A Behavioral Economic Examination of Sexual Behaviors in the Era of Pre-exposure Prophylaxis via Explanatory Sequential Mixed Methods.

Pre-exposure prophylaxis (PrEP) use may be associated with condom use decisions. The current investigation examined sexual decision-making in the context of PrEP among young adult men who have sex with men (MSM) between 18 and 30 years old, using an explanatory sequential mixed methods design. For the quantitative aim, 99 MSM currently taking PrEP (i.e., PrEP-experienced) and 140 MSM not currently taking PrEP (i.e., PrEP-naive) completed an online survey, including the Sexual Delay Discounting Task (SDDT), which captures likelihood of condom use. For the qualitative aim, 15 people from each group were interviewed about their (1) conceptualizations of risky sex and (2) ways they manage their sexual risk. Participants were, on average, 25.69 years old (SD = 3.07) and 64% White. Results from the quantitative aim revealed, controlling for covariates, PrEP-experienced participants exhibited significantly lower likelihood of (1) using an immediately available condom and (2) waiting for a delayed condom (i.e., sexual delay discounting) compared to PrEP-naive participants. Qualitative themes explaining what young adult MSM consider to be risky sex included: (1) any sex as risky sex, (2) risky sex as "sex without a conversation," and (3) risky sex as sex with risk for physical harm. Themes on ways young adult MSM manage sexual risk were classified as proactive, reactive, and passive. Results suggest that PrEP use is related to condom use decisions. Taken together, quantitative differences in sexual delay discounting, but qualitatively similar conceptualizations and management of risky sex, suggest that the SDDT may be a useful tool in sex research to capture processes (i.e., delay discounting) underlying sexual decision-making that may be missed by traditional self-reports. Implications of results, including potentially providing (good quality) condoms with every PrEP prescription, and future research topics are discussed.

Use of preexposure prophylaxis and condom purchasing decisions.

Preexposure prophylaxis (PrEP) prevents human immunodeficiency virus (HIV) but not other sexually transmitted infections (STIs). Men who have sex with men (MSM) who take PrEP tend to report reduced condom use, but little is known about the underlying mechanisms. For this study, MSM who take PrEP (i.e., PrEP experienced; n = 88) and MSM who do not (i.e., PrEP naïve; n = 113) completed an online study, including the condom purchase task (CoPT). The CoPT assesses decisions to purchase condoms across escalating prices (range: free-$55) for sex with different types of hypothetical partners: those least likely to have an STD (least STD) and those that participants most want to have sex with (most want sex with). When condoms were free, PrEP-experienced MSM had a lower rate of condom purchasing than did PrEP-naïve MSM. For both partner types, PrEP-experienced MSM reached a price break point (i.e., would not buy condoms) at a lower price than did PrEP-naïve pariticipants. For the most-want-sex-with partner at the price at which participants elected not to buy condoms, only 23% of PrEP-experienced MSM chose to abstain from sex when not purchasing condoms versus 53% among PrEP-naïve MSM. Similar patterns were observed for the least-STD partner. The results support the potential utility of the CoPT in identifying behavioral mechanisms related to condom use and PrEP.

Associations Between Family History of Alcohol and/or Substance Use Problems and Frontal Cortical Development From 9 to 13 Years of Age: A Longitudinal Analysis of the ABCD Study.

Background: Previous investigations that have examined associations between family history (FH) of alcohol/substance use and adolescent brain development have been primarily cross-sectional. Here, leveraging a large population-based sample of youths, we characterized frontal cortical trajectories among 9- to 13-year-olds with (FH+) versus without (FH-) an FH and examined sex as a potential moderator. Methods: We used data from 9710 participants in the Adolescent Brain Cognitive Development (ABCD) Study (release 4.0). FH+ was defined as having ≥1 biological parents and/or ≥2 biological grandparents with a history of alcohol/substance use problems (n = 2433). Our primary outcome was frontal cortical structural measures obtained at baseline (ages 9-11) and year 2 follow-up (ages 11-13). We used linear mixed-effects models to examine the extent to which FH status qualified frontal cortical development over the age span studied. Finally, we ran additional interactions with sex to test whether observed associations between FH and cortical development differed significantly between sexes. Results: For FH+ (vs. FH-) youths, we observed increased cortical thinning from 9 to 13 years across the frontal cortex as a whole. When we probed for sex differences, we observed significant declines in frontal cortical thickness among boys but not girls from ages 9 to 13 years. No associations were observed between FH and frontal cortical surface area or volume. Conclusions: Having a FH+ is associated with more rapid thinning of the frontal cortex across ages 9 to 13, with this effect driven primarily by male participants. Future studies will need to test whether the observed pattern of accelerated thinning predicts future substance use outcomes.

