What can forest therapy offer those living with a longterm neurological condition?
By Dr Claire McDonald
Within the UK, an estimated 14.7 million people are living with a long term-neurological condition, including; stroke, Parkinson’s disease, brain cancer, epilepsy, epilepsy and acquired brain injury.
Long-term cognitive and psychological problems can be the most stressful consequences for individuals and their family members, with feelings of social isolation also commonly being reported within the literature. Access to psychological and neuropsychological input is challenging within the current climate, with long NHS waiting times and a ‘postcode lottery’ in terms of access to community neuro-rehabilitation.
It feels more important than ever therefore, that families living with neurological conditions are being informed of and supported to access any resource that may benefit their wellbeing, and there is a compelling evidence that time spent in nature should be considered as one such resource.
The appreciation and integration of nature within a healthcare context is not a new phenomenon; for some time now hospital and rehabilitation units have been designed to incorporate elements of nature, and dedicated garden spaces.
Using hospital records, Ulrich (1984) compared the post-surgical data of patients who underwent gall bladder surgery who had a window view of a tree, compared to those patients who had a view of a brick wall. Those with the view of the tree were found to have shorter postoperative hospital stays, had fewer negative evaluative comments from nurses, took fewer moderate and strong analgesic doses, and had slightly lower scores for minor postsurgical complications.
For centuries, ‘being outdoors’ has been recognised as being helpful to humans, however it was the adoption of Shinrin-Yoku or ‘forest bathing’ as a prescribed health intervention in Japan in the late 1980’s that prompted more rigorous exploration of the health benefits of being immersed in nature.
Forest therapy is based upon the practice of ‘Shinrin-Yoku’ and may be broadly defined as an intentional nature connection, in which participants pay close attention to their present moment surroundings through engaging fully with their senses (e.g. sight, smell, hearing, touch). This may take the form of a slow, mindful walk through a forest or local park, but may also be practiced at home with a plant or in a garden.
Literature reviews (eg.Yi et al, 2022; Kotera et al, 2020; Song et al. 2019) have summarised a wealth of physical, psychological and social benefits associated with forest therapy.
Two key theories can support our understanding of the mechanisms behind these benefits.
Firstly, Stress Reduction Theory (Ulrich, 1981) suggests that humans have evolved to find natural environments both soothing and rewarding, due to the important role such settings have played in our safety and survival. Natural settings are postulated to directly impact our physiology via the autonomic nervous system.
Support for this theory has been generated through a growing body of research in which participants’ neurophysiological responses have been measured before, during and after exposure to natural environments. For example, studies have demonstrated that time spent in a forest environment, such as walking through a forest and/or viewing the scenery can reduce levels of salivary cortisol, a stress hormone, blood pressure, pulse rate as well as increase parasympathetic nervous activity (Song et al., 2019).
Furthermore, sympathetic nervous activity is found to be suppressed (Lee et al., 2014), and there is a decrease in the cerebral blood flow in the prefrontal cortex, indicative of a relaxation effect (Park et al., 2007).
A forest therapy trip has also been shown to increase natural killer (NK) cell activity and improve immunity, with these effects lasting for approximately one month. Viewing plants and foliage has been found to improved self reported positive feelings of comfort, relaxation, naturalness, and vigor, and decrease negative feelings of tension, anxiety, and fatigue (Park et al., 2016; Song et al. 2017).
Secondly, Attention Restoration Theory (Kaplan & Kaplan, 1989) may offer a foundation from which to understand the reported impact of nature upon cognition.
This theory suggests that modern urban environments heavily tax the top-down voluntary attentional control that is required to filter relevant from irrelevant stimuli adequately (Bratman et al. 2015). Competing demands from urban environments are hypothesised to impact focused attention capacity. In contrast, nature based environments are believed to enhance our cognitive capacities through offering opportunity to:
“be away” from everyday stresses
experience expansive spaces and contexts (“extent”)
engage in activities that are “compatible” with our intrinsic motivations
critically experience stimuli that are “softly fascinating”
These opportunities are hypothesised to result in the replenishment of directed attention because we are less cognitively taxed in natural environments, leading to improved memory and attention.
A number of studies give weight to this theory. For example, students who had views of nature through their dormitory windows performed better on tasks that require concentration (Necker Cube pattern test) than students without such views (Tennessen and Cimprich, 1995).Furthermore on a task of sustained attention (sustained attention to response test), participants who viewed nature photographs performed better than those who viewed images of urban environments (Berto, 2005).
