Posted by on September 15, 2011 - 6:35am

A new Northwestern University study provides compelling evidence that human males are biologically wired to care for their offspring, conclusively showing for the first time that fatherhood lowers a man’s testosterone levels. So guys, there is no excuse for not pitching in and, ladies, this is good news if you are a new mother who could use some help with that new family addition!.

The effect is consistent with what is observed in many other species in which males help take care of dependent offspring. Testosterone boosts behaviors and other traits that help a male compete for a mate. After they succeed and become fathers, “mating-related” activities may conflict with the responsibilities of fatherhood, making it advantageous for the body to reduce production of the hormone.

“Humans are unusual among mammals in that our offspring are dependent upon older individuals for feeding and protection for more than a decade,” said Christopher W. Kuzawa, co-author of the study and associate professor of anthropology in the Weinberg College of Arts and Sciences. “Raising human offspring is such an effort that it is cooperative by necessity, and our study shows that human fathers are biologically wired to help with the job.”

Past studies showing that fathers tend to have lower testosterone levels were small and not conclusive regarding whether fatherhood diminished testosterone or whether men with low testosterone in the first place were more likely to become fathers. The new study takes a novel approach by following a large group of men who were not fathers and seeing whether their hormones changed after becoming fathers.

“It’s not the case that men with lower testosterone are simply more likely to become fathers,” said Lee Gettler, a doctoral candidate in anthropology at Northwestern and co-author of the study. “On the contrary, the men who started with high testosterone were more likely to become fathers, but once they did, their testosterone went down substantially. Our findings suggest that this is especially true for fathers who become the most involved with child care.”

The new study’s findings also suggest that fathers may experience an especially large, but temporary, decline in testosterone when they first bring home a newborn baby. “Fatherhood and the demands of having a newborn baby require many emotional, psychological and physical adjustments,” Gettler said. “Our study indicates that a man’s biology can change substantially to help meet those demands.”

The authors also suggest that their findings may provide insight into one reason why single men often have poorer health than married men and fathers. “If fathers have lower testosterone levels, this might protect them against certain chronic diseases as they age,” Kuzawa said.

The study followed a group of 624 males aged 21.5 to 26 years old for 4.5 years in the Philippines.

“Longitudinal Evidence That Fatherhood Decreases Testosterone in Human Males” was published Sept. 12, 2011, in the Proceedings of the National Academy of Sciences.

Author:  Hilary Hurd Anyaso,  law and social sciences editor, Northwestern Newscenter.

Posted by on June 24, 2011 - 10:07am
Testosterone Molecule

Testosterone might protect the memory of healthy aging women, according to a small open-label pilot study reported at the Endocrine Society 93rd Annual Meeting held in June 2011.  Nine postmenopausal women who used a transdermal testosterone spray for about 6 months saw improvements over baseline in verbal learning and memory. A group of matched untreated women saw no change from baseline in their test results. The study was small and further exploration is needed but the idea has merit.

"The results of our study offer a potential therapy, where none currently exists, to slow cognitive decline in women," said lead investigator Sonia Louise Davison, MD, PhD, from the Women's Health Research Program at Monash University in Melbourne, Australia. "Testosterone should be further studied in randomized placebo-controlled trials to determine whether it improves cognitive performance in postmenopausal women," she added.

At a press briefing, Dr. Davison said predictions of the number of people who will develop dementia in the coming years are "pretty worrying." Dementia is set to become an "enormous" and costly public health problem. Women develop dementia at double the rate of men; lower testosterone levels in women might play a role in this sex difference.

Dr. Davison's team explored the effects of testosterone on cognitive performance in 9 nondepressed cognitively normal women. The women were between 47 and 60 years of age (mean age, 55 years) and were receiving stable-dose hormone replacement therapy that was not administered orally. They applied the testosterone spray to the abdomen once daily for 26 weeks. A control group of 30 women provided normative data for comparison.At baseline and 26 weeks, all of study subjects took a computerized cognitive test battery, called CogState, which is capable of detecting small changes in cognitive performance, Dr. Davison explained.