Effects of parental mental health and family environment on impulsivity in preadolescents: a longitudinal ABCD study®.

Introduction: Impulsivity is a known risk factor for the development of substance use disorders and other psychiatric conditions that is influenced by both genetics and environment. Although research has linked parental mental health to children's impulsivity, potential mediators of this relationship remain understudied. The current investigation leverages the large national Adolescent Brain Cognitive Development (ABCD) Study to assess the mediating role of family conflict - an important social context for youth development - in the relationship between parental mental health and youth impulsivity. Methods: Data were from the first three annual waves of the ABCD study (Baseline N = 11,876 children, Mage = 9.9 years; 48% female; 52% White). Parental mental health conditions were self-reported internalizing, externalizing, and total problems. Youth completed the family conflict scale, and Urgency, Planning (lack of), Perseverance (lack of), Sensation Seeking, and Positive Urgency (UPPS-P) scale to measure impulsivity. To determine if within-family change in conflict from baseline to year 1 explained changes in the strength of relations between baseline parental mental health and year 2 youth impulsivity, longitudinal causal mediation analyses were conducted, controlling for demographic factors (i.e., age, sex, race, household income, parental education, marital status), as well as baseline levels of family conflict and outcomes. Separate mediation models were run for each mental health condition and each UPPS-P subscale. Results: Above and beyond bivariate relations, longitudinal mediation models, which included covariates, showed family conflict significantly (ps < 0.001) mediated relations between all three parental mental health conditions and all but one (i.e., sensation seeking) UPPS-P subscales. The proportion mediated through family conflict for internalizing problems and total problems on facets of impulsivity (except sensation seeking) ranged from 9% (for lack of perseverance) to 17% (for lack of planning). Proportion mediated via family conflict for externalizing problems on youth's impulsivity (except sensation seeking) was slightly higher, ranging between 13% (lack of perseverance) to 21% (lack of planning). Discussion: Family conflict may be an important intergenerational factor linking parental mental health and youth's impulsivity. Addressing parental mental health and family conflict may help curb increased impulsivity in youth, and in turn reduce adolescent substance use disorders.

Sexual Arousal-Delay Discounting: When Condoms Delay Arousal.

Sexual arousal plays an important role in condom use decisions. However, combined effects of reduced sexual arousal and delay to achieving arousal on condom use decisions remain understudied. This study used a novel sexual arousal-delay discounting (SADD) task to measure individuals' willingness to use a condom in situations where condom use would (1) delay time to arousal and (2) reduce the level of arousal one could achieve even after the delay (e.g., 5 minutes to reach 50% arousal). In Study 1, U.S. college students (N = 115; Mage = 18.6) reported their willingness to have sex with a condom in hypothetical scenarios where the condom delayed and reduced their partner's sexual arousal. In Study 2, U.S. college students (N = 208; Mage = 19.6; 99% ≤ 24 years old) completed the same task for two partners-partner perceived as most desirable and partner perceived as least likely to have an STI. In this study, a condom would affect either participants' own or partner's arousal. Study 3 replicated Study 2 using a non-college sample in the U.S. (N = 227; Mage = 30.5; 84% ≥ 25 years old). Across studies, willingness to use a condom decreased as the delay to reduced arousal increased. This effect of SADD was stronger when condoms reduced participants' own (vs. partner's) arousal, whereas comparisons between most desirable and least likely-to-have-STI partners provided mixed findings. Men had higher discounting rates than women across conditions. Greater SADD was associated with lower condom use self-efficacy, providing initial evidence for the task's validity. The role of delayed arousal in condom use and implications are discussed.

"That's Pot Culture Right There": Purchasing Behaviors of People Who Use Cannabis Without a Medical Cannabis Card.

