Parental Care and the Brain

Many researchers have suspected that infants must benefit from the close physical attention of their caregivers, but the extent and nature of the benefit was unclear. Now an increasing amount of biological research on animals is determining that while a number of factors are vital for proper brain development, physical attention appears to play a role in maintaining brain chemistry, brain architecture and possibly some mental functioning. Researchers hope that the insights will lead to new strategies that can boost the effects of human parenting in normal situations, as well as treat neglected children. An aloof, detached and withdrawn child has a severe mental disorder. How did it happen? Bad parents? Today scientists know that this assumption is false. Research shows that a number of disorders once blamed on bad parenting, actually are born of biology. It turns out, however, that a parent's care may be important in more subtle ways. An increasing number of biological studies on animals suggest that even though many other factors are important, a parent's caressing, cuddling and coochie-cooing play a role in maintaining proper brain development in the infant. The research is leading to: * A new understanding of the importance of parenthood. * Treatments for severe parental neglect. Much of the research indicates that a parent's physical attention helps the stress system in the infant's brain develop and function normally. This system and its hormones help carry out physiological adjustments over the course of daily living and help you adapt to stressful events. It's thought, however, that abnormal functioning of the stress system can contribute to disease. Rodent studies show that babies who have increased physical contact with their moms also have positive alterations in their stress system for life. Rodent moms do not exactly cuddle their infants like humans, but they do provide physical care by licking and grooming them. In one study, moms and babies were briefly separated and reunited, which led the moms to intensely lick and groom them. As adults, these rodents were more resistant to stressful situations and had less anxiety. The researchers also found that infant rodents who were naturally lavished by exceptional physical attention from their mothers had similarly stable stress responses and low anxiety in adulthood. On the flip side, animal research indicates that situations where babies are blocked from a parent's physical attention cause life-long abnormalities in the stress system. In the studies, rodent infants were removed from their moms and placed in an incubator as a group for a few hours a day for several days. These animals had an increased response to stress in adulthood. It's thought that lack of touch triggers an inappropriate activation of the stress system. Scientists found that merely stroking the infant rodents with a tiny brush could prevent many of the effects of the long separation. Researchers also have found that physical attention helps maintain the architecture of the brain and, possibly, certain memory abilities. Studies show that rodents who receive more physical attention in youth have less cell loss during old age in the hippocampus, a brain area important for memory. These rats also perform better on certain memory tasks in old age. On the other hand, studies show that blocking the physical attention from a parent negatively changes the architecture of their baby's brain as well as certain memory abilities. One rodent study shows that long separation situations cause brain cells to die (see images below). Other new animal research shows that the separation results in impaired growth of brain cells in the hippocampus. Preliminary observations found that as adults, these animals perform poorly on certain learning and memory tasks. Researchers have yet to directly link the animal findings to humans. Some research, however, suggests that positive touch also is important for human development. For example, scientists found that neglected children from overcrowded, understaffed Romanian orphanages had abnormal stress systems. Moreover, the children with the most abnormal stress systems had the lowest scores on tests of mental and movement ability. Once a human effect is confirmed, scientists hope to find methods to treat children who come from extreme situations of neglect. Already, researchers have found evidence in animals that certain therapies can reverse the effects of separation situations. It's also possible that further insight could lead to ways to boost the effects of parenting in normal situations. In the meantime, scientists say it can't hurt to dole out some extra hugs. THE TWO IMAGES PICTURED ABOVE INDICATE THE IMPORTANCE OF MATERNAL CARE. MORE BRAIN CELLS DIED IN AN INFANT RODENT (RIGHT IMAGE) DEPRIVED OF PHYSICAL ATTENTION FROM ITS MOTHER COMPARED WITH AN INFANT RODENT (LEFT IMAGE) RAISED UNDER NORMAL CIRCUMSTANCES. THE BRAIN CELLS THAT HAVE UNDERGONE DEATH ARE TINTED A BROWN COLOR.

