Addressing a Critical Gap: Integrating Sexual Aggression and Coercion Measures into Substance Administration Research

1. Introduction

The use of substances (e.g., alcohol, cocaine) does not cause sexual aggression or sexual assault. However, in some cases substances facilitate sexually violent individuals (e.g., decrease inhibition), or facilitate physically overpowering victims or impair a victim’s memory of the attack (e.g., “date rape” drugs). Here, I briefly review sexual assault statistics, and explore the interplay of substances and culture in sexual assault and aggression. I then discuss substance use, general aggression, and sexual aggression findings. Finally, I identify gaps in the literature that could inform important future questions related to human substance administration and sexual aggression research.

2. Sexual Assault Statistics

Sexual assault remains a consistent and significant public health crisis worldwide and in the U.S. Victims of sexual aggression, sexual assault and coercion, sexual violence and rape – the majority of which are women and girls – experience profound deleterious consequences, including negative impacts on lifelong health, depression, anxiety, post-traumatic stress disorder (PTSD), decreased well-being, decreased opportunity, and suicide (CDC, 2022). The Center for Disease Control and Prevention statistics remain overwhelming. More than one in three women experience sexual violence involving physical contact during their lifetime (for men: one in four), one in three female rape victims were raped for the first time between the ages of 11 and 17 years old (for males: nearly one in four), and for 1 in 8, this rape occurred before age 10 (for males: about one in four). These statistics are likely under-reported, as many victims never report sexual assault for fear of retribution, not being believed, stigma, blame, harassment, repeat assault, or murder. The risk of sexual assault for women and girls of color is elevated, and experiences of sexual assault can be more difficult (e.g., lack of resources such as rape crisis centers and healthcare, racism; Olive, 2012). Sexual violence impacts communities broadly, and affects people of all genders, sexual orientations, and ages. I focus on sexual violence perpetrated by men, as this constitutes the vast majority of cases (and not victimization research, as this sidesteps core cultural issues related to male violence).

3. Cultural Considerations in Sexual Assault and Drug Use

Critical to the interaction of substances and sexual assault, is the underlying culture in which hate and violence against women/girls is normalized, and even glorified. For example, internet searches for rape-oriented pornography are increasing (Makin & Morczek, 2015). Rape myths, which can be further reinforced by rape pornography, often shift blame to the victim and absolve the perpetrator, including trivializing the act itself, perpetuating “she asked for it”, or men “deserve” sex misconceptions. This dynamic is partially captured by organizations that have developed in response to the normalization of violence against women and girls during sex. Specifically, there is an increase in the use of “rough sex” as justification/defense for murdering or violent injury of women and girls (see for example “We Can’t Consent to This”). Some men may confirm a history of sexually violent perpetration in one context -- but deny it in another context or when evaluated with a different scale (e.g., Davis et al., 2020). These inconsistencies may represent outright misrepresentations or underpin a reluctance to recognizing they themselves are perpetuators of sexual assault (e.g., feelings that they were justified, rationalization, or not ‘recognizing’ sexually coercive tactics as sexual assault). In a study conducted among college students in the 1980s, an average of about 35% of men reported some likelihood of rape when provided assurances they would never be caught (Malamuth, 1981). This historical backdrop and current culture are essential for considering acute substance effects, which could exacerbate behavior already reinforced by misogynist systems.

4. Substance-Associated Aggression and Sexual Aggression, and the Need for Causal Research

4.1. Alcohol and Sexual Aggression

The interplay between alcohol and sexual aggression is reasonably well documented. Sexual aggression and coercion scales have been included in alcohol administration research for some time, elucidating variables that contribute to sexual aggression when alcohol is on board (e.g., Abbey et al., 2009; Davis et al., 2020). For example, men that have greater trait hostility and are intoxicated (via alcohol) report feeling more justified in coercing nonconsensual sex than do sober men (Abbey et al., 2009). Further, men with greater sexual arousal report stronger intentions to engage in sexual aggression (Ariely & Lowenstein, 2006), and alcohol intoxication can disrupt men’s regulation of their sexual arousal (George et al., 2006). Emotion regulation “difficulties” among men have been proposed more broadly to explain sexual aggression, and alcohol may reduce the ability to regulate emotions (see Davis et al., 2020 for discussion). Importantly, these findings have helped to build the foundational research required to target underlying mechanisms of sexual aggression to inform interventions to reduce the likelihood of sexual assault and aggression, specifically while intoxicated via alcohol (e.g., targeting emotion regulation during sober and intoxicated states; Davis et al., 2020).

4.2. Other Substances, Aggression, and Sexual Aggression

What is far less researched is the causal contribution of other substances (e.g., cocaine, methamphetamine, oxycodone, polysubstances) to the sexually aggressive behavior of men in laboratory settings. This line of research is important because comparisons across studies (e.g., Berry & Johnson, 2018), have shown that cocaine, for example, leads to greater self-reported arousal than alcohol, and could potentially represent a different risk profile (see Berry & Johnson, 2018 for discussion). This is particularly relevant as men with greater sexual arousal report stronger intentions to engage in sexual aggression (Ariely & Lowenstein, 2006).

