Men who are older when they father children tend to have children who score slightly lower on IQ tests and other measures of cognitive function, according to a new study. That conclusion, which researchers called unexpected and startling, adds to a recent surge of evidence that, like women, men also have a biological clock. Older fathers have been linked to a range of health problems, including an increased risk of birth deformities, autism and neuropsychiatric conditions, such as schizophrenia and bipolar disorder…. Experts believe mutations in a man’s sperm, which build over time, may be a factor [BBC News].
However, lead researcher John McGrath says that the findings shouldn’t cause panic. “With respect to childhood intelligence, a vast array of factors is far more powerful than paternal age,” McGrath cautions. These factors include nutrition, health care and family income [Science News]. Researchers say that adjusting for socioeconomic factors like family income lessened the link between paternal age and children’s cognitive scores, but didn’t erase it. The average IQ of a child born to a 20-year-old father was six points higher than that of a child with a 50-year-old father, but adjustments reduced the difference to three points. Researchers say that gap is statistically significant, but is modest in practical terms [Science News].
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Lab rats who were exposed to alcohol while in the womb had a skewed sense of taste and showed a marked preference for ethanol as young rats, researchers say. The findings may shed new light on why human studies have previously linked fetal alcohol exposure to increased alcohol abuse later in life, and to a lower age at which a person first starts drinking alcohol [New Scientist].
The taste of alcohol has both sweet and bitter components, and study coauthor Steven Youngentob wondered whether prenatal exposure could affect how rats respond to those elements. He gave young rats a choice between ethanol, sweet water flavored with sugar, and bitter water flavored with quinine. Those rats whose mothers had consumed alcohol while they were pregnant preferred ethanol and the bitter water. By contrast, rats who were not exposed to alcohol tended to plump for the sweeter alternative [Telegraph].
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Peanut lovers everywhere may have reason to celebrate. Doctors in England believe they have cured the peanut allergy, at least on a temporary basis. Using the simple technique of desensitization, doctors at the Addenbrooke Hospital in Cambridge exposed four children to peanuts over six months, during which time they successfully built up a tolerance. The children were started on 5 milligrams (.02 percent of an ounce) of peanut flour daily and by the end of the trial were able to ingest 880 milligrams a day, the equivalent of 5 whole peanuts. The study, which has been published in Allergy, continues and now includes 20 children between the ages of seven and 17, some of whom are able to ingest 12 peanuts a day. They would be monitored for the next three or four years to assess their tolerance levels, [lead researcher Andrew] Clark said, adding that there was no reason why the clinical trial could not be extended to adults [AFP].
Consultant allergist Pamela Ewan said, “Until now there has been no treatment that has modified the disease. There has only been effective management of the problems” [Medical News Today]. The new research brings hope to the many people, adults as well as children, who suffer from peanut allergy, which most often triggers breathing problems but can also cause potentially fatal anaphylactic shock or cardiac arrest.
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A chemical found in common household products and cosmetics has been linked to a decrease in fertility in women, according to a new study. Researchers examined more than 1,000 pregnant women and found that those exposed to higher levels of perfluorinated chemicals (PFCs) had experienced more difficulty getting pregnant. PFCs are used to make textiles and leather resistant to water, dirt or oil. They are also found in personal care products such as nail polish, dental floss or facial moisturizer. The chemicals resist breakdown and tend to persist in the environment and in the body for decades [Bloomberg]. “If this finding can be replicated, one would have to look for other chemicals to replace these,” [Washington Post] said lead researcher Jorn Olsen. Although experts caution that the correlation doesn’t prove causation, many manufacturers have already taken steps to cut back on PFCs.
Data for the study was taken from 1,240 women in the Danish Birth Cohort when they were six to 12 weeks pregnant. If they reported that it took them longer than 12 months to get pregnant or if they used drugs designed to increase their chances of conceiving, they were considered to have infertility. This is a generally accepted definition of infertility by experts in the field [ABC News]. The women were divided into four groups based on levels of two types of PFCs, perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), found in their blood. Compared to women in the group with the lowest levels of PFOS, women with higher levels took from 70 percent to 134 percent longer to conceive. For PFOA, women with higher levels took from 60 percent to 154 percent longer to conceive. The researchers accounted for factors such as age and economic and social factors, although they admit that they lacked information on other factors that could influence fertility such as timing and frequency of intercourse and sperm quality.
