Competing Motivations: Proactive Response Inhibition Toward Addiction-Related Stimuli in Quitting-Motivated Individuals

We examined whether addiction-related cues impact proactive inhibition (the restraint of actions in preparation for stopping) in individuals who are motivated to quit gambling or cannabis use. In Study 1, treatment-seeking individuals with cannabis use disorder and matched controls performed a stop-signal task that required them to inhibit categorizing cannabis or neutral pictures, and within varying levels of stop-signal probability. In Study 2, two groups of individuals, who applied to a voluntary self-exclusion program toward gambling, performed the stop-task following relaxation or gambling craving induction, with results compared to non-gamblers. Study 1 showed that despite being less efficient in proactive inhibition, individuals with cannabis use disorder exhibited heightened proactive inhibition toward cannabis cues. In Study 2, proactive inhibition toward gambling cues was heightened in gamblers after craving, but the degree of proactive adjustment decreased as a function of induced changes in gambling-related motivation. Present findings demonstrate that exposure to addiction-related cues can modulate proactive inhibition in individuals who are motivated to restrict their addictive behaviors.     

Maximum likelihood drift estimation for a threshold diffusion

We study the maximum likelihood estimator of the drift parameters of a stochastic differential equation, with both drift and diffusion coefficients constant on the positive and negative axis, yet discontinuous at zero. This threshold diffusion is called drifted oscillating Brownian motion. For this continuously observed diffusion, the maximum likelihood estimator coincides with a quasi-likelihood estimator with constant diffusion term. We show that this estimator is the limit, as observations become dense in time, of the (quasi)-maximum likelihood estimator based on discrete observations. In long time, the asymptotic behaviors of the positive and negative occupation times rule the ones of the estimators. Differently from most known results of the literature, we do not restrict ourselves to the ergodic framework: indeed, depending on the signs of the drift, the process may be ergodic, transient, or null recurrent. For each regime, we establish whether or not the estimators are consistent; if they are, we prove the convergence in long time of the properly rescaled difference of the estimators towards a normal or mixed normal distribution. These theoretical results are backed by numerical simulations.     

Risky business: emotion,decision-making,and addiction

Although metabolic abnormalities in the orbitofrontal cortex have been observed in substance dependent individuals (SDI) for several years, very little attention was paid to the role of this brain region in addiction. However, patients with damage to the ventromedial (VM) sector of the prefrontal cortex and SDI show similar behaviors. (1) They often deny, or they are not aware, that they have a problem. (2) When faced with a choice to pursue a course of action that brings an immediate reward at the risk of incurring future negative consequences, they choose the immediate reward and ignore the future consequences. Studies of patients with bilateral lesions of the VM prefrontal cortex support the view that the process of decision-making depends in many important ways on neural substrates that regulate homeostasis, emotion, and feeling. Parallel lines of study have revealed that VM cortex dysfunction is also evident in subgroups of individuals who are addicted to substances. Thus, understanding the neural mechanisms of decision-making has direct implications for understanding disorders of addiction and pathological gambling, and the switch from a controlled to uncontrolled and compulsive behavior. On the clinical front, the approach to treat addictive disorders has been dominated by a diagnostic system that focuses on behaviors, physical symptoms, or choice of drugs. The article emphasizes the concept of using neurocognitive criteria for subtyping addictive disorders. This is a significant paradigm shift with significant implications for guiding diagnosis and treatment. Using neurocognitive criteria could lead to more accurate subtyping of addictive disorders, and perhaps serve as a guide for more specific, and potentially more successful, behavioral and pharmacological interventions.     

Structural landscape changes in urban and peri-urban agricultural systems of two West African cities and their relations to ecosystem services provided by woody plant communities

Urban Ecosystems - High urbanization pressure in Sub-Saharan Africa led to changes in the composition and configuration of rural and peri-urban agricultural production systems and to the...     

Estimation of cyclic long-memory parameters

This paper studies cyclic long-memory processes with Gegenbauer-type spectral densities. For a semiparametric statistical model, new simultaneous estimates for singularity location and long-memory parameters are proposed. This generalized filtered method-of-moments approach is based on general filter transforms that include wavelet transformations as a particular case. It is proved that the estimates are almost surely convergent to the true values of parameters. Solutions of the estimation equations are studied, and adjusted statistics are proposed. Monte-Carlo study results are presented to confirm the theoretical findings.     