Introduction: The legal landscape surrounding purchasing cannabis without a medical cannabis card (i.e., without MCC) is changing rapidly, affecting consumer access and purchasing behaviors. Cannabis purchasing behaviors are related to subsequent use and experiencing greater cannabis-related negative consequences. However, purchasing behaviors of individuals who use cannabis without MCC are understudied. Methods: The current study analyzed qualitative data from focus groups with adults who use cannabis without MCC (n = 5 groups; 6-7 participants/group; n = 31 total participants). Focus groups followed a semi-structured agenda, and were audio recorded and transcribed. Two coders applied thematic analysis to summarize topics pertaining to cannabis purchasing attitudes and behaviors. Focus groups occurred in 2015 and 2016 in Rhode Island, when purchasing and use of cannabis without MCC was decriminalized but still considered illegal. Results: On average, participants (72% male) were 26 years old (SD = 7.2) and reported using cannabis 5 days per week (SD = 2.1). Thematic analysis revealed three key themes related to cannabis purchasing behaviors: (1) regular purchasing routines (i.e., frequency, schedule, amount of purchases), (2) economic factors (i.e., financial circumstances), and (3) contextual factors (i.e., quality of cannabis, convenience/availability) were perceived to influence purchasing decisions. Dealers' recommendations affected participants' purchases, who also reported minimal legal concerns. Participants reported saving money and using more cannabis when buying in bulk. Discussion: Purchasing behaviors were found to vary and were perceived to be affected by individual-level (e.g., routines) and contextual factors (e.g., availability) that, in turn, may impact use patterns. Future research should consider how factors (e.g., availability) that differ across contexts (e.g., location) and demographic groups interact to affect purchasing behaviors.

Substance Use and Adherence to HIV Pre-Exposure Prophylaxis in Studies Enrolling Men Who Have Sex with Men and Transgender Women: A Systematic Review.

Optimal adherence to pre-exposure prophylaxis (PrEP) is critical, but challenging. Men who have sex with men and transgender women have high rates of HIV incidence and substance use. Substance use is associated with reduced adherence to other medications, but associations between substance use and adherence to PrEP are less clear. Thus, the current review 1) systematically evaluates the measurement of substance use and PrEP adherence in studies examining both and 2) summarizes reported findings. Peer-reviewed articles published between 2010 - April 2021 examining associations between substance use and PrEP adherence were reviewed. Fifty studies met inclusion criteria. Assessment of substance use (i.e., mostly via self-reports at baseline) and PrEP adherence (i.e., often via tenofovir diphosphate [TFV-DP] concentration levels at follow-up) varied considerably across studies. Many studies used categorical variables (e.g., substance use: yes/no). Studies using TFV-DP levels defined adherence consistently (i.e., TFV-DP ≥ 700 fmol/punch), with slight variations. Qualitative studies (n = 10) indicated that substance use (mainly alcohol) is related to poorer PrEP adherence. While quantitative findings to date are equivocal for alcohol, there is a pattern of findings linking stimulant use with poorer PrEP adherence. This review reveals four methodological gaps, which can be addressed in future research by: 1) use of uniform benchmarks for substance use measures, 2) prospective assessment for substance use, 3) use of continuous outcome variables wherever possible, and 4) more extensive consideration of potential confounders. Addressing these methodological gaps may help us reach more definitive conclusions regarding associations between substance use and PrEP adherence.

A hypothetical lottery task to assess relative resource allocation toward alcohol and cannabis.

OBJECTIVE: Relative spending on substances (vs. alternatives) is predictive of several substance use outcomes, but it can be challenging to assess. We examined a novel method of assessing relative resource allocation through the use of a hypothetical lottery task wherein participants assume they collected $100,000 United States dollars in lottery winnings and were tasked with allocating their winnings across spending categories (e.g., savings, leisure, alcohol, cannabis). We hypothesized relative allocation of funds toward alcohol and cannabis would be positively associated with more use and problems of each substance. METHOD: College students (N = 479; Mage = 19.9 [SD = 2.2]) reported on their substance use and problems, alcohol and cannabis demand, and the hypothetical lottery task. RESULTS: Relative resource allocation toward alcohol and cannabis on the lottery task positively correlated with alcohol and cannabis demand indices (intensity, breakpoint, Omax, and elasticity [negatively]), respectively. Using zero-inflated modeling, greater relative allocation toward alcohol positively related to alcohol use and problems in models that controlled for alcohol demand indices. For cannabis, relative resource allocation was also positively associated with cannabis use, but not problems, independently from cannabis demand indices. CONCLUSIONS: Results provide initial support for the hypothetical lottery task as an indicator of relative resource allocation toward substances. Generally, these results extend previous behavioral economic research demonstrating the utility of relative resource allocation as a unique predictor of clinically relevant outcomes. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Differences in cannabis use characteristics, routines, and reasons for use among individuals with and without a medical cannabis card.

