production 30000003 Louis J. Sheehan

Louis J. Sheehan.  Men and women’s brains age differently, a new study demonstrates.

Researchers led by Carl Cotman and Nicole Berchtold at the University of California, Irvine, find that the activity of genes in men’s brains begins to change earlier than it does in women’s brains. The types of genes that change with age also differ between the sexes.  http://louisejesheehan.blogspot.com

The study, which appears online September 22 in the Proceedings of the National Academy of Sciences, also found that in both genders, each part of the brain examined had its own pattern of aging.

“This is a very interesting study in what is, curiously, an under-studied area, normal aging,” says Etienne Sibille, a neuroscientist at the University of Pittsburgh, who was not involved in the study. “You have a combination of expected and surprises in each finding.” For instance, the fact that men and women’s brains age differently could be predicted based on women’s increased longevity, but the type and scope of the differences were unexpected, he says.

Cotman and Berchtold and their colleagues collected brains from people who had died of various causes between ages 20 and 99. The researchers isolated messenger RNA, or mRNA, from the people’s brains. Messenger RNA is a courier molecule that carries instructions encoded in genes to the cellular machinery that will build proteins using those instructions. Genes that produce higher levels of mRNA are more active.

The researchers examined gene activity in four parts of the brain: the hippocampus, the entorhinal cortex, the postcentral gyrus and the superior frontal gyrus.

Brain scientists expect changes in gene activity as the brain ages, and previous studies have demonstrated some changes in other parts of the brain. Cotman and his colleagues thought the parts of the brain that would have the most change in gene activity would be the hippocampus and entorhinal cortex, because they are most vulnerable to diseases of aging, such as Alzheimer’s.

But the team discovered that these disease-susceptible parts of the brain in older people have the least amount of change in gene activity when compared to younger people. In contrast, the postcentral gyrus, a part of the brain dedicated to perception, changes most. Scientists had expected that region to have the least change, if any.

“This is one of those fun head-scratchers, which is what science is all about,” Cotman says.

Overall gene activity was similar in people aged 20 to 59. And people aged 60 to 99 showed similar patterns of overall gene activity. But the team detected variability in their data. Cotman and Berchtold sat down to discuss the source of the variability and decided to see whether gender differences might explain it. “She thought it was the men, and I said it was the women,” Cotman laughs.

“The big surprise, and one I wasn’t too happy about frankly, was that with age, men show changes in metabolic activity,” Cotman says. Specifically, genes that control energy production in the brain are less active in men starting at about age 60, meaning that metabolic activity slows down. But after the initial drop in activity, men stabilize their gene activity and show no further decline after age 80, the researchers found. http://louisejesheehan.blogspot.com

Women’s brains change too, but the changes begin later and keep marching on the older women get, Berchtold says. Women showed gene activity changes in genes that help establish connections between brain cells and in genes that control information exchange in the brain. Women also showed a drop in energy production, but the decrease was not as great as for men.

“What I think it means, especially for men, is that interventions — either lifestyle or medication — may be needed to keep these energy pathways robust,” Berchtold says. Cotman agrees. He pointed out (on his way to a tennis lesson) that exercise is a good way to keep metabolic genes in the brain going strong. Louis J. Sheehan

near-death 0000199.2 Louis J. Sheehan

Louis J. Sheehan.  At least 1 in 10 people treated for cardiac arrest, a condition in which the heart stops pumping after it beats unusually quickly, describes mystical-seeming experiences that accompanied the brush with death, according to the largest survey to date of this phenomenon among heart patients. http://www.myspace.com/louis_j_sheehan_esquire

In contrast, only about 1 in 100 people treated for other comparably serious cardiac problems, such as a heart attack or unstable angina, says that his or her current physical symptoms led to near-death experiences, says psychiatrist Bruce Greyson of the University of Virginia Health System in Charlottesville.

Greyson directed interviews of 1,595 people admitted to his hospital’s cardiac-care unit during a recent 30-month period. A total of 27 individuals, including 11 of 116 cardiac-arrest patients, reported having had a near-death experience along with their latest heart symptoms. Near-death events often included sensations of time speeding up or slowing down, peacefulness, separation from one’s body, and being in an unearthly place. http://www.myspace.com/louis_j_sheehan_esquire

Near-death patients cited more instances of losing consciousness when their symptoms struck and greater acceptance of death than other cardiac patients did. Many members of the near-death group also reported prior instances of extrasensory perception or other purportedly paranormal experiences.

The new results underestimate the frequency of near-death experiences among cardiac-arrest patients, Greyson contends in the July/August General Hospital Psychiatry. Amnesia, which often accompanies cardiac arrest, may make it difficult to recall near-death sensations, and some of those who do remember them may stay quiet for fear of being ridiculed or diagnosed as mentally ill. Louis J. Sheehan

bias 0000149.049932 Louis J. Sheehan

Racial bigotry creates undeniable hardships for its targets. Such prejudice may cut two ways, though. A provocative new study suggests that intolerance undermines the mental resources of biased individuals when they interact with those whom they deem inferior. Louis J. Sheehan

White people who hold biased feelings toward blacks have to work to control their thoughts and behaviors during interracial encounters, say psychologist Jennifer A. Richeson of Dartmouth College in Hanover, N.H., and her coworkers. This social strategy depletes the limited pool of mental resources available for monitoring and using various types of information, the scientists propose.

Their investigation appears in the December Nature Neuroscience.

The results “suggest that harboring racial bias may be maladaptive to optimal cognitive functioning,” Richeson’s group concludes. Further research will be needed to establish how such laboratory findings relate to racial attitudes and behaviors in real-world situations, the team adds.

The researchers measured 14 male and 16 female college students, all of whom were white, for unconscious, or implicit, racial attitudes. First, participants were instructed to press a certain computer key when they saw a name paired with a word with positive connotations and to press another key when they saw a name paired with a negative word.

Volunteers generally were slower and less accurate at reacting to combinations of typically black names, such as Lakisha and Tyrone, with positive words, such as health and beauty, than with negative words, such as filth and ugly. One-third of the volunteers exhibited strong implicit racial bias, indicated by a pronounced difficulty in pairing black names with positive words and white names with negative words.

Participants then briefly conversed with either a black or a white experimenter.

Next, the students performed a task that required considerable mental control. They had to indicate the ink color in which color words such as red and green were printed. This task requires a person to override the impulse to read the word and instead report the ink color.

After talking with a black experimenter, volunteers who had scored high on implicit racial bias performed more poorly on the color-naming task than the other people did, the researchers say. No such pattern appeared after participants talked to the white experimenter. http://ljsheehan.blogspot.com

Finally, when shown pictures of black faces, the people rated high on implicit racial bias showed more activity in brain areas involved in controlling thoughts and actions than the others did. http://ljsheehan.blogspot.com

Richeson’s investigation remains open to alternative interpretations, say psychologist William J. Gehring of the University of Michigan in Ann Arbor and his colleagues in a comment published with the new study.

For example, a high score in implicit racial bias may occur when a person has been exposed to lots of racially biased information, even if he or she doesn’t endorse it, Gehring and his coworkers hold. Moreover, participants may have monitored their thoughts and actions during testing because they figured out that the experiment concerned race and feared that they had been tagged as racists.

Racial bias may have a broad influence on thinking processes, remarks psychologist Elizabeth A. Phelps of New York University. The new results need to be confirmed with different measures of bias and mental control, she says. Louis J. Sheehan