Posts Tagged ‘ testosterone ’

Early Intervention May Reduce Adults’ Aggressive Behavior

Thursday, April 3rd, 2014

A decade-long education program aimed at teaching children self-regulation and other healthy cognitive techniques is showing results in reducing aggressive behavior when the schoolchildren become adults, according to new research published in the journal Psychological Science. More from the journal:

The research, led by psychological scientist Justin Carré of Nipissing University in Ontario, Canada, indicates that dampened testosterone levels in response to social threats may account for the intervention’s success in reducing aggression.

The Fast Track intervention program teaches children social cognitive skills, such as emotional regulation and social problem solving, and previous research suggests that the program may lead to decreased antisocial behavior and aggression in childhood and adolescence.

But it wasn’t clear whether the skills that children learned in the program would have impacts that carried over into adulthood.

Carré and colleagues suspected that the program would have long-term effects, and that those effects would be linked to a specific biological mechanism: alterations in testosterone reactivity to social provocation.

To test these hypotheses, the researchers recruited 63 participants from Fast Track schools in Durham, North Carolina. To ensure the participants in the sample were similar demographically, all of the participants were African American men who were about 26 years old.

Half of those participants were involved in the Fast Track program from ages 5 to 17, consisting of tutoring, peer coaching, home and family visits, and social-emotional learning lessons with friends. The rest of the participants attended the same schools but weren’t involved in the Fast Track program.

More than 8 years after the intervention ended, the researchers brought the participants into the lab to play a game, the goal of which was to earn as much money as possible by pressing three buttons: one which accrued money, one which prevented money from being stolen, and another which stole money from an opponent. The participants believed they were playing against an actual opponent, but the game was actually determined by a computer program. The fictitious opponent provoked participants during the task by stealing their hard-earned money.

Overall, participants who completed the Fast Track program showed less aggression toward their opponent – that is, they opted to steal less money from their opponent than did participants who didn’t complete Fast Track.

Participants who hadn’t received the intervention showed an increase in testosterone levels after having their money stolen, but Fast Track participants didn’t, a finding that could explain their reduced aggression.

“Interestingly, there were no differences between intervention and control groups in baseline testosterone concentrations or aggressive behavior at the beginning of the experiment,” Carré explains. “Differences in aggressive behavior and testosterone concentrations emerged only later in the game.”

Ultimately, the findings suggest that Fast Track was successful in reducing participants’ aggression toward a hostile peer in part because it changed the way their neuroendocrine systems responded to social provocation.

Image: Angry boy, via Shutterstock

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Attentive Fathers, Study Finds, Have Smaller Testicles

Wednesday, September 11th, 2013

Researchers at Emory University have concluded, in a study published in the Proceedings of the National Academy of Sciences, that attentive, nurturing fathers are statistically more likely to have smaller testicles than distant, less empathetic fathers.  The finding is consistent with the belief that lower testosterone levels contribute to a father‘s enjoyment of parenting, patience, kindness, and other characteristics.  More from NBC News:

“The general idea is that lower testosterone on a day-to-day basis helps attune fathers to the needs of their children,” University of Notre Dame anthropologist Lee Gettler, who studies this effect, told NBC News.

Lower testosterone may also make men more empathetic, less aggressive, less interested in mating, or all these.

The idea is part of Life History Theory. The theory holds that many animals, including people, trade off between putting resources into mating, versus parenting. The more energy devoted to having sex, and engaging in competition with others to do so, the less that’s left for raising offspring, and vice versa.

The life histories of children have shown that the more stress and family disruption they experience, the greater the risk they’ll face troubles later. Girls with an absent father, for example, are more likely to start their periods sooner, have sex sooner, and to become single mothers. Boys with absent fathers or stressful childhoods are more likely to begin having sex earlier. They are more likely to put more effort into mating, less into parenting.

The Emory group, led by post-doctoral fellow Jennifer Mascaro in the lab of James Rilling, is the first to use testicle size as a physical marker, and to see if testicle size correlates with brain reward – positive feelings — from nurturing as a way to help explain variation in male parenting.

Image: Happy father and son, via Shutterstock

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Obese Teenaged Boys Have Half Normal Testosterone Levels

Monday, October 15th, 2012

Teenaged boys who are obese have testosterone levels that are lower than normal-weight teens, to the point of being “alarming,” researchers have found in a new study published in the journal Clinical Endocrinology.  The research may offer a clue into at least one medical explanation for obesity in boys.  CNN has more:

“It has its origins in earlier research, which showed that type II diabetes and obesity in older men are linked to a high rate (25-33%) of hypogonadism, or low testosterone levels. According to the new study, the rate of hypogonadism in type II diabetic men ages 18-35 is greater than 50%.

In addition, concentrations of free testosterone — testosterone that isn’t chemically bound and thus available to the body — were shown to be negatively related to BMI:  The higher the body mass, the lower the concentration.

“This raises the question whether obesity is associated with lower testosterone concentrations, even in younger males,” the study said.

Controlling for age, physical maturity and certain medical factors, 25 obese and 25 lean males between the ages of 14 and 20 were studied.

Blood samples were drawn in the morning to measure both total and free testosterone.

Mean testosterone concentration was 50% lower in obese males. Mean free testosterone concentration was 46% lower.

The results present several problems for those affected, according to Dr. Paresh Dandona, chief of the Division of Endocrinology, Diabetes and Metabolism at the University of Buffalo’s medical school and the study’s lead author.

Obesity can lead to diabetes and heart disease. What’s more, low testosterone can slow or stop sexual maturation — and there’s nothing more hurtful than “a male not having his maleness,” Dandona said.”

Image: Obese boy, via Shutterstock

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Study: Testosterone Levels Lower in Fathers

Tuesday, September 13th, 2011

dadanddaughterThe first longitudinal study of testosterone levels in fathers has found that the longer a man has been a father–and the more involved with the daily care of his children he is–the lower his testosterone level drops.

The study measured testosterone levels in 21-year-old men before they became fathers, and then again 5 years later.  Those who became fathers had more than double the drop in testosterone than non-fathers (all men experience a drop in testosterone as they age).  And those men who spent more than three hours caring for their children each day had the lowest level of all.

The New York Times reports on the study, which was published in the journal Proceedings of the National Academy of Sciences:

“The real take-home message,” said Peter Ellison, a professor of human evolutionary biology at Harvard who was not involved in the study, is that “male parental care is important. It’s important enough that it’s actually shaped the physiology of men.”

“Unfortunately,” Dr. Ellison added, “I think American males have been brainwashed” to believe lower testosterone means that “maybe you’re a wimp, that it’s because you’re not really a man.

“My hope would be that this kind of research has an impact on the American male. It would make them realize that we’re meant to be active fathers and participate in the care of our offspring.”

The study, experts say, suggests that men’s bodies evolved hormonal systems that helped them commit to their families once children were born. It also suggests that men’s behavior can affect hormonal signals their bodies send, not just that hormones influence behavior. And, experts say, it underscores that mothers were meant to have child care help.

“This is part of the guy being invested in the marriage,” said Carol Worthman, an anthropologist at Emory University who also was not involved in the study. Lower testosterone, she said, is the father’s way of saying, “ ‘I’m here, I’m not looking around, I’m really toning things down so I can have good relationships.’ What’s great about this study is it lays it on the table that more is not always better. Faster, bigger, stronger — no, not always.”

(image via: http://www.hfihouston.org)

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