As recreational and medical cannabis use increases in the U.S., the proliferation of novel cannabis products is expected to continue. Understanding cannabis product preferences and use patterns may inform public health and policy decisions. This study investigated similarities and differences in cannabis use patterns, product preferences, and beliefs about cannabis' subjective effects and therapeutic benefits among individuals with and without a medical cannabis card (MCC). Participants with an MCC completed individual interviews (N = 25; 40% male). Participants without an MCC completed focus groups (N = 31; 6-7 participants/group; 72% male). All sessions followed a semistructured agenda. Participants were queried about their use routines, reasons for using cannabis, and perceptions and experiences of subjective cannabis effects. Thematic analysis of coded transcripts revealed that MCC participants had structured, daily cannabis use routines whereas non-MCC participants' use routines were less structured. Product information including strain and cannabinoid composition were important to MCC participants whereas non-MCC participants primarily evaluated quality based on perceptual (e.g., olfactory) cues. Regardless of MCC status, participants reported misconceptions about cannabis' therapeutic benefits and agreed that the two primary cannabis strains-Indica and Sativa-produced primarily sedative and stimulant effects, respectively. Results have clinical, public health, and policy implications surrounding cannabis recommendation guidelines and ways providers can relay accurate information to patients seeking medical cannabis. Future research assessing demographic and geographic differences in cannabis product preferences and beliefs about medical cannabis use is warranted. Further, quantitative research is needed to evaluate whether cannabis' therapeutic value differs across products. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Measuring Sexual Risk-Taking: A Systematic Review of the Sexual Delay Discounting Task.

The Sexual Delay Discounting Task (SDDT; Johnson & Bruner, 2012) is a behavioral economic task that assesses sexual risk-taking by measuring likelihood of immediate and delayed condom use. The SDDT is ecologically valid and has been used to test effects of various substances on sexual risk-taking. However, considerable variety in implementation, analysis, and reporting of the SDDT may limit rigor and reproducibility of findings. The current review synthesized studies that used the SDDT to evaluate these possible variabilities systematically. A two-step search (citation-tracking and keyword-based search) was conducted to identify studies that met inclusion criteria (i.e., used the SDDT). Eighteen peer-reviewed articles met inclusion criteria. The SDDT has been implemented primarily in three populations: individuals who use cocaine, men who have sex with men, and college students. Comparable results across diverse populations support the SDDT's validity. A few studies administered substances before the SDDT. Evidence suggests that while cocaine and alcohol increased sexual risk-taking under some conditions, buspirone decreased preference for immediate condomless sex. There was also heterogeneity in the determination of data orderliness (i.e., outliers) and inconsistent reporting of task design and analysis. Considerable differences present in methodologic approaches could influence results. Reducing variation in the administration, analysis, and reporting of the SDDT will enhance rigor and reproducibility and maximize the task's tremendous potential.

Relationships among Substance Use, Sociodemographics, Pre-Exposure Prophylaxis (PrEP) Awareness and Related Attitudes among Young Adult Men Who Have Sex with Men.

