After each walk, the children were given a standard test called Digit Span Backwards, in which a series of numbers are said aloud and the child recites them backwards. The test is a useful measure of attention and concentration because practice doesn’t improve the score. The order of the walks varied for all the children, and the tester wasn’t aware of which walk the child had just taken.

The study, published online in the August The Journal of Attention Disorders, found that children were able to focus better after the “green” walks compared to walks in other settings.

Although the study is small, the data support several earlier studies suggesting that natural settings influence psychological health. In 2004, a survey of parents of 450 children found that “green” outdoor activities reduced A.D.H.D. symptoms more than activities in other settings.

“What this particular study tells us is that the physical environment matters,” said Frances E. Kuo, director of the university’s Landscape and Human Health Laboratory. “We don’t know what it is about the park, exactly – the greenness or lack of buildings – that seems to improve attention.”

Dr. Kuo noted that the study used tight controls to make sure that the walks were identical except for the environment. Who the child was with, noise levels, the length of time, the time of day and whether the child was on medication stayed constant.

“If we kept everything else the same, and we just changed the environment, we still saw a measurable difference in children’s symptoms,” Dr. Kuo said. “And that’s completely new. No one has done a study looking at a child in different environments, in a controlled comparison where everything else is the same.”

Dr. Kuo said more children were initially involved in the study, but logistical problems like weather changes, late arrivals or changes in medication made it difficult to maintain tight control, leaving the study with just 17 children from which to draw conclusions.

Despite the small size, the study is important because it involves an objective test of attention and doesn’t rely on children’s or parents’ impressions. During the walks, all of the children were unmedicated — participants who normally took medications to control their A.D.H.D. symptoms stayed off the drugs on the days of the walks.

The researchers found that a “dose of nature” worked as well or better than a dose of medication on the child’s ability to concentrate. What’s not clear is how long the nature effect can last.

Dr. Kuo said that while there are “hints” exposure to green outdoor settings offers a benefit, the science isn’t advanced enough to give parents a strict formula.

“We can’t say for sure, ‘two hours of outdoor play will get you this many days of good behavior,’ but we can say it’s worth trying,” she said. “We can say that as little as 20 minutes of outdoor exposure could potentially buy you an afternoon or a couple of hours to get homework done.”

Dr. Kuo said it’s notable that parents themselves consistently report benefits for their children from green settings.

“One reason we believe this is that if the effect were short-lived, we don’t think that parents would have so consistently observed it,” she said. “But they do. They report it over and over.”

Assistant professors Robin Bartlett and Mona M. Shattell, from the School of Nursing at the University of North Carolina at Greensboro, interviewed 16 college students who had been diagnosed with A.D.H.D. as children. The investigators talked to them about how the disorder affected life at home, school and friendships.

Like most kids, the students described a life of both conflict with and support from their parents. But in their case, fighting with parents was often triggered by attention-related problems like failing to complete laundry chores or cleaning their rooms.

Doing things for my parents and being aware of what needs to be done around the house, that’s the only time it really gets to me or hurts me.

Despite the conflict, many students viewed their parents as supportive. One student noted that support from parents often felt like “nagging,” but they had little choice.

They had to play 20 questions. I wasn’t trying to withhold information; it just took 20 questions to get the full description. You couldn’t ask, “What do you have for homework?” It was like, “Do you have any homework?” “Yes.” “What is it?” “Math.” “What’s it on?” “This stuff.” “Do you have English homework?” “Yes.” They had to go through a much larger spectrum of questions just to get the answer to, “Do you have any homework?”

Students also noted that their mothers often made flash cards, helped them organize and prioritize, gave them books on tape, proofread papers and developed numerous other strategies to help them in school.

Children with A.D.H.D. felt different from their classmates. One student told the story of being called over the public address system to report to the “special ed” office. Teachers who spent extra time to help them soothed their feelings of isolation, they said.

The students said they ended up “missing a lot of stuff” at school because of trouble listening, paying attention and completing homework. However, the students also described developing coping strategies like taking a test on a computer rather than on paper or recording lectures they could later listen to on their iPods.

The students’ recollections about friendships in childhood show that while their struggles with schoolwork were obvious, their attention problems also affected their ability to make friends.

People looked at me differently, like, oh, she has a disability, oh she’s stupid, she’s retarded. I mean…I just don’t get things as easily as others. And I don’t think they understood that.”

Not only do I have a tendency to interrupt…but the main problem I have is, you need to think before you say something that can offend other people, or when you ask too many questions…they’ll say it makes them feel uncomfortable.

Students noted that even their friends would sometimes mock their disability.

I have friends who say, “Oh, it’s my A.D.D. and I don’t want to do my work. It’s my A.D.D. kicking in.”…and they’ll say it in front of me when they know I have it…and I’ll have it the rest of my life.

But friends could also help them cope, the students noted.

Get a friend who understands, who can call out your name, or tap you or something to get you to focus when you’re zoned out.

While the report gives insights into the sadness and frustration felt by kids with attention deficits, Dr. Bartlett said she chose the students because they had “achieved some measure of success by virtue of now being college students.” She said she hopes the research can be used to help identify strategies and coping skills students found helpful “as they were growing up and struggling with A.D.H.D. symptoms.”

One student gave a particularly moving description of how her mother helped her adjust to life with the disorder.

I remember just breaking down….And she was like, “Kerri, I did not know any of this. I’m so sorry.” And she just held me and I just cried and cried. And she said “You are not different. You are beautiful and sweet.” …It didn’t take away the problem, but it affirmed to me that she cared. No matter how much I went to school and felt like…nobody liked me…when I went home, I knew it wasn’t fake. And it was a good place. There I was loved; I fit in and I was fine.