# Motivation and emotion/Book/2024/Testosterone and violent crime

* Multimedia presentation (3 min)

## Overview

* Figure 1. Testosterone, a hormone that is primarily produced in the testicles of males and in the ovaries of females.
* Scenario
* Imagine a scenario where two individuals, both facing similar socioeconomic challenges, react differently to a stressful situation. One individual, driven by impulsive aggression, engages in violent behaviour, while the other manages to de-escalate the conflict peacefully. What could explain these divergent responses? One potential factor is testosterone—a hormone often associated with aggression and dominance.
Recent statistics indicate a troubling 30% increase in domestic violence incidents and a 5% rise in overall violent crimes over the past year (Australian Bureau of Statistics, 2024). This surge raises critical questions about the underlying factors contributing to aggressive behaviours.
The importance of understanding the relationship between testosterone and violent crime lies in its implications for public safety and mental health interventions. Testosterone is often associated with aggression; however, it is crucial to recognize that aggression doesn't always lead to violence. Factors such as mental health conditions, socioeconomic stressors, and substance abuse can amplify or mitigate these tendencies.
Research indicates that while higher testosterone (see Figure1) levels may correlate with increased aggression in some individuals, it is not a direct cause of violent crime. Instead, it interacts with other variables, such as psychological state and environmental context to influence behaviour. Understanding these interactions can help inform prevention strategies aimed at reducing violent crime rates.
* Focus questions:
* What is testosterone, and what are its biological mechanisms?
* What role does testosterone play in violent behaviour?
* What factors influence the relationship between testosterone and violence?
* What are alternative explanations for violent behaviour?

## Introduction to testosterone, violent crimes and aggression

Research has indicated a complex relationship between testosterone levels and aggressive behaviours, particularly in the context of violent crimes. Understanding this connection is crucial for exploring the underlying factors that contribute to aggression and violence in society.

### What is testosterone?

Testosterone is a hormone that is predominantly produced in the testes in males, in women smaller amounts are produced in the ovaries and adrenal glands[factual?]. Testosterone belongs to a class of hormones known as androgens, which are responsible for the development of male characteristics and reproductive functions[factual?] . Testosterone plays a crucial role in various physiological processes such as development of male characteristics, regulation of reproductive function, muscle mass and mood regulation (Nassar & Leslie, 2023).

### Criteria for violent crimes

There is a criteria[grammar?] that classifies a crime as being violent, the 'violent' crime has to fall under one or more of these categories; murder and nonnegligent manslaughter, rape, robbery, and aggravated assault (U.S. Department of Justice—Federal Bureau of Investigation, 2020). A crime is classified as violent when it involves the use, attempted use, or threatened use of physical force against another person or their property (National Institute of Justice, 2022).

### The biological mechanisms linking testosterone to aggression

There are several biological mechanisms that link testosterone to aggression, this includes but not limited to;
Hormonal Influence on Brain Structure and Function Hormones play a significant role in shaping brain structure and function, particularly in areas such as the prefrontal cortex and amygdala[factual?]. The prefrontal cortex is involved in decision-making, impulse control, and social behaviour, while the amygdala is crucial for emotional processing and responses to threats[factual?]. Hormonal fluctuations can affect these brain regions’ development and functioning, influencing behaviours related to aggression and emotional regulation (Batrinos, 2012).
Genetic factors:
Genetic influences also contribute to behavioural tendencies. The functionality of androgen receptors has been associated with male aggression and violent criminal activity, as indicated by research examining CAG repeat polymorphisms in the androgen receptor gene[factual?]. Studies suggest that variations in this gene may predispose individuals to aggressive behaviours through hormonal pathways (Cheng et al., 2005).
Neurotransmitters like serotonin play a crucial role in modulating mood and behaviour[factual?]. Serotonin is linked to various psychological states, including aggression and anxiety[factual?]. Changes in serotonin levels can alter the functioning of brain circuits associated with these behaviours, potentially leading to increased aggression or mood disorders[factual?]. Study [grammar?] Birger et al. (2003) established that elevated testosterone levels appeared to diminish the calming effects of serotonin, leading to an increase in aggressive behaviours[Provide more detail]. This suggests a complex interplay where high testosterone may override the regulatory effects of serotonin.
From an evolutionary standpoint, higher testosterone levels have been associated with increased competitiveness and dominance behaviours that may enhance reproductive success[factual?]. With this increased behaviour an aggressive nature and/or undertone can be produced from competitive or dominate[spelling?] behaviours (Muñoz-Reyes et al., 2020).
* Critical takeaways
* Criteria for a violent crime; murder and nonnegligent manslaughter, rape, robbery and aggravated assault.
* Biological mechanisms - testosterone and aggression; Hormonal influence on brain structure and function, genetic factors and neurotransmitter interaction.

