Doctor's orders could look a little greener in the future. Researchers at the Beth Israel Digital Psychiatry Lab are investigating the correlation between mental health and time spent in green spaces. 

"I think where it becomes interesting, at least from a mental health point of view, is we know the environment has a tremendous impact on all of health. But we've never been able to quantify people's environmental exposures well, because you need two things: You need to know where someone is and for how long," Dr. John Torous, director of the digital psychiatry division at Beth Israel, told MobiHealthNews. 

Torous' lab is looking at using its platform mindLamp, which focuses on examining "digital biomarkers," or patient data gathered from both active and passive data, to help measure the correlation between schizophrenia symptoms and time spent in nature. 

"The idea is with the smartphone, we can set a frequency where we can ask the phone to collect the GPS ping. So that's happening in the background passively, and what we do then is encrypt that data and send it to our computer," Torous said.

"The computer has this map of the state of Massachusetts, where the people in our study were from. And there is something called NDVI, which is normalized density vegetation index, which is a measure of green space the state does, and it's kind of used for school planning to see how much green space.

"So, because there is this measure called NDVI, we can actually say for this GPS coordinate what is the score of the green space, and the score is -1 to 1. So basically, we don't take the coordinates, the coordinates get transformed into a measure of: Are you in a parking lot with no green space, or are you in a rainforest?"

What the studies say about mental health and nature 

In the lab's initial study, which was published in Plos One in September, researchers looked at the relationship on green space with symptomatology from 37 participants with schizophrenia, as well as 26 controls without diagnosed mental illness. 

Researchers found that participants with schizophrenia had less exposure to green space than their peers in the control but that "their exposure demonstrated a dosage effect." Participants who had schizophrenia who spent more time in green space environments had lower symptoms of anxiety, depression and psychosis. However, authors found that the effects were negligible on healthy participants. 

"The notion that green space may have a more pronounced effect on individuals with mental illness presents both potential areas for recovery as well as implications for health care policy, especially in cities with a broad range of green space environments," authors of the report wrote. 

Torous said it's also important to keep in mind factors about a patient's ability to seek out green spaces. 

"What we did in this study was get green space exposure scores, and we controlled it by socioeconomic status," he said. This was done in order to make sure the study wasn't biased against people who didn't have access to green space.  

The results are correlational, not causational, Torous stressed. The participants were not instructed to spend a certain amount of time in nature. However, that could be in the books for future research. 

"But in the future, it wouldn't be hard for us to randomize people and say: We hypothesize. We've asked so many people on weekends to do these things in green space areas. It wouldn't be a stretch to begin to do causal research, but I think that's always the caveat.

"It's an association. There could be something else explaining it. I think there is a pretty good story of why it's likely related to it, but it's still hard to make that claim per se."

Beyond just research, the environmental data from study is sparking conversations between patients and physicians in Torous' lab. 

"Usually how we approach it is, we don't want to talk about data for the whole visit when we are meeting with someone. So we say, let's look at data for the first few minutes as part of our protocol and usually say, is this a trend? Does this match what you feel or you experience?"

These conversations allow not only patients to discuss their experiences, but researchers to explain some of the data. For example, if a patient leaves their phone home all weekend, the GPS data will be inaccurate. 

Patients are also able to view their weekly data against their history and look at things like consistency and stability in lifestyle. While 10,000 steps a day has become the universal standard for healthy living, Torous said, what's more important is how a patient is doing against their own data. 

But he warns that providers and companies collecting biomarkers, such as time spent in green space, need to be responsible with this sensitive data or patient trust will be lost. 

"There are privacy concerns. If you do let the app in to understand the environment, this potential has more information on it," he said. "That's where the trust becomes more important. So, we would use this in the context of research studies, or part of our digital clinic, where we work with people, and we kind of explain why we do it…

"I think there is the potential for it not to be used well or to become something that's almost one of the greatest risks. If people don't use it well, or the data gets abused, not for someone's personal benefit, I think then you could potentially see a backlash of people in the future saying ‘That's not how I want to use my phone and technology.’"

The future of research 

Next, Torous is looking to explore more than a patient's relationship to green space, but also the impacts of pollution on mental health. He coauthored a case study published in JMIR where a mental health patient was given a sensor to capture air pollution levels. 

"There was someone who had a serious mental illness, and we wanted to see as pollution levels increased through the day, because we know with automobile exhaust the highest pollution levels are at 1 or 2 o'clock. If we are having someone wear a small wearable that captures pollution or partials per million, can we see their symptoms change?

"So, if someone is accessing their symptoms across a day and pollution across a day, we showed it's very possible to get that data today. We weren't designed to make a conclusion for this person, but I think it shows we can really get a very personalized measurement."

While the research is evolving on green space, Torous said it's important to keep in mind that environment means a lot of things, including social space. During the last year, people's social space and relationship with nature has been upended. 

"What I think is important too for mental health is getting the social space we are in. Are you in a green space, but you are isolating, and not talking to anyone, and have no contact? Are you in an environment that is not conducive to mental health, but you have a lot of great social support? You have a lot of great friends? So I think that getting the social part is the environment."

The mental health space is very much growing. In the future, Torous said that when medicine better understands certain conditions, like types of depression, then prescribing green space could be a tool in the toolbox. 

"As we know, depression is such a broad term. There are so many subtypes of depression we don't know how to classify, that I wonder if we are going to eventually figure out that green space and environmental exposure is really helpful for one type of depression, or a different type of depression, a certain type of therapy is the go-to treatment.

 "So, I think as the field matures, we'll probably be able to say, ‘Hey John, you have depression subtype E for the environment and the most effective thing is this.’ So, in part, we know not everyone gets better in a more diverse environment, too.

"It’s a low-risk thing to do per se, but it's still hard to know which patients will respond to it. It's early days for that as well."