Cocaine-Dependent Adults and Recreational Cocaine Users Are More Likely Than Controls to Choose Immediate Unsafe Sex Over Delayed Safer Sex

Cocaine users have a higher incidence of risky sexual behavior and HIV infection than non-users. Our aim was to measure whether safer-sex discount rates, a measure of the likelihood of having immediate unprotected sex versus waiting to have safer sex, differed between controls and cocaine users of varying severity. Of the 162 individuals included in the primary data analyses, 69 met DSM-IV-TR criteria for cocaine dependence, 29 were recreational cocaine users who did not meet dependence, and 64 were controls. Participants completed the sexual delay discounting task, which measures one’s likelihood of using a condom when immediately available and how that likelihood decreases as a function of delay to condom availability with regard to four images chosen by the participants of hypothetical sexual partners differing in perceived desirability and likelihood of having a sexually-transmitted infection. When a condom was immediately available, stated likelihood of condom use sometimes differed between cocaine users and controls, which depended on the image condition. Even after controlling for rates of condom use when immediately available, the Cocaine Dependent and Recreational Users groups were more sensitive to delay to condom availability than controls. Safer-sex discount rates were also related to intelligence scores. The sexual discounting task identifies delay as a key variable that impacts the likelihood of using a condom among these groups and suggests that HIV-prevention efforts may be differentially effective based on an individual’s safer-sex discount rate

Effects of methylphenidate on attention in Wistar rats treated with the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4)

The aim of this study was to assess the effects of the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) on attention in rats as measured using the 5-choice-serial-reaction-time task (5CSRTT) and to investigate whether methylphenidate has effects on DSP4-treated rats. Methylphenidate is a noradrenaline and dopamine reuptake inhibitor and commonly used in the pharmacological treatment of individuals with attention deficit/hyperactivity disorder (ADHD). Wistar rats were trained in the 5CSRTT and treated with one of three doses of DSP4 or saline. Following the DSP4 treatment rats were injected with three doses of methylphenidate or saline and again tested in the 5CSRTT. The treatment with DSP4 caused a significant decline of performance in the number of correct responses and a decrease in response accuracy. A reduction in activity could also be observed. Whether or not the cognitive impairments are due to attention deficits or changes in explorative behaviour or activity remains to be investigated. The treatment with methylphenidate had no beneficial effect on the rats’ performance regardless of the DSP4 treatment. In the group without DSP4 treatment, methylphenidate led to a reduction in response accuracy and bidirectional effects in regard to parameters related to attention. These findings support the role of noradrenaline in modulating attention and call for further investigations concerning the effects of methylphenidate on attentional processes in rats

Value-based decision-making battery: A Bayesian adaptive approach to assess impulsive and risky behavior

Using simple mathematical models of choice behavior, we present a Bayesian adaptive algorithm to assess measures of impulsive and risky decision making. Practically, these measures are characterized by discounting rates and are used to classify individuals or population groups, to distinguish unhealthy behavior, and to predict developmental courses. However, a constant demand for improved tools to assess these constructs remains unanswered. The algorithm is based on trial-by-trial observations. At each step, a choice is made between immediate (certain) and delayed (risky) options. Then the current parameter estimates are updated by the likelihood of observing the choice, and the next offers are provided from the indifference point, so that they will acquire the most informative data based on the current parameter estimates. The procedure continues for a certain number of trials in order to reach a stable estimation. The algorithm is discussed in detail for the delay discounting case, and results from decision making under risk for gains, losses, and mixed prospects are also provided. Simulated experiments using prescribed parameter values were performed to justify the algorithm in terms of the reproducibility of its parameters for individual assessments, and to test the reliability of the estimation procedure in a group-level analysis. The algorithm was implemented as an experimental battery to measure temporal and probability discounting rates together with loss aversion, and was tested on a healthy participant sample