Men who have sex with men (MSM) account for two-thirds of new HIV diagnoses. Pre-exposure prophylaxis (PrEP), a highly efficacious HIV preventive medication, is underutilized. Identifying correlates of PrEP awareness and attitudes may help increase PrEP use. Thus, we evaluated (1) PrEP awareness; (2) differences in awareness related to substance use and sociodemographics; (3) initial PrEP information sources; and (4) possible associations between information sources and PrEP-related attitudes.Young adult (ages 18-30) HIV-negative MSM from Southern U.S. undertook a web survey including questions about substance use, sexual behaviors, perceived HIV risk, and PrEP. Participants were recruited using in-person and online approaches between January 2018-January 2020.Of 506 participants, 89% were aware of PrEP. Participants with high alcohol consumption and greater perceived HIV risk had higher odds of PrEP unawareness with a trend for minority race/ethnicity. PrEP-aware participants reported high overall perceived safety, confidence in PrEP's efficacy, and low perceived difficulties with adherence though those with higher perceived HIV risk and individuals who used tobacco had less favorable attitudes. Most participants first heard about PrEP from the internet. There were no statistically significant differences in PrEP-related attitudes across initial information sources.Associations between substance use and racial/ethnic minority status and lack of PrEP awareness suggest priority subgroups for educational campaigns. Future campaigns may tailor outreach materials to the respective audience (e.g., Spanish materials for Hispanic people) and disseminate where individuals who use substances may be more likely to see them (e.g., liquor and convenience stores).Supplemental data for this article is available online at https://doi.org/10.1080/10826084.2022.2040030 .

Are Drinking Cognitions Associated with Marijuana and Concurrent Alcohol and Marijuana Use among Adolescents and Young Adults?

Background: Concurrent use of alcohol and marijuana (i.e., CAM use) is the most common poly-drug use pattern among adolescents and young adults and is associated with negative outcomes. Research indicates that Prototype Willingness Model (PWM) drinking cognitions are associated with alcohol use. This secondary analysis was conducted to explore cross-sectional associations between PWM drinking cognitions, alcohol, marijuana, and CAM use. Methods: Adolescents and young adults between 15-25 years (N = 124, M age = 18.7) completed a baseline assessment as part of a larger study, including questions on alcohol and marijuana use, and PWM drinking cognitions. Results: In the social reaction pathway, descriptive norms, perceived vulnerability, and prototype favorability, but not willingness were associated with greater alcohol use, whereas in the reasoned pathway attitudes and intentions were associated with frequency of drinking whereas injunctive norms were not. Both willingness and intention to drink were related to marijuana and CAM use when controlling for alcohol use frequency. Greater willingness to drink was the only significant predictor of marijuana use, and only descriptive norms predicted CAM use. However, of the cognitions within the reasoned pathway, greater attitudes toward drinking and drinking intention were related to greater marijuana and CAM use. Results also indicated that CAM users displayed higher levels of certain risk cognitions than non-users or single substance users. Conclusions: Findings support and extend the utility of the PWM by indicating that specific alcohol cognitions are associated with alcohol, marijuana, and CAM use in adolescents and young adults.

Associations amongst form of cocaine used (powder vs crack vs both) and HIV-related outcomes.

INTRODUCTION: Cocaine (including powder and crack) use is common among people with HIV (PWH). We identified socio-demographic and behavioral factors associated with cocaine use (overall and various forms) among PWH; we also examined differences in HIV treatment outcomes across cocaine exposure groups. METHODS: The study sample (N = 1166) was derived from two cohorts of PWH in Florida between 2014 and 2020. Baseline data were linked to the Enhanced HIV/AIDS Reporting System (eHARS) which tracks HIV viral load. Socio-demographics and polysubstance use were compared by cocaine use and the three cocaine use groups (powder only n = 101, crack only n = 91, or both n = 65). The association between the three cocaine use groups, ART adherence, and HIV viral suppression (<200 copies/mL) in the following year was assessed by multivariate logistic regression. RESULTS: People who used cocaine had lower HIV treatment adherence and viral suppression than those who did not use. People who used powder cocaine only were more likely to be younger, Hispanic/Latinx, and employed than those who used crack only or both. Compared to people who used both powder and crack cocaine, those who used one form of cocaine had 3 + odds of having durable viral suppression in the following year. CONCLUSION: The dual use of both powder and crack cocaine was associated with significantly worse HIV outcomes compared to use of only one form of cocaine. Screening for powder and crack cocaine use and timely intervention are needed to improve HIV treatment outcomes among this high-risk population.

The Relationship of Alcohol to ART Adherence Among Black MSM in the U.S.: Is it Any Different Among Black MSM in the South?

