Alcohol effects on human risk taking

Rationale Despite a well-established relationship between alcohol and risky behavior in the natural environment, laboratory investigations have not reliably shown acute alcohol effects on human risk-taking.Objectives The present study was designed to demonstrate a dose-response relationship between acute alcohol administration and human risk taking. Further, this investigation sought to delineate behavioral mechanisms that may be involved in alcohol-induced changes in the probability of risky behavior.Methods Using a laboratory measure of risk taking designed to address acute drug effects, 16 adults were administered placebo, 0.2, 0.4, and 0.8 g/kg alcohol in a within-subject repeated measures experimental design. The risk-taking task presented subjects with a choice between two response options operationally defined as risky and non-risky. Data analyses examined: breath alcohol level (BAL), subjective effects, response rates, distribution of choices between the risky and non-risky option, and trial-by-trial probabilities of making losing and winning risky responses.Results The alcohol administration produced the expected changes in BAL, subjective effects, and response rate. Alcohol dose-dependently increased selection of the risky response option, and at the 0.8 g/kg dose, increased the probability of making consecutive losing risky responses following a gain on the risky response option.Conclusions Acute alcohol administration can produce measurable changes in human risk-taking under laboratory conditions. Shifts in trial-by-trial response probabilities suggest insensitivity to past rewards and more recent losses when intoxicated, an outcome consistent with previous studies. This shift in sensitivity to consequences is a possible mechanism in alcohol-induced changes in risk taking.     

Acute marijuana effects on social conversation

The present study assessed the acute effects of smoked marijuana on social conversation. Speech quantity was recorded continuously in seven moderate marijuana users during separate 1 h experimental sessions following the paced smoking of 0, 1.01, 1.84, and 2.84% THC marijuana cigarettes. Subjects engaged in conversation with undrugged partners who smoked placebo marijuana cigarettes. The active marijuana produced significant decreases in speech quantity, increases in heart rate, and increases in self-reports of high and sedation. Partners showed no effects in speech quantity or self-reports of drug effects that were systematically related to the doses administered to the subject pair members. The effects on speech quantity observed in the present study after acute dosing are similar to the effects on social conversation reported previously during chronic marijuana dosing. Marijuana appears to be an exception to the general rule that drugs of abuse increase verbal interaction.     

Acute effects of smoking marijuana on hormones, subjective effects and performance in male human subjects

Four healthy male subjects smoked two marijuana cigarettes or one marijuana cigarette and one placebo cigarette, or two placebo cigarettes on separate days in a random order crossover design. Each marijuana cigarette contained 2.8% delta-9-tetrahydrocannabinol (THC). Plasma hormones and THC were measured before and after each smoking session. Plasma LH was significantly depressed and cortisol was significantly elevated after smoking marijuana. Nonsignificant depressions of prolactin, FSH, testosterone and free testosterone and elevation of GH also occurred. Concurrent measures of subjective effects via subscales of the Addiction Research Center Inventory, Single Dose Questionnaire and a Visual Analog Scale were generally elevated. Significant impairment on a psychomotor performance task paralleled elevations in subjective effects, hormone effects and peak THC determinations. Although all the hormone effects were within normal basal ranges, interactions between these systems, and their effects on behavior cannot be discounted.     

Sexual risk taking among young adult dual alcohol and marijuana users

Use of alcohol and marijuana among college students is common and use of these substances may increase the likelihood of risky sexual behavior. The present study found significant associations between risky sexual behavior and both mean BAC per drinking day and marijuana use intensity. However, hypothesized interactions between marijuana use and BAC were not supported. In addition, positive and negative urgency and premeditation were each significantly associated with the likelihood of risky sex. Substance use and facets of impulsivity and self-control exhibited direct associations with risky sexual behavior but hypothesized moderation effects were not supported. Associations between urgency and risky sexual behavior varied as a function of gender and trait positive affect.     

A twin study on sensation seeking, risk taking behavior and marijuana use

The contribution of genetic and environmental factors to the covariation between risk-taking and marijuana use was assessed in adolescent twins. Genetic factors were found to significantly influence some traits (i.e. risk-taking attitude), while familial environmental factors were important for others (i.e. sexual promiscuity). For marijuana use, genetic and environmental factors were equally important; however, the association between risk taking and marijuana use may not be comparable for different behaviors. Results suggest that different etiological factors may underlie various risk taking traits which is relevant to both prevention efforts and attempts to identify genes involved in risk taking and shared genetic influences with substance use.     

