Study: Walking in nature promote mental health

Reference

Bratman GN, Hamilton JP, Hahn KS, Daily GC, Gross JJ. Nature experience reduces brooding and subgenal prefrontal cortex activation. Proc NATL ACAD SCI USA . 2015; 112 (28): 8567-8572.

Design & participants

randomized comparison between the groups of a 5.3 km long solo walk either in a nature park with grassland and oak or a busy urban road in Palo Alto, California. Each participant received a smartphone with GPS tracking to monitor their location and take photos of their experience to ensure compliance with the study instructions and the hiking route.

All participants were city dwellers (n = 38, 18 female, average age 26.6 years) of the San Francisco Bay metropolitan region, without neuropsychiatric diseases in the history or current use of psychotropic drugs. They were either assigned to the nature or urban hike group according to the random principle. No significant differences were found in the middle age or gender distribution of the groups.

target parameter

Immediately before and after the walk, the participants carried out a psychometric and biomarker evaluation of their experience.

• Psychometrical: Reflection rumation Questionnaire (RRQ) is a validated scale for measuring mental brooding, which is an associated history of clinical conditions such as depression and anxiety.
• Biomarker: Arterial spin labeling-MRI-neuroimaging measures the neural activity of the subgenual prefrontal cortex (SGPFC) over cerebral blood flow. An increased SGPFC activity is associated with experience of sadness, social withdrawal and negative self-reflection, which are all connected to the brooding and the resulting conditions. ²

heart and breathing rate was measured during the neurobiism to consider individual differences in the physiological reaction to walking; No physiological differences between the groups were found before or after the walks.

important knowledge

Statistically significant differences between nature and urban hiking groups for both psychometric and for biomarker analyzes that show subjective and objective changes in psychophysiological brooding experience. The mean RRQ values ​​were significantly reduced after the natural walk [T (17) =-2.69, p <0.05, d = 0.34] were unchanged after the city walk. Similarly, the SGPFC blood flow in the natural hike group was significantly reduced [t (15) =-6.89, p <0,0001, d = 1.01], however, remained unchanged for the Urban walk group.

Comment & implications

This is the first study that demonstrates neuroimaging and corresponding psychological changes in response to real natural vs. environmental pollution. Other studies have reported similar FMRI results after looking at natural vs. built pictures in a laboratory. 3 and there is extensive literature that uses animal models that demonstrate advantageous neurostructural and neurofunctional changes through life in "natural" contexts. ^{4 In addition, the most extensive FMRI study on this topic shows healthier stress reactions in other brain areas (e.g. PACC*, Amygdala) of adults who grew up in the country as adults who grew up in a city; These results were consistent after the current place of residence of the participants was checked. 5 Taken together, these studies show the objective changes in the functional brain that result from contact with nature.}

Of course, these objective changes in the brain lead to the positive subjective Experience with the exposure to the natural environment that have been discussed in detail in the literature. ^{6.7,8 There are indications that natural -based experiences are legitimate and useful supplementary therapies in order to address mental illnesses and ADHS. In addition, contact with nature also increases positive mental health experiences. Time in nature can improve the attitude to life of a patient, 11 Life satisfaction, 12 and subjective well -being. 13 These aspects of "positive psychology" are increasingly propagated in the disciplines of health promotion 14 and are as important components to improve general health and effective Administration and treatment recognized.}

A facet of this positive, health -promoting quality of nature is the ability to inspire and awaken in awe. Awe is a feeling of raising and appreciation for things that are greater than yourself, and as discussed in the 2015 August edition magazine for naturopathy it has the ability to modulate the function of the immune system and reduce inflammatory cytokines. Awe helps us "to put things in the right light" and let us recognize how small and at the same time connected to each other in a larger universal context. ¹⁸ It is possible that this relative perspective helps us to overcome our own personal worries and work on breaking through the cycle of self -doubt and brooding, which leads to mental illness. The study also showed that nature inspired by nature leads to prosocial behavior, which essentially means that people behave towards better people. This is exciting because it means that nature inspired by nature is a really "biopsychosocial" health promotion factor.

As far as the restrictions on the current study is concerned, it must always be pointed out that each “field study” contains an almost infinite number of variables that can influence the results. It is not possible to list all types in which the natural and urban environments differ in this study, or to isolate which of these variables are the causal factors. However, it is important to recognize that trying to do this would fail to make sense. Environments in which people live, work and play are not isolated biochemical active ingredients that are suitable for a randomized, placebo -controlled double binding study. They are complex matrices from experience and commitment that constantly influence us at all levels. We are just starting to appreciate this awareness and include in our health paradigm.

It is useful for the clinical practitioner to have a wide range of tools when working with patients. Bringing patients outside and into a natural environment helps to clarify the mind, revitalize the body and restore the mind. Everything in a way that works with "the healing power of nature" and does not have to come in a pill.

graduation

There are still supporting evidence that show that time to spend in nature is a valuable and useful activity to improve mental health, especially for city dwellers, for which exposure to natural environments may be limited.

*pacc = perigenual anterior cyngulate gyrus, a region of the brain in which increased activity is associated with healthy cognitive and affective processing and a reduced activity with a mental-emotional pathology.