Let’s Talk About Sex….The Science Of It

Let’s Talk About Sex….The Science Of It

By Charlotte Wincott, Ph.D.

Neurons communicate with each other to help you “learn” what pleasure is. Striatal neuron images courtesy of Dr. Heather Bowling.

Most researchers agree that drug addiction is a disease of the brain that occurs as the result of environmental factors and genetic predisposition. However, there is no general consensus on whether sex addiction should be perceived in the same way as heroin or cocaine addiction. Researchers and clinicians alike have been struggling for years to reduce the stigma associated with drug addiction with some success. On the other hand, questions about sex-related behaviors are answered in hushed tones at the end of scientific talks on drug addiction. Why are we as a society so afraid to talk about sex addiction when so many individuals suffer from its consequences? Perhaps similar efforts should be made to understand the behaviors associated with sex addiction, which may be driven by some of the same brain circuits that control drug-related behaviors. 

The pleasant feelings that are experienced by users of cocaine, for instance, are produced by activity in our brain’s reward center. This brain region is called the nucleus accumbens. Our brains are extremely complicated but, to make it simple, the nucleus accumbens receives information in the form of a molecule called dopamine. Dopamine allows us to learn that something is pleasurable. When the nucleus accumbens receives dopamine signals, it tells other brain regions what to do in order to get more of the drug or whatever it was that caused the pleasant feeling. Rats, like humans, also have this reward center which undergoes changes when animals eat sugar;1 sexual behavior is also driven by some of the same molecules and brain structures. Scientists at the University of Cincinnati College of Medicine showed that when rats have sex or are presented with sex-related cues, dopamine messages are sent to the nucleus accumbens,2 and rats are not alone. Imaging studies of college students have shown a strong relationship between activity of this brain region during the presentation of sexual images and students’ sexual desire as measured by a questionnaire after six months. Scientists also found that there was a correlation between how much the nucleus accumbens “lit up” during the presentation of food pictures and how much weight the students gained six months later.3

Photo courtesy of Jack Zalium.

Obviously, the nucleus accumbens is not the whole story. Other parts of the brain also play roles in conveying the pleasure that is associated with both drugs and sex.  In many cases, those parts of the brain overlap. In a recent study, Valerie Voon and colleagues found that when those with compulsive sexual behavior were presented with sexually explicit cues, not only was the nucleus accumbens involved, but the team also observed increased activation of a brain region called the amygdala as well as the substantia nigra.4 The substantia nigra is also involved in the dopamine system, which has long been associated with disrupted reward perception. In 1996, scientist Kenneth Blum coined the phrase Reward Deficiency Syndrome (RDS), which he described as a syndrome where some people do not experience pleasure in their everyday environments like others. Lack of pleasure in those with RDS may involve an imbalance of the dopamine system which might make some people more susceptible to becoming addicts.5 Mutations in genes that have roles in the dopamine system have also been linked to cocaine dependence, gambling, obesity, and smoking.5,6 Even though many studies have shown similar brain pathways involved in drug and sex addiction, overeating, and excessive gambling, the manual that psychiatrists use to diagnose patients (the DSM-V) does not include sexual addiction in its characterization of addiction6,7. However, this manual does recognize pathological gambling. Notably, excessive gambling and hypersexuality have been observed in Parkinson’s disease patients treated with drugs that act on the dopamine system, suggesting that both addictions may be caused by disrupted brain function as opposed to a lack of self-control.8,9 

Science Muddied By Morality?

Without question, sexual behavior and sex addiction need further study.  Does the lack of scientific investigation and peer-reviewed evidence supporting sex addiction as a diagnosable condition have to do with society’s fear of talking about sex?  Derbyshire and Grant (2015) point out that the understanding of sexual behavior is muddied by ideas of what “morality” means in today’s culture. Are those who struggle with sex addiction fearful of talking to doctors because of its taboo subject matter? Are scientists too embarrassed to write about it or submit funding proposals to study it for the same reasons? An addiction expert who was asked to comment on this piece mentioned an important point: psychiatry may be reluctant to formalize “sex addiction” because of its complexity. Hypersexuality that is sometimes observed in those with mood disorders compared to compulsive sexual behavior that can result in violence or abuse are quite different. 

Regardless of its form, sex addiction can be enormously damaging to not only those who suffer directly but also to the people in their periphery, such as loved ones or victims. Popular culture is filled with reports of celebrities, politicians, or church members who have struggled with sex-related behavior and its fallout. Millions of users p hj members of sites like Ashley Madison.  Pornography is a multi-billion dollar industry.  If these phenomena were adequately addressed and talked about in peer-reviewed journal articles, grant proposals, doctors’ offices, and psychiatry manuals, would fewer individuals suffer? Probably.  

So let’s start talking about sex.  Getting rid of the stigma associated with sex addiction is the first step in getting more individuals into treatment.

Many thanks to the scientists who gave comments on this article.


1. Tukey, D. S., Ferreira, J. M., Antoine, S. O., D’Amour J, A., Ninan, I., Cabeza de Vaca, S., Incontro, S., Wincott, C., Horwitz, J. K., Hartner, D. T., Guarini, C. B., Khatri, L., Goffer, Y., Xu, D., Titcombe, R. F., Khatri, M., Marzan, D. S., Mahajan, S. S., Wang, J., Froemke, R. C., Carr, K. D., Aoki, C. & Ziff, E. B. (2013). Sucrose ingestion induces rapid AMPA receptor trafficking. J Neurosci 33, 6123-32.

2. Balfour, M. E., Yu, L. & Coolen, L. M. (2004). Sexual behavior and sex-associated environmental cues activate the mesolimbic system in male rats. Neuropsychopharmacology 29, 718-30.

3. Demos, K. E., Heatherton, T. F. & Kelley, W. M. (2012). Individual differences in nucleus accumbens activity to food and sexual images predict weight gain and sexual behavior. J Neurosci 32, 5549-52.

4. Voon, V., Mole, T. B., Banca, P., Porter, L., Morris, L., Mitchell, S., Lapa, T. R., Karr, J., Harrison, N. A., Potenza, M. N. & Irvine, M. (2014). Neural correlates of sexual cue reactivity in individuals with and without compulsive sexual behaviours. PLoS One 9, e102419.

5. Blum, K., Sheridan, P. J., Wood, R. C., Braverman, E. R., Chen, T. J., Cull, J. G. & Comings, D. E. (1996). The D2 dopamine receptor gene as a determinant of reward deficiency syndrome. Journal of the Royal Society of Medicine 89, 396-400.

6. Blum, K., Werner, T., Carnes, S., Carnes, P., Bowirrat, A., Giordano, J., Oscar-Berman, M. & Gold, M. (2012). Sex, Drugs, and Rock ‘N’ Roll: Hypothesizing Common Mesolimbic Activation as a Function of Reward Gene Polymorphisms. J Psychoactive Drugs 44, 38-55.

7. APA. (2013). Diagnostic and statistical manual of mental disorders (5th ed.).

8. Weintraub, D., Koester, J., Potenza, M., Siderowf, A. D., Stacy, M., Voon, V., Whetteckey, J., Wunderlick, G. & Lang, A. (2010). Impulse control disorders in Parkinson disease: a cross-sectional study of 3090 patients. Arch Neurol 67, 589-595.

9. Potenza, M. N. (2014). Non-substance addictive behaviors in the context of DSM-5. Addict Behav 39, 1-2.

10. Derbyshire, K. L. & Grant, J. E. (2015). Compulsive sexual behavior: a review of the literature. J Behav Addict 4, 37-43.

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