Alcohol-using Black MSM (Men who have sex with men) are disproportionately impacted by HIV in the U.S.-particularly in the southern U.S.-despite the availability of antiretroviral therapy (ART). The purpose of this study was to summarize the current evidence on alcohol use and ART adherence among Black MSM in the U.S. and in the South and to identify future research needs. A systematic review was conducted using eight databases to identify relevant peer-reviewed articles published between January 2010 and April 2021. The authors also snowballed remaining studies and hand-searched for additional studies. Including both quantitative and qualitative studies, five published studies examined alcohol and ART adherence among Black MSM in the U.S. The search identified 240 articles, the study team reviewed 114 in full-text and determined that only five met the inclusion criteria. Three of the five included studies identified alcohol use as a barrier to ART adherence. In conclusions, the general lack of literature on HIV disparities among alcohol-using Black MSM in the U.S. (specifically in the South) indicates a critical need for research on this population's unique risks and needs to inform the development of tailored interventions.

PrEP awareness among people living with HIV in Florida: Florida Cohort study.

In 2017, Florida ranked 2nd nationally in prevalence and incidence rates of HIV infections in the United States. Due to the high burden of HIV and low viral suppression in Florida, it is of increased importance to study methods of HIV prevention such as preexposure prophylaxis(PrEP) in this state. Our study aimed to examine correlates of PrEP awareness among PLWH in Florida and describe patterns of PrEP awareness/information sources. Using data collected from the Florida Cohort study between 2014 and 2018, 530 PLWH answered items that were hypothesized to be correlated with PrEP awareness. Of our sample, 53.8% were aware of PrEP. Urban location of recruitment, sexual partner's use of PrEP, use of viral suppression as an HIV prevention strategy, and engagement in transactional sex were all significantly associated with higher odds of PrEP awareness. Care providers and HIV/AIDS support groups were the most frequently listed sources of PrEP awareness, sources of future PrEP information, and most trusted sources for PrEP information. Findings from this study could inform future interventions that aim to increase PrEP awareness among PLWH to increase PrEP awareness and uptake among their HIV-negative social and sexual networks.

Communication strategies for designing Facebook advertising campaigns to recruit rural participants to develop healthcare delivery interventions.

BACKGROUND: Little is known about designing research recruitment campaigns that connect with underserved, geographically isolated rural populations. A theoretically informed process is needed to assist research teams and practitioners in their evaluation of Facebook's feasibility as a recruitment tool and development of online materials for recruiting rural adults into healthcare delivery intervention development studies. METHODS: We drew from research and theory in communication and incorporated process analysis techniques to develop replicable procedures for designing and evaluating Facebook campaigns for rural recruitment. We describe our process and illustrate using two case studies. RESULTS: Campaigns received approximately 1000 link clicks from the target rural demographic and successfully enrolled participants using Facebook as a primary method of recruitment. The rural tobacco intervention development study received a total of 477 link clicks, cost only $155.80, and enrolled three (23%) of its 13 participants from Facebook. The rural mental health intervention development study received a total of 518 link clicks, cost only $233.28, and enrolled 178 participants. CONCLUSIONS: Our process yielded two successful recruitment campaigns. Facebook was an affordable and efficacious strategy for enrolling adults in behavioral research studies on tobacco and mental health. Future work should apply these theoretical techniques to additional study topics and evaluate specific message features associated with recruitment.

Relationships among impulsive, addictive and sexual tendencies and behaviours: a systematic review of experimental and prospective studies in humans.

Impulsivity's relationships to addictive and sexual behaviours raise questions regarding the extent impulsivity may constitute a vulnerability factor for subsequent addictive and sexual behaviours and/or results from each of these. Here, we systematically reviewed empirical support for impulsivity as a precipitating factor or a consequence of addictive or sexual behaviours. We restricted ourselves to recent, human studies with assessments over time, including at least one measure of impulsivity, addictive and sexual behaviours, yielding a review including 29 published reports from 28 studies. Findings point to generalized, self-reported impulsivity as a predictor of addictive and sexual behaviours at a wide range of severity, with elements of both impulsivity and compulsivity to these acts. Alcohol consumption often increases impulsive behaviour, including inclinations towards impulsive and potentially compulsive sexual acts. Research using the Sexual Delay Discounting Task has yielded findings linking impulsivity, addictive and sexual behaviour and as such is a valuable research tool that should be used more extensively. The present review identified gaps to be addressed in further research that concurrently examines facets of impulsivity, addictive and sexual behaviours, especially because criteria for compulsive sexual behaviour disorder have been included in the eleventh edition of the International Classification of Diseases. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.