On the Processes Underlying the Relationship Between Alexithymia and Gambling Severity

A great number of individuals with persistent problematic gambling behavior exhibit alexithymic tendencies, greater impulsivity, impaired working memory and poor mood. However, the relationship between these cognitive, affective and personality factors in problem gambling remains poorly understood. Our aim was to investigate multiple pathways of the alexithymia and problem gambling relationship. One hundred and six male subjects with different levels of gambling problem severity were recruited. Alexithymia, impulsivity and verbal working memory were evaluated, and their relationships to disordered gambling was examined by means of a path analysis. Results indicate that alexithymia is related to an increase in the severity of gambling indirectly, i.e., through distress severity. In addition, a rise of alexithymic tendencies was also associated with problem gambling severity through enhanced impulsivity that directly increased distress. Working memory capacity failed to significantly impact our path model. Overall, our findings contribute a new finding to the literature by highlighting the importance of alexithymia, in addition to impulsivity, in the understanding of gambling problem severity and its clinical course.     

Feeling Attached and Feeling Accepted: Implications for Political Inclusion among Visible Minority Immigrants in Canada

Immigrants’ sense of belonging to their host communities is viewed as a core condition for their successful inclusion, but there is no consensus on which attributes of belonging are most relevant to understanding inclusion, nor is there agreement on how the sense of belonging ought to be measured empirically. This study examines how two related but independent dimensions of belonging help to better understand the political inclusion of visible minority immigrants in Canada. More specifically, it examines the role of feeling attached (immigrants’ feeling toward the host community) and the role of feeling accepted (immigrants’ sense of how their host communities feel about them). We assess the relationship between attachment, acceptance and political inclusion for both first- and second-generation visible minority Canadians; the results suggest there is analytical value in utilising separate measures of attachment and acceptance: political inclusion is more likely when both are stronger.     

LIFE‐CYCLE PREFERENCES REVISITED

An axiomatic construction for life‐cycle preferences accounting for the finiteness and the randomness of life duration is provided. We emphasize the role of intertemporal correlation aversion and explain why multiplicative preferences provide an interesting alternative to additive preferences, allowing risk aversion and intertemporal elasticity of substitution to be separated. Implications regarding the shape of the optimal consumption profiles are discussed.     

Optimizing trial design in pharmacogenetics research: comparing a fixed parallel group,group sequential,and adaptive selection design on sample size requirements

Two‐stage clinical trial designs may be efficient in pharmacogenetics research when there is some but inconclusive evidence of effect modification by a genomic marker. Two‐stage designs allow to stop early for efficacy or futility and can offer the additional opportunity to enrich the study population to a specific patient subgroup after an interim analysis. This study compared sample size requirements for fixed parallel group, group sequential, and adaptive selection designs with equal overall power and control of the family‐wise type I error rate. The designs were evaluated across scenarios that defined the effect sizes in the marker positive and marker negative subgroups and the prevalence of marker positive patients in the overall study population. Effect sizes were chosen to reflect realistic planning scenarios, where at least some effect is present in the marker negative subgroup. In addition, scenarios were considered in which the assumed ‘true’ subgroup effects (i.e., the postulated effects) differed from those hypothesized at the planning stage. As expected, both two‐stage designs generally required fewer patients than a fixed parallel group design, and the advantage increased as the difference between subgroups increased. The adaptive selection design added little further reduction in sample size, as compared with the group sequential design, when the postulated effect sizes were equal to those hypothesized at the planning stage. However, when the postulated effects deviated strongly in favor of enrichment, the comparative advantage of the adaptive selection design increased, which precisely reflects the adaptive nature of the design. Copyright © 2013 John Wiley & Sons, Ltd.     

Use and Misuse of Indicators in Spatial Planning: The Example of Land Take

The use of indicators to assess the impacts of spatial planning policies has experienced a strong increase in the last decades, despite the difficulties to identify clear causality links in this discipline. The aim of this article is to critically reflect on the impacts of such a phenomenon on spatial planning policies and practices. In order to do so, it explores the issue of land take and how the European Community has set up a policy objective, based on an indicator, to try to tackle the phenomenon.