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The good news about depression – Part 3
Getting outdoors in nature is highly beneficial for psychological health - at all ages.
In Part 1 of this mini-series, I summarised recent research demonstrating the benefits of better nutrition – specifically, increased consumption of fruits, vegetables, mushrooms and legumes – for reducing the risk of developing depression and anxiety, and hastening recovery from these increasingly prevalent conditions.
In Part 2, I delved into recent research on the link between physical activity and the prevention and treatment of depression and anxiety.
And now, in Part 3, I’m going to take you on a guided tour of recent research on the effect of getting outdoors on mood and anxiety.
Outdoor and nature-based activities, depression and anxiety: Put down your dang device and go outside
In a previous article, Can getting in the green help beat COVID-19?, I explored research documenting the immune-boosting, stress-relieving, resilience-building and even crime-reducing effects of spending time in nature and increasing green spaces in urban centres.
Many more studies on the benefits of heeding the call of the wild have been published since; I’ll focus on those that are relevant to depression and anxiety.
Study #1 – The longitudinal associations of physical activity, time spent outdoors in nature and symptoms of depression and anxiety during COVID-19 quarantine and social distancing in the United States
Remember this study, from Part 2? It tracked more than 20 000 adults enrolled in the Kaiser Permanente healthcare plan, analysing data from surveys and electronic health records during April to August 2020 – a period when mediaeval approaches to infectious disease control that completely contradicted the CDC’s own pandemic preparedness plan were imposed on the majority of Americans. The participants were mostly older, white women who adhered to these “public health” diktats.
Aside from assessing participants’ physical activity levels during the early months of the manufactured COVID crisis, researchers also examined changes in the average duration of time spent outdoors, and looked for correlations with anxiety and depression.
Those who reported spending less time outdoors in nature than in the previous month were more likely to be depressed or anxious than those who had not changed the amount of time they spent outdoors. The anxiety- and depression-buffering effect of outdoor time was more pronounced in women, and in those aged under 66 (although the oldest age group had the lowest anxiety and depression scores anyway).
The researchers also found that those who had increased the amount of time they spent outdoors also had higher anxiety scores; this apparent paradox could be the result of ‘self-medicating’ by anxious people who intuitively sense that time spent in nature calms them down.
And it turns out that intuitive sense is firmly grounded in reality. Bring on…
Study #2 – Nature-based outdoor activities for mental and physical health: Systematic review and meta-analysis
Researchers at the University of York scoured the published literature and identified 50 studies (comprising 16 randomised controlled trials, 18 controlled studies and 16 single group before and after designs) on the effects of nature-based interventions (NBIs) on depression and anxiety.
NBIs “support people to engage with nature in a structured way”, and include gardening, “green exercise” – physical activity conducted in natural, outdoor settings – and nature-based therapy such as conservation activities and “forest bathing”.
Across the board, NBIs had a “large and significant effect in favour of reductions in symptoms of depressive mood” and “a large and significant effect size in favour of reducing anxiety symptoms.”
The forest plots below show the results of meta-analyses for the three different types of studies. If the square or diamond representing each study is on the left of the solid line, this indicates that the nature-based intervention was superior to the control. The horizontal lines running through each shape indicate the confidence interval; if this line crosses the solid vertical line, there’s a higher probability that the results could have been due to chance:
a) Randomised controlled trials:
b) Controlled studies:
c) Before-and-after studies:
a) Randomised controlled trials
b) Controlled studies:
c) Before-and-after studies:
Conversely, NBIs were found to enhance positive affect and reduce negative affect – in other words, to increase the frequency with which participants experienced enjoyable and uplifting emotions, such as happiness, joy, contentment and a sense of connectedness and belonging; and decrease the frequency of unpleasant emotions such as anger, frustration, fear, isolation and disconnection.
Interestingly, the researchers found much stronger and more consistent evidence of mental health benefits of NBIs than of physical benefits, such as reduced blood pressure and cholesterol.
Activities that lasted for 20 to 90 minutes, and were sustained over the course of 8 to 12 weeks, were found to have the most positive outcomes for improving mood and reducing anxiety.
Unsurprisingly, given the role that loneliness and isolation play in both depression and anxiety, the benefits of NBIs were greatest for those delivered in group settings.
