African American children are twice as likely as whites to develop asthma, a disease that makes it hard to breathe. Black children also are more likely than white kids to die from the disease. Doctors have been puzzled by these differences. Now a study finds evidence that racial bigotry may play some role in making asthma in black children especially hard to control.
The new data find a correlation between discrimination and hard-to-control asthma. Such a link can never prove racial bias was responsible (see Explainer, just below). But it can point to a possible explanation — one that calls for more study.
In fact, the new study’s findings make some sense, says Esteban Burchard. He’s a lung doctor at the University of California, San Francisco (UCSF), who worked on the project. He also is Hispanic, noting that his ancestors include Native Americans, Europeans and Africans. Stress can mess with the body’s immune system. Asthma is one type of immune disease, he notes. And discrimination based on race or ethnic heritage is one type of social stress.
“Asthma clearly is due to genetics and environmental factors,” Burchard says. And knowing that social stressors are one type of environmental factor, his group decided to look at whether racial bias might play some role.
And they now report signs it can. They shared their findings June 13 in PLOS ONE. Additional information appears in a companion report in the April issue of Chest, a medical journal.
‘Not just one disease’
Symptoms of asthma include wheezing, coughing, shortness of breath, tightness in the chest and other problems. Some 6.2 million American children suffer from this disease, according to the National Center for Health Statistics.
“We used to think all asthma was allergic,” says Neeta Thakur. That’s why doctors often prescribe allergy medicines to treat asthma. But allergies explain only four to six out of every 10 cases of asthma, points out this lung doctor on Burchard’s team at UCSF.
So “asthma is not one disease,” she says Just as someone might take different routes to school, different problems can lead to asthma. In terms of this disease, “We’re trying to figure out the other pathways.”
Burchard’s group had already collected information from many African American children and teens in the San Francisco Bay area. The new study used data from more than 1,000 of them.
The researchers asked about whether the children and teens had been exposed to tobacco smokers, had attended daycare and other matters. The researchers also had data on each person’s medical history and treatments. For instance, many kids took a daily medicine to control their disease. When an asthma attack did occur, such kids often took a so-called “rescue” medicine. One type is albuterol (Al-BU-tur-ol). It helps open up the lungs’ airways.
Tests at a clinic or office also measured each person’s response to the rescue medicine. In this instance, it was given when there wasn’t an asthma attack. A strong response now pointed to airways that were especially reactive, or twitchy. And that meant daily medicines were not doing a good job at keeping their asthma under control.
Finally, the young people were asked about any incidents of discrimination. For example, had they been prevented from doing something at school or in other situations because of their race or ethnic group? Did people hassle them because of their ethnic group, skin color or language?
Nearly half — 49 percent — reported facing such racial or ethnic bigotry.
Half of the teens and younger kids who faced this discrimination also had poorly controlled asthma. In contrast, only one-third of kids who reported no history of discrimination had poorly controlled asthma.
What the blood showed
Each person who took part in the study supplied a sample of blood. The researchers examined its plasma. That’s the liquid that holds red and white blood cells. It’s also where a protein called TNF-alpha shows up. High levels of this protein have been linked to a form of asthma that scientists think is related to environmental and social stresses, Thakur explains.
Levels of TNF-alpha varied among the kids who reported episodes of discrimination. The team homed in on the group who had the highest levels of this protein and who also faced racial bigotry. On average, their response to the rescue medicine tended to be the strongest. So their asthma was very poorly controlled.
This confirms, says Thakur, that people with that stress-related asthma will likely have more trouble controlling it if they also face discrimination. She now suggests that if patients of color have ongoing asthma problems, doctors should ask them about any social stress they may feel.
Discrimination isn’t the only type of stress that people of color may face. Thakur plans to spend several years tracking health and social experiences in a group of African Americans and Latinos. During that time, her team will also monitor urban air pollution in their neighborhoods. Her team hopes to learn more about the role of social and environmental factors in asthma.
Probing other possible factors
Lara Akinbami is a pediatrician at the National Center for Health Statistics in Hyattsville, Md. There, she works as an epidemiologist — a disease detective — who focuses on childhood asthma. She did not take part in the new study. But she too has been probing racial trends in asthma.
In one 2014 study, she and other scientists showed that in America, black children are twice as likely as whites to develop asthma. Moreover, that racial gap in asthma rates grew between 2001 and 2010. Over that time, the numbers of affected black children jumped about 40 percent, while rates in white kids remained largely unchanged.
Curious about why, Akinbami and her colleagues dug deeper. They already knew obesity could play a role in asthma. And childhood obesity has been more common in black children than in whites. Many doctors, she noted, had wondered “if the asthma patterns we see in the population — asthma going way up in black children — had anything to do with obesity rates.”
So her team studied U.S. rates of this disease (yes, obesity is a disease). And it rose in kids between 2001 to 2010. But asthma rates in black and white children did not change much over that period. So, Akinbami now concludes, “You don’t really need fancy math to see that obesity isn’t the answer.” Her group’s data on this have just been published in the July 14 Annals of Epidemiology.
“We have to keep looking for that answer” on why asthma rates are growing faster for black children, Akinbami says. Indeed, that’s why she finds the study by Burchard and Thakur’s team so interesting. It found that children who reported discrimination had more reactive airways. And that suggests they had more poorly controlled asthma. But Burchard and Thakur’s group “went a step further,” Akinbami adds. They also found a link to a specific type of asthma — one that has been linked to stress.
