Patrick S. Johnson

Delay and Probability Discounting of Sexual and Monetary Outcomes in Individuals with Cocaine Use Disorders and Matched Controls

Individuals with cocaine use disorders are disproportionately affected by HIV/AIDS, partly due to higher rates of unprotected sex. Recent research suggests delay discounting of condom use is a factor in sexual HIV risk. Delay discounting is a behavioral economic concept describing how delaying an event reduces that event’s value or impact on behavior. Probability discounting is a related concept describing how the uncertainty of an event decreases its impact on behavior. Individuals with cocaine use disorders (n = 23) and matched non-cocaine-using controls (n = 24) were compared in decision-making tasks involving hypothetical outcomes: delay discounting of condom-protected sex (Sexual Delay Discounting Task), delay discounting of money, the effect of sexually transmitted infection (STI) risk on likelihood of condom use (Sexual Probability Discounting Task), and probability discounting of money. The Cocaine group discounted delayed condom-protected sex (i.e., were more likely to have unprotected sex vs. wait for a condom) significantly more than controls in two of four Sexual Delay Discounting Task partner conditions. The Cocaine group also discounted delayed money (i.e., preferred smaller immediate amounts over larger delayed amounts) significantly more than controls. In the Sexual Probability Discounting Task, both groups showed sensitivity to STI risk, however the groups did not differ. The Cocaine group did not consistently discount probabilistic money more or less than controls. Steeper discounting of delayed, but not probabilistic, sexual outcomes may contribute to greater rates of sexual HIV risk among individuals with cocaine use disorders. Probability discounting of sexual outcomes may contribute to risk of unprotected sex in both groups. Correlations showed sexual and monetary results were unrelated, for both delay and probability discounting. The results highlight the importance of studying specific behavioral processes (e.g., delay and probability discounting) with respect to specific outcomes (e.g., monetary and sexual) to understand decision making in problematic behavior.

Investigation of “Bath Salts” Use Patterns Within an Online Sample of Users in the United States

Abstract “Bath salts” are synthetic stimulant “legal highs” that have recently been banned in the US. Epidemiological data regarding bath salts use are limited. In the present study, 113 individuals in the US reporting use of bath salts completed an anonymous, online survey characterizing demographic, experiential, and psychological variables. Respondents were more often male, 18–24 years old, and Caucasian/White with some college education. Past-year use was typically low (≤ 10 days), but marked by repeated dosing. Intranasal was the most frequently reported administration route and subjective effects were similar to other stimulants (e.g., cocaine, amphetamines). Bath salts use was associated with increased sexual desire and sexual HIV risk behavior, and met DSM-5 diagnostic criteria for disordered use in more than half of respondents. Bath salts use persists in the US despite federal bans of cathinone-like constituents. Self-reported stimulant-like effects of bath salts suggest their use as substitutes for traditional illicit stimulants. Data revealed more normative outcomes vis-à-vis extreme accounts by media and medical case reports. However, indications of product abuse potential and sexual risk remain, suggesting bath salts pose potential public health harm.

Early and Prolonged Exposure to Reward Delay: Effects on Impulsive Choice and Alcohol Self-administration in Male Rats

Naturally occurring impulsive choice has been found to positively predict alcohol consumption in rats. However, the extent to which experimental manipulation of impulsive choice may modify alcohol consumption remains unclear. In the present study, we sought to: (a) train low levels of impulsive choice in rats using early, prolonged exposure to reward delay, and (b) determine the effects of this manipulation on subsequent alcohol consumption. During a prolonged training regimen, three groups of male, adolescent Long-Evans rats (21-22 days old at intake) responded on a single lever for food rewards delivered after either a progressively increasing delay, a fixed delay, or no delay. Posttests of impulsive choice were conducted, as was an evaluation of alcohol consumption using a limited-access, two-bottle test. Following delay-exposure training, both groups of delay-exposed rats made significantly fewer impulsive choices than did rats in the no-delay group. In addition, fixed-delay rats consumed significantly more alcohol during daily, 30-min sessions than no-delay rats. Possible mechanisms of these effects are discussed, as is the significance of these findings to nonhuman models of addiction.

Test-Retest Reliability and Construct Validity of the Experiential Discounting Task

Delay discounting (the devaluation of delayed rewards) has been studied extensively using animal models with psychophysical adjustment procedures. Similar procedures have been developed to assess delay discounting in humans and these procedures most often use hypothetical rewards and delays. The Experiential Discounting Task (EDT) was developed to assess human delay discounting using real rewards and delays. In the present study we examined the test-retest reliability and construct validity of the EDT. Construct validity was evaluated by comparing it with a standard delay discounting task. The EDT had poor test-retest reliability and discounting rates obtained with this task were uncorrelated with those obtained in the standard delay discounting task. Area under the EDT discounting curve was negatively correlated with scores on a measure of boredom proneness (i.e., individuals prone to boredom more steeply discounted delayed money in the EDT). This correlation may underlie previous reports that discounting in the EDT is correlated with addictions, as some evidence suggests boredom proneness is correlated with gambling, cigarette smoking, alcohol consumption, and sensation seeking. Boredom proneness scores were correlated with no other measure of discounting. These findings suggest the EDT measures a different construct than that measured by traditional delay discounting tasks.