And also unsurprisingly in light of the existential understandings of depression and anxiety, which position them as crises of meaning, purpose and connection, NBIs offer greater potential for fostering well-being than just sitting under a tree:
“Compared with just exposure to green space, nature-based interventions offer opportunities to variously connect with nature, derive social support, and engage in physical and/or purposeful activity, and these factors are hypothesised to be potential mechanisms that underpin observed health benefits.”
Importantly, NBIs appear to not only reduce the risk of becoming anxious or depressed, but to alleviate these conditions in people who have already developed them:
“Nature-based interventions are efficacious as both a therapeutic response to manage pre-existing mental health problems, and as a preventive approach to keep people well.”
But why does spending time outdoors in nature offer such dramatic benefits to our mental well-being? Part of the answer is exposure to natural light, which brings us to…
Study #3 – Time spent in outdoor light is associated with mood, sleep, and circadian rhythm-related outcomes: A cross-sectional and longitudinal study in over 400,000 UK Biobank participants
Many people are now aware that they should avoid bright light (and especially blue light) exposure at night, in order to get better sleep.
However, the health impact of spending most of the day indoors in artificial light is not as well known.
In this cross-sectional and longitudinal study of participants in the UK Biobank program, a lack of daytime full-spectrum sunlight exposure was a risk factor for depressive symptoms, poor mood, and insomnia, which have a self-perpetuating relationship with each other.
On average, participants reported spending 2.5 daylight hours outdoors per day. However, each additional hour spent outdoors during the day was associated with lower odds of lifetime major depressive disorder and antidepressant usage, less frequent anhedonia (inability to experience happiness during activities that would ordinarily engender it) and low mood, greater happiness and lower neuroticism, independent of demographic, lifestyle, and employment covariates.
In addition, each hour of daytime light was associated with greater ease of getting up, less frequent tiredness, fewer insomnia symptoms, and earlier chronotype (i.e. being a morning lark rather than a night owl.
What’s so important about getting out in daylight, you might be wondering. Is it just that getting all that sunshine on our skin increases our vitamin D levels? No. A study of over 18 000 adults aged over 50 found that taking supplemental vitamin D (2000 IU daily) for a median of just over 5 years did not reduce the incidence or recurrence of depression or depressive symptoms.
So you can’t just cheat by popping a pill. You actually have to go outside and be exposed to sunlight, on your skin and through your eyes (unfiltered by window glass) in order to experience benefits.
And those benefits include structural and functional changes in our brains, which leads me to…
Study #4 – Spend time outdoors for your brain – an in-depth longitudinal MRI study
As the title implies, the researchers behind this study weren’t messing around. They conducted regular magnetic resonance imaging (MRI) scans of six young adult city-dwelling volunteers over the course of six to eight months.
On average, each volunteer (all of whom were employees of the Max Planck Institute for Human Development in Berlin) had two MRIs per week, allowing the researchers to build an impressive database of real-time changes in the brain and their relationship to daily activities.
On each day that they underwent an MRI scan, volunteers were asked how much of each of the following they had experienced in the previous 24 hours:
How much time they had spent outdoors;
How much fluid they had consumed;
How much spare time they had had;
How many cups of caffeinated drinks they had drunk; and
How many hours of physical exercise they had engaged in.
They were also asked about their present emotional state, and equipped with a Fitbit to measure their daily steps. Hours of daily sunlight were obtained from the German Weather Service.
Time spent outdoors, sunshine duration and hours of spare time in the previous 24 hours were all predictive of greater positive affect (happy feelings), whilst fluid intake and physical activity were not.
But where things got really interesting was when the researchers examined the effects of all of the above factors on participants’ brains. It turned out that only the number of hours spent outdoors correlated with any changes in regional grey matter volume.
Specifically, participants who had spent more hours outdoors in the previous 24 hours had higher grey matter volumes in their right dorsolateral-prefrontal cortex, a region of the brain involved in the planning and regulation of actions as well as cognitive control – the ability to control and moderate one’s own behaviour in order to achieve goals (also known as executive function). Many psychiatric disorders are known to be associated with a reduction in grey matter in the prefrontal area of the brain.
You may be surprised that what participants had been doing in the previous 24 hours could change the physical structure of the brain, but the researchers pointed out that other recent studies have demonstrated day-to-day variations in brain structure, occurring in just hours.