Other general correlations with substances and aggression highlight the need for more focused sexual aggression research. For example, via retrospective interviews and self-reports, one study found that cocaine may be associated with increased violence, and this relationship may differ by route of administration (e.g., Giannini et al., 1993). Sexual aggression/violence specifically, however, was not measured. Similarly, a recent systematic review and meta-analysis showed associations with individual drug classes/polysubstance use (although not necessarily acute intoxication) and other forms of violence, however sexual violence was not highlighted, and was rarely a focus in the articles covered (e.g., Zhong et al., 2020). Moore et al. (2008) reviewed the literature and found associations between cocaine, amphetamines and cannabis use and polysubstance use with intimate partner violence, both within the general population and men seeking treatment for either substance use or intimate partner violence. Gerra et al. (2001) and (2004) suggest more aggressive behavior was associated with chronic opioid exposure in a general laboratory procedure, and Moore et al. (2011) showed that when compared to community controls, fathers who use opioids reported greater prevalence of physical, sexual, and psychological aggression directed at the mother of their child.

4.3. Integrating Laboratory-Based Substance Administration and Sexual Aggression Research

These areas of research establish general linkages between substances and aggression, however, a causal link between acute substance intoxication (other than alcohol) and aggression, and more specifically sexual aggression, cannot at present be inferred from the correlational or event-level methodologies that have been used to study these relations thus far. Critical questions remain regarding the potential causal mechanisms of substances other than alcohol and sexually aggressive behavior. For example, the influence of disinhibitory effects or increased sexual arousal associated with various substances, or expectancy effects that may differ by substance. The effects of these contributors to sexual aggression have yet to be disentangled.

Laboratory-based human drug administration methods constitute a complement to the correlational and naturalistic methods, and allow causal examination of the effects of substance intoxication on sexually aggressive behaviors or intentions. If substances do indeed play a causal role in sexual aggression, then this would directly inform the development of interventions that could reduce the likelihood of sexual aggression and sexual assault, particularly while acutely intoxicated. Sexual aggression scales could be added to already in place substance administration studies and could add a wealth of information to the scant existing literature. These questions should also be the subject of prospectively designed studies. Some scales commonly used in alcohol administration studies that could be readily applied to other substance administration research include both past sexual aggression measures and emotion regulation, arousal, and coercive tactic intentions measures that may be altered by intoxication levels. For example, the Sexual Strategies Scale (Struckman-Johnson et al., 2003) which measures whether participants have ever (yes/no) engaged in behaviors consistent with five levels of sexual aggression: sexual enticement, verbal coercion, use of older age or authority, use of intoxication and threats or force to have sexual activity “with a woman when she did not want to.” Another scale includes the Sexual Experiences Scale (e.g., revised version; Koss et al., 2007) to assess a range of sexually aggressive acts (nonconsensual sexual contact, attempted rape, rape). A Coercive Tactic Intentions scale allows participants to indicate the likelihood that they would engage in a spectrum of coercive tactics (1 = not at all, to 7 = extremely likely) to have sex with a person in a sexual scenario if she refused (Davis et al., 2020). General emotion regulation and arousal scales may also be incorporated. Scales that could detect acute changes might be administered under placebo and active drug dose-response conditions to understand the contribution of various substances to likelihood of engaging in sexually aggressive behaviors.

Interactive drug effects might also be explored using similar methods and sexual aggression scales. It is possible interactive drug effects could occur with polysubstance administration and sexual aggression, including additive, supra-additive, or antagonistic effects. Laboratory paradigms may be especially important for extricating poly-drug effects, a critical area given frequent polysubstance use among many individuals who use substances. Further, human drug administration methods that include measures of sexual aggression may offer a critical window into empathogens (e.g., MDMA) which are often used specifically to enhance the social experience (with parallels to alcohol in this regard), but are also simultaneously recognized for acutely increasing empathy and social connectedness. It is possible drugs such as MDMA offer protective effects against sexual aggression among men, or alternatively, lead to issues of sexual abdication for women. Future research should examine these suppositions empirically, particularly given the increased consideration of MDMA as a potential therapeutic.

5. Conclusion

In conclusion, laboratory-based drug administration and sexual aggression studies should be given higher priority given the widespread nature of this public health crisis. Moving forward, labs already conducting human substance administration research (including both alcohol and other substances) could integrate sexual aggression scales into their research. Importantly, these questions should also be the focus of prospectively designed research agendas. Past substance administration studies that have not included such scales (e.g., Berry et al., 2020) may have missed an opportunity, but future work might prioritize these questions to address this critical gap. The lack of sexual assault research in the context of substance administration also points to the need for additional gender and racial diversity and representation in this area, and may be a result of a male-dominated field. Increasing the proportion of women assessing the laboratory effects of substance administration would also help to strengthen and diversify the science as a whole, and would likely lead to additional novel questions and interventions in these important areas.