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The fossilized pelvis of a Homo erectus woman who lived 1.2 million years ago on the banks of an Ethiopian river has been discovered, and while researchers say it casts new light on human evolution, some of their conclusions are challenging previous theories about these early human ancestors. The pelvis reveals a short, squat woman who wasn’t built for long-distance running, but also a woman with a wide birth canal to accommodate big-brained infants.
Study coauthor Scott Simpson says the pelvis’s wide birth canal indicates that hominds’ increasing brain size was a driving factor in human evolution. Getting through the birth canal is “the most gymnastic thing we ever do,” he says. To accommodate big-brained babies, humans must have developed larger and wider birth canals over time, but with few pelvic fossils, researchers had little idea when these changes began. The Busidima pelvis shows that a wide birth canal was already in place 1.2 million years ago [New Scientist].
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Two separate groups of researchers have developed a non-invasive test for Down syndrome, using only a blood sample from the pregnant woman to examine the fetus’ DNA. While the genetic tests are still in clinical trials, experts are hailing the achievement as significant because current prenatal tests like amniocentesis require inserting a needle in the uterus, and carry a risk of miscarriage.
A biotechnology company called Sequenom says it will begin selling its test next June, while researchers from Stanford, who just published their results in the Proceedings of the National Academy of Sciences, are still planning a large-scale clinical trial. Some experts say that the results are somewhat preliminary, and should be viewed cautiously: The Stanford test has been tried on only 18 blood samples. Sequenom has tried its test on only about 400 samples and has not yet published its results in peer-reviewed journals. Still, both tests have perfect records so far: no false negatives or false positives. “This is quite simply a major step forward, if it works at all like we expect it might,” [says Down Syndrome expert] Jacob A. Canick [The New York Times].
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A new analysis of the skulls of three Neanderthal babies shows that the cranium of a newborn Neanderthal was about the same size as that of a newborn Homo sapiens, and that the Neanderthal children grew faster than modern humans in the first few years of life. The report on the young skeletons, which date from between 45,000 to 50,000 years ago, adds fuel to the debate over how similar Neanderthal culture was to that of our early Homo sapiens ancestors.
A big-headed infant skeleton found in Russia suggests that childbirth was no easy task for for Neanderthal women. Neanderthal mothers had slightly larger birth canals, but the prominent face of Neanderthal babies made it just as hard to push out as a modern human. This suggests that both groups had the social structures needed to help with childbirth [New Scientist].
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Older men have an increased risk of fathering children who eventually develop bipolar disorder, according to new research. It’s the latest study to refute the earlier theory that men could father children into their old age with no ill effects; other recent studies have linked older fathers to an increased risk of miscarriages, and to children with schizophrenia or autism.
The theory linking paternal age with an offspring’s health rests on the genetics of aging sperm. Spontaneous mutations can accumulate in the genes of a man’s sperm cells as he ages. These cells divide as many as 660 times by the time a man reaches 40, by some estimates. Each division increases the risk of acquiring a harmful mutation from erroneous gene copying, the theory holds [Science News]. Women are born with their full complement of eggs already in place in the ovaries, and therefore don’t have to worry about increased genetic errors as they age.
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A broad study of couples seeking fertility help has shown that men are not immune from the ticking of the biological clock: They become less fertile after the age of 35. Researchers at a French fertility clinic studied over 12,000 couples who sought treatment at the clinic, and found that older men were less likely to conceive a child with their partners, and were more likely to conceive a child that ultimately miscarried.
Yves Ménézo, an embryologist involved in the study, says the researchers didn’t look for the cause of the would-be fathers‘ declining fertility. But researchers believe that as men age, genetic defects build up in their sperm. In younger men, the damage is minor and can be repaired inside the fertilised egg. But in older men the amount of DNA damage can overwhelm the body’s natural repair mechanisms. “We think there’s a critical threshold of DNA damage and above that, the damage can no longer be repaired. When that happens, genetic mistakes get through to the embryo and you get an increase in miscarriages,” Ménézo said [The Guardian].
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