A Single Dose of Nicotine Enhances Reward Responsiveness in Nonsmokers: Implications for Development of Dependence

Background: Tobacco smoking, driven by the addictive properties of nicotine, is the most prevalent preventable cause of death in the Western world. Accumulated evidence suggests that nicotine may increase appetitive responding for nondrug incentives in the environment. Methods: To test this hypothesis, we conducted a randomized, double-blind, placebo-controlled, crossover study of the effect of a single dose of transdermal nicotine on reward responsiveness in 30 psychiatrically healthy nonsmokers. A novel signal detection task in which correct responses were differentially rewarded in a 3:1 ratio was used to assess the extent to which participants modulated their behavior as a function of reward. Results: Despite expected adverse effects such as nausea, nicotine significantly increased response bias toward the more frequently rewarded condition, at the expense of accuracy, independent of effects on attention or overall vigilance. Additionally, response bias on placebo was greater in participants who received nicotine in the first session, indicating that an effect of nicotine on reward responsiveness or reward-based learning persisted for at least 1 week. Conclusions: These findings suggest that a single dose of nicotine enhances response to non-drug-related rewards in the environment, with lasting effects. This effect may contribute to reinforcement of early smoking behavior and development of nicotine dependence.Psycholog

Single Dose of a Dopamine Agonist Impairs Reinforcement Learning in Humans: Behavioral Evidence from a Laboratory-based Measure of Reward Responsiveness

Rationale. The dopaminergic system, particularly D2-like dopamine receptors, has been strongly implicated in reward processing. Animal studies have emphasized the role of phasic dopamine (DA) signaling in reward-related learning, but these processes remain largely unexplored in humans. Objectives. To evaluate the effect of a single, low dose of a D2/D3 agonist-pramipexole-on reinforcement learning in healthy adults. Based on prior evidence indicating that low doses of DA agonists decrease phasic DA release through autoreceptor stimulation, we hypothesized that 0.5 mg of pramipexole would impair reward learning due to presynaptic mechanisms. Materials and methods. Using a double-blind design, a single 0.5-mg dose of pramipexole or placebo was administered to 32 healthy volunteers, who performed a probabilistic reward task involving a differential reinforcement schedule as well as various control tasks. Results. As hypothesized, response bias toward the more frequently rewarded stimulus was impaired in the pramipexole group, even after adjusting for transient adverse effects. In addition, the pramipexole group showed reaction time and motor speed slowing and increased negative affect; however, when adverse physical side effects were considered, group differences in motor speed and negative affect disappeared. Conclusions. These findings show that a single low dose of pramipexole impaired the acquisition of reward-related behavior in healthy participants, and they are consistent with prior evidence suggesting that phasic DA signaling is required to reinforce actions leading to reward. The potential implications of the present findings to psychiatric conditions, including depression and impulse control disorders related to addiction, are discussed.Psycholog

Bionic bodies, posthuman violence and the disembodied criminal subject

This article examines how the so-called disembodied criminal subject is given structure and form through the law of homicide and assault. By analysing how the body is materialised through the criminal law’s enactment of death and injury, this article suggests that the biological positioning of these harms of violence as uncontroversial, natural, and universal conditions of being ‘human’ cannot fully appreciate what makes violence wrongful for us, as embodied entities. Absent a theory of the body, and a consideration of corporeality, the criminal law risks marginalising, or altogether eliding, experiences of violence that do not align with its paradigmatic vision of what bodies can and must do when suffering its effects. Here I consider how the bionic body disrupts the criminal law’s understanding of human violence by being a body that is both organic and inorganic, and capable of experiencing and performing violence in unexpected ways. I propose that a criminal law that is more receptive to the changing, technologically mediated conditions of human existence would be one that takes the corporeal dimensions of violence more seriously and, as an extension of this, adopts an embodied, embedded, and relational understanding of human vulnerability to violence

Efficacy and Safety of Pharmacotherapeutic Smoking Cessation Aids in Schizophrenia Spectrum Disorders: Subgroup Analysis of EAGLES.

