What are sensation seekers seeking?

Modelling Differential Vulnerability to Substance Use Disorder in Rodents: Neurobiological Mechanisms

Despite the prevalence of drug use within society, only a subset of individuals actively taking addictive drugs lose control over their intake and develop compulsive drug-seeking and intake that typifies substance use disorder (SUD). Although research in this field continues to be an important and dynamic discipline, the specific neuroadaptations that drive compulsive behaviour in humans addicted to drugs and the neurobiological mechanisms that underlie an individual's innate susceptibility to SUD remain surprisingly poorly understood. Nonetheless, it is clear from research within the clinical domain that some behavioural traits are recurrently co-expressed in individuals with SUD, thereby inviting the hypothesis that certain behavioural endophenotypes may be predictive, or at least act in some way, to modify an individual's probability for developing this disorder. The analysis of such endophenotypes and their catalytic relationship to the expression of addiction-related behaviours has been greatly augmented by experimental approaches in rodents that attempt to capture diagnostically relevant aspects of this progressive brain disorder. This work has evolved from an early focus on aberrant drug reinforcement mechanisms to a now much richer account of the putatively impaired cognitive control processes that ultimately determine individual trajectories to compulsive drug-related behaviours. In this chapter we discuss the utility of experimental approaches in rodents designed to elucidate the neurobiological and genetic underpinnings of so-called risk traits and how these innate vulnerabilities collectively contribute to the pathogenesis of SUD.

Behavioral endophenotypes of drug addiction: Etiological insights from neuroimaging studies

This article reviews recent advances in the elucidation of neurobehavioral endophenotypes associated with drug addiction made possible by the translational neuroimaging techniques magnetic resonance imaging (MRI) and positron emission tomography (PET). Increasingly, these non-invasive imaging approaches have been the catalyst for advancing our understanding of the etiology of drug addiction as a brain disorder involving complex interactions between pre-disposing behavioral traits, environmental influences and neural perturbations arising from the chronic abuse of licit and illicit drugs. In this article we discuss the causal role of trait markers associated with impulsivity and novelty-/sensation-seeking in speeding the development of compulsive drug administration and in facilitating relapse. We also discuss the striking convergence of imaging findings from these behavioural traits and addiction in rats, monkeys and humans with a focus on biomarkers of dopamine neurotransmission, and highlight areas where further research is needed to disambiguate underlying causal mechanisms. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

High-novelty-preference rats are predisposed to compulsive cocaine self-administration

Sensation/novelty-seeking is amongst the best markers of cocaine addiction in humans. However, its implication in the vulnerability to cocaine addiction is still a matter of debate, as it is unclear whether this trait precedes or follows the development of addiction. Sensation/novelty-seeking trait has been identified in rats on the basis of either novelty-induced locomotor activity (high-responder (HR) trait) or novelty-induced place preference (high-novelty-preference trait (HNP)). HR and HNP traits have been associated with differential sensitivity to psychostimulants. However, it has recently been demonstrated that HR rats do not develop compulsive cocaine self-administration (SA) after protracted exposure to the drug, thereby suggesting that at least one dimension of sensation/novelty seeking in the rat is dissociable from the vulnerability to switch from controlled to compulsive cocaine SA. We therefore investigated whether HNP, as measured as the propensity to choose a new environment in a free choice procedure, as opposed to novelty-induced locomotor activity, predicts the vulnerability to, and the severity of, addiction-like behavior for cocaine. For this, we identified HR/LR rats and HNP/LNP rats before any exposure to cocaine. After 60 days of cocaine SA, each rat was given an addiction score based on three addiction-like behaviors (persistence of responding when the drug is signaled as not available, high breakpoint under progressive ratio schedule and resistance to punishment) that resemble the clinical features of drug addiction, namely inability to refrain from drug seeking, high motivation for the drug and compulsive drug use despite adverse consequences. We show that, as opposed to HR rats, HNP rats represent a sub-population predisposed to compulsive cocaine intake, displaying higher addiction scores than LNP rats. This study thereby provides new insights into the factors predisposing to cocaine addiction, supporting the hypothesis that addiction is sustained by two vulnerable phenotypes: a 'drug use prone' phenotype such as HR which brings an individual to develop drug use and an 'addiction prone' phenotype, such as HNP, which facilitates the shift from sustained to compulsive drug intake and addiction.

A Validation and Psychometric Examination of the Arnett Inventory of Sensation Seeking (AISS) in German Adolescents1

Summary: The present study examines the reliability (internal consistency) and the the factorial validity, as well as the construct validity and the criterion-oriented validity (criterion: Delinquent behavior) of the Arnett Inventory of Sensation Seeking (AISS; Arnett, 1994 ). The study analyzed a sample of German adolescents aged 14 to 16 years (N = 1236) who, in addition to the AISS, also completed the NEO-Five Factor Inventory (NEO-FFI) and the subscale Delinquent Behavior of the Youth Self-Report (YSR). The results, indeed, confirm the hypothesized two-factor structure of the AISS (novelty vs. intensity of stimulation), however, as indicated by modification indices and standardized expected parameter chances, some items had to be excluded from the model to provide an adequate fit for the data. Nevertheless, the internal consistencies of the shortened two-factor scale are considerably low, ranging from .46 to .58. As an index of construct validity, males scored higher than females on both the Intensity subscale and the Total scale. Correlation with the scales of the NEO-FFI revealed that the convergent and discriminant validities of the AISS-scales were quite satisfying. Indications of criterion-oriented validity were obtained by prediction of delinquent behavior (setting fire, stealing, and playing truant) using the Intensity subscale. On the whole, the results yielded sufficient support for the validity of the AISS, while pointing to certain desirable modifications.