3.5.3 Sex

The Neural Circuits Involved in Sex, Including Effects of Hormonal Treatments, Gender Identity, Disturbances Related to Psychiatric Disorders, and Psychotropic-Induced Disturbances

Sex:

The neural circuits involved in sexual behaviour and desire are complex and involve many different brain regions and neurotransmitter systems. These circuits are influenced by a variety of hormones, including testosterone and estrogen, which play a role in the development and maintenance of sexual behaviour.

The hypothalamus, a region of the brain that regulates many of the body’s basic functions, is involved in the control of sexual behaviour. The hypothalamus produces hormones that help to regulate sexual behaviour, and it receives input from other brain areas that are involved in sexual arousal and desire.

The amygdala, which is involved in emotional processing, is also thought to play a role in sexual behaviour. The amygdala helps to modulate the intensity of sexual arousal and may influence the types of sexual behaviours that are engaging or appealing.

The prefrontal cortex, which is involved in decision-making and impulse control, is also thought to play a role in sexual behaviour. It helps to regulate the expression of sexual behaviour and can inhibit inappropriate or risky sexual behaviours.

Overall, the neural circuits involved in sexual behaviour are complex and involve many different brain regions and neurotransmitter systems. These circuits are influenced by a variety of hormones and other factors, and they help to regulate the expression of sexual behaviour and desire (Andersson, 2004).

Effects of hormonal treatments:

Hormonal treatments can have a variety of effects on neural circuits, depending on the specific hormones involved and the brain regions that are affected.

For example, testosterone and estrogen, which are important hormones for sexual development and function, can influence the structure and function of neural circuits that are involved in sexual behaviour. Testosterone can enhance the formation of connections between neurons in the brain and stimulate the growth of new neurons, while estrogen can have the opposite effect and inhibit neurogenesis.

Hormonal treatments can also influence the release of neurotransmitters, which are chemical substances that transmit signals between neurons. For example, estrogen can increase the release of serotonin, a neurotransmitter that is involved in mood and emotion, while testosterone can increase the release of dopamine, a neurotransmitter that is involved in reward and pleasure.

The effects of hormonal treatments on neural circuits can be complex and depend on the specific hormones involved and the brain regions that are affected. Hormonal treatments can alter the structure and function of neural circuits and influence the release of neurotransmitters, which can have wide-ranging effects on behaviour and cognition (Granados, 2018).

Gender identity:

There is ongoing research into the neural circuits that are involved in gender identity and how these circuits may be related to biological sex.

Some studies have suggested that certain brain regions, such as the hypothalamus and amygdala, may be involved in gender identity. For example, research has found that transgender individuals have brain structures that are more similar to those of their experienced gender rather than their assigned gender at birth.

Other research has suggested that hormones may play a role in the development of gender identity. For example, testosterone and estrogen, which are important hormones for sexual development and function, may influence the structure and function of neural circuits that are involved in gender identity.

This study used diffusion tensor imaging (DTI) to examine the white matter microstructure of the brains of female to male transgender individuals before they received cross-sex hormonal treatment. The results of the study suggested that the white matter microstructure of these individuals was more similar to that of cisgender men (individuals who identify with the gender they were assigned at birth) than cisgender women. These findings suggest that there may be a neural basis for gender identity and that hormones may play a role in the development of gender identity (Rametti, 2011).

The neural basis of gender identity is not fully understood and more research is needed to fully understand the relationship between neural circuits and gender identity. It is likely that both genetics and environmental factors play a role in the development of gender identity and that the neural circuits involved are complex and involve many different brain regions and neurotransmitter systems.

Disturbances related to psychiatric disorders:

There is evidence to suggest that sex can be related to the development and presentation of psychiatric disorders. For example, certain psychiatric disorders are more common in one sex than the other. For example, depression is more common in women, while substance abuse disorders are more common in men.

Hormonal differences between the sexes may contribute to these differences in the prevalence of psychiatric disorders. For example, fluctuations in estrogen levels during the menstrual cycle and menopause have been linked to an increased risk of mood disorders in women. Testosterone levels have also been linked to an increased risk of certain psychiatric disorders in men, such as aggression and substance abuse.

Additionally, social and cultural factors may contribute to the relationship between sex and psychiatric disorders. For example, women may be more likely to experience certain types of stressors, such as sexual harassment and discrimination, which can increase their risk of developing psychiatric disorders.

The relationship between sex and psychiatric disorders is complex and multifaceted, and more research is needed to fully understand this relationship (Bethell, 2013).

Psychotropic-induced disturbances:

There is evidence to suggest that certain psychotropic medications can cause sexual side effects in some individuals. These side effects can include changes in libido (sex drive), difficulty with arousal and orgasm, and changes in sexual function.

The specific sexual side effects that are caused by psychotropic medications can vary depending on the medication and the individual. Some common psychotropic medications that are associated with sexual side effects include selective serotonin reuptake inhibitors (SSRIs), which are used to treat depression and anxiety, and antipsychotics, which are used to treat psychosis and bipolar disorder (Clayton, 2006).

References:

(1) Andersson, K.-E., & Wagner, G. (2004). Sexual behaviour and the brain. Annual Review of Sex Research, 15, 27-61.

(2) Bethell, C. D., & Russell, S. T. (2013). Gender and mental health: An epidemiological review. Journal of Adolescent Health, 52(2), S7-S20.

(3) Clayton, A. H., Pradko, J. F., Croft, H. A., & Kornstein, S. G. (2006). Prevalence and impact of sexual dysfunction associated with antidepressant agents. Journal of Clinical Psychiatry, 67(2), 33-49.

(4) Granados, M. O., & Sánchez, J. M. (2018). Hormones and the developing brain. Frontiers in Neuroendocrinology, 48, 32-47.

(5) Rametti, G., Carrillo, B., Gómez-Gil, E., Junque, C., Zubiarre-Elorza, L., Segovia, S., … & Guillamon, A. (2011). White matter microstructure in female to male transsexuals before cross-sex hormonal treatment. A diffusion tensor imaging study. Journal of Psychiatric Research, 45(2), 199-204.