Acute effects of marijuana on cognition: relationships to chronic effects and smoking techniques.

A double-blind, placebo-controlled study assessed acute effects on human cognition of marijuana smoking involving long or short durations of inhalation and breath holding. During eight test sessions, 48 adult, male volunteers completed standardized, pencil-and-paper tests of educational development and ability, as well as computerized tests of learning, associative processes, abstraction, and psychomotor performance. Marijuana impaired all capabilities except abstraction and vocabulary. These impairments were more pervasive than those associated with heavy, chronic marijuana use in a previous study involving the same tests, but showed some similarities. Marijuana altered associative processes, encouraging more uncommon associations. Marijuana-induced impairment in learning pairs of words was influenced by associative relationships between the words. There were a few hints that prolonged breath holding increased marijuana's effects under some test conditions, but in general it did not. Prolonged breath holding itself affected performance in four tests, regardless of whether subjects smoked marijuana or placebo. Whether physiological or psychological factors (e.g., exposure to carbon monoxide in smoke or subjects' expectations) produced these effects could not be determined.     

Acute marijuana effects on response-reinforcer relations under multiple variable-interval schedules

Acute marijuana administration may alter response-reinforcer relationships via a change in reinforcer efficacy, but may also impair coordination and motor function. One approach to evaluating drug effects on both motor function and reinforcer efficacy involves fitting the matching law equation to data obtained under multiple variable interval (VI) schedules. The present report describes an experiment that examined the effects of acute marijuana on response properties using this approach. Six human subjects responded under a multiple VI schedule for monetary reinforcers after smoking placebo and two active doses of marijuana. The low marijuana dose produced unsystematic changes in responding. As measured by the matching law equation parameters (k and rB), at the high dose five subjects showed a decrease-motor-related properties of response rate and four subjects' responding indicated a decrease in reinforcer efficacy. These data raise the possibility that, at high doses, marijuana administration alters both motor function and reinforcer efficacy.     

The effects of d-amphetamine on risk taking

Summary The effect of d-amphetamine on the risk-taking behavior of penitentiary inmates was investigated, utilizing a gambling situation involving cigarettes. The experimental situation consisted of choices between alternative gambles involving different amounts of risk. The 29 men served as their own controls, with the number of high-risk choices made by each subject when under drug (10 mg d-amphetamine sulfate, orally) being compared with the number of choices made during his placebo session. The difference was significant in the direction of increased risk-taking under the drug. The results are interpreted as offering tentative support to the hypothesis that d-amphetamine increases risk-taking, although alternative interpretations are provided.The author thanks W. M. Lepley, J. H. Grosslight, and the late S. Siegel of The Pennsylvania State University, and also H. M. Janney, Medical Director of the U.S. Bureau of Prisons, and F. T. Wilkinson, Warden, and the staff of the Northeastern States Federal Penitentiary, for granting access to the subject population.     

Application of a computational decision model to examine acute drug effects on human risk taking

In 3 previous experiments, high doses of alcohol, marijuana, and alprazolam acutely increased risky decision making by adult humans in a 2-choice (risky vs. nonrisky) laboratory task. In this study, a computational modeling analysis known as the expectancy valence model (J. R. Busemeyer & J. C. Stout, 2002) was applied to individual-participant data from these studies, for the highest administered dose of all 3 drugs and corresponding placebo doses, to determine changes in decision-making processes that may be uniquely engendered by each drug. The model includes 3 parameters: responsiveness to rewards and losses (valence or motivation); the rate of updating expectancies about the value of risky alternatives (learning/memory); and the consistency with which trial-by-trial choices match expected outcomes (sensitivity). Parameter estimates revealed 3 key outcomes: Alcohol increased responsiveness to risky rewards and decreased responsiveness to risky losses (motivation) but did not alter expectancy updating (learning/memory); both marijuana and alprazolam produced increases in risk taking that were related to learning/memory but not motivation; and alcohol and marijuana (but not alprazolam) produced more random response patterns that were less consistently related to expected outcomes on the 2 choices. No significant main effects of gender or dose by gender interactions were obtained, but 2 dose by gender interactions approached significance. These outcomes underscore the utility of using a computational modeling approach to deconstruct decision-making processes and thus better understand drug effects on risky decision making in humans.     

