Home Mental Health & Well-Being Limited Evidence Supports Nature Therapy for Stress Reduction, According to New Study

Limited Evidence Supports Nature Therapy for Stress Reduction, According to New Study

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A recent systematic review published in the European Journal of Investigation in Health, Psychology and Education has evaluated the effectiveness of nature-based therapeutic interventions on mental health, specifically focusing on stress, anxiety, and depression. The review analysed eight randomised clinical trials to determine whether these natural therapies provide significant psychological benefits.

Nature-based therapeutic interventions, including activities like shinrin-yoku (forest bathing), mindfulness in natural settings, and physical exercises in green spaces, have been proposed as potential solutions to mitigate mental health issues such as stress, depression, and anxiety. Given the increasing urbanisation and the subsequent rise in mental health problems, the researchers aimed to critically assess the efficacy of these interventions.

The study included trials involving healthy participants aged 18 years or older who were exposed to nature through activities such as walking, observing, and relaxation exercises in various natural settings like forests, parks, and gardens. Physiological markers, such as blood pressure and cortisol levels, and neuropsychological scales, such as the Profile of Mood States (POMS), Positive and Negative Affect Schedule (PANAS), Restorative Outcome Scale (ROS), and Stress Response Inventory (SRI-MF), were used to measure the results.

The review’s findings were mixed and inconclusive. 

Two studies measured cortisol levels, a biomarker of stress. A 2016 study found a significant decrease in blood cortisol levels in the nature group compared to the control group. However, this study lacked specific methodological details, complicating the analysis. A previous study observed a significant difference in saliva cortisol levels between pre-test and post-test in the intervention group. Another study assessed blood pressure and found significant reductions in post-test systolic pressure in the intervention group compared to the control group.

Several studies investigated stress levels using different assessment scales. One study found a significant reduction in stress levels in the intervention group, whereas others using different scales reported no significant differences between intervention and control groups.

Research evaluating anxiety and depression with the PANAS scale yielded mixed results. Some studies found no significant differences between natural and built environments for both negative and positive effects. Another study reported higher positive affect in natural environments, while another observed no significant difference in positive affect but noted a significant decrease in negative affect post-test.

The studies using the POMS scale reported varied results. While some studies indicated a reduction in anxiety and depression levels in the intervention groups, the pooled result was not significant due to high heterogeneity among the studies.

The review highlights several limitations in the existing body of research on nature-based therapies. The diverse methodologies, including differences in the duration, frequency, and type of interventions, make it challenging to draw definitive conclusions. Moreover, variations in sample sizes, lack of standardised protocols, and inadequate reporting of key methodological details further complicate the synthesis of findings.

The authors emphasised the need for more rigorous and standardised research designs to assess the true impact of nature-based interventions on mental health. They suggest that future studies should include clear descriptions of interventions, comprehensive randomisation procedures, and control for potential biases to improve the reliability of results.

The review noted that while nature-based therapies might have potential benefits for individuals with pre-existing mental health conditions, the current evidence primarily focuses on healthy populations. Therefore, more research is needed to evaluate the effects of these interventions on individuals experiencing stress, anxiety, or depression.

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