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Can you tell by the way you walk that a person is sick?

Can you tell by the way you walk that a person is sick?

In the event of disease, the body's various defense systems, both immune and behavioral, are activated. The immune system reacts, but our behavior patterns can change too. In her thesis, Lena Hansson explores this phenomenon known as pathological behavior.

Photo: Cottonpro from Pexels.

Lena Hansson defended her thesis on May 17 with the title Intimidating or nurturing? How immune processes shape the perception of disease-relevant stimuli in humans. In her work as a doctoral student, she tried to connect research on how people avoid getting sick with research on how people behave when they get sick.

It is an interesting topic to discuss as the vast majority of people can relate to what the disease means, and often have many thoughts about the results of our research.

When she has to explain her research to someone outside the academy, she usually uses a trick:

-I usually ask the person to think about the last time they had the flu and then ask the person what they did and how they felt afterward. These questions are usually a good opportunity for me to be able to explain that I study “illness behavior,” that is, how the ongoing course of illness affects the way we act and feel.

Next, Lena Hanson usually goes on to say that she also studies how others view patients.

– It is an interesting topic to discuss as the vast majority of people can relate to what the disease means, and often have a lot of thoughts about the results of our research.

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A research project at two universities

Lena Hansson did her thesis at Karolinska Institutet, but during half of her doctoral studies she was working at the Department of Psychology and the Institute for Stress Research at Stockholm University. For the rest of the period, she remained in contact with Stockholm University. Many of the projects included in the thesis also had Karolinska Institutet and Stockholm University as research directors.

– My workplace was Campus Albano throughout my PhD, which made me feel at home at the Stress Research Institute the entire time.

People with temporary illness provide answers to researchers – this is how studies work:

In order to be able to study how sick people behave or are perceived by others, Lena Hansson and her fellow researchers experimentally made study participants sick by injecting a small amount of bacterial fragments. This activates the immune system even in the absence of live bacteria. Activation of the immune system results in an inflammatory response and short-term illness reaction in which participants may experience symptoms such as fever, headache, and fatigue.

During the period that participants are ill (about 4-6 hours), researchers collect various data via questionnaires and behavioral tests. They also collect photos, scent samples and videos of participants when they are sick. These so-called illness triggers can then be used in studies looking at how others perceive and behave around sick individuals.

Gait reveals disease

In one study, we used videos in which the walking technique of sick and healthy people was demonstrated using a few moving points of light. We showed these videos to people who would judge whether each person was sick or healthy.

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The result showed that untrained people could detect the disease better than chance by assessing walking style alone. The researchers saw similar results in two relatively large substudies, which strengthens the finding, says Lena Hansson. She thinks the interesting thing is that people seem to be able to use walking to make judgments about the health status of others.

– A future question is what happens after someone is perceived as sick, for example if that person is avoided.

How do you as a researcher come to the conclusion that gait style is the one you should study?

Photography by Lena Hanson.

Lena Hanson.

The tests we choose to perform are often based on results we and other researchers have seen in previous studies. For example, our research group and our partners have conducted several studies that have shown that untrained people can detect whether someone is sick based on smells and images of faces. This, combined with research by us and others suggesting that sick individuals appear to walk differently, has led to the question of whether disease can be detected by gait alone.

– I believe that research into how people perceive someone's illness and how a sick person behaves around other individuals is important for understanding how infectious diseases spread between people.

Pieces of the puzzle for understanding how disease affects behavior

Lena Hansson says there is a lot to be gained from understanding how disease affects the way we see the world. In another study within her dissertation, it was also investigated whether patients perceived different types of caregivers differently compared to whether they were healthy. It was found that sick individuals, compared to when they were healthy, were more willing to be cared for by doctors who were seen caring for another sick person in a video. But this does not apply to the doctors who did not care about anyone in the video.

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– This could be interesting to understand the relationship between patients and healthcare staff, says Lena Hansson.

What do you hope the conclusions of the thesis will lead to?

– I believe that the studies included in the thesis are pieces of the puzzle for understanding how persistent illness affects behavior, as well as how the sick individual is perceived by others. I hope that these pieces of the puzzle will lead to new entries in the field of research.

What will you do next?

– This fall I will start a postdoctoral position at Karolinska Institutet. But first, I'm looking forward to some summer vacation.

Read the thesis

Read more about Lena Hanson

Last updated: June 20, 2024

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