Polydrug Use among IDUs in Tijuana, Mexico: Correlates of Methamphetamine Use and Route of Administration by Gender

Tijuana is situated on the Mexico–USA border adjacent to San Diego, CA, on a major drug trafficking route. Increased methamphetamine trafficking in recent years has created a local consumption market. We examined factors associated with methamphetamine use and routes of administration by gender among injection drug users (IDUs). From 2006–2007, IDUs ≥18 years old in Tijuana were recruited using respondent-driven sampling, interviewed, and tested for HIV, syphilis, and TB. Logistic regression was used to assess associations with methamphetamine use (past 6 months), stratified by gender. Among 1,056 participants, methamphetamine use was more commonly reported among females compared to males (80% vs. 68%, p < 0.01), particularly, methamphetamine smoking (57% vs. 34%; p < 0.01). Among females (N = 158), being aged >35 years (AOR, 0.2; 95% CI, 0.1–0.6) was associated with methamphetamine use. Among males (N = 898), being aged >35 years (AOR, 0.5; 95% CI, 0.3–0.6), homeless (AOR, 1.4 (0.9–2.2)), and ever reporting sex with another male (MSM; AOR, 1.9; 95% CI, 1.4–2.7) were associated with methamphetamine use. Among males, a history of MSM was associated with injection, while sex trade and >2 casual sex partners were associated with multiple routes of administration. HIV was higher among both males and females reporting injection as the only route of methamphetamine administration. Methamphetamine use is highly prevalent among IDUs in Tijuana, especially among females. Routes of administration differed by gender and subgroup which has important implications for tailoring harm reduction interventions and drug abuse treatment

Provision of ancillary medications during buprenorphine detoxification does not improve treatment outcomes

For individuals dependent on opioids, recovery efforts begin with a period of withdrawal that typically includes discomfort from symptoms, possibly precipitating a return to drug use. The study described here investigated whether the provision of ancillary medications for opioid withdrawal symptoms affected treatment outcomes in 139 participants receiving buprenorphine in a 13-day detoxification trial. Outcome measures include the number of opioid-free urine samples collected and retention in treatment. Ancillary medications were provided to 70% of participants: 59% received medication for insomnia, 45% for anxiety, 40% for bone pain, 35% for nausea, and 28% for diarrhea. Findings indicate no difference in the number of opioid-free urine samples between the group receiving ancillary medication and the group who did not, although tests of specific ancillary medications indicate that those who received diarrhea medication had fewer opioid-free urines than those who did not (P =.004). Results also indicate that participants attended fewer days of treatment if they received anxiety, nausea, or diarrhea medication compared to no medication (all P values <.05). Copyright © Taylor & Francis Group, LLC.link_to_OA_fulltex

The effects of acute, chronic, and withdrawal from chronic nicotine on novel and spatial object recognition in male C57BL/6J mice

Rationale: Spatial and novel object recognition learning is different from learning that uses aversive or appetitive stimuli to shape acquisition because no overt contingencies are needed. While this type of learning occurs on a daily basis, little is known about how nicotine administration affects it.Objectives: To determine the effects of acute, chronic, and withdrawal from chronic nicotine on two related but distinct incidental learning tasks, novel and spatial object recognition.Methods: In C57BL/6J mice, the effects of acute (0.045-0.18 mg/kg), chronic (6.3 mg/kg/day), and withdrawal from chronic nicotine on novel and spatial object recognition were examined.Results: With a 48-h delay between training and testing, acute nicotine enhanced spatial (difference score, saline?=?3.34 s, nicotine?=?7.71 s, p?=?0.029) but resulted in a deficit in novel object recognition (difference score, saline?=?8.76 s, nicotine?=?4.48 s, p?=?0.033). Chronic nicotine resulted in a strong trend towards a deficit in spatial object recognition (difference score, saline?=?4.01 s, nicotine?=?1.81 s, p?=?0.059) but had no effect on novel object recognition, and withdrawal from chronic nicotine disrupted spatial object recognition (difference score, saline?=?3.00 s, nicotine?=?0.17 s, p?=?0.004) but had no effect on novel object recognition.Conclusions: The effects of nicotine on spatial object recognition shift from enhancement to deficit as administration changes from acute to chronic and withdrawal. These effects were specific for spatial object recognition, which may be due to differing underlying neural substrates involved in these tasks. Understanding how nicotine alters learning has implications for understanding diseases associated with altered cholinergic function<br/

Smoking Reduces Conflict-Related Anterior Cingulate Activity in Abstinent Cigarette Smokers Performing a Stroop Task

Prior research suggests that abrupt initiation of abstinence from cigarette smoking reduces neural cognitive efficiency. When cognitive efficiency is high, processing speed and accuracy are maximized with minimal allocation of cognitive resources. The study presented here tested the effects of resumption of smoking on cognitive response conflict after overnight abstinence from smoking, hypothesizing that smoking would enhance cognitive efficiency. Twenty paid research volunteers who were chronic cigarette smokers abstained from smoking overnight (>12 h) before undergoing fMRI while performing a color-word Stroop task during two separate test sessions: one that did not include smoking before testing and another one that did. Statistical analyses were performed by modeling the Stroop effect (incongruent >congruent) BOLD response within a collection of a priori regions of interest that have consistently been associated with cognitive control. Behavioral assessment alone did not reveal any significant differences in the Stroop effect between the two sessions. BOLD activations, however, indicated that in the right anterior cingulate cortex (ACC), smokers had significantly less task-related activity following smoking (p<0.02). In contrast, the right middle frontal gyrus exhibited significantly greater activity after smoking as compared to the no-smoking session (p<0.003). Exaggerated neural activity in the ACC during nicotine withdrawal may reflect a compensatory mechanism by which cognitive control networks expend excessive energy to support selective attention processes. Resumption of smoking may enhance cognitive control in smokers, involving a reduction in ACC response conflict activity together with improvement in conflict resolution involving the dorsolateral prefrontal cortex