## What is the role of testosterone in violent behaviour?

The relationship between testosterone and violent crimes has been a subject of considerable debate and research[factual?]. While discussions often center on the potential influence of testosterone on violent behaviour, it is important to note that no direct causal links have been established between testosterone levels and the commission of[factual?] violent crimes. However, a wealth of studies suggests that elevated testosterone levels are associated with increased aggression, a behavioural trait that can predispose individuals to engage in violent acts[factual?]. Therefore, it is essential to explore this complex interplay by examining how testosterone affects aggression in both humans and animals, as well as considering other contributing factors that may influence testosterone levels and therefore violent behaviour.

### Correlation between testosterone levels and aggressive acts - animal and human studies

It is widely recognized that studies show a significant correlation between testosterone levels and aggressive behavior in animals (Ruizdelatorre & Manteca, 1999). Research indicates that lowering testosterone levels can reduce aggressive behaviors, such as fighting and dominance displays[factual?]. Animals exhibiting aggression often become more submissive when testosterone levels decrease (Albert et al., 1986). These findings suggest potential implications for understanding human behavior in relation to testosterone. Furthermore, a comprehensive meta-analysis [grammar?] Book et al. (2001) looked at fourty[spelling?]-five studies that examined the relationship between testosterone and aggression, the meta-analysis revealed a significant positive correlation between testosterone levels and aggressive behaviours similar base findings to those in Albert et al. (1986)[grammar?]. This analysis indicated that higher testosterone levels are associated with increased aggression, although it is essential to consider various contextual factors that may also influence this relationship. These factors include an individual’s sex, their social environment, and distinct personality traits that can vary from person to person[factual?]. Thus, while there is a notable link between testosterone and aggression, individual differences and situational contexts play a crucial role in shaping this dynamic.

### Gender differences in testosterone’s impact on violence

An adult male produces almost twenty times more testosterone then a adult female (see Figure 2) (Handelsman et al., 2018).Therefore [grammar?] the relationship between testosterone and violence is particularly pronounced in males, where higher levels of this hormone are correlated with increased aggression and violent behaviour[factual?]. This phenomenon can be understood through both biological and evolutionary lenses. This is not to say that testosterone doesn't have a significant influence on women and aggression. Studies Book et al. (2001), Van Anders et al. (2015), Armstrong et al. (2022) all support that there is a strong correlation between increased testosterone level and and aggression within men, which has the potential to lead to violent behaviour[grammar?]. The causation for most of these studies was due to the high levels of testosterone as well as an evolutionary and biological perspective. While few studies indicate that women may produce similar or higher results in aggression linked to testosterone, such as those by Dabbs et al. (1988) and Assari et al. (2014), a strong correlation between testosterone and aggression exists for both genders. Factors influencing aggression expression include biological hormonal effects, socialization patterns, environmental stressors, and psychological factors. Evidence suggests gender significantly affects testosterone’s role in violent behaviour, yet the specific determinants of these gender-specific outcomes remain unclear. Explanations often stem from biological and evolutionary perspectives while considering social context and psychological states.
Test your knowledge
Testosterone has the same effect on men as it does on women?
True
False :

## What psychological factors influence the relationship between testosterone and violence?

It has been established that testosterone does trigger aggression and can result in violence and violent crimes[factual?], but what about other factors that can heighten this response and the likelihood of this increase in testosterone occurring? Let's look at a scenario:
* Scenario:
* Two friends, Josh and Ben, find themselves at a local bar after a long week. Josh, who has been diagnosed with bipolar disorder, is on medication but struggles with adherence due to his fluctuating moods. Ben, on the other hand, has recently started using anabolic steroids to enhance his athletic performance. As the night progresses, their conversation shifts from light-hearted banter to heated debates about life choices.
Lets discuss how other factors can influence this scenario...