There were no differences between the 2 groups in any parameter at baseline.After 26 weeks, "significant improvements" from baseline were observed in learning (verbal and visual) and memory in the testosterone group. In contrast, there were no significant differences between baseline and 26 weeks in the control group.

Support for the Neuroprotective Effects of Testosterone

Dr. Davison called these results "exciting," and said they provide more evidence that testosterone exerts neuroprotective effects.In men, age-related declines in testosterone increase the risk for Alzheimer's disease, she said. It's been shown that healthy older men and men with mild cognitive impairment and early dementia have demonstrated improvements in cognitive performance, including memory, after testosterone treatment.

"There obviously is some important link between testosterone and cognition that needs to be explored further," Dr. Davison said.

The testosterone spray used in the study is "novel," she noted, "in that it uses a propellant of sunscreen to introduce the testosterone into the skin."

Source:   Medscape Medical News for ENDO 2011: The Endocrine Society 93rd Annual Meeting: Abstract P1-314. Presented June 4, 2011.

Posted by on August 23, 2010 - 9:15am

No, you did not open the wrong page.   Yes, this blog is posted by the Institute for Women's Health Research at Northwestern. As an advocate for better  sex and gender based research, we support all avenues that increase our knowledge about sex differences and that includes  a better understanding of  hormone changes in women AND MEN.

Furthermore, women are generally the source of health information for their families and that includes their male partners! So, women and men, read on!

Low testosterone levels to blame for low libido, fatigue and weight gain

While most frequently associated with women’s health, age-related hormone changes, often dubbed menopause, can occur in men as well, causing symptoms of fatigue, mood swings, decreased desire for sex, hair loss, lack of concentration and weight gain. Experts estimate that more than 5 million men are affected, yet worry the number may be considerably higher since symptoms are frequently ignored.  Male hypogonadism, as it’s referred to in the medical community, occurs when the testicles do not produce enough testosterone, the hormone that plays a key role in masculine growth and development. When hormone levels drop, men can experience significant mental and physical changes.

“This is a highly prevalent disorder,” said Robert Brannigan, MD, urologist at Northwestern Memorial Hospital. “Unfortunately, we estimate that 95 percent of cases are undiagnosed and therefore untreated. When ignored, symptoms can seriously disrupt one’s quality of life.”

Brannigan explains hormone variations are a normal aspect of getting older. “In females, ovulation comes to an end and hormone production declines in a relatively quick period of time, whereas men experience hormone shifts more slowly, with testosterone levels dropping around one percent each year beginning in a man’s late thirties,” adds Brannigan. He goes on to explain that by age seventy, the reduction in a male’s testosterone level could be as high as fifty percent or more compared to baseline levels, but notes that aging men are not the only ones at risk. A number of genetic causes can impact males from birth and are usually diagnosed with failure to progress normally through puberty during the teenage years.

Treatment options for male hypogonadism include hormone replacement therapy (HRT) via absorbable pellet implants, topical gels, patches, and injections. Through HRT, doctors can restore sexual function and muscle strength. In addition, men often experience an increase in energy and an improved overall sense of well-being.

“We are seeing more men affected by male hypogonadism than we saw ten years ago,” said Brannigan. “However, many men continue to suffer in silence due to a lack of awareness surrounding the disorder. Because male hypogonadism can significantly impact the quality of one’s life, it’s important that men pay attention to their body and openly discuss symptoms with their physician in order to prevent overlooking the cause and avoid missing an opportunity for appropriate therapy.”

Although research to determine the exact association continues, doctors also warn that male hypogonadism has been linked to chronic medical conditions such as high cholesterol, diabetes and cardiovascular disease. It’s also closely associated with infertility.

“This disorder is not something that should be ignored,” said Brannigan, who is working to educate patients and physicians about the symptoms and treatments available in order to ensure therapies are made available to men in need.

Male hypogonadism is most commonly diagnosed through a simple blood test. Brannigan notes hormone replacement therapy is not appropriate for all patients especially those with history of prostate and breast cancer and men trying to conceive. He suggests consulting your doctor if you are experiencing symptoms.