Prof Andrea Mechelli: ‘People who live near a green space are less likely to have mental health problems’

andrea Mechelli, a clinical psychologist and neuroscientist, is professor of early intervention in mental health at King’s College London. He is a project leader Urban spirit, a study developed together with art foundation Nomad Projects and landscape architects J&L Gibbons, which since 2018 has been investigating how aspects of the urban environment influence mental well-being worldwide. The recent findings suggest that nature – and certain features such as natural diversity and birdsong – can improve our mental health.

We know that being outdoors – walking, jogging or exercising – is good for our physical health, but what role does nature play in our mental health?
Several studies show that people who live near parks, canals, rivers – any green space – are less likely to suffer from mental health problems. And this is the case even if we take into account individual differences in socio-economics. The risk of developing depression is about 20% lower in people who live near green spaces or spend a lot of time there. But what we don’t know is which specific aspects of the natural environment are beneficial.

How can we access the psychological benefits of being in nature?
One of the key findings of our Urban Mind project is that you don’t need a big park to ensure people can benefit from nature: even small areas of green space can lead to measurable improvements in mental wellbeing that can last over the course of keep the time. It is important to redefine nature as something that is all around us. So even in a dense urban environment you can get to trees and hear birdsong. We found that when people can see trees, their mental well-being increases, and this lasts for at least eight hours. We find similar results for birdsong. Small can still have an impact.

Active participation – when you take care of the landscape – can also be very powerful. For example, planting or caring for trees will increase biodiversity, but also reduce air pollution and have a direct benefit to our own mental well-being.

What could someone living in a small urban apartment or house do, with an emphasis on the smaller scale?
Even having a small garden on a terrace, or not paving your garden but allowing flowers and biodiversity to take place in that space. Also watering the green areas around your place of residence. For example, there is a group of individuals in London who take care of tree pits: they plant flowers and water tree pits. This is a very small intervention, but when people take care of the landscape in which they live, they also take care of themselves.

When you focus on the bigger picture of climate change and biodiversity loss, it can be overwhelming. The current language can feel quite doom and gloom because so much emphasis is placed on the fact that we need to change our lifestyle and give up all kinds of merchandise. And this is negative language, which does not help. Whereas if we reframe it in a more positive way, and we help people understand that by supporting our environment and tackling climate change, we are also supporting our own health, it becomes a win-win.

Can you tell us something about your studies? A smartphone app was used; how did this work?
I am a clinical psychologist who has worked in NHS mental health for many years. So I’m very interested in understanding why people who live in cities are at greater risk of developing mental health problems – a well-established finding that we’ve known about for years. To understand this, we had to move away from studies that simply reported a link between urban living and the risk of mental illness; we had to understand the specific factors.

I developed a smartphone app called Open Mind, which measured people’s environment, including both the social aspects and the built aspects (the built environment). And at the same time, the app measured how people felt: their anxiety levels, stress, loneliness. I expected social aspects to be very important; for example, whether someone feels safe and included in their environment, and our results indeed indicate that he or she is really important. But to my surprise, by far the strongest effect was nature’s benefit. In different countries and cultures, encounters with nature lead to an increase in mental well-being that lasts for several hours. These benefits are evident even when people come into incidental contact with nature in their daily lives. For example, hearing birdsong on the way to work.

Can you tell me more about the specific effects of nature you found?
Loneliness was of interest to us, especially chronic loneliness, as it has been on the rise since the start of the Covid-19 pandemic and is expected to reach epidemic proportions in the coming years. We found that people are 28% less likely to feel lonely when they are in an environment with natural features. For example, trees, plants or birds, compared to when they are in an environment where these do not occur. We found that too more diverse natural environments lead to stronger mental health than monocultural natural environments, where for example you only have grass and nothing else.

How does nature have this beneficial effect on our minds?
Firstly, we think nature helps improve concentration and reduce mental fatigue. This means that people’s memory and attention span improve. This is a theory that has been around for many years; there is some evidence, especially in children, that there is a cognitive benefit. There is also evidence that when people have access to high-quality nature, they tend to exercise and socialize more in nature, leading to the release of endorphins and other mood-boosting hormones, which are good for mental health. And there is some evidence that nature can help reduce stress levels. Research shows that when people spend time in nature, their blood pressure improves. Levels of stress-inducing hormones such as cortisol, adrenaline and norepinephrine also decrease.

Have health professionals looked at prescribing nature for mental health?
It is not part of regular healthcare within the NHS. So there are small projects, and most of them have had really positive, promising results. It has been used for a range of mental health conditions, especially psychosis, a serious mental illness. People who live in cities are more likely to develop psychosis; somehow urban environments increase risk. But spending even a short period of time in nature can lead to tangible improvements. It is also used in people with depression – and again the results were encouraging. So as a mental health professional, I wonder why we aren’t tapping into this resource. It’s a free intervention that can lead to measurable improvements without side effects, which is amazing.