Oregon doctors are among 75 physicians in the Pacific Northwest who have begun writing prescriptions for people to spend time walking in parks.

12 Oregon doctors are partnering with a non-profit called Park Rx America to prescribe time in nature for conditions like anxiety, depression and ADHD, NW News Network first reported.

Park Rx America was founded two years ago to advocate for nature therapy. The group cites medical studies that say outdoor activity "increases physical activity and stimulates the parasympathetic autonomic nervous system, hence decreasing the risk of developing chronic disease."

Dr. Atoosa Kourosh, a pediatrician and allergist in Seattle, told NW News Network that writing physical prescriptions for outdoor recreation makes people take it more seriously.

"I have seen several cases where they were able to come off of their ADHD medications," Kourosh said. "We can definitely see they are happy and functional without their medications, these children."

In Portland, the partnership with Park Rx America is a renewed initiative from 10 years ago, when four health care groups teamed up with Portland Parks and Recreation for a project called "Rx Play," which aimed to encourage children ages 6-12 outside and exercising.

The new effort appears to have more traction in Washington than in Oregon—the Washington State Parks system is on board, and considering offering free parking to people with nature prescriptions.