ObjectiveThis study aimed to evaluate the efficacy and safety of varenicline, bupropion, and nicotine replacement therapy (NRT) among smokers with schizophrenia spectrum disorders in post hoc analyses of Evaluating Adverse Events in a Global Smoking Cessation Study data.MethodsSmokers with schizophrenia spectrum disorder (N=390) and without a psychiatric illness (control group, N=4,028) were randomly assigned to receive varenicline, bupropion, NRT patch, or placebo for 12 weeks. Outcomes included abstinence rates during treatment and follow-up, number needed to treat (NNT) for abstinence, incidence of neuropsychiatric adverse events (NPSAEs), and temporal relationship between NPSAEs and abstinence status.ResultsSmokers with schizophrenia smoked more and had greater dependence and fewer prior trials of cessation pharmacotherapy at baseline. At each time point, smokers with schizophrenia assigned to varenicline had significantly greater odds of abstinence compared with their matched placebo group, with NNT comparable to the control group. Bupropion and NRT increased odds of abstinence; confidence intervals (CIs) included 1 for some comparisons, and NNT for smokers with schizophrenia was greater than for the control group. No treatment was associated with significantly more NPSAEs, compared with placebo, in either cohort. The estimated NPSAE rate was 5% (95% CI=3.0-7.7) for smokers with schizophrenia and 1% (95% CI=0.6-2.1) for the control group. Over one-third of NPSAEs occurred during partial or full abstinence, suggesting a multifactorial nature.ConclusionsFor smokers with schizophrenia, varenicline led to significantly higher abstinence rates, and NNT was comparable to the control group. A significant proportion of NPSAEs occurred during early abstinence. No treatment significantly increased NPSAE prevalence

Neuropsychiatric Safety and Efficacy of Varenicline, Bupropion, and Nicotine Patch in Smokers With Psychotic, Anxiety, and Mood Disorders in the EAGLES Trial.

BACKGROUND:Neuropsychiatric safety and relative efficacy of varenicline, bupropion, and transdermal nicotine patch (NRT) in those with psychiatric disorders are of interest. METHODS:We performed secondary analyses of safety and efficacy outcomes by psychiatric diagnosis in EAGLES (Evaluating Adverse Events in a Global Smoking Cessation Study), a 12-week, randomized, double-blind, triple-dummy, placebo- and active (NRT)-controlled trial of varenicline and bupropion with 12-week follow-up, in a subset population, n = 4092, with a primary psychotic (n = 390), anxiety (n = 792), or mood (n = 2910) disorder. Primary end-point parameters were incidence of prespecified moderate and severe neuropsychiatric adverse events (NPSAEs) and weeks 9 to 12 continuous abstinence rates (9-12CAR). RESULTS:The observed NPSAE incidence across treatments was 5.1% to 6.3% in those with a psychotic disorder, 4.6% to 8.0% in those with an anxiety disorder, and 4.6% to 6.8% in those with a mood disorder. Neither varenicline nor bupropion was associated with significantly increased NPSAEs relative to NRT or placebo in the psychiatric cohort or any psychiatric diagnostic subcohort. There was a significant effect of treatment on 9-12CAR (P < 0.0001) and no significant treatment-by-diagnostic subcohort interaction (P = 0.24). Abstinence rates with varenicline were superior to bupropion, NRT, and placebo, and abstinence with bupropion and NRT was superior to placebo. Within-diagnostic subcohort comparisons of treatment efficacy yielded estimated odds ratios for 9-12CAR versus placebo of greater than 3.00 for varenicline, greater than 1.90 for bupropion, and greater than 1.80 for NRT for all diagnostic groups. CONCLUSIONS:Varenicline, bupropion, and nicotine patch are well tolerated and effective in adults with psychotic, anxiety, and mood disorders. The relative effectiveness of varenicline, bupropion, and NRT versus placebo did not vary across psychiatric diagnoses