What Apple has learned from ResearchKit so far - including that anger causes asthma in New York

Apple operations chief Jeff Williams says that ResearchKit - the suite of medical research tools for the iPhone that Apple launched in March - has already helped researchers make a lot of interesting discoveries, including that anger is one of the biggest triggers for asthma in New York.

Apple originally partnered with five different companies and research centers to create apps that study Parkinson's, diabetes, asthma, breast cancer, and cardiovascular disease.

With the assurance that Apple itself will never see their data, iPhone owners can use the apps, letting researchers collect huge amounts of data "at a fraction of the cost."

William's said on stage at Re/code's Code Conference on Wednesday that data from the Parkinson's app in particular has already surfaced some valuable insight for researchers.

For example, comparing the tests of people who have Parkinson's who use the app, to the results of people who decided to join the app as part of the control group, Williams says that researchers made a startling discovery.

"We're almost certain that a set of the people who signed up as part of the control group have Parkinson's and don't know it," he said. ResearchKit isn't a legal diagnostic tool yet, but it's clear that it could go there eventually, he said.

Another valuable data point comes from looking at how people's medication affects their test results. After someone with Parkinson's takes their medicine, they should be able to complete the app's tests better. For many people who use the app though, the medicine didn't change their test results.

That's incredibly useful data for patients who want to show their doctor whether or not their medication is working, Williams said. People don't usually have that concrete data - if they use the Parkinson's app, they will.

"If we only got these two learnings out of this app, it would already be worth it," Williams says.

Williams says that the asthma app has already helped researchers at Mount Sinai pinpoint different triggers for asthma based on location.

In Texas, for example, heat is the main trigger for asthma. In New York, the number on trigger is anger.

Getting that information only took researchers weeks and months, instead of years, like it usually would, Williams said.