Low sex drive in men linked to chemical imbalance, study says

‘It just didn’t enter my mind to initiate sex;’ Low sex drive in men linked to chemical imbalance

By Sandee LaMotte, CNN
Updated 3:23 AM EDT, Wed April 12, 2023

This article is a repost which originally appeared on CNN

Edited for content. The opinions expressed in this article may not reflect the opinions of this site’s editors, staff or members.

Key Points

‧ Not everyone thinks of sex in the same way.

‧ The hormone Kisspeptin plays a role in pubertal development and reproduction.

‧ Distress over sexual interest can itself contribute to issues.

While hanging out with his college roommates, Peter (not his real name) realized he felt differently about sex than other heterosexual men.
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“I’ve never been somebody who was interested in pornography, but I’d laugh along with their jokes,” said Peter, now 44, who is British. “Of course I never mentioned that … as a man, you’d be kicked out of the herd.”

As he developed “proper, serious relationships” with women, Peter discovered he didn’t have the sexual drive many of his partners did.

“I would make excuses around getting tired or feeling stressed, that kind of thing,” he said. “It wasn’t an issue with attraction to my partner. It just didn’t enter my mind to initiate sex.”

In 2021, Peter saw an ad recruiting male volunteers for a new study on hypoactive sexual desire disorder, or HSDD. Researchers planned to inject the study’s participants with kisspeptin —a naturally occurring sexual hormone — to see if it increased their sex drive. Kisspeptin plays a key role in reproduction; without adequate levels of the hormone children do not go through puberty, for example.

In a long-term, committed relationship with a woman he says has a higher sexual appetite, Peter signed up, intrigued by the thought that a biological imbalance might help explain his behavior.

In the week after the final session, Peter said, something amazing occurred.

“All of a sudden, I wanted to initiate intimacy. I can only presume it was driven not by my mind remembering something, but my body wanting something,” he said. “I did initiate sex more and it improved things with my partner incredibly.”

Wiring in the brain

Experts believe HSDD affects at least 10% of women and up to 8% of men, although those numbers may be low, said Stanley Althof, a professor emeritus of psychology at Case Western Reserve University School of Medicine in Cleveland, Ohio and executive director of the Center for Marital and Sexual Health of South Florida.

“Men are embarrassed to go to the doctor to begin with, and you’re supposed to be a macho guy,” said Althof, who was not involved in the kisspeptin study.

“So it’s difficult for men to say, ‘Hey, I’ve got a problem with my sex drive.’ That’s why the majority of male patients I see with HSDD are sent in by their partners.”

To be diagnosed with the disorder, a person must have no other issues that might cause a change in libido, such as erectile dysfunction or premature ejaculation.

“Losing interest due to performance issues is common, but HSDD is its own thing,” Althof said. “It’s an absence of erotic thoughts and a lack of desire for sex that has to be present for six months. It also cannot be better explained by another disorder or other stressors: It can’t be due to depression. It can’t be due to a bad relationship. It can’t be due to taking an antidepressant.”

One more key point: A man or woman must have clinically significant distress to have HSDD, said clinical psychologist Dr. Sheryl Kingsberg, a professor in reproductive biology and psychiatry at Case Western Reserve University, who was also not involved in the kisspeptin study.

“Some people aren’t bothered by their lack of interest in sex, so we wouldn’t treat them for HSDD,” said Kingsberg, who is also chief of behavioral medicine at MacDonald Women’s Hospital and University Hospitals Cleveland Medical Center.

“The women coming into my office are deeply distressed,” she said. “They tell me ‘I used to have desire but it’s gone. I could be on a desert island with no pressures, but I just don’t have the appetite. I want it back.’ Those women have HSDD.”

‘Surreal’ experience

Dr. Waljit Dhillo, a professor in endocrinology and metabolism at Imperial College London, has been studying the relationship between low sexual desire and the hormone kisspeptin for years, first in animals, then in people.

Prior studies by Dhillo of healthy men with no libido problems found giving them kisspeptin boosted levels of testosterone and luteinizing hormone, which is important for gonad function.

His newest study, published in the journal JAMA Network Open in February, enrolled 32 men with verified HSDD. Peter was one of them.