### Mental health considerations

Depression: Individuals with depression have indicated they have low levels of testosterone (Anderson et al., 2022). However [grammar?] once treated with antidepressants there is an increase in testosterone which generally balances out the hormone to a stable level, however there have been some cases where the treatment of antidepressants has significantly increased testosterone, resulting in emotions of aggression and irritation as a side effect (Määttänen et al., 2021). An example of this involved a middle-aged man undergoing treatment for major depressive disorder who initially presented with low testosterone levels. After several months of antidepressant therapy combined with lifestyle changes (including exercise), his testosterone levels increased significantly. Following this increase, he reported feelings of heightened confidence but also noted instances of irritability that led to aggressive outbursts when provoked (Maj et al., 2020).
Bipolar disorder: Lyu et al. (2023) investigated the hormonal and inflammatory markers that were associated with various mood episodes in individuals diagnosed with bipolar disorder. The research aimed to identify specific biological signatures that correlate with manic, depressive, and euthymic (stable) states in bipolar patients. Notably, testosterone levels were specifically mentioned as being significantly altered during different mood episodes. Higher testosterone levels were correlated with manic states, indicating a potential link between elevated testosterone and increased manic symptoms. Additionally, these manic states were associated with increased activity of neurotransmitters such as dopamine and norepinephrine, which are linked to reward-seeking behaviour and can amplify feelings of euphoria and invincibility. Individuals with bipolar disorder may be at higher risk for violent behaviour during manic states due to increases in testosterone levels coupled with neurobiological changes that promote impulsivity and aggression[factual?].
* Scenario - the influence of mental health ...
* As they drink and share stories, underlying psychological factors begin to surface. Josh's bipolar disorder leads him to experience intense emotional highs and lows. During a manic phase, he feels invincible and overly confident, which can heighten aggressive tendencies when provoked. Conversely, during depressive episodes, he may feel hopeless and withdrawn but can also react violently if he perceives a threat or insult.

### The influence of substance abuse

Anabolic steroid abuse: Anabolic steroid abuse refers to the non-medical use of anabolic steroids, which are synthetic derivatives of testosterone, they are primarily used for the purpose of enhancing physical performance and improving appearance (National Institute on Drug Abuse [NIDA], 2024). Anabolic steroids have been proven to hold the potential to significantly alter mood and behaviour[factual?]. It can be noted that users may experience heightened aggression, irritability, and mood swings, commonly referred to as “roid rage”[factual?]. This phenomenon is characterized by sudden outbursts of anger or violence that are disproportionate to the triggering event. Research indicates that these aggressive tendencies can lead to an increased likelihood of engaging in violent acts (Christoffersen et al., 2019). Also to be noted [grammar?] when anabolic steroids are combined with alcohol individuals can face an increased risk of defensive aggression (Johansson et al., 2000).
Smokers (nicotine): Nicotine, a highly addictive compound in tobacco, rapidly enters the bloodstream and reaches the brain, binding to receptors that mimic neurotransmitters and trigger dopamine release, enhancing mood (Tiwari et al., 2020). Research on nicotine’s effects on testosterone has yielded conflicting results; some studies suggest smoking increases testosterone levels such as Trummer et al. (2002), Blanco-Muñoz et al. (2012) and Svartberg et al. (2003), while others find no difference[factual?]. Additionally, studies indicating increased testosterone have not addressed participants’ physical or emotional side effects. This lack of information complicates the assessment of whether elevated testosterone from smoking could lead to increased aggression or violent crime.
* Scenario - the impact of substance abuse ...
* Meanwhile, Ben's substance abuse intensifies his aggression. The anabolic steroids increase his testosterone levels significantly, which is linked to heightened aggression and impulsivity. When combined with alcohol (a depressant that lowers inhibitions), Ben becomes increasingly confrontational as the night wears on.

### Social environment and upbringing

Socioeconomic factors that should be considered include; income, education, employment status, housing stability, food security and social support networks (Australian Institute of Health and Welfare, 2024). Socioeconomic factors can significantly influence both testosterone levels and aggressive behaviour. Individuals from lower socioeconomic backgrounds may experience higher stress levels, leading to increased aggression and violence, especially when combined with high testosterone levels (Soler et al., 2000). Stress levels can increase testosterone levels due to that stress can make the testes more sensitive to hormones such as LH (luteinising hormone), a hormone that triggers testosterone production (Deuter et al., 2021). For instance, Dabbs et al. (1987) conducted a study on a prison population consisting of 89 male offenders, analyzing their saliva for testosterone levels. The researchers compared these testosterone levels with the types of crimes committed, categorizing them into violent and nonviolent offenses. It was found that individuals with lower testosterone levels were more likely to engage in nonviolent crimes, whereas those from ‘delinquent’ and ‘low socioeconomic’ backgrounds exhibited higher testosterone levels and were associated with a greater incidence of violent crimes. Additionally, offenders with elevated testosterone who committed nonviolent crimes received longer and harsher sentences compared to those with lower testosterone levels who also committed nonviolent offenses. This research indicates that there is a multifaceted relationship between testosterone levels and violent crime influenced by socioeconomic status. Higher testosterone is associated with an increased likelihood of committing violent offenses among individuals from disadvantaged backgrounds, while also affecting judicial perceptions regarding sentencing severity.
* Scenario - the influence of an individuals[grammar?] socioeconomic status ...
* Additionally [grammar?] their socioeconomic status plays a role; both come from low-income backgrounds where stressors such as job insecurity and lack of access to mental health resources are prevalent. This environment fosters feelings of frustration and anger that can manifest in violent behaviour.