While uncertain how to explain their findings, the researchers speculated that the answer might be related to other research that has found that time spent outdoors in nature enhances cognitive functioning. Or, in simple terms, we think better when we are immersed in nature. But why? What is it about being in nature that stimulates more creative and rigorous thinking? Perhaps it’s that being in natural environments stimulates our sense of adventure. Which brings me to…
Study #5 – Child’s Play: Examining the Association Between Time Spent Playing and Child Mental Health
As a child of the 1970s, who grew up engaging in a lot of outdoor “free range” play both alone and in the company of my siblings and neighbourhood children – much of which involved poking around in uninhabited spaces – I’ve become increasingly dismayed at the lack of opportunities that today’s kids have to engage in the kinds of unsupervised, adventurous and creative play that I and my peers enjoyed.
Instead of riding bikes full tilt down steep slopes, climbing trees, building bridges across streams that spring up after storms, and constructing forts out of scavenged materials then inventing games to play in and around them, the children of Gen Xers and Millennials have “playdates” arranged and supervised by their parents, who hover on the margins, ready to intervene at the merest hint of their offspring engaging in anything physically – and god forbid, emotionally – dangerous. Barf.
That’s why this study caught my eye. Researchers from the University of Exeter noted the correlation between declines in children’s independent mobility and outdoor play in recent decades, and the 49 per cent increase in rates of emotional disorders in UK children aged 5–16 years between 1994 and 2017. They noted that recent data suggested that one in six UK children had a probable mental health problem in July 2020, when lockdown lunacy was at its zenith.
Pointing to a hypothesis that “adventurous play experiences during childhood may help to prevent anxiety in children” and hence that “reductions in children’s outdoor, risky play, may have negative consequences for children’s mental health, and may be contributing in part to the increase in children’s mental health problems”, the researchers used data from two samples of parents to examine associations between the time that children aged 5–11 years spent playing adventurously and their mental health.
Parents from Northern Ireland (Study 1) and Great Britain (Study 2) answered a questionnaire about the time that their children spent in adventurous, unadventurous and outdoor play, and their current mental health.
Both studies found that the more time children spent in adventurous play – which, the researchers noted, was facilitated by being in nature – the fewer symptoms of anxiety and depression they displayed. The protective effects of adventurous play were particularly pronounced in children from low-income families. Importantly, children who spent more time playing adventurously displayed less symptoms of anxiety and depression, and more positive mood, during the COVID-19 lockdown.
The implications of this study are thought-provoking:
“This finding therefore provides some initial support for the idea that adventurous play may help children to cope, or at least maintain positive affect, during difficult periods, even if it does not prevent negative affect…
Whilst play offers broad benefits for children’s development, happiness and wellbeing, it is adventurous play specifically that provides learning opportunities which buffer against anxiety.”
Or, in layman’s terms, engaging in forms of play that provoke fear and uncertainty trains you to be able to handle those emotions when they crop up in other settings. And conversely, cossetting kids so that they don’t experience these difficult emotions makes them more likely to drop their bundle when they’re confronted with the inevitable challenges of life.
Does this explain why we have a whole generation who require “safe spaces” to be able to cope with hearing ideas they disagree with? Maybe their parents should have sent them outside to ride their bikes and climb trees. It’s not too late though, according to…
Study #6 – Connection to Nature Boosts Adolescents’ Mental Well-Being during the COVID-19 Pandemic
This study explored the relationship between connection to nature and psychological well-being both before and during the mismanaged public health response to COVID-19, via a nationally representative survey of US children aged 10-18, and their parents, conducted between April and June 2020.
Sadly, during the manufactured COVID crisis, the respondents reported a 41 per cent decline in nature experience activities, a 43 per cent decline in outdoor play activities, a 45 per cent decline in connection to nature scores and a 21 per cent decline in mental well-being scores.
Mediation analyses indicated “direct relationships between during COVID-19 declines in mental well-being and declines in connection to nature.” I’m sure the people who imposed the policies that resulted in these terrible outcomes got promoted though.
