Studies link air pollution to mental health issues in children

September 25, 2019

Science Daily/Cincinnati Children's Hospital Medical Center

Three new studies by scientists at Cincinnati Children's Hospital Medical Center, in collaboration with researchers at the University of Cincinnati, highlight the relationship between air pollution and mental health in children.

A study to be published Sept. 25 in Environmental Health Perspectives found that short-term exposure to ambient air pollution was associated with exacerbations of psychiatric disorders in children one to two days later, as marked by increased utilization of the Cincinnati Children's emergency department for psychiatric issues. The study also found that children living in disadvantaged neighborhoods may be more susceptible to the effects of air pollution compared to other children, especially for disorders related to anxiety and suicidality.

The lead authors of this study are Cole Brokamp, PhD, and Patrick Ryan, PhD. They are researchers in the division of Biostatistics and Epidemiology at Cincinnati Children's.

"This study is the first to show an association between daily outdoor air pollution levels and increased symptoms of psychiatric disorders, like anxiety and suicidality, in children," says Dr. Brokamp. "More research is needed to confirm these findings, but it could lead to new prevention strategies for children experiencing symptoms related to a psychiatric disorder. The fact that children living in high poverty neighborhoods experienced greater health effects of air pollution could mean that pollutant and neighborhood stressors can have synergistic effects on psychiatric symptom severity and frequency."

Two other Cincinnati Children's studies were recently published that also link air pollution to children's mental health:

 ·      A study published in Environmental Research found an association between recent high traffic related air pollution (TRAP) exposure and higher generalized anxiety. The study is believed to be the first to use neuroimaging to link TRAP exposure, metabolic disturbances in the brain, and generalized anxiety symptoms among otherwise healthy children. The study found higher myoinositol concentrations in the brain -- a marker of the brain's neuroinflammatory response to TRAP.

·      The lead authors of this study are Kelly Brunst, PhD, a researcher in the department of Environmental Health at the University of Cincinnati, and Kim Cecil, PhD, a researcher at Cincinnati Children's.

·      A study published in Environmental Research found that exposure to TRAP during early life and across childhood was significantly associated with self-reported depression and anxiety symptoms in 12 year olds. Similar findings have been reported in adults, but research showing clear connections between TRAP exposure and mental health in children has been limited.

The lead authors of the study are Kimberly Yolton, PhD, director of research in the division of General and Community Pediatrics at Cincinnati Children's, and Dr. Ryan.

"Collectively, these studies contribute to the growing body of evidence that exposure to air pollution during early life and childhood may contribute to depression, anxiety, and other mental health problems in adolescence," says Dr. Ryan. "More research is needed to replicate these findings and uncover underlying mechanisms for these associations."

https://www.sciencedaily.com/releases/2019/09/190925075731.htm

Is pollution linked to psychiatric disorders?

August 20, 2019

Science Daily/PLOS

Researchers are increasingly studying the effects of environmental insults on psychiatric and neurological conditions, motivated by emerging evidence from environmental events like the record-breaking smog that choked New Delhi two years ago. The results of a new study publishing August 20 in the open-access journal PLOS Biology by an international group of researchers using large data sets from the US and Denmark suggests a possible link between exposure to environmental pollution and an increase in the prevalence of psychiatric disorders.

The team found that poor air quality was associated with higher rates of bipolar disorder and major depression in both US and Danish populations. The trend appeared even stronger in Denmark, where exposure to polluted air during the first ten years of a person's life also predicted a more than two-fold increase in schizophrenia and personality disorders.

"Our study shows that living in polluted areas, especially early on in life, is predictive of mental disorders in both the United States and Denmark," said computational biologist Atif Khan, the first author of the new study. "The physical environment -- in particular air quality -- warrants more research to better understand how our environment is contributing to neurological and psychiatric disorders."

Although mental illnesses like schizophrenia develop due to a complex interplay of genetic predispositions and life experiences or exposures, genetics alone do not account entirely for variations in mental health and disease. Researchers have long suspected that genetic, neurochemical and environmental factors interact at different levels to affect the onset, severity and progression of these illnesses.

Growing evidence is beginning to provide insight into how components of air pollution can be toxic to the brain: Recent studies on rodents suggest that environmental agents like ambient small particulate matter (fine dust) travel to the brain through the nose and lungs, while animals exposed to pollution have also shown signs of cognitive impairment and depression-like behavioral symptoms. "We hypothesized that pollutants might affect our brains through neuroinflammatory pathways that have also been shown to cause depression-like signs in animal studies," said Andrey Rzhetsky, who led the new study.