“So many people say to themselves, ‘It’s just me. I’ve got a problem.’ But actually, HSDD may be how your brain is wired,” said Dhillo, who is a dean at the United Kingdom’s National Institute for Health and Care Research Academy in Newcastle upon Tyne.

“The biology is telling us there’s increased activation of inhibitory areas in the brain — the same areas that tell us it’s not OK to walk around in public naked — and those areas are switching off sexual desire. How can we tackle that? We give a hormone that would naturally give you increased sexual desire, essentially hijacking the normal system.”

The men participating in the new study visited Dhillo’s lab twice. On each occasion, they were fitted with a device to objectively measure arousal, given an injection and asked to watch pornography while their brains were scanned via functional magnetic resonance imaging (fMRI).

Neither the subjects or the researchers knew if that day’s injection was kisspeptin or a placebo.

“It was extraordinarily surreal, lying there with something resembling a hangman’s noose around your bits and watching a mixture of ’70s to modern-day pornographic images and videos,” Peter said. “You’d get about five or six seconds of one type of image or video, rate your arousal for the researchers, and then move on to the next.”

Brain scans showed a significant dual effect after the kisspeptin injection, Dhillo said. Activity in the areas of the brain that inhibit behavior slowed, while areas of the brain connected to sexual interest lit up.

“As a group, the men had a 56% higher sexual response to sexual images after the kisspeptin than the placebo,” Dhillo said. “And we found no side effects at the very, very small dose that we are using.”

Peter noticed a difference immediately after finishing the treatments. His sex life was so robust, in fact, that it wasn’t long before his partner was pregnant with their first child.

As published, the study did not follow the men long-term to see if the effects of kisspeptin lasted. For Peter, however, its impact has been life-changing.

“I have found there’s been a lasting effect for me,” he said. “I do find I have a much better sexual appetite even now some years after the treatment.”

Even the arrival of a baby boy didn’t deter his new interest in sex.

“The cliche is when you have kids, your sex life takes a bit of a hit,” he told CNN. “But that hasn’t been the case for us. In fact, we’re pregnant with our second child, due in July.”

More research is needed

While Peter had a positive long-term result, it’s too soon to say kisspeptin injections were the reason, Althof said.

“When you hear dramatic results like Peter’s, I would be cautious in saying that is the typical outcome. While it’s wonderful that it happened for him, these fMRI studies are difficult to interpret and not conclusive,” he said.

“Sexual desire is very complicated — I say it’s a combination of brain function, hormones and love, wine and roses,” Althof added. “This study is promising, but it needs replication in larger groups.”

And even if future research does confirm kisspeptin’s benefits, medical treatment is not a substitution for healthy communication about sex between partners and with health care providers, Dhillo said.

“These are society’s taboos, but actually, the more we talk about real (sexual) issues that affect real people, the more we find it’s actually quite common,” he said.”If you’re not troubled by low libido, it’s not an issue at all, but if you are troubled by it, this can lead to marital breakdown, unhappiness and reduced quality of life.”

Sperm counts are decreasing, study finds. What might it mean for fertility?

Karen Weintraub
USA TODAY

This article is a repost which originally appeared on USA TODAY.

Edited for content. The opinions expressed in this article may not reflect the opinions of this site’s editors, staff or members.

Key Points

‧ A new study found men are likely to have lower sperm counts than 50 years ago.

‧ The reason? Experts say it’s hard to tell but may be due to environmental exposures, chemicals or changes in weight.

‧ Being healthy overall is important for reproductive health, experts said. Men should talk to their doctor if they’re concerned about their sperm count.

Sperm counts and concentration are down all over the world, according to a new study that updates previous research and raises questions about exposures and men’s health.

From 1973 to 2000, sperm counts dropped by 1.2% per year, “which is a lot,” said Hagai Levine, who helped lead the research. From 2000 to 2018, the decline was 2.6% per year, “which is an amazing pace.”

The United States is part of this larger trend.

“In the U.S., due to availability of good data, we have the highest certainty that there is a strong and sustainable decline, but it’s similar globally,” Levine said.

It’s unclear why sperm counts have been falling.

“We don’t understand why we’re seeing this pattern, so I think it’s hard to be alarmist for an individual,” said Dr. Michael Eisenberg, a urologist focused on male fertility and sexual function at Stanford University and Stanford Health Care in California. He was not involved in the new study.

“But at a policy level, this should be a wake-up call to try and understand,” Eisenberg said.

