Role of individual and developmental differences in voluntary cocaine intake in rats.

RATIONALE: Early-onset drug taking is associated with increased likelihood of addiction, but it is unclear whether early onset is causal in development of addiction. Many other factors are associated with increased risk of addiction and also promote early intake. Here, a rodent model is used to explore the causality of early onset in development of self-administration and addiction-like behavior and to examine factors that promote self-administration. METHODS: We used cocaine self-administration to examine drug taking and addiction-like behavior in adolescent and adult rats a priori characterized for their locomotor responses to novelty and cocaine and behavior in the light-dark task. RESULTS: Adolescent animals initially sought more cocaine than adults. However, as the adolescents matured, their intake fell and they did not differ from adults in terms of unreinforced lever-pressing, extinction or reinstatement behavior. For both age groups, self-administration was positively correlated with the locomotor response to novelty, the locomotor response to cocaine, and with time in light in the light-dark task. The rats that were insensitive to cocaine's locomotor effects and that spent the least time in light in the light-dark task sought the least cocaine, appearing to be "protected" from the reinforcing effects of cocaine. There was no difference between the two age groups in appearance of this "protected" phenotype. CONCLUSIONS: These results suggest that early onset of drug taking may promote increased use, but does not promote progression to addiction-like behavior. Furthermore, protective factors, such as innate anxiety and insensitivity to cocaine's pharmacological effects, function across developmental stages.

Bridging the gap between statistical analysis and decision making in public health research.

Statisticians have eagerly taken on the role of presenting statistical summaries of quantitative data. In areas of health, this means providing point and interval estimates for quantities of interest such as diagnostic risks and treatment effects or providing curve estimates for quantities of interest such as survival probabilities across time. Methods for providing such summaries are highly formalized and constantly evolving. While decision making is the incentive for nearly all such efforts, the process that transforms statistical summaries into decisions usually remains informal and ad hoc. Statisticians have not eagerly accepted the role of promoting formalized decision-theoretic techniques. This paper will argue that the gap between statistical synthesis and decision making is an unnatural and undesirable one, because it undermines the impact of quantitative information. An argument for bridging the gap by expanding the role of statisticians will be presented.