“We don’t know all the reasons why this racial divide exists for developing asthma or for suffering from its consequences,” she says. “But a bunch of people are working on it.”
allergy The inappropriate reaction by the body’s immune system to a normally harmless substance. Untreated, a particularly severe reaction can lead to death.
asthma A disease affecting the body’s airways, which are the tubes through which animals breathe. Asthma obstructs these airways through swelling, the production of too much mucus or a tightening of the tubes. As a result, the body can expand to breathe in air, but loses the ability to exhale appropriately. The most common cause of asthma is an allergy. Asthma is a leading cause of hospitalization and the top chronic disease responsible for kids missing school.
bias The tendency to hold a particular perspective or preference that favors some thing, some group or some choice. Scientists often “blind” subjects to the details of a test (don’t tell them what it is) so that their biases will not affect the results.
bigotry An attitude of intolerance — and often fear — of people who are different. It typically manifests as hatred and bullying of, or prejudice towards, people who belong to some particular group that is defined by their race, religion or ethnicity. Bigotry is not due to the actions or opinions of an individual, but to the prejudged expectations that the bigot has of anyone who belongs to the perceived “outsider” group.
colleague Someone who works with another; a co-worker or team member.
correlation A mutual relationship or connection between two variables. When there is a positive correlation, an increase in one variable is associated with an increase in the other. (For instance, scientists might correlate an increase in time spent watching TV with an increase in rates of obesity.) Where there is an inverse correlation, an increase in one value is associated with a drop in the other. (Scientists might correlate an increase in TV watching with a decrease in time spent exercising each week.) A correlation between two variables does not necessarily mean one is causing the other.
discrimination (in social science) An attitude of prejudice again people or things based on a bias about one or more of their attributes (such as race, sex, religion or age). It is not based on the actions of an individual but instead based on yet-unfounded expectations that are being applied broadly to a whole group.
epidemiologist Like health detectives, these researchers figure out what causes a particular illness and how to limit its spread.
factor Something that plays a role in a particular condition or event; a contributor.
genetic Having to do with chromosomes, DNA and the genes contained within DNA. The field of science dealing with these biological instructions is known as genetics. People who work in this field are geneticists.
immune system The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.
link A connection between two people or things.
National Center for Health Statistics An agency of the U.S. government, based in Hyattsville, Md., it's part of the Centers for Disease Control and Prevention. Formed in 1960, this agency collects statistical information to guide actions and policies to improve the health of the U.S. population. Four of its major programs are: the National Vital Statistics System (birth and death records provided by all of the states), the National Health Interview Survey (health data collected by census workers), the National Health and Nutrition Examination Survey (periodic random surveys of medical data from households across the nation) and the National Health Care Surveys (on the activities of insurance companies, hospitals, nursing homes and medical workers).
Native Americans Tribal peoples that settled North America. In the United States, they are also known as Indians. In Canada they tend to be referred to as First Nations.
obesity (adj. obese) Extreme overweight. Obesity is associated with a wide range of health problems, including type 2 diabetes and high blood pressure.
pediatrician A field of medicine that has to do with children and especially child health. A doctor who works in this field is known as a pediatrician.
plasma (in medicine) The colorless fluid part of blood.
population (in biology) A group of individuals from the same species that lives in the same area.
protein A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.
social (adj.) Relating to gatherings of people; a term for animals (or people) that prefer to exist in groups. (noun) A gathering of people, for instance those who belong to a club or other organization, for the purpose of enjoying each other’s company.
statistics The practice or science of collecting and analyzing numerical data in large quantities and interpreting their meaning. Much of this work involves reducing errors that might be attributable to random variation. A professional who works in this field is called a statistician.
stress (in biology) A factor — such as unusual temperatures, moisture or pollution — that affects the health of a species or ecosystem. (in psychology) A mental, physical, emotional or behavioral reaction to an event or circumstance (stressor) that disturbs a person or animal’s usual state of being or places increased demands on a person or animal; psychological stress can be either positive or negative. (in physics) Pressure or tension exerted on a material object.
symptom A physical or mental indicator generally regarded to be characteristic of a disease. Sometimes a single symptom — especially a general one, such as fever or pain — can be a sign of any of many different types of injury or disease.
urban Of or related to cities, especially densely populated ones or regions where lots of traffic and industrial activity occurs. The development or buildup of urban areas is a phenomenon known as urbanization.
white blood cells Blood cells that help the body fight off infection.
Journal: L Akinbami et al. Contribution of weight status to asthma prevalence racial disparities, 2–19 year olds, 1988–2014. Annals of Epidemiology. Published online July 14, 2017. doi: 10.1016/j.annepidem.2017.07.004.
Journal: S. Carlson et al. Self-reported racial/ethnic discrimination and bronchodilator response in African American youth with asthma. PLOS One. June 13, 2017. doi: 10.1371/journal.pone.0179091.
Journal: N. Thakur et al. Perceived discrimination associated with asthma and related outcomes in minority youth: The GALA II and SAGE II studies. Chest. Vol. 151, April 2017, p. 804. doi: 10.1016/j.chest.2016.11.027.
Journal: L. Akinbami et al. Trends in racial disparities for asthma outcomes among children 0 to 17 years, 2001-2010. Journal of Allergy and Clinical Immunology. Vol. 134, September 2014, p. 547. doi: http://dx.doi.org/10.1016/j.jaci.2014.05.037.