FRIDAY, May 9, 2014 (HealthDay News) -- Do you ever feel a bit tortured by the idea that you left the iron on or caught a dread disease in that dirty restroom? Ever have a random thought about hurting someone even though you're not a violent person?
You're far from alone.
A new study reports that many college students around the world routinely have these kinds of "intrusive" worries -- even if they don't have obsessive-compulsive disorder (OCD).
The findings suggest it's not the thoughts that are the problem for people with OCD but the way they react to them, said study lead author Adam Radomsky, director of the Center for Clinical Research in Health at Concordia University, in Montreal.
"Almost everyone has these kinds of thoughts. They're normal, and they're a part of being human," Radomsky said. For people who suffer from OCD, this knowledge "can be incredibly helpful to change the meaning that they ascribe to the intrusive thoughts," he said.
About 1 percent of adults in the United States have suffered from OCD within the past 12 months, and about half of those -- one in 200 -- are classified as severe, according to the U.S. National Institute of Mental Health (NIMH).
On average, people develop OCD at age 19, according to the NIMH. People with the condition can develop two types of symptoms, sometimes together. They can suffer from obsessive thoughts, like a broken record in their head, based on fears like contamination from germs. Or they may develop compulsions, such as endlessly checking a faucet to make sure it's off.
Researchers in the Western world, particularly in English-speaking countries, have shown that so-called intrusive thoughts are common and not just found in people with OCD. "We were interested in knowing whether this applies in other cultures," Radomsky said. "Is it fair to say that humans experience these intrusions?" Or just those with OCD?
The study authors gave surveys to 777 college students in 13 countries across six continents: Argentina, Australia, Canada, China, Iran, Israel, Italy, France, Greece, Sierra Leone, Spain, Turkey and the United States.
Almost 94 percent of the students said they'd had unwanted and intrusive thoughts during the past three months. "For most people, it was more than once," Radomsky said.
The surveys defined intrusive thoughts as having to do with subjects like contamination (worrying about germs, for instance), aggression (such as thinking about hurting someone else), and doubt.
An expert who praised the new study said people with OCD carry these thoughts further.
"The difference between individuals with OCD having a violent thought -- for example, thinking of pushing someone in front of a car -- is that they worry about the fact that they have the thought: 'What does this mean? Why am I thinking this? Does this mean I might actually do it?'" said Jeff Szymanski, executive director of the International OCD Foundation.
By contrast, he said, someone without OCD might respond by thinking the thought was peculiar but go on with their day.
Why would evolution give humans the ability to have fearful and unwanted thoughts? It may have something to do with people's natural ability to multitask and "think all sorts of things," study author Radomsky said.
The study acknowledges several caveats that could affect the reliability of its findings.
For one, the surveys were taken in different countries with different cultures and languages, potentially making it hard to directly compare the responses. Also, the survey questions may not have turned up an accurate number of intrusive thoughts among the participants. And the study only looks at college students, not older or younger people.
The study authors call for more research to confirm the findings and discover how they compare with scientific theories about OCD.
The study appeared in the Journal of Obsessive-Compulsive and Related Disorders.
For more about OCD, try the International OCD Foundation.