Why does one person develop asthma or allergies while another does not?

Scientists began monitoring a group of around 4,000 young people even before they were born as part of a study into asthma and allergies. Today, these young people are around 25 years old and approximately 1,000 of them are returning to Utrecht University for a medical examination. Ulrike Gehring and Marieke Oldenwening have been working on this study for a long time, with the latter being present from the very start in 1996. “We want to find out which factors affect the development of asthma and allergies.”

“Welcome back to our study!” Marieke Oldenwening says to participant Mirte, who takes off her jacket and sits down in a chair across from Oldenwening. “First, we'll go over what we’re going to do today.” Step by step, Oldenwening explains what she will be measuring: blood pressure, height and weight, circumference of the waist and hips, grip strength, vertical jump and lung function. She will also use a cotton swab to collect cells from the nose and throat, “just like for a COVID test”. During the process, she checks in with Mirte the whole time: “Is everything clear?”

Concerns about asthma and allergies

“We study the differences between people who have asthma or allergies and those who don't,” Oldenwening says later. “In the 1990s, concerns arose in society because a lot of Dutch children were getting asthma and allergies. People didn’t know why this was. The goal of the PIAMA study is to track down the causes of asthma and allergies.” PIAMA stands for Prevention and Incidence of Asthma and Mite Allergies. Once the causes are identified, it might be possible to develop preventive measures that could help keep people from getting asthma and allergies in the first place.

“Initially, we wanted to track children for a period of eight years. But the study was so successful and the participants were so committed to taking part that we decided to keep going,” says Ulrike Gehring, one of the project coordinators and an associate professor at the Faculty of Veterinary Medicine’s Institute for Risk Assessment Sciences. “At that point, we decided to expand the study to include other chronic health conditions, such as overweight, cardiovascular disease and diabetes. While people typically don’t develop cardiovascular disease until they’re older, sometimes the first signs are already visible in a young person. We are also looking at the participants’ living environments: for instance, where they live, what the air quality there is like, whether they live in a green environment, does their family use a gas stove, does anyone smoke, is there mould in their homes?”

I have the best job at the University

Predictor for pulmonary disease

“Around a person’s 25th year, the age the participants are now, their lung function reaches its maximum capacity,” Gehring continues. “As a child grows, their lungs grow, too. We repeatedly tested the participants’ lung function over time in order to chart that growth. With the current measurements, we are looking at how the participants score as young adults. What is their maximum lung capacity? And which factors influence that? Is it their living environment, their genes or a combination of the two? That’s what we want to know. If your lungs don’t grow properly, it can limit your day-to-day activities. The maximum lung capacity is also a predictor for pulmonary diseases, like COPD, in adulthood.”

Pregnant or short of breath?

But back to Mirte’s medical examination. “Do you smoke? How long has it been since your last meal? When was the last time you took part in vigorous exercise?” Oldenwening asks her. “Could you be pregnant? Do you use nasal spray? Are you ever short of breath?” Together, they tick off an extensive list of questions. Mirte, who works in the healthcare sector, is used to questions of this nature. Next up are the lung function tests: she’s curious about what they’ll show. “I'm a little nervous; I hope everything is normal.”

What made her decide to take part in this study? “I think scientific research is important, including in my work as a nurse. It also offers insight into your own health. I've noticed that smoking seems to be becoming increasingly popular with people in my generation; there are a lot of social smokers and I wonder how that impacts your lung function. Hopefully this study will shed some light on that.” Mirte thinks her own living environment is relatively healthy. “I do live in the city, but not near any chemical plants, and the motorway is two kilometres away.” 

Some participants are now missing

When they were looking for participants in 1995/1996, the researchers had help from obstetricians. Ultimately, near 4,000 mothers signed their babies up for PIAMA. Since then, a portion of them have either withdrawn from the study or gone ‘missing’. “We literally lost some of them,” Oldenwening says. “Especially at the beginning of the study, when we still kept all the details on paper. If someone moved house and didn’t give us a new address, we just lost them. Later, email addresses became common and that part got easier.” Currently, there are around 2,700 participants still involved in the PIAMA study.

Our goal is to track down the causes of chronic health conditions

Will spit or a piece of fingernail work, too?

The researchers sent the children a study questionnaire every year until the kids turned eight. After that, the frequency decreased to once every three or four years. On top of the questionnaires, some of the children were invited for a medical examination when they were one, four, eight, twelve and sixteen years old. Recently, they were once again approached about taking part in a physical examination, now that they are between the ages of 25 and 27. A large group choose to participate. Oldenwening considers this remarkable. “This research is tremendously enjoyable; I get to experience some really special things and I have the best job at the University. This week, we had an appointment with a young man who had sent us a letter when he was eight years old. The invitation for the medical examination back then said that we needed a small amount of his blood in order to study his genetic material. So he wrote back to say he was a little worried about that bit. He asked if some of his spit or a piece of hair or fingernail would work instead. I pulled that letter out of the file and gave it to him when he came in the other day. He didn’t remember writing it, but he got a good laugh out of it all the same.”

Nothing to worry about

“Your lung volume is 4.4 litres,” Oldenwening tells Mirte after three tests. “That's slightly above average for someone of your size.” Mirte is visibly relieved; now she can head home with nothing to worry about.

Oldenwening, Gehring and their colleagues will continue to examine study participants at least until the end of the year. After that, the researchers will analyse the data in cooperation with colleagues from partner institutions RIVM and the University Medical Center Groningen. Luckily, they are nowhere near tired of the research yet. “Young adults are an interesting age group and, generally speaking, there aren’t a lot of studies focusing on them. We’re eager to keep working on PIAMA for the foreseeable future.”

Interested in seeing a few of the results from the PIAMA study? Read more about it in the three text boxes accompanying this interview.

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