Personality and gender differences in effects of d-amphetamine on risk taking

The effects of stimulant drugs on risk-taking behavior vary across individuals, even in healthy samples. These differences could relate to personality, which may share common mechanisms with drug effects or impulsive, risk-taking behavior. The current study investigated the role of temperament and gender in the effects of amphetamine on risk taking. Forty healthy men and women, aged 18 to 35, completed the Balloon Analogue Risk Task (BART; Lejuez et al., 2002) with three reward values after ingesting placebo or d-amphetamine (10, 20 mg). They completed the Multidimensional Personality Questionnaire Brief Form (MPQ-BF; Patrick et al., 2002), with three main scales: Trait reward sensitivity (Agentic Positive Emotionality; AgPEM), impulsivity (Constraint; CON), and negative affect (Negative Emotionality; NEM). d-Amphetamine (20 mg) decreased risk behavior in low AgPEM males, but increased risk behavior in high AgPEM males, producing positive correlations with AgPEM in men (r >or= +.55, p<.05). The drug did not affect risk-taking in women. There was evidence of discriminant validity between the AgPEM, NEM, and CON dimensions and behavioral responses to amphetamine. Implications for treatment and addiction are discussed. (c) 2008 APA, all rights reserved.     

Effects of marijuana on human reproduction

As U.S. states steadily legalize its distribution and the prevalence of its use in people of reproductive age continues to rise, the need to understand the effects of marijuana on human physiology is becoming increasingly urgent. While marijuana is well-known for its psychoactive effects and applications in controlling pain and nausea, little is known about its effects on reproduction. This review includes in vitro studies which consistently demonstrate associations between marijuana consumption and low sperm count, dysregulated menstruation, and abnormal placentation. While many in vivo studies associate maternal marijuana use with stillbirth, neonatal intensive care unit (NICU) admission, and offspring psychosis, significant literature negates these relationships by controlling for poly-substance use and socioeconomic status. Data limited by self-reporting and confounds precludes the drawing of definitive conclusions regarding the effects of marijuana on reproduction. This review serves as a call to action to elucidate these effects and discourage marijuana use in people of reproductive age.     

Normalization of marijuana use: its effects on adolescents' intentions to use marijuana

The comparative salience of attitudes, normative influences, and perceptions of the ease or difficulty of engaging in marijuana use was examined in 91 adolescents from three subsamples: those living in Nimbin, Australia, where marijuana use appears to have become normalized, a control group, and a group of homeless adolescents, surveyed in 1997. There were no differences between two of the groups in relation to their attitudes towards marijuana, and no differences in perceived access to the drug. For those who intended using marijuana, personal beliefs were significantly more salient than beliefs about what important others thought they should do.     

Acute effects of marijuana smoking on aggressive,escape and point-maintained responding of male drug users

Aggressive, escape and point-maintained operant responding of male marijuana smokers were measured during six 25-min sessions conducted over an 8-h experimental day. Aggressive responding ostensibly subtracted points exchangeable for money from another subject. Escape responding protected the subject's counter from point subtractions initiated by the other subject for some period of time. Aggressive and escape responding were engendered by subtracting points from the subjects and maintained by initiation of intervals free of point subtractions. Point subtractions presented to the subjects were attributed to other persons. Subjects earned points exchangeable for money on a third response option. Subjects participated in one session prior to smoking and five sessions after smoking. Subjects smoked placebo or three different potencies of active marijuana cigarettes. Marijuana smoking effects on escape responding were not significant and depended upon the frequency of provocation. Point-maintained responding was decreased after marijuana smoking. Aggressive responding was increased for the first hour after smoking and returned to placebo levels later in the day. These effects of marijuana smoking on aggressive responding are discussed in terms of subject characteristics, particularly drug use history.     

Expectancy mediated effects of marijuana on menopause symptoms

Background Medical marijuana alleviates a variety of symptoms, including those associated with menopause, such as insomnia, irritability, depression and joint pain. However, little work has addressed the use of marijuana in a population of menopausal women, or the role of menopausal women’s marijuana treatment expectancies in regard to consumption. We hypothesized that menopausal women who used marijuana would expect it to alleviate symptoms that have responded well to the plant in previous research. Based on the marijuana expectancy literature, we also hypothesized that links from menopause symptoms to marijuana use would arise via indirect paths through expectancies. Methods Menopausal and post-menopausal women (N = 115) who endorsed lifetime marijuana use completed an online survey assessing their frequency of use, average intoxication – a proxy for quantity, menopause symptoms, and expectancies of relief from menopause symptoms. Results Women expected marijuana to improve joint/muscle discomfort, irritability, sleep problems, depression, anxiety and hot flashes, but not sex problems, heart discomfort, exhaustion, vaginal dryness and bladder problems. Expectancies mediated the links between menopause symptoms and frequency of use. Average intoxication did not correlate with symptoms or expectations of relief. Symptoms, expectancies, and frequency of marijuana use were all independent of marijuana-related problems. Conclusions Particularly as the population ages, increased research on how medical marijuana might help menopause symptoms without increasing marijuana-related problems could prove heuristic.     