Experts say falling sperm counts might mean it takes longer to have children. Here’s what to know.

What’s the evidence?

The new study is a meta-analysis, which means it combined findings from more than 250 previous studies. It also updates a previous meta-analysis the team published in 2017, adding data on sperm counts from 2011 to 2018 and regions in South America, Asia and Africa, where data had been incomplete before.

Men in the global south have seen the same significant decline in sperm count and concentration as the team showed in 2017 among men in North America, Europe and Australia, whose sperm counts and concentrations continued to fall, according to the new study.

Sperm count is a imperfect measure of fertility, but there is a threshold below which a low sperm count affects the chances of reproduction. On a population level, the study suggests that median sperm counts have dropped from 104 to 49 million per milliliter over five decades.

That means more men are likely to have sperm counts below the fertility threshold than was the case 50 years ago, said Levine, an epidemiologist and public health physician at the Braun School of Public Health, at Hadassah University Medical Center.

What’s the impact on fertility?

But Amy Sparks, a reproductive physiologist at the University of Iowa, who was not involved in the research, cautioned that sperm counts are falling, but not enough to affect the human population.

The paper is not “suggesting that our sperm concentrations are crashing at a rate that is going to lead us out to every man needing to walk into an infertility center. Heavens to Betsy, no.”

People have raised questions about sperm counts for generations. Sparks said she found a 1974 study of 390 men at the University of Iowa that raised concerns about low sperm counts.

“We can’t ignore that things are changing. Lifestyles have changed. Dietary patterns certainly have changed,” she said. “Through these changes, we are exposing our body to altered conditions. In response to those altered conditions, we’re seeing a decrease in sperm concentration.”

Levine, however, sees the drop in sperm count as a problem for today’s families, not just future ones.

Although most American couples can manage to have the one or two children they want, it may take them longer now than in the past. In Israel, some religious families want 10 or more children. Slower fertility may mean they run out of time before they can have that many, he said.

It’s challenging to study sperm counts and fertility is even harder, said Dr. Bruce Redmon, a professor at the University of Minnesota Medical School, who was not involved in the research but studies male reproductive disorders.

It’s not really feasible, he said, to sample sperm in a randomly selected population of men every year for decades. And men who seek help for fertility problems are not reflective of the entire population.

But overall, Redmon said, the new study was a reasonable way to look at the issue.

“It’s probably something we have to continue to take seriously and look at,” he said.

Why are sperm counts falling?

Studies haven’t yet explained why sperm counts are falling, but Levine has a few ideas.

Total sperm capacity is determined during fetal development, so exposures to human-made chemicals, stress and poor diet during pregnancy might all be contributing factors, Levine said.

Environmental exposures of the father before conception may also be related to poor fetal outcomes. In a man’s adult life, his sperm count can also be reduced by exposure to pesticides, lack of physical activity, poor diet, smoking and obesity, he said.

Excess weight changes hormone levels, adding more estrogen to the male body, Sparks said. And extra fat around male reproductive organs could increase heat there, which will decrease sperm production.

Sparks doesn’t think any one thing is causing the drop. It’s happening too fast to blame on reproductive technologies. But the world’s population is carrying more weight, spending more time spent sitting at a computer, eating more processed foods and packing those food in plastic. Any or all of those could be driving the drop in sperm count, she said.

“We need to be motivated to invest in the research to work on this,” she said. “It points to a need.”

What can men do to boost their sperm count?

Men concerned about their fertility should to talk to their doctor, Eisenberg said. It’s important to be evaluated and determine whether there are specific treatments that may help.

Being healthy overall is important for reproductive health. Eisenberg suggests a healthy diet, regular exercise and smoking cessation.

“I always tell men there’s a strong link between fertility and health, so anything that’s good for your heart is good for fertility,” Eisenberg said.

A few other tips:

►Alcohol use: Moderate alcohol use is OK, Eisenberg noted, with studies suggesting that semen quality drops only after about 20 drinks a week.

►Avoid extreme heat: There’s no strong link between what kind of underwear men wear – boxers or briefs. But heat exposure isn’t good, so he advises avoiding hot tubs and saunas while trying to conceive.

►Taking testosterone: He also discourages his patients from using testosterone, which has been tested as a contraceptive, because it reduces sperm production.