## Implications for Policy and Prevention Strategies: Critiques and Counterarguments Regarding Testosterone and Violent Crime

While evidence indicates that testosterone, both independently and alongside other factors, plays a role in violent crime, there are significant limitations in the existing studies on this topic. Additionally, there are alternative explanations for violent behaviour beyond attributing it solely to testosterone. Furthermore, quantifying the extent to which testosterone contributes to violent crime is challenging due to the lack of definitive criteria.

### Alternative explanations for violent behaviour

Alternative explanations for violent behaviour include several interrelated factors. Biological influences encompass genetics and brain chemistry, which can predispose individuals to aggressive tendencies. Psychological influences involve mental health disorders, difficulties in emotional regulation, a history of trauma, and the impact of certain drugs that may lower testosterone but heighten feelings of aggression. Environmental influences are shaped by exposure to violence, peer pressure, and access to weapons, all of which can contribute to violent behaviour. Lastly, cultural influences play a significant role through cultural norms regarding aggression, the impact of media portrayals of violence, and socioeconomic factors such as gang involvement.[factual?]

### Limitations of current studies

Current studies face several limitations, including a notable lack of gender-specific research, particularly concerning female subjects. It remains unclear whether emotions associated with aggression are likely to lead to violent crimes. Additionally, certain substances known to reduce testosterone levels have been observed to provoke aggressive or violent behaviour, raising questions about the true nature of the connection between hormones and aggression. This suggests that complex interactions may be at play rather than a straightforward deterministic relationship between testosterone and violent crime.[factual?]
Test your knowledge
What additional factors contribute to violent behaviour?
Environmental
Biological
Psychological
Cultural :

### Potential interventions targeting high-risk individuals

It is essential to recognize the influence of hormones and other factors—biological, psychological, environmental, and cultural—that contribute to rising testosterone levels and violent crime. A comprehensive understanding of these elements allows for effective prevention strategies. A holistic approach addresses various aspects of the issue, leading to better outcomes. The interventions include psychological strategies for high-risk individuals (Table 1), medical interventions related to testosterone levels (Table 2), social interventions for at-risk individuals (Table 3), and educational programs that enhance community awareness and skills for those at risk of committing violent crimes (Table 4).[factual?]
Table 1. Psychological interventions
| Intervention | Description |
| Cognitive Behavioural Therapy (CBT) | This therapy helps individuals recognize and change negative thought patterns that lead to aggression. |
| Anger Management Programs | These programs teach individuals how to control their anger and respond to provocations more constructively. |
Table 2. Medical interventions
| Intervention | Description |
| Hormonal Treatments | In some cases, anti-androgens or medications that lower testosterone levels may be considered for individuals exhibiting extreme aggression linked to high testosterone. (A similar approach to Ruizdelatorre & Manteca, 1999) |
| Regular Screening | Monitoring hormone levels in at-risk populations could help identify those who might benefit from intervention before violent behaviour occurs. |
Table 3. Social interventions
| Intervention | Description |
| Community Programs | Initiatives aimed at reducing violence through community engagement can help address underlying issues such as poverty and lack of education. |
| Support Groups | Creating support networks for at-risk individuals can provide them with resources and coping strategies. |
Table 4. Educational programs
| Intervention | Description |
| Awareness Campaigns | Educating communities about the signs of aggression and available resources can empower individuals to seek help before situations escalate. |
| Life Skills Training | Teaching conflict resolution skills, emotional regulation, and stress management can reduce the likelihood of violent outbursts. |

## Conclusion

The relationship between testosterone levels and violent crime is complex and multifaceted. While there is evidence suggesting that elevated testosterone can contribute to increased aggression, the extent of this influence remains a topic of ongoing research. It is crucial to recognize that individual responses to hormonal fluctuations vary significantly, influenced by a myriad of biological, psychological, and environmental factors. Furthermore, it is clear that testosterone alone doesn't account for violent crime; rather, there are numerous other explanations for aggressive behaviour, including biological, psychological, environmental, and cultural influences beyond just testosterone. The potential for addressing hormone imbalances, particularly concerning testosterone, presents an opportunity for mitigating aggressive behaviours and reducing instances of violent crime. However, further investigation is necessary to fully understand these dynamics and develop effective interventions. Ultimately, acknowledging the interplay between hormones and behaviour may lead to more comprehensive strategies aimed at enhancing public safety and well-being.