To quantify air pollution exposure among individuals in the United States, the University of Chicago team relied on the US Environmental Protection Agency's measurements of 87 air quality measurements. For individuals in Denmark, they used a national pollution register that tracked a smaller number of pollutants with much higher spatial resolution.

The researchers then examined two population data sets, the first being a U.S. health insurance claims database that included 11 years of claims for 151 million individuals. The second dataset consisted of all 1.4 million individuals born in Denmark from 1979 through 2002 who were alive and residing in Denmark at their tenth birthday. Because Danes are assigned unique identification numbers that can link information from various national registries, the researchers were able to estimate exposure to air pollution at the individual level during the first ten years of their life. In the US study, exposure measurements were limited to the county level. "We strived to provide validation of association results in independent large datasets," said Rzhetsky.

The findings have not been without controversy. "This study on psychiatric disorders is counterintuitive and generated considerable resistance from reviewers," said Rzhetsky. Indeed, the divided opinions of the expert reviewers prompted PLOS Biology to commission a special companion article from Prof. John Ioannidis of Stanford University (Ioannidis is unconnected with the study, but assisted the journal with the editorial process).

"A causal association of air pollution with mental diseases is an intriguing possibility. Despite analyses involving large datasets, the available evidence has substantial shortcomings and a long series of potential biases may invalidate the observed associations," says Ioannidis in his commentary. "More analyses by multiple investigators, including contrarians, are necessary."

Rzhetsky also cautioned that the significant associations between air pollution and psychiatric disorders discovered in the study do not necessarily mean causation, and said that further research is needed to assess whether any neuroinflammatory impacts of air pollution share common pathways with other stress-induced conditions.

https://www.sciencedaily.com/releases/2019/08/190820141604.htm

Exposure to air pollution before and after birth may affect fundamental cognitive abilities

May 23, 2019

Science Daily/Barcelona Institute for Global Health (ISGlobal)

A growing body of research suggests that exposure to air pollution in the earliest stages of life is associated with negative effects on cognitive abilities. A new study led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by "la Caixa," has provided new data: exposure to particulate matter with a diameter of less than 2.5 μm (PM2.5) during pregnancy and the first years of life is associated with a reduction in fundamental cognitive abilities, such as working memory and executive attention.

The study, carried out as part of the BREATHE project, has been published in Environmental Health Perspectives. The objective was to build on the knowledge generated by earlier studies carried out by the same team, which found lower levels of cognitive development in children attending schools with higher levels of traffic-related air pollution.

The study included 2,221 children between 7 and 10 years of age attending schools in the city of Barcelona. The children's cognitive abilities were assessed using various computerized tests. Exposure to air pollution at home during pregnancy and throughout childhood was estimated with a mathematical model using real measurements.

The study found that greater PM2.5 exposure from pregnancy until age 7 years was associated with lower working memory scores on tests administered between the ages of 7 and 10 years. The results suggest that exposure to fine particulate matter throughout the study period had a cumulative effect, although the associations were stronger when the most recent years of exposure were taken into account. Working memory is a cognitive system responsible for temporarily holding information for subsequent manipulation. It plays a fundamental role in learning, reasoning, problem-solving and language comprehension.

Sex-stratified analysis showed that the relationship between PM2.5 exposure and diminished working memory was found only in boys. "As yet, we don't understand what causes these differences, but there are various hormonal and genetic mechanisms that could lead to girls having a better response to inflammatory processes triggered by fine particulate matter and being less susceptible to the toxicity of these particles," commented Ioar Rivas, ISGlobal researcher and lead author of the study.

The study also found that higher exposure to particulate matter was associated with a reduction in executive attention in both boys and girls. Executive attention is one of the three networks that make up a person's attention capacity. It is involved in high-level forms of attention, such as the detection and resolution of conflicts between options and responses, error detection, response inhibition, and the regulation of thoughts and feelings.

Whereas previous studies in the BREATHE project analysed exposure to air pollution at schools over the course of a year, this study assessed exposures at the participants' homes over a much longer time: from the prenatal period to 7 years of age.

"This study reinforces our previous findings and confirms that exposure to air pollution at the beginning of life and throughout childhood is a threat to neurodevelopment and an obstacle that prevents children from reaching their full potential," commented Jordi Sunyer, Childhood and Environment Programme Coordinator at ISGlobal and last author of the study.

https://www.sciencedaily.com/releases/2019/05/190523104925.htm