These findings have also been reported within children; for example, Taylor, Kuo and Sullivan (2002) reported that children living in urban areas children living in urban environments, with everyday views of nature (e.g., a tree outside their apartment window, instead of a view of concrete) performed better on tasks that measured working memory (backward digit span, backward alphabet span), impulse inhibition (matching familiar figures task), selective attention (Stroop colour-word task), and concentration (Necker Cube pattern control task).
Similarly, walking through a natural greenspace, compared to walking through an urban environment, yields benefits for verbal working memory (backward digit span), cognitive control (executive attention component of the attention network task), and concentration (Necker Cube pattern test) (Berman et al., 2008, 2012; Hartig et al., 2003).
It has been suggested therefore that exposure to nature improves performance on cognitive tasks that require directed attention. Bratman et al. (2015) reported a slightly mixed picture, and found that participants who took a nature based walk performed better on the OSPAN, a complex verbal working memory task, but not on a visual working memory task or a task of ‘executive attention’.
There is an increasing use of nature in the rehabilitation process among neuro therapists, particularly in the aftermath of the Covid-19 pandemic; this interest is also reciprocated among those individuals living with long term neurological conditions (Vibholm et al., 2019).
Yet, unfortunately the current evidence base is limited and there is a lack of clarity around the specific benefits of nature-based interventions for this population (Annerstedt and Währborg 2011). A systematic review of Nature-Based Rehabilitation (NBR) for individuals with acquired brain injury undertaken by Vibholm et al. (2019), located seven papers on Horticultural Therapy, Forest Therapy and Outdoor Adventure Programmes. Positive outcomes of NBR were reported including, improved sensory motor-functioning (Kim et al. 2010), psychosocial adjustment and goal attainment (Walker et al, 2005) and also improved motivation, proactivity and engagement in rehabilitation (Barello et al., 2016).
A study by Chun et al (2017) explored the impact of forest therapy upon symptoms of anxiety and depression in patients with chronic stroke. Physiological measurements of stress (oxidative stress levels and antioxidative capacity) were recorded before and after a 3 day forest therapy programme, alongside self-report measures of anxiety and depression. The intervention comprised guided mindfulness practice, experiencing of the forest through the senses, and gentle walking in the forest.
When compared with an ‘urban group’, who performed mediation and walking activities in an urban environment, those in the forest therapy group were found to have significantly lower scores on self-report measures of anxiety symptoms following treatment and their antioxidative capacity was higher. The effect on symptoms of depression within this study was unclear however positive effects on depression have been reported by Kim et al. (2010) who looked at the effects of Horticultural therapy on mood and physical functioning on stroke patients.
Physical access to a greenspace remains one of the biggest challenges for those with a neurological condition and this has been reflected in the literature. A recent national Danish survey found that people with mobility disabilities visit green spaces much less frequently than the able-bodied population (Stigsdotter, Corazon & Ekholm 2017).
Given that people restricted by physical disability generally have greater mental and physical health problems than the able-bodied population (Damgaard & Steffensen 2013; WHO 2011), access to the potential health benefits of contact with green spaces could be an important health resource for this population (Corazon et al., 2019).
Virtual nature engagement has been proposed as an alternative means of connecting with nature for people living with mobility issues.
Within the UK, a study undertaken with patients diagnosed with Long Covid highlighted a positive impact of a four week virtual intervention (McEwan et al., 2022). Specifically, when compared with waitlist controls, participants in the virtual forest bathing group self-reported statistically significant improvements in Anxiety (49% decrease), Rumination (48% decrease), Social Connection (78% increase), and Long-COVID symptoms (22% decrease).
While virtual forest therapy may offer promising benefits to those with mobility issues, it should not be considered an either–or option and participants should be provided with choice, control and appropriately tailored interventions.
McEwan et al. (2023) emphasise that it is important to understand how people with disabilities may experience virtual forest bathing that incorporates possible direct contact with nature. These insights may be useful in understanding how to make virtual programs, and possibly onsite programs, more accessible and inclusive.
Forest therapy using houseplants also offers health and wellbeing benefits. For example, Ochiai et al (2017) found that viewing a bonsai tree houseplant altered brain activity, improved cardiovascular health, increased positive feelings, and reduced anxiety and depression in people with spinal cord injury and older adults going through rehabilitation (Song et al., 2018).
Furthermore, participant feedback in a feasibility study of virtual nature exposure for older adults suggested that virtual nature needed to be more immersive (rather than simply visual), offer better image quality and increase the narrative or guidance of the video content to improve the experience (Appel et al, 2019).
In light of the available evidence therefore, clinicians working within the area of neurorehabilitation should be advocating for people with long term neurological conditions to increase their nature connection, and access forest therapy interventions alongside more traditional forms of rehabilitation.