People who have autism feel pain at a higher intensity than others, the opposite of what many believe, new research suggests.

The prevailing belief is that those with autism are indifferent to pain, possibly because of a tendency for self-harm. However, "this assumption is not necessarily true," said Dr. Tami Bar-Shalita, of the Sackler Faculty of Medicine at Tel Aviv University in Israel.

"We know that self-harm could stem from attempts to suppress pain, and it could be that they hurt themselves in order to activate, unconsciously, a physical mechanism of 'pain inhibits pain,'" Bar-Shalita said in a news release.

The researchers wanted to know if people with autism hurt more than the general population.

About 10% of the general population suffer from sensory modulation dysfunction, Bar-Shalita said. That means a level of sensory hypersensitivity that can interfere with normal daily functioning, such as having trouble ignoring or adapting to buzzing or flickering lights or humming of air conditioners or fans.

Past studies have found that people with this sensory modulation dysfunction experience more pain, Bar-Shalita said. This dysfunction occurs in people with autism at a rate of 70% to 90%. It's one of the criteria used to diagnose autism and is associated with autism severity.

The study included 52 adults with high-functioning autism and 52 healthy people. Researchers used psychophysical tests to evaluate pain to examine the link between stimulus and response.

A researcher, using a computer, would control the duration and intensity of stimulus. The person examined was asked to rank the intensity of the pain on a scale of 0 to 100.

The study found that people with autism hurt more and that their pain suppression mechanism is less effective.

"The prevalent belief was that they are supposedly 'indifferent to pain,' and there are reports that medical and other professional staff treated them accordingly," Bar-Shalita said.. "The results of our study indicate that in most cases, the sensitivity to pain of people with autism is actually higher than that of most of the population, while at the same time they are unsuccessful at effectively suppressing painful stimuli.

"We hope that our findings will benefit the professionals and practitioners handling this population and contribute to the advancement of personalized treatment," Bar-Shalita said.

The study was funded by the Israel Science Foundation. Findings were published in the journal PAIN.