Low serotonin may perpetuate child abuse across generations

Science Blog Low serotonin may perpetuate child abuse across generations By BJS Created 11/02/2006 - 06:48 Infant abuse may be perpetuated between generations by changes in the brain induced by early experience, research shows at the University of Chicago shows. A research team found that when baby rhesus monkeys endured high rates of maternal rejection and mild abuse in their first month of life, their brains often produced less serotonin, a chemical that transmits impulses in the brain. Low levels of serotonin are associated with anxiety and depression and impulsive aggression in both humans and monkeys. Abused females who became abusive mothers in adulthood had lower serotonin in their brains than abused females who did not become abusive parents, the research showed. Because the biological make up of humans and monkeys is quite similar, the findings from the monkey research could be valuable in understanding human child abuse, said Dario Maestripieri, Associate Professor in Comparative Human Development at the University of Chicago. "This research could have important implications for humans because we do not fully understand why some abused children become abusive parents and others don't," Maestripieri said. The research suggests that treatments with drugs that increase brain serotonin early in an abused child's life could reduce the likelihood that the child will grow up to become abusive, Maestripieri said. Maestripieri is lead author of a paper reporting the research, "Early Maternal Rejection Affects the Development of Monoaminergic Systems and Adult Abusive Parenting in Rhesus Macaques" published in the current issue of Behavioral Neuroscience. The study is the first to show that naturally occurring individual variation in maternal behavior in monkeys can affect the brain development of the offspring, and the first to show a link between serotonin and infant abuse in primates. Other research using rats as animal models has shown that serotonin production is influenced by a mother's treatment of her offspring early in their lives and affects the offsprings's responses to stress in adulthood. In earlier research on abuse of infant monkeys, Maestripieri and his colleagues studied females that were switched at birth between abusive and non-abusive mothers. That research showed that the offspring of non-abusive mothers were likely to become abusive themselves if they were raised by abusive mothers. That finding showed that the intergenerational transmission of abusive parenting was the result of early experience and not of genetic similarities between mothers and daughters. "We didn't know if the reason that the babies grew up to be abusive was that they watched how their mothers parented and repeated their behavior or whether their early experience produced long-term changes in brain processes that regulate emotions. We also noticed that about half of the babies exposed to abuse became abusive parents, whereas the other half did not. This is also the case in humans as not all abused children grow up to be abusers." In order to study the possible effects of early abuse on brain development, the team watched the mothers as they parented to note hitting and other negative behaviors toward their infants, and took samples of their cerebrospinal fluid to measure the metabolite concentrations of brain neurotransmitters such as serotonin every six months. They followed the infants until they became mothers themselves and studied their maternal behavior to note any abusive behaviors toward their infants. The team found that infants who became abusive as adults had about 10 to 20 percent less serotonin than did infants who did not become abusive as parents or infants who were not exposed to maternal abuse. The reduced level of serotonin remained constant into adulthood. Monkeys who were rejected more by their mothers early in life had lower serotonin in their brains than monkeys reared by less rejecting mothers. The effects of maternal behavior on brain serotonin in the offspring were observed in both infants that were reared by their genetic mothers and infants reared by foster mothers. From University of Chicago [1] Source URL: http://www.scienceblog.com/cms/low-levels-of-neurotransmitter-serotonin-may-perpetuate-child-abuse-across-generations-11907.html Links: [1] http://www-news.uchicago.edu

Child Abuse May Alter Victims' Brain Chemistry, Study Shows

Chicago Tribune, November 1, 2006

CHICAGO - A new study on monkeys raised by abusive mothers suggests that growing up in an abusive household can alter brain chemistry in a way that makes some youngsters prone to mistreating their own children when they grow up.

In other words, abuse is not just something that's learned from living with abusive parents, although that may have an influence, according to authors of the report, published in Thursday's issue of the journal Behavioral Neuroscience.

Suffering through abuse also appears to permanently lower the brain's production of an important regulator of emotions called serotonin, said Dario Maestripieri, the study's lead author and an associate professor at the University of Chicago in comparative human development. Low serotonin can make people more prone to acts of rejection, impulsive aggression and violence.

Of course, most children who were abused do not become abusers themselves. But some do, and the findings of the study may help explain this troubling cycle where victims of abuse later mistreat their own children.

The results emphasize the need for programs to reduce child abuse and to develop behavior-modification strategies for abusive parents. But they also open the door to the development of medications, such as antidepressants, to boost brain serotonin to normal levels in both children and mothers, Maestripieri said.

"This suggests that children who early on have differences in their brain in terms of serotonin could be treated with some of these drugs and maybe these unwanted consequences could be avoided," he said.

Other scientists said that because monkeys are not humans such findings should be interpreted cautiously. Nevertheless, there are enough genetic and biological similarities between the two species, they said, that the results may have important implications for people.

"We know that child abuse is bad for kids and that it's associated with all sorts of mental health outcomes," said University of Wisconsin psychologist Seth Pollak, who was not involved in the research. "But we don't understand how that experience seems to get under children's skin. This emphasis on serotonin seems to really help explain a lot of the behavioral problems that these children have as they grow up."

The findings add to a growing body of scientific evidence showing that nature and nurture interact to produce behavior. Environmental experiences can significantly influence how genes act in the body, affecting behavior, while an individual's genetic makeup can help determine the impact those experiences will have.

Researchers have already documented that humans who have low serotonin levels tend to be more anxious, depressed and impulsive, and earlier studies in rodents linked infant abuse and low serotonin.

Other studies have shown that among monkeys exposed to abuse as infants, those that have a shortened version of the serotonin transporter gene appear to be more vulnerable to experiencing low serotonin levels.

And recent brain scan studies found that people with the short serotonin gene have a more active amygdala, the brain's fear center. A person who has a heightened sensitivity to fear may see threats where none exist and lash out inappropriately.

The study by Maestripieri and his colleagues involved 15 baby rhesus monkeys from a colony housed at Emory University's Yerkes National Primate Research Center. Researchers noted which adult female monkeys displayed abusive behavior to their offspring and which females were nurturing mothers.

When these monkeys became pregnant again, the babies of the abusive mothers were given to the nonabusive females to raise and vice versa. Serotonin levels were measured from the infants' cerebral spinal fluid at birth and at regular intervals into adulthood.