Marijuana and tobacco cigarettes: Estimating their behavioral economic relationship using purchasing tasks.

Although marijuana and tobacco are commonly coused, the nature of their relationship has not been fully elucidated. Behavioral economics has characterized the relationship between concurrently available commodities but has not been applied to marijuana and tobacco couse. U.S. adults ≥18 years who coused marijuana and tobacco cigarettes were recruited via Mechanical Turk, a crowdsourcing service by Amazon. Participants (N = 82) completed online purchasing tasks assessing hypothetical marijuana or tobacco cigarette puff consumption across a range of per-puff prices; 2 single-commodity tasks assessed these when only 1 commodity was available, and 2 cross-commodity tasks assessed these in the presence of a concurrently available fixed-price commodity. Purchasing tasks generated measures of demand elasticity, that is, sensitivity of consumption to prices. In single-commodity tasks, consumption of tobacco cigarette puffs (elasticity of demand: &agr; = 0.0075; 95% confidence interval [0.0066, 0.0085], R2 = 0.72) and of marijuana puffs (&agr; = .0044; 95% confidence interval [0.0038, 0.0049], R2 = 0.71) declined significantly with increases in price per puff. In cross-commodity tasks when both tobacco cigarette puffs and marijuana puffs were available, demand for 1 commodity was independent of price increases in the other commodity (ps > .05). Results revealed that, in this small sample, marijuana and tobacco cigarettes did not substitute for each other and did not complement each other; instead, they were independent of each other. These preliminary results can inform future studies assessing the economic relationship between tobacco and marijuana in the quickly changing policy climate in the United States.

Differential Relations Between Delay Discounting and Distress Tolerance as a Function of Opportunity Cost and Alcohol Use

Delay discounting refers to one process by which an individual devalues delayed outcomes. Typical discounting tasks provide no information about events during delays to larger-later rewards. Imposing opportunity costs during the delay increases how steeply delayed rewards are discounted (P. S. Johnson, Herrmann, & Johnson, 2015). The present research evaluated whether distress tolerance (i.e., one’s ability to tolerate distressing emotions and events) is related to discounting rates when opportunity costs are low, high, or unspecified. In a sample of predominantly female college students, we partially replicated that delay discounting was related to distress tolerance when opportunity costs were unspecified (significant relations confined to particular facets of distress tolerance), but distress tolerance was not related to delay discounting when opportunity costs were specified as low or high. The nature of the relation between distress tolerance and discounting when opportunity costs were unspecified was clarified by a significant interaction between alcohol use and distress tolerance; distress tolerance was unrelated to delay discounting except among participants with problematic alcohol use. Further research is needed to characterize relations between alcohol use, distress tolerance, and delay discounting and inform prevention and treatment efforts in at-risk populations.

Morning administration of oral methamphetamine dose-dependently disrupts nighttime sleep in recreational stimulant users

INTRODUCTION Use of amphetamine-type stimulants (e.g., methamphetamine) is associated with acute sleep disruptions. No prior reports have characterized the acute effects of methamphetamine on sleep using polysomnography, the gold standard for objective sleep monitoring. METHODS Recreational stimulant users (n=19) completed a baseline assessment, which included questionnaires assessing demographic and substance use characteristics, and the Pittsburgh Sleep Quality Index (PSQI), which assesses sleep quality over the past month. Participants were administered 0mg (placebo), 20mg, or 40mg oral methamphetamine at 08:15h on study days, using a double-blind, randomized, within-subjects design. Sleep was monitored using polysomnography from 22:20 that evening until 06:15 the following morning. RESULTS PSQI scores indicated more than half of participants reported poor sleep quality at baseline. Methamphetamine dose-dependently increased sleep latency, and decreased total sleep time, sleep efficiency, time in NREM 2 sleep, number of REM periods, and total time in REM sleep. Sleep under placebo conditions was consistent with what would be expected from healthy adults. CONCLUSIONS Morning oral administration of methamphetamine produces robust disruptions in nighttime sleep. Future research should examine relations between stimulant use and sleep disruption in naturalistic settings, with regard to both stimulant abuse and licit prescription use.

Novel Drugs of Abuse: Cannabinoids, Stimulants, and Hallucinogens

Abstract A paradigm shift in the illicit drug market has occurred in the 21st century with a dramatic increase in the number of novel psychoactive drugs available. These novel drugs of abuse include: synthetic cannabinoids; synthetic cathinones; novel phenethylamines, piperazines, and tryptamines; and Salvia divinorum. This chapter provides an overview of these compounds, with emphasis on providing basic information on the history, pharmacology, epidemiology, and behavioral effects. Similarities and differences of substances in each category with regard to molecular structure and physiological, subjective, and behavioral effects are highlighted. We also present safety concerns associated with use of these drugs, and describe how attempts to regulate the legal status of novel drugs may promote an ever-growing number and variety of psychoactive drugs available for nonmedical use.