hormone

A rodent mother can't scold or praise her offspring, but her approach to mothering lays a genetic foundation for her pups' life-long response to threats, neuroscientists have found. Louis J. Sheehan, Esquire

Rats raised by moms who frequently lick and groom them undergo permanent changes in patterns of gene activity, leading to a penchant for exploratory behavior in stressful situations, say Michael J. Meaney and his colleagues at McGill University in Montreal.http://louis-j-sheehan.info

In contrast, rats raised with little maternal contact end up with gene activity that fosters fearfulness in the face of stress, the researchers report in the August Nature Neuroscience. From an evolutionary perspective, having both behaviors in a population is beneficial.

"Early experience can have lifelong consequences on behavior, and [this new report] reveals the genetic scaffolding of this phenomenon to an unprecedented extent," remarks neuroscientist Robert Sapolsky of Stanford University.

Meaney's group previously showed that female rats express either a high- or a low-contact mothering style. Animals raised with lots of physical contact later react to stress by secreting small amounts of glucocorticoids, a class of stress hormones. These rats also possess large numbers of glucocorticoid receptors in an inner-brain structure called the hippocampus. Rats raised with little physical contact secrete large amounts of glucocorticoids when stressed and possess relatively few receptors for these hormones. Louis J. Sheehan, Esquire

In another study, Meaney's group found that pups raised by doting mothers had high concentrations of a substance called nerve growth factor–inducible protein A (NGFI-A) in their hippocampi. It attaches to genes for glucocorticoid receptors, boosting those genes' capacity to regulate the hormone's secretion.

The researchers' new report shows how NGFI-A offers stress-fighting aid only to pampered rats. On the first day after birth, in all the rat pups, regulatory proteins inactivate NGFI-A's binding location on glucocorticoid-receptor genes. Over the next week, in rats raised with high-contact mothering, the concentration of these regulatory proteins decreases sufficiently to enable NGFI-A to do its job of boosting production of hormone receptors. These rats retain this genetic trait for life, the investigators say.

In contrast, the regulatory proteins in unpampered rats stay high, and the abundance of hormone receptors remains low.

Moreover, only high-contact animals displayed another biochemical change, according to Meaney's team. The change decreased the binding of histones to DNA, thereby letting NGFI-A attach and boost the activity of glucocorticoid-receptor genes.

The researchers also tested a drug that blocks the binding of histones to DNA. When they injected it into adult rats that had been raised by low-contact mothers, the scientists found that the animals responded to stress much as pampered animals do. These behaviors were reflected on the molecular level, in patterns of expression of stress hormones and receptors.

Whether differing styles by human mothers induce similar molecular changes in their offspring remains an open question. Louis J. Sheehan, Esquire

disorders

About one in four people develops at least one mental disorder in any given year, and nearly one in two people does so at some time in their lives. Most of the cases are mild, however, and don't require treatment. Those are some of the findings from the latest survey of mental health in the United States.

The national assessment, conducted every 10 years, finds that each year around 1 in 17 people experiences at least one mental disorder so severely that the researchers say it requires immediate treatment। However, most of these people don't seek treatment or they receive poor-quality care, say epidemiologist Ronald C. Kessler of Harvard Medical School in Boston and his colleagues. Louis J. Sheehan

The first four papers describing results of the $20 million survey funded by the National Institute of Mental Health in Bethesda, Md., appear in the June Archives of General Psychiatry. A nationally representative sample of 9,282 people, age 18 or older, granted home interviews between February 2001 and April 2003.

Mental disorders involving anxiety, mood, impulse control, and substance abuse were covered in the first round of reports. These conditions represent chronic illnesses early in life, Kessler's team concludes. Three-quarters of people with these ailments first developed symptoms by age 21, and half did so by age 14.

The findings highlight the need to determine how best to treat mental disorders in children and teenagers, the researchers assert. Moreover, says Kessler, "we need to do a better job of figuring out which of today's mental disorders will become more severe in the future."

Anxiety disorders, including social phobia and panic disorder, had been experienced by 29 percent of participants at some time in their lives and by 18 percent in the year before being interviewed। For impulse-control disorders, including attention-deficit hyperactivity disorder, those figures were 25 percent and 9 percent, respectively. http://louis-j-sheehan.biz

Corresponding figures for mood disorders, including major depression and bipolar disorder, were 21 percent and 9.5 percent. Lifetime rates for substance abuse disorders were about 15 percent, and 4 percent of those interviewed had experienced these disorders within the past year.