Researchers found that infants raised under abusive conditions tended to develop low serotonin levels and become abusive mothers themselves, even though they were born to nonabusive mothers. Infants born to abusive mothers but raised by nonabusive ones retained normal serotonin levels and were not abusive.

"What's really happening to the infants raised by nonabusive mothers is that they're getting the right input into their brain," said J. Dee Higley of Brigham Young University, who participated in the study, which was funded by the National Institute of Mental Health.

The scientists suspect that low levels of serotonin may serve as a useful survival skill in a threatening situation by making primates more vigilant. But when the level is set low right from birth and stays there, it makes them impulsively aggressive.

"The big news in the new study is that certain patterns of maternal behavior have consequences for their offspring that are not only behavioral but biological and those consequences are possibly lifelong and they appear to be passed on to the next generation," said Stephen Suomi of the National Institute of Child Health and Human Development.

Sumoi did the study showing that monkeys who were raised among other young monkeys instead of by mothers had lower serotonin and became more aggressive if they possessed the shorter serotonin gene. Those with the longer version had higher serotonin levels and basically behaved normally.

(c) 2006, Chicago Tribune. Distributed by Mclatchy-Tribune News Service.

Child Abuse and the Brain

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There's no doubt that child abuse has serious consequences. The effects, however, may be even worse than you think. An increasing amount of research indicates that severe maltreatment at an early age can create an enduring negative influence on a child's developing brain. The findings highlight the seriousness of childhood abuse and may lead to increased prevention efforts as well as new approaches for treatment.

A twisted arm. No food. Rape. It's heartbreaking to think about. Almost 900,000 children faced some form of abuse or neglect in 2000, according to the most recent data from the U.S. Department of Health and Human Services. Clearly these actions have serious consequences, but the extent and nature of the effects were unclear. Now, an increasing amount of research indicates, that while physical wounds often heal over time, severe maltreatment at an early age can create an enduring, harmful influence on a child's developing brain. The research is leading to:

• A better understanding of how negative environments affect the brain.
• Increased efforts to intervene and protect children from maltreatment.
• New ways to treat abuse.

As children sprout in stature over the years, so do their brains. The cells and circuits build and refine. Researchers recently began to suspect that maltreatment might throw a stick in the gear of this sensitive time of growth and cause problems. Although still in an early stage, when looked at altogether, several lines of study support this theory.

For starters, evidence indicates that many maltreated children end up with mental ailments. They appear more likely than healthy individuals to experience learning problems, depression and post-traumatic stress disorder (PTSD), a condition marked by intense anxiety that sometimes erupts after a horrific experience, according to some studies.

Maltreatment also may affect brain anatomy. Compared with healthy individuals who never experienced abuse, some brain areas are smaller in those who experienced maltreatment and have PTSD (see illustration). It's possible that maltreated kids are born with the smaller structures, but many scientists suspect that the finding signals that abuse harms brain development. And these developmental issues may help spur the disorders common in abused and neglected children.

At the root of these problems may be the stress associated with maltreatment. When we experience a stressful situation, our brain's stress system activates a slew of biological actions. This helpful response prepares our body to fight or flee. However, perpetual or intense stress, especially during the brain's sensitive development time in childhood, may harm this system.

In fact, research that measures various stress molecules finds that sometimes they are out of whack in maltreated children and adult survivors. In another example, young rodents separated from their moms for a few hours each day, a source of significant stress, show signs that as adults their stress system does not work properly.

The altered stress system may trigger other problems. Extremely stressful situations appear to cause brain cell death in rodents and may do so in humans as well. In addition, infant monkeys raised individually have a smaller corpus callosum. This collection of fibers that connects the two halves of the brain also was found to be smaller in some maltreated children.

Recently researchers discovered a group of monkeys that will help them better test the effects of stress in child abuse. The mothers naturally act abusive to their offspring. Early findings indicate that the bad parenting alters the stress systems of the abused. Plans to examine brain anatomy are under way.

On the positive side, researchers also are examining maltreated children who do not seem to suffer from mental ailments and function fine in life. They want to know if a person's genetic makeup, a teacher's support or other factors could play a role.

In addition, investigators are testing ways to block or reverse abuse-related biological alterations. For example, early findings indicate that some medications used for depression can reverse problems with the stress system in rats raised in stressful environments and may aid abused children.

Of course, researchers say that the best solution is to prevent maltreatment from occurring in the first place.

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Some research shows that maltreatment may affect brain anatomy. For example, in one study researchers examined the brains of maltreated children and adolescents with PTSD. Compared with healthy individuals who never experienced abuse, those who were maltreated have smaller brain areas. Included is the cerebral cortex and prefrontal cortex, which help carry out complex actions; the corpus callosum, which helps the two sides of the brain communicate; as well as the temporal lobes and the amygdala, areas thought to be involved with emotion and memory. Research also finds that a memory area, the hippocampus, is smaller in adult survivors of abuse with PTSD. Although still under investigation, it's possible that experiencing maltreatment during youth harms overall brain development and helps spur the ailments that seem to be common in these individuals.

Illustration by Lydia Kibiuk, copyright © 2003 Lydia Kibiuk.