A new study at the University of Arizona is exploring whether inflammation in the body has an impact on the way people behave in their day-to-day lives.
Scientists have known for many years that medically ill individuals are at an increased risk for developing depression, anxiety and irritability. While this is sometimes attributed to the sheer level of stress that accompanies chronic illness, mounting evidence over the past 15 or so years has shown that the body's physiological response to disease also plays a role, Raison said.
When the body is sick, it produces inflammatory chemicals, called cytokines, as part of the natural immune response to illness. Those chemicals can essentially commandeer the brain, and make a person feel depressed, said Raison, who is also the Barry and Janet Lang Associate Professor of Integrative Mental Health in the UA's John & Doris Norton School of Family and Consumer Sciences.
"These cytokines, these inflammatory chemicals, are very helpful. They evolved to help us kill bugs in the body," Raison explained. "But when they're activated, they can actually get up to the brain and cause the same sort of brain changes that we see in people who are depressed from other reasons, such as psychological stress."
Raison is now looking at whether inflammation also affects a person's daily social interactions - like how much they laugh, argue, complain, or how much time they spend alone versus with others.
"What this is going to tell us is: What is the role of inflammation in stress-induced and medical illness-induced depression, anxiety, fatigue, misery, and what actually does it do to people's lives?" Raison said.
Research has already shown that people who have positive social lives and feel interpersonally connected to others tend to have well-balanced immune systems and lower levels of inflammation than those who are lonely or have a lot of conflict in their lives, Raison said. This new research will consider the inverse relationship ‚Äì looking at whether changes in inflammation affect the quality of people‚Äôs social lives.
The study will take place at the UA and Emory University and will look at 100 patients with hepatitis C, a viral disease that causes swelling of the liver and is commonly treated with interferon alpha, which stimulates inflammation in the body. Researchers will evaluate the social behaviors of individuals before and after receiving treatment with interferon alpha, as well as the behaviors of hepatitis C patients who do not receive the treatment.
"Inflammation is the central feature of chronic illness, so this study allows us to isolate out the primary sickness mechanism to see how much it contributes to behavioral changes," Raison said.
Raison is teaming up with UA associate psychology professor Matthias Mehl, PhD, a social psychologist and expert in behavioral measurement, to record participants' social behaviors with an Electronically Activated Recorder, or EAR. Developed by Mehl, the EAR is operated through an iPod Touch, which study participants wear on their hips over the course of a weekend. The EAR turns on and off intermittently during that period, recording 30-second sound bites of people's daily lives. Participants can't tell when the device is recording.
The EAR, which has been used in several studies in social psychology, was designed to provide a more accurate reporting of people's behavior than questionnaires and other self-reporting methods, Mehl said.
"What we get is an acoustic log of the person's day as it naturally unfolds," Mehl said. "From that, we identify, through each sound file, is the person alone? Is the person with other people? Is the person laughing? Is the person arguing? Is the person showing affection? We look at all different kinds of variables."
If the study reveals that individuals who receive the pro-inflammatory interferon alpha treatment demonstrate more negative social behaviors, it might suggest that blocking inflammation could be helpful, Raison said.
"We've" shown that hostile, isolative social interactions drive inflammation," Raison said. "Now, what we‚Äôre trying to do is see whether in turn inflammation produces hostile and isolative social interactions."
Mehl said this study should provide a fascinating look at how social behavior might be regulated, in part, by the immune system.
"I'm a social psychologist, and when we think of social behavior, we think of personality variables, we think of the situation, we think of how the brain is involved and maybe we think of how hormones regulate social behavior, but we hardly ever think that the immune system does anything else but helping us to stay healthy, that the immune system could be involved in making us grumpy or nice or more socially withdrawn," he said.
"This is one of the first studies where we're really looking how people's daily lives change in subtle but traceable ways with interventions such as a pro-inflammatory treatment."