The effects of medical marijuana laws on potency

BackgroundMarijuana potency has risen dramatically over the past two decades. In the United States, it is unclear whether state medical marijuana policies have contributed to this increase.MethodsEmploying a differences-in-differences model within a mediation framework, we analyzed data on n = 39,157 marijuana samples seized by law enforcement in 51 U.S. jurisdictions between 1990 and 2010, producing estimates of the direct and indirect effects of state medical marijuana laws on potency, as measured by Δ⁹-tetrahydrocannabinol content.ResultsWe found evidence that potency increased by a half percentage point on average after legalization of medical marijuana, although this result was not significant. When we examined specific medical marijuana supply provisions, results suggest that legal allowances for retail dispensaries had the strongest influence, significantly increasing potency by about one percentage point on average. Our mediation analyses examining the mechanisms through which medical marijuana laws influence potency found no evidence of direct regulatory impact. Rather, the results suggest that the impact of these laws occurs predominantly through a compositional shift in the share of the market captured by high-potency sinsemilla.ConclusionOur findings have important implications for policymakers and those in the scientific community trying to understand the extent to which greater availability of higher potency marijuana increases the risk of negative public health outcomes, such as drugged driving and drug-induced psychoses. Future work should reconsider the impact of medical marijuana laws on health outcomes in light of dramatic and ongoing shifts in both marijuana potency and the medical marijuana policy environment.     

Effects of alcohol pretreatment on human marijuana self-administration

Alcohol and marijuana are frequently used together, yet there has been little study of how the presence of one drug might affect consumption of the other. The present study examined the effects of alcohol pretreatments on marijuana self-administration in a group of 15 males and 5 females who were users of both drugs. During evening sessions in a recreational setting, pairs of subjects consumed drinks containing 0.0, 0.3 or 0.6 g/kg alcohol 30 min before a 60-min period of ad libitum marijuana smoking. Marijuana self-administration was assessed in several ways: by measuring the number of cigarettes smoked, the increase in expired air carbon monoxide resulting from marijuana smoke inhalation, and the increase in heart rate due to THC absorption. None of these variables was significantly affected by the alcohol pretreatments, although substantial individual differences were observed. These results indicate that low to moderate doses of alcohol do not systematically influence marijuana self-administration.     

The pharmacologic effects of daily marijuana smoking in humans.

Six healthy male, paid volunteers smoked one NIDA cigarette containing 1.0% THC each day for 13 consecutive days. They were tested before and after the period of drug administration by the following procedure: the subjects smoked one NIDA marijuana cigarette containing 1.0% THC followed 15 minutes later by the intravenous infusion of 52 micrograms/min of deuterated THC for 50 minutes. The THC plasma concentrations, ratings of "high" and heart rate effects produced by the combined drug administration were measured, and absolute bioavailability of smoked THC was calculated on Days 1 and 22. Statistical analyses indicate that the only significant changes induced by daily marijuana exposure were in cardioacceleration.     

Acute and residual effects of alcohol and marijuana,alone and in combination,on mood and performance

The duration of behavioral impairment after marijuana smoking remains a matter of some debate. Alcohol and marijuana are frequently used together, but there has been little study of the effects of this drug combination on mood and behavior the day after use. The present study was designed to address these issues. Fourteen male and female subjects were each studied under four conditions: alcohol alone, marijuana alone, alcohol and marijuana in combination, and no active treatment. Mood and performance assessments were made during acute intoxication and twice the following day (morning and mid-afternoon). Acutely, each drug alone produced moderate levels of subjective intoxication and some degree of behavioral impairment. The drug combination produced the greatest level of impairment on most tasks and strong overall subjective ratings. There were few significant interactions between the two drugs, indicating that their effects tended to be additive. Only weak evidence was obtained for subjective or behavioral effects the day after active drug treatments, although consistent time-of-day effects (morning versus afternoon) were observed on several subjective and behavioral measures. In sum, this study provided little evidence that moderate doses of alcohol and marijuana, consumed either alone or in combination, produce behavioral or subjective impairment the following day.