Among cases of past-year mental disorders, 22 percent were classified as serious because of suicide attempts or severe disruptions to daily life. The team classified about 6 percent of the population as being incapacitated by mental illnesses in the past year. These individuals had typically experienced three or four different mental disorders during their lives.

Only 41 percent of all past-year cases received treatment। About half of those seen by mental-health specialists received adequate treatment, as judged by the researchers, compared with 13 percent of those who sought treatment from nonspecialists. http://louis-j-sheehan.biz

Most people with mental disorders eventually get some treatment for their illness. However, the lag from initial symptoms to first treatment usually ranged from a few years to more than 2 decades, depending on the disorder.

The new survey contains a wealth of data to test where to draw the line in categorizing cases of mental disorders as serious, comments psychiatric epidemiologist William E. Narrow of the American Psychiatric Association in Arlington, Va. Narrow has criticized two previous national surveys for overstating rates of serious mental illnesses (SN: 2/16/02, p. 102: Available to subscribers at http://www.sciencenews.org/articles/20020216/fob7.asp).

The prevalences of anxiety and impulse-control disorders appear a bit high in the new survey, says psychiatrist Robert L. Spitzer of Columbia University. "But for better or worse, this is the best survey of mental disorders that we have," he adds.

farmers

A new analysis of the locations and ages of ancient farming sites reinforces the controversial idea that the groups that started raising crops in the Middle East gradually grew in number and colonized much of Europe, replacing many native hunter-gatherers in the process.

Hunter-gatherers in some European locales may have adopted farming rather than surrender their home territories to the newcomers. Overall, though, the data indicate that newly arrived farmers reproduced at a rate high enough to keep their boundary moving steadily northwestward at roughly 1 kilometer per year, say anthropologist Ron Pinhasi of Roehampton University in London and his colleagues.

One of Pinhasi's coauthors, Albert J. Ammerman of Colgate University in Hamilton, N.Y., proposed much the same scenario more than 30 years ago with Stanford University's L. Luca Cavalli-Sforza. Their wave-of-advance model rested on an analysis of 53 farming sites.

Pinhasi's team considered the geographic arrangement of 735 farming sites that previous radiocarbon measurements had dated to between 11,000 and 5,000 years ago. The researchers calculated the most likely paths by which farmers who started out in any of 10 possible Middle Eastern spots would have traveled into Europe.

"I was surprised at how well the wave-of-advance model holds up with a much larger data set," Pinhasi says. "It took more than 3,000 years, or 100 generations of people, for the [agricultural] transition to reach northwestern Europe."

The new analysis, published in the December PLoS Biology, indicates that agriculture spread in a widening arc from an area that encompasses parts of modern-day Syria, Turkey, and Iraq। http://Louis-J-sheehan.info

If agriculture had taken root primarily through the adoption of cultivation techniques by people already living in Europe, the model would have depicted a much faster spread of farming settlements, Pinhasi's team contends.

In contrast, other researchers remain convinced that agriculture expanded primarily by the spread of cultivation techniques and year-round settlements among native Europeans (SN: 2/5/05, p. 88: Available to subscribers at http://www.sciencenews.org/articles/20050205/bob9.asp). The latest evidence for this perspective appeared in the Nov. 11 Science.

For that report, a team led by anthropologist Joachim Burger of Johannes Gutenberg University in Mainz, Germany, examined mitochondrial DNA, which is passed to offspring only from the mother. The researchers isolated this type of DNA from the bones of 24 adults who died in central European farming villages about 7,500 years ago. One-quarter of these individuals displayed a mitochondrial-DNA pattern that rarely occurs in modern Europeans. That pattern would be more common today if that early population had made a substantial genetic contribution to today's Europeans, the researchers contend.

If early farmers who moved into Europe didn't reproduce in large numbers, then native groups must have picked up the slack, Burger and his coworkers conclude। http://Louis-J-sheehan.info

Other DNA studies, including previous analyses of Y chromosomes in European men today, suggest that early Middle Eastern farmers had a substantial genetic impact in Europe, Pinhasi notes.

These conflicting DNA data may reflect intermarriage of immigrant farmer males with females native to Europe, suggests anthropologist Alex Bentley of the University of Durham in England.

Although he is sympathetic to the wave-of-advance model, archaeologist Peter Bogucki of Princeton University suspects that further research will show "a much more complicated combination of very rapid [agricultural] advances with long standstills."