Showing posts with label growth. Show all posts
Showing posts with label growth. Show all posts

Sunday, May 12, 2013

How the Individual Develops: Experience Leads to Growth of New Brain Cells

The adult brain continues to grow with the challenges that it faces; its changes are linked to the development of personality and behaviour.

  • What is the link between individual experience and brain structure? 
  • Why do identical twins not resemble each other perfectly even when they grew up together? 

To shed light on these questions, the scientists observed forty genetically identical mice that were kept in an enclosure offering a large variety of activity and exploration options.

Gerd Kempermann
"The animals were not only genetically identical, they were also living in the same environment," explains principal investigator Gerd Kempermann, Professor for Genomics of Regeneration, CRTD, and Site Speaker of the DZNE in Dresden.

"However, this environment was so rich that each mouse gathered its own individual experiences in it. Over time, the animals therefore increasingly differed in their realm of experience and behaviour."

New neurons for individualized brains
Each of the mice was equipped with a special micro-chip emitting electromagnetic signals.

This allowed the scientists to construct the mice's movement profiles and to quantify their exploratory behaviour.

The result: Despite a common environment and identical genes the mice showed highly individualized behavioural patterns.

They reacted to their environment differently. In the course of the three-month experiment these differences increased in size.

"Though the animals shared the same life space, they increasingly differed in their activity levels. These differences were associated with differences in the generation of new neurons in the hippocampus, a region of the brain that supports learning and memory," says Kempermann.

"Animals that explored the environment to a greater degree also grew more new neurons than animals that were more passive."

"Hence, we assume that we have tracked down a neurobiological foundation for individuality that also applies to humans" says Kempermann.

Ulman Lindenberger
"The finding that behaviour and experience contribute to differences between individuals has implications for debates in psychology, education science, biology, and medicine," states Prof. Ulman Lindenberger, Director of the Center for Lifespan Psychology at the Max Planck Institute for Human Development (MPIB) in Berlin.

"Our findings show that development itself contributes to differences in adult behaviour. This is what many have assumed, but now there is direct neurobiological evidence in support of this claim. Our results suggest that experience influences the aging of the human mind."

Journal Reference:
  1. J. Freund, A. M. Brandmaier, L. Lewejohann, I. Kirste, M. Kritzler, A. Kruger, N. Sachser, U. Lindenberger, G. Kempermann. Emergence of Individuality in Genetically Identical MiceScience, 2013; 340 (6133): 756 DOI:10.1126/science.1235294

Monday, April 30, 2012

Breastfeeding is associated with a Healthy Gut

Early colonization of the gut by microbes in infants is critical for development of their intestinal tract and in immune development.

A new study, published in BioMed Central’s open access journal Genome Biology, shows that differences in bacterial colonization of formula-fed and breast-fed babies leads to changes in the infant’s expression of genes involved in the immune system, and in defense against pathogens.

The health of individuals can be influenced by the diversity of microbes colonizing the gut, and microbial colonization can be especially important in regulating both intestinal and immune development in infants. However, little is known about the potential interactions between the host’s health at a molecular level, their gut microbes, and diet.

The human intestine is lined by epithelial cells that process nutrients and provide the first line of defense against food antigens and pathogens. Approximately one-sixth of intestinal epithelial cells are shed every day into feces, providing a non-invasive picture of what is going on inside the gut.

In this study, the authors used transcriptome analysis to compare the intestines of three month old exclusively breast-fed or formula-fed infants, and relate this to their gut microbes.

Transcriptome analysis looks at the small percentage of the genetic code that is transcribed into RNA molecules and is a measure of what genes are actively making proteins. Concurrently the microbes (microbiome) were identified by genetic analysis.

The results showed that the breast-fed babies had a wider range of microbes in their gut than the formula-fed infants but that their immune systems had developed to cope.

Robert Chapkin from the Texas A&M University, who led this multi-centre study, explained, “While we found that the microbiome of breast-fed infants is significantly enriched in genes associated with ‘virulence’, including resistance to antibiotics and toxic compounds, we also found a correlation between bacterial pathogenicity and the expression of host genes associated with immune and defense mechanisms.”

He continued, “Our findings suggest that human milk promotes the beneficial crosstalk between the immune system and microbe population in the gut, and maintains intestinal stability.”

Monday, April 2, 2012

Autism: Why Some Children ‘Bloom’ and Overcome Their Disabilities

A new study offers some good news for families with autism. Most children affected by the disorder do not have intellectual disabilities, the study finds, and even among the severely low-functioning, about 10% may improve dramatically over time, with some growing out of their diagnosis by their teens.

The study tracked nearly 7,000 autistic children born in California between 1992 and 2001. The group included most of the children who received an autism diagnosis in the state during that time period.

The kids were followed from diagnosis to age 14 or the oldest age they had reached by the time the data collection was concluded.

The researchers found that 63% of the children did not have intellectual disabilities. Although autism is known to cause cognitive deficits in some children, it is also associated with certain enhanced intellectual abilities, and some affected children have extremely high IQs.

About one-third of the study group were considered low- to low/medium-functioning in terms of communication and social skills, meaning that they may have trouble talking, interacting with others or socializing and making friends with peers.

