Although the spread of mass psychogenic illnesses during a disaster presents significant problems for health care responders, scientists have been hindered in their study of the phenomenon by the lack of a method for simulating it in a safe and controlled experimental environment.
Mass psychogenic illness is a social phenomenon that tends to occur in groups during a disaster. Group members develop symptoms—nausea, dizziness, fainting, etc.—which, though real, have no identifiable organic cause. A real-world example occurred in Tokyo in 1995 when 5,000 people flooded hospital emergency rooms, paralyzing the emergency response system, after the neurotoxin sarin was released in subway cars. Analysis of the hospital surge, described as “a monsoon of worried well,” indicated that the ratio of patients who displayed psychogenic symptoms, but no chemical injuries to those who actually sustained injury was 450:1.
In a recent article in the American Journal of Disaster Medicine, Joan E. Broderick, PhD and colleagues advanced the science of disaster medicine by describing a method for inducing mass psychogenic illness in a group of healthy adult volunteers by giving them a harmless pill and exposing them to actors who feigned symptoms. The experimental group reported 11 times more symptoms than a randomly assigned control group. When the purpose and methods of the experiment were revealed to the volunteers, their symptoms dissipated and they experienced no lasting effects.
Dr. Broderick is an Associate Professor in the Department of Psychiatry and Behavioral Science. She was joined in the study by Evonne Kaplan-Liss, MD, MPH, Research Assistant Professor in the Department of Preventive Medicine and School of Journalism, and Elizabeth Bass, MPH, Director, Center for Communicating Science in the School of Journalism.
Dr. Broderick and her colleagues found that the rate at which symptoms developed were similar in men and women. Prior experience of trauma increased the likelihood of developing symptoms, as did the presence of depression. Exposing subjects to an historical documentary about a disaster did not increase the number or severity of symptoms, though it is possible that other types of media exposure may exacerbate symptoms.
The study will help social and behavioral scientists learn more about how psychogenic illness spreads within groups. The authors conclude that the mechanism is more complex than a simple reflection of suggested symptoms.
