Air pollution slows brain development: study

Air pollution takes a double toll on babies' brains

Studies have tied air pollution to a wide range
of problems in children.

A common pollutant in vehicle exhaust, power plant emissions and cigarette smoke can shrink white matter in fetal brains and cause developmental damage during the toddler years, a new study suggests.

In 40 children examined by researchers, prenatal exposure to polycyclic aromatic hydrocarbons was correlated with reduced white matter on the left side of children's brains during their early childhood.

Those physical changes in the brain's internal wiring also were correlated with slower cognitive processing and with symptoms of attention deficit and hyperactivity, according to the study published in the journal JAMA Psychiatry.

“They tend to be fidgety and hyperactive and very impulsive, so they leap before they look,” said Dr. Bradley Peterson, director of the Institute for the Developing Mind at Children's Hospital Los Angeles and the lead author of the report.

The researchers had previously tied behavioral and cognitive problems to eight common types of these pollutants, which are a product of incomplete combustion of organic materials.

The new study now suggests those problems have a biological root in the altered architecture of the brain.

The research involved 655 New York City women of Dominican and African American descent who gave birth between 1997 and 2006.

During late pregnancy, the women carried detector backpacks that measured exposure to PAHs over 48 hours. Their children later were tested for exposure and underwent several rounds of cognitive and behavioral testing.

For the JAMA Psychiatry study, Peterson and his colleagues selected a representative sample from the original study group: 20 children whose own PAH readings were below the median and 20 whose PAH levels were above it.

All the children were about 8 years old when they underwent magnetic resonance imagery scans.

Those scans showed that white matter was significantly reduced from normal volumes throughout the left hemisphere, an area that controls language and cognition, among other higher functions.

In fact, the higher their prenatal exposure to PAH was, the more white matter was reduced and the more acute the behavioral and developmental problems were, the study found.

Scientists don’t know why the left side seemed to be affected more, but they suspect the compounds interfere with an early biochemical process that helps the fetal brain divide into slightly asymmetrical hemispheres.

The damage, however, is not isolated to prenatal stages, or to the left hemisphere. Postnatal PAH exposure, measured at age 5, correlated with diminished white matter in areas of the prefrontal cortex of both hemispheres, the study found.

“It’s a double hit,” Peterson said. “They have the abnormality from prenatal life throughout the left hemisphere and then on top of that they have this bilateral frontal hit from exposures around age 5.”

The 40 children were from nonsmoking homes and had little or no exposure to lead or insecticides that likewise have been linked to developmental and behavioral problems, according to the study. All were right-handed.

Although it remains possible that other pollutants could be affecting the results, the researchers said their sampling methods eliminated the major contenders, helping to isolate the effects of the PAH compounds.

Numerous studies have linked air pollution — especially particulate matter — to respiratory and cardiac problems. But over the last decade, researchers have accumulated more evidence that particles and other types of airborne pollution can affect brain development.

A 2012 study using a database of 19,000 nurses found greater cognitive decline among older women exposed to high levels of particulate matter.

A 2011 Boston study involving 680 men showed similar results. A series of studies involving children in Mexico City linked air pollution with the brain inflammation that is typical of diseases such as multiple sclerosis.

“It is worrisome,” Peterson said of the latest findings. “California has gone a long way toward improving and cleaning up the air, but there’s a long way to go. Future generations depend on it.”

Source: LA Times

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Asthma drugs suppress children's growth say researchers

Corticosteroid drugs that are given by inhalers to children with asthma may suppress their growth, evidence suggests.

Two new systematic reviews published in The Cochrane Library focus on the effects of inhaled corticosteroid drugs (ICS) on growth rates.

The authors found children’s growth slowed in the first year of treatment, although the effects were minimized by using lower doses.

Inhaled corticosteroids are prescribed as first-line treatments for adults and children with persistent asthma.

They are the most effective drugs for controlling asthma and clearly reduce asthma deaths, hospital visits and the number and severity of exacerbations, and improve quality of life.

Yet, their potential effect on the growth of children is a source of worry for parents and doctors.

Worldwide, seven ICS drugs are currently available: beclomethasone, budesonide, ciclesonide, flunisolide, fluticasone, mometasone and triamcinolone.

Ciclesonide, fluticasone and mometasone are newer and supposedly safer drugs.

The first systematic review focused on 25 trials involving 8,471 children up to 18 years old with mild to moderate persistent asthma.

These trials tested all available inhaled corticosteroids except triamcinolone and showed that, as a group, they suppressed growth rates when compared to placebos or non-steroidal drugs. 14 of the trials, involving 5,717 children, reported growth over a year.

The average growth rate, which was around 6-9 cm per year in control groups, was reduced by about 0.5 cm in treatment groups.

The researchers found that growth suppression varied across studies, and so they looked at the relationship between a variety of factors and their effects on growth. Some of the variation could be explained by the drugs used, although since this was an indirect comparison the authors say more evidence is needed.

“Conclusions about the superiority of one drug over another should be confirmed by further trials that directly compare the drugs,” said Zhang.

More long-term trials and trials comparing different doses are also needed, particularly in children with more severe asthma requiring higher doses of inhaled corticosteroids, the researchers conclude.

“Only 14% of the trials we looked at monitored growth in a systematic way for over a year. This is a matter of major concern given the importance of this topic,” said Francine Ducharme, one of the authors of both reviews and senior author of the second review, based at the Department of Paediatrics at the University of Montreal in Montreal, Canada.

“We recommend that the minimal effective dose be used in children with asthma until further data on doses becomes available. Growth should be carefully documented in all children treated with inhaled corticosteroids, as well in all future trials testing inhaled corticosteroids in children.”

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Diet during pregnancy and early life affects children’s behaviour and intelligence

The statement “you are what you eat” is proving significant for child development.

Researchers from the NUTRIMENTHE project looked at hundreds of European families with young children over a 5 year period. They examined the effect of B-vitamins, folic acid, breast milk versus formula milk, iron, iodine and omega-3 fatty acids - on the cognitive, emotional and behavioural development of children from before birth to age nine.

The study found that folic acid, which is recommended during the first three months of pregnancy, can reduce the likelihood of behavioural problems during early childhood. Eating oily fish is also very beneficial, not only for the omega-3 fatty acids they which are ‘building blocks’ for brain cells, but also for the iodine content which has a positive effect on reading ability in children when measured at age nine.

A long-term study was needed as explained by Professor Cristina Campoy, who led the project.

“Short term studies seem unable to detect the real influence of nutrition in early life”, explained Prof Cristina Campoy, “NUTRIMENTHE was designed to be a long-term study, as the brain takes a long time to mature, and early deficiencies may have far-reaching effects. So, early nutrition is most important.”

Many other factors can affect mental performance in children including; the parent’s educational level, socio-economic status of the parents, age of the parents and the genetic background of the mother and child. This can influence how certain nutrients are processed and transferred during pregnancy and breastfeeding and in turn, affect mental performance.

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