High-functioning kids with autism, meanwhile, can communicate effectively with others, maintain friendships and are willing to engage in social pursuits.

While the highest-functioning children tended to show the most improvement over time in the California study, about 10% of those who started out in the low-functioning group also moved into the highest group by age 14.

“The critical finding is that when you look at those children that this study refers to as ‘bloomers’, the children who seemed very low-functioning at the beginning and then did extremely well, they [tend not to] have any intellectual disabilities,” says Rahil Briggs, assistant professor of pediatrics at Albert Einstein College of Medicine, she was not associated with the research.

Low-functioning children without intellectual disabilities were twice as likely to “bloom” as those who had cognitive deficits.

Briggs adds that another “very key” factor is that the mothers of the kids who bloomed tended to be more educated and not minorities.

This suggests that low-income immigrant or minority families may not be receiving the services and support for their children that educated, affluent parents are able to access more easily.

With developmental disorders, the earlier a child receives help, the more likely he or she is to overcome disabilities.

Early intervention matters because the brain is remarkably vulnerable early in life, built to shape itself to the environment it initially faces. “The young brain is disproportionately receptive to input, whether positive or negative,” says Briggs.

“That’s why young children can learn a second language easily and why early exposure to domestic violence and toxic stress are so incredibly damaging.”

If autistic children receive intervention before such coping mechanisms as repetitive behaviours and extreme social withdrawal are firmly entrenched, for example, their innate oversensitivity to their environment is far less likely to become or remain disabling, and their other abilities and gifts can flourish.

If these children are reached early enough, “we can actually start to change brain functioning if we provide the right kind of repetitive and focused intervention,” Briggs says.

Parents Need to be Aggressive Champions
The American Academy of Pediatrics currently recommends that doctors screen children for autism at their 18-month well-child visit. Briggs adds that parents must become aggressive champions for their children.

“So much can depend on how good that parent is at advocating for the child,” says Briggs, noting that parents need to be aware not only of what services are available, but also which ones are best, which are not helpful and how to get the best care.

“That puts an incredible burden on parents,” she acknowledges. With the Centers for Disease Control and Prevention reporting last week that autism now affects 1 in 88 children, it is becoming a burden shared by more and more American families.

Briggs says that the findings in the new study reflect the types of developmental trajectories she sees in children in her practice as director of the Healthy Steps program at Montefiore Hospital in the Bronx (NY), which helps disadvantaged families access numerous services, including autism therapies, through their pediatricians’ office visits.

She describes working with a 5-year-old autistic boy and his family. The family said he would come home from kindergarten crying, but they couldn’t figure out what was wrong.

Finally, he described how he felt while he waited for his mother to pick him up in the school’s cafeteria:
“There were so many echoes bouncing off the walls that it felt like people were having a party in my head and they wouldn’t turn down the music,” he said.

Identifying the problem led Briggs to enroll the boy in listening therapy, which helped him cope with his sensitivity to sounds.

When such sensory issues, which are common in autism, can be mitigated, children become far less stressed and far better able to learn other skills like social interaction and communication.

Most children from disadvantaged backgrounds aren’t able to get these kinds of services, however. “If we still see these huge differences in children with autism based on socioeconomic factors, we clearly don’t have enough programs or haven’t made them available enough,” Briggs says.

The research was published in Pediatrics.

Tuesday, March 6, 2012

Antidepressants During Pregnancy: What Are the Risks?

What is a woman struggling with depression supposed to do when she becomes pregnant?

A study published on Monday in the Archives of General Psychiatry tackles the tough decision of deciding to keep taking the medication, or risk harming the fetus.

Roughly six percent of pregnant women are taking antidepressants. The struggle to live with depression or risk your baby's health has plagued women for quite some time.

The latest study included 7,696 pregnant women. Five hundred and seventy of the women suffering from depression were not on medication, and 99 women with depression "were being treated with selective serotonin reuptake inhibitors (SSRIs), a common class of antidepressants."

What this study found is that women going untreated for depression gave birth to babies that had a reduction in total body growth.

This affected the fetal head growth as well. Those women taking prenatal SSRI also had babies that suffered from a reduced growth of the fetal head, but the overall growth of the body during pregnancy was not affected.

What are the risks for the fetus during pregnancy with antidepressants? Mothers taking antidepressants could have preterm babies, who face higher health risks like respiratory and gastrointestinal disorders.

Not only could these children be born preterm, but according to the authors of the study, reduced fetal head-growth can lead to behavioural problems and psychiatric disorders later on.

However, the risks for the mother may outweigh the risks of the pregnancy, if she discontinues antidepressant medication.

Dr. Sudeepta Varma, clinical assistant professor of psychiatry at NYU Langone School of Medicine reported "If we are talking about a woman who can't take care of her health as a result of battling with moderate to severe depression, she faces risks to herself as well as the baby that are associated with untreated depression during pregnancy."

According to Varma, "if you don't take care of the mom, there may be no baby to speak of."

These findings however are inconclusive according to the authors of the study. "More long-term drug safety studies are needed before evidence-based recommendations can be derived," concluded the authors.