The authors’ discussion of their findings is worth quoting at length:
“Our findings indicate that during the COVID-19 pandemic, adolescent connection to nature, mental well-being, and participation in nature experience and outdoor play activities declined. We also found that declines in connection to nature predicted declines in mental well-being, with connection to nature mediating the relationship between participation in either outdoor activity group and mental well-being both before and during the pandemic. Comparisons between the mediating role of connection to nature before and during the pandemic demonstrate that while connection to nature continues to play an important role in enhancing mental well-being, the role was reduced during the pandemic. Conversely, the direct effect of participation in outdoor activities played an increased role in driving improved adolescent mental well-being during the pandemic.
Declines in outdoor activity participation, connection to nature, and mental well-being observed in this study could be an unanticipated consequence of community health initiatives aimed at slowing the spread of the virus. Pandemic-related changes to adolescent daily routines such as the closure of schools, public parks, and recreation spaces, coupled with the cancellation of youth sports and clubs, have limited opportunities for adolescent contact with nature, as evidenced by COVID-19-related declines in participation in outdoor activities  and increases in sedentary activities . As contact with nature diminished due to reduced participation in outdoor activities, connection to nature appears to have declined as well . The widespread decline in adolescent connection to nature found in this study suggests that this trait might be less stable and more malleable in youth than it is in adults . If these adverse shifts in adolescents’ daily routines continue following the pandemic, they may contribute to lower levels of outdoor activity participation that persist across the lifespan [32,84,85], and further contribute to an ‘extinction of (nature) experience’ [86,87], highlighting the potential for long-term impacts to connection to nature and mental well-being.”
A cynic might wonder whether such an outcome might be just what those pushing a transhuman future in which we no longer wander freely in nature, engaging with it via all our senses, but instead are drip-fed a shabby replica of it through our Metaverse headsets, had in mind.
Which brings me to…
Study #7 – Psychological impacts of “screen time” and “green time” for children and adolescents: A systematic scoping review
Noting the correlation between increased time that young people spend engaging with screen-based technologies (“screen time”), reduction in their contact with nature (“green time”) and declining mental health and well-being, researchers from the University of Adelaide analysed the findings of 186 studies to collate evidence assessing associations between screen time, green time, and psychological outcomes (including mental health, cognitive functioning, and academic achievement) for children and adolescents.
By now, you probably won't be surprised to learn that after sifting through all these studies, they concluded that
"High levels of screen time appeared to be associated with unfavourable psychological outcomes while green time appeared to be associated with favourable psychological outcomes."
Specifically, in children aged under 5, increased screen time showed deleterious associations with cognitive development, effortful control, language and communication abilities, behaviour problems, self-regulation and prosocial behaviour. On the other hand, access to outdoor education and play spaces, and increased residential green space, was associated with reduced depressed mood, internalising problems (anxiety and depression symptoms), peer problems, and total difficulties, as well as superior prosocial behaviour, cognitive, language, emotional, and social development.
Studies in children aged 5-11 were less consistent, but “where statistically significant associations were reported, ST [screen time] exposures were generally associated with unfavourable psychological outcomes (n = 16 studies), while GT [green time] exposures were typically associated with favourable psychological outcomes (n = 18 studies).”
Likewise in early adolescents (12–14 years), “where statistically significant associations were reported, ST exposures were generally associated with unfavourable psychological outcomes (n = 32 studies), while GT exposures were typically associated with favourable psychological outcomes (n = 8 studies).”
And in older adolescents (15-18 years), high total screen time was associated with higher levels of depression/depressive symptoms and anxiety/anxiety symptoms, while high levels of video game playing were associated with lower emotional functioning, health-related quality of life, psychosocial scores, and quality of life. On the other hand, outdoor programs, camp experiences, and wilderness expeditions were found to increase self-efficacy and positive identity, and decrease long-term total difficulties and anxiety.
There is some comfort for all those parents who have long since learned that the only way to get their teen's life-support device from them is to pry it out of their cold, dead hand:
"There is preliminary evidence that green time could buffer consequences of high screen time, therefore nature may be an under-utilised public health resource for youth psychological well-being in a high-tech era."
Perhaps one day we'll be able to get our kids outside in nature without them feeling the pathological urge to video themselves in it. We live in hope.
In Part 4, I'll be delving into the role of social connection and sleep in psychological well-being, along with effective psychotherapy for anxiety and depression.
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