Posts Tagged Gender
High levels of estrogen may help protect a woman from mood disorders, while low levels of the hormone can make a woman more susceptible to trauma at certain times in her menstrual cycle, according to new research by Harvard and Emory University neuroscientists.
Depression and anxiety disorders are twice as common in women as in men, but the reason for this gender difference has remained unclear. The new research, however, suggests that women are most at risk for symptoms of post-traumatic stress disorder (PTSD) when their estrogen is low during the menstrual cycle.
“PTSD is a disorder of recovery,” said author Mohammed Milad, associate professor of psychiatry at Harvard Medical School (HMS) and director of the Behavioral Neuroscience Laboratory at Massachusetts General Hospital (MGH).
Men may be less susceptible to mood disorders since testosterone is regularly converted into estrogen in the male brain, resulting in a more steady flow of estrogen.
In healthy women and female rats, estrogen calms the fear response, according to the Harvard researchers, who were led by Kelimer Lebron-Milad, an HMS instructor of psychiatry.
The Emory researchers, led by postdoctoral researcher Ebony Glover, proved that the same is true for women suffering from PTSD. The higher their blood levels of estrogen were when they completed a fear-extinction task, the less likely women were to act startled.
Both studies used “fear-conditioning” experiments, in which the participant is trained to fear a safe “conditioned stimulus” such as a colored shape, paired with a frightening or painful “unconditioned stimulus” like a shock to the finger or a puff of air to the neck or eye.
Overall, women or female rats showed less fear to the neutral stimulus when their estrogen levels were high rather than low.
PTSD is common in women after a trauma such as rape or sexual assault, which studies say are experienced by 25 to 30 percent of women in their lifetimes, and the symptoms last on average four times as long in women as in men after trauma.
This new research suggests the reason for this vulnerability may be the monthly menstrual change in estrogen.
“People are afraid to look into the influence of sex hormones on ‘fear learning’ and extinction,” said Mohammed Milad, “because it’s such a complex system.”
When Milad studied fear as a Ph.D. student, his lab used only male rats. But when he began to study fear in humans as a postdoctoral researcher, he saw that female data were much more variable.
“The data led me there,” to sex differences, Milad said. “Since females add variance, scientists have tended to avoid studying them” in rodent research, he said. Studies of the human brain would tend to combine men and women, assuming that neurological gender differences were minimal. But this attitude is changing.
In addition, since birth control pills affect estrogen levels, they may be used as a future treatment against post-traumatic stress.
The research is published in Biological Psychiatry.
Source: Biological Psychiatry
New research has demonstrated that the effects on white matter brain volume from long-term alcohol abuse are different for men and women.
Researchers from Boston University School of Medicine (BUSM) and Veterans Affairs (VA) Boston Healthcare System also suggest that when they stop drinking, women recover their white matter brain volume more quickly than men.
Previous research has linked alcoholism with white matter reduction, according to the researchers, who explain that white matter forms the connections between neurons, allowing communication between different areas of the brain.
In this latest study, a research team, led by Susan Mosher Ruiz, Ph.D., a postdoctoral research scientist in the Laboratory for Neuropsychology at BUSM and research scientist at the VA Boston Healthcare System, and Marlene Oscar Berman, Ph.D., professor of psychiatry, neurology and anatomy and neurobiology at BUSM and research career scientist at the VA Boston Healthcare System, employed structural magnetic resonance imaging (MRI) to determine the effects of drinking history and gender on white matter volume.
They examined brain images from 42 abstinent alcoholic men and women who drank heavily for more than five years and 42 nonalcoholic men and women. The researchers found that a greater number of years of alcohol abuse was associated with smaller white matter volumes in the alcoholic men and women. In the men, the decrease was observed in the corpus callosum, while in women this effect was observed in cortical white matter regions.
“We believe that many of the cognitive and emotional deficits observed in people with chronic alcoholism, including memory problems and flat affect, are related to disconnections that result from a loss of white matter,” said Mosher Ruiz.
The researchers also found that the number of daily drinks had a strong impact on alcoholic women, with the volume loss 1.5 to 2 percent for each additional drink. Additionally, there was an 8 to 10 percent increase in the size of the brain ventricles, which are areas filled with cerebrospinal fluid (CSF) that play a protective role in the brain. When white matter dies, CSF produced in the ventricles fills the ventricular space.
The researchers also found that in men, white matter brain volume in the corpus callosum recovered at a rate of 1 percent per year for each year of abstinence. For people who abstained less than a year, the researchers found evidence of increased white matter volume and decreased ventricular volume in women, but not in men. However, for people in recovery for more than a year, those signs of recovery disappeared in women and became apparent in men.
“These findings preliminarily suggest that restoration and recovery of the brain’s white matter among alcoholics occurs later in abstinence for men than for women,” said Mosher Ruiz. “We hope that additional research in this area can help lead to improved treatment methods that include educating both alcoholic men and women about the harmful effects of excessive drinking and the potential for recovery with sustained abstinence.”
The research was published online in Alcoholism: Clinical and Experimental Research.
Source: Boston University Medical Center
New research finds that playfulness and a sense of humor are important traits sought in romantic partners.
Researchers at Penn State University liken playful behavior and a sense of humor to bright plumage on birds to attract a mate.
“Humans and other animals exhibit a variety of signals as to their value as mates,” said professor Garry Chick.
“Just as birds display bright plumage or coloration, men may attract women by showing off expensive cars or clothing. In the same vein, playfulness in a male may signal to females that he is nonaggressive and less likely to harm them or their offspring. A woman’s playfulness, on the other hand, may signal her youth and fertility.”
Chick and his colleagues expanded on a previous survey that included a list of 13 possible characteristics that individuals seek in prospective mates. To the original list, they added three new traits: “playful,” “sense of humor” and “fun-loving.” The authors gave the survey to 164 male and 89 female undergraduate students, ages 18 to 26.
Of the 16 items, “sense of humor,” “fun-loving” and “playful” ranked second, third and fourth, respectively, among traits that females sought in males. Males rated three traits — “physically attractive,” “healthy,” and “good heredity,” all characteristics of female fertility — significantly higher than women.
“The fact that the subjects tended to rank ‘sense of humor,’ ‘fun-loving’ and ‘playful’ at or near the top of the list of 16 characteristics does not mean that the mates they have selected or will select will actually exhibit these traits,” said Chick.
“In addition, the results may be skewed by the fact that most of the study subjects were college students from a Western culture. Despite these caveats, it seems to us that signaling one’s virtues as a potential long-term mate through playfulness is not far-fetched. Our results suggest that adult playfulness may result from sexual selection and signal positive qualities to potential long-term mates.”
Source: Penn State