Home » Vol 18, No 1 » Immunity and Sexual Behavior

New Research to Link Immunity with Sexual Behavior

In the midst of flu and cold season, you may be adding more vitamin c or zinc to your diet. But what if changing your sexual habits could build your immune system, too?

In previous research, Tierney Lorenz, postdoctoral fellow at The Kinsey Institute and the Common Themes in Reproductive Diversity (CTRD) research training group at IU, found that a healthy sex life could contribute to a healthy immune system.

Image of ecoli bacteria.

Lorenz’s previous work with Sari van Anders at the University of Michigan measured the level of antibodies in saliva and the sexual habits of an individual. In their paper “Interactions of Sexual Activity, Gender, and Depression on Immunity” (Journal of Sexual Medicine, February 2013), they reported that sexual behavior affects immune system markers.

"However, we don’t know yet if a person is more or less likely to get sick due to sex,” Lorenz says.

Lorenz’s current postdoctoral work at Indiana University aims to answer this question. Conducted in collaboration with the departments of psychology and biology, the Women, Immunity and Sexual Health (WISH) study will examine how the presence or absence of sexual activity may influence immune response in healthy human females across the menstrual cycle. Past research has shown other social behaviors, like athletic competition and positive friendly interactions, can change how the immune system reacts to threats, but this study will be one of the first to show if sexual activity is another one of the factors the immune system takes into account in determining how high of an alert to set.

“Sex is important and the body expects sex—we are wired to reproduce— but we know so little about how and why the body is reacting to sex and influencing health,” Lorenz says.

The study will collect blood and saliva samples from pre-menopausal female volunteers in Bloomington over the course of a month, or one menstrual cycle. The study will include both sexually active and sexually abstinent subjects. With the help of Dr. Greg Demas from the department of biology, the samples will be infected with E. coli, and after an incubation period, will show how effective the antibodies are due to the amount of bacteria remaining.

Insights Into Depression

Lorenz ultimately wants to apply this research to further understand and treat mental health. She specializes in sexual health and wellbeing in people with mood disorders, and her pre-doctoral study sampled both depressed and non-depressed women. The WISH study will examine differences in healthy women’s immune reactions depending on their sexual activity, but Lorenz wants to later expand this to compare sexual behavior and health in depressed and non-depressed women:

“There is only very broad literature out there suggesting the immune system plays an important role in mental illness, and I’m interested in how the immune system plays a role in depression and why people stay depressed,” she says. “This is an exciting field because sexual behavior and mental health is for the most part untouched.”

She explains that our immune systems, hormones, and mental health are all intertwined. Depressed women frequently experience mild, cold-like symptoms like fatigue, headaches, or achiness because there is a constant, physical immune reaction that accompanies persistent depression. How sexual activity plays a role in this is still something of a mystery.

“Despite the very high rates of depression in women, we don’t know why some depressed women continue to have sexual desire and others don’t; why some women experience antidepressant sexual side effects and others don’t; what influence sexual activity might have on some of the physical effects of depression; how sex might protect a relationship from the negative effects of depression…That, to me, seems like a big gap!” Lorenz says.

Immunity and Reproduction

The WISH study will not only lead to an understanding of how the immune system and sexual behavior interact, it will also add to what is known about the immune system and reproduction. The study will monitor immune response over the course of a menstrual cycle.   Lorenz explains that women’s immunity strength is like an on/off switch when the body is ready to reproduce. This is important because the immune system dampens down at the point of ovulation in order to allow potential sperm to survive; otherwise, a super strong immunity would lead to sperm attack, and that would be the end of the human species! This study will examine whether or not having sex affects this on/off switch of immunity in women.

So what does this all mean for women?

“Knowing how female bodies react to sexual activity can help women and their doctors make better choices: for example, if a woman is much more sexually active than the average person, she might have artificially high ratings on allergy tests or other tests of immune function. This might lead to misdiagnosis of immune dysfunction,” Lorenz says. “Also, if this study shows that sexual activity at a particular point of a woman’s menstrual cycle might trigger the inflammation that increases risk of depression, a woman who is at risk for depression might avoid sex during that part of her cycle.”

Though the science is preliminary, Dr. Lorenz hopes her findings will bring new insight to the interaction of sexual behavior and physical and mental health that can lead to applied research and treatment in the future.

“As a psychologist, it is really fun for me to see a lot of parallels between hormones and immune function. This is something psychologists are just now getting in touch with.”

Women interested in participating in the WISH study can find more information here »

 


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