme effects, methamphetamine is relatively inexpensive, making it even more accessible to the young population. Misuse of methamphetamine has long been associated with profound psychological and cognitive disturbance. In reviewing the cognitive data from reasonably well-matched groups of chronic methamphetamine users and healthy controls, the majority of studies have found that chronic methamphetamine users had lower scores on at least some cognitive tests, although some studies are exceptions with entirely nonsignificant differences. A meta-analysis of 17 cross-sectional studies found that chronic methamphetamine users demonstrated significantly lower cognitive scores than healthy controls. The effects were largest for measures of learning, executive functions, memory, and processing speed, although the majority of cognitive domains significantly differed between the groups. Concerns has been emerging regarding the methodology of the aforementioned results. In particular, the appropriateness of using healthy controls to examine the cognitive effects of stimulant use has been questioned. Much of the published research has fallen victim to using controls with significant baseline differences from the chronic stimulant users, such as years of education. In addition, none of the studies available provided scatter plots of their cognitive data to evaluate the overlap in performance between chronic stimulant users and healthy controls. In fact, many chronic stimulant users have normal cognitive function when compared with normative data. Therefore, the use of the term 'impairment' or 'deficit' in many studies is not fully justified. Another limitation is that it cannot differentiate cognitive weaknesses that may predate stimulant use from those that result from it. Notably, longitudinal studies have shown that childhood deficits in executive function can predict drug abuse in adolescence, suggesting that at least some of the cognitive weaknesses pre-exist in chronic stimulant user. These and other limitations provoked a conclusion that the evidence for cognitive deficits in chronic stimulant users is weak. In order to overcome the methodological issues observed in previous cross-sectional studies, we propose to conduct a prospective studies to determine the change in cognitive function among stimulant users over time.
The investigators will examine the acute effects of stimulant medication on executive functioning. The rationale for the proposed study is to examine the efficacy of stimulants for college students with ADHD and help prevent stimulant misuse among college students without ADHD. The working hypothesis is that stimulants, compared to baseline and placebo conditions, will improve executive functioning for college students with ADHD but not for college students without ADHD. Improvements on executive functioning measures (e.g., CPT-IP, Spatial Span) will be examined through 2 (ADHD vs. non-ADHD) x 3 (Baseline, Placebo, Stimulant) repeated measures ANOVAs. Follow-up analyses will include paired comparisons. Expected outcomes are to confirm these hypotheses and demonstrate the need for further study of stimulants. If confirmed, the results will provide pilot data for a larger NIH grant proposal aimed at further examining the acute effects of stimulants (i.e., improved cognitive functioning with stimulants) and comparing them to the acute effects of physical exercise (i.e., improved cognitive functioning immediately after exercise). The investigators expect this outcome to have an important positive impact because it can help support stimulant medication as an effective treatment for college students with ADHD (DuPaul et al., 2012). Additionally, demonstration that stimulants do not improve executive functioning for college students without ADHD can be used to help prevent and discourage stimulant misuse and diversion on college campuses (Hartung et al., 2013).
The primary aim of this project is to use a randomized single-blind sham-controlled study to investigate if high frequency repetitive transmagnetic stimulation (HF-rTMS) can modulate cue-induced craving in adult methamphetamine (METH) users. The investigators hypothesize that HF-rTMS directed at left dorsolateral prefrontal cortex (DLPFC) will result in a reduction in craving for METH compared to sham-controlled rTMS in adults with methamphetamine use disorder (MUD) as evidenced by validated measures of METH craving. Neurobiologically, the investigators anticipate rTMS mediated stimulation of the DLPFC could result in inhibition of cue-induced craving through potential disruption of involved circuitry. The current project proposes that participants who are recently abstinent from METH will be randomized into four experimental groups to provide two rTMS conditions (real versus sham) and two picture cues conditions (METH versus neutral). The experiment will have an induction phase where each subject will receive 10 daily treatments within 2 weeks. Just before each rTMS/sham session participants will be shown visual cues (METH or neutral). Participants will then undergo a maintenance phase for an additional month with assessments to evaluate craving and relapse. Urine samples for urine drug screening (UDS) will be collected at screening day and on days 1, 5 and 10. Just before each rTMS/sham session participants will be shown visual cues (METH and neutral). VAS craving scores will be assessed before and after picture presentation and after the rTMS/sham session. Before the first and 10th treatment session, participants were evaluated by the the Stimulant Craving Questionnaire (STCQ) and the Severity of Dependence Scale (SDS) questionnaires. Participants will then undergo a maintenance phase for an additional month. During the first week of maintenance, three rTMS/sham sessions will be administered. During each of the following 3 weeks, one rTMS/sham session will be given per week. As with the induction phase, urine samples will be collected for screening and STCQ and the SDS questionnaires will be completed at each maintenance session. To evaluate the long-term effects of the rTMS treatment, the investigators plan on contacting participants 6 months after treatment termination for all subjects who completed the 10 treatment sessions. During that phone conversation, craving and relapse will again be assessed.