Research Summary

Life course nature exposure and mental health outcomes: A systematic review and future directions

A review of the literature finds that early nature exposure can contribute to later-life mental health

International Journal of Environmental Research and Public Health
2021

During the past decade, there has been a dramatic increase in research on connections between nature exposure during an earlier stage of life and mental health in later stages of life.  To date, however, there has not been a systematic review that synthesizes and evaluates this research. This review addressed this challenge. Questions guiding the review focused on (1) the types of mental health benefits associated with early-life nature exposure, (2) the strength and consistency of related evidence, (3) the possibility of a critical period for acquiring the benefits of nature, and (4) challenges and unanswered questions for future studies.

Twenty-nine studies were included in the review – most of them, longitudinal studies. The majority of the studies examined populations from Western countries, primarily in Europe and North America. Most of the studies were published between 2016 and 2020. Three categories of greenness exposure were identified: (1) availability/density/cover, (2) frequency/duration, and (3) quality. Of these, availability/density/cover was the most common measure type; quality the least common.

Twenty-seven of the 29 articles reported a significant advantageous relationship between nature exposure and one or more mental health outcomes. The domains of mental health outcomes identified include incidence of mental disorders, psychiatric symptoms and emotions, conduct problems in children, cognitive function, and subjective well-being. Of these, nature exposure was the most advantageous in reducing risks of mental disorders. However, other than schizophrenia and ADHD, none of the mental disorders were examined in more than one study. The majority of studies with findings relating to psychiatric symptoms and emotions showed that any relation between nature and this outcome area existed only for certain populations or measures. Of the five studies examining children’s behavioral problems, three reported a significant effect of exposure to nature. Findings relating to cognitive function were inconsistent and often depended on a specific measure and age range. Five studies examined subjective well-being (SWB). While two reported a positive connection with earlier nature exposure, “it remains questionable whether early-life exposure benefits later-life SWB.” Disadvantaged individuals seemed to benefit more from early-life nature exposure than more advantaged individuals. Childhood nature exposure also seemed to be more beneficial in deprived neighborhoods and in neighborhoods perceived to be safer. The overall results did not support the possibility of a critical period for acquiring the benefits of nature.

The findings of this review support the idea that early nature exposure can contribute to later-life mental health. As such, these findings have important policy implications, especially in relation to severe health disparities experienced by many individuals living in disadvantaged neighborhoods or families. A number of challenges and unanswered questions for future studies were identified; and specific suggestions for such research offered.

Citation
Li, D., Menotti, T., Ding, Y., & Wells, N. M.. (2021). Life course nature exposure and mental health outcomes: A systematic review and future directions. International Journal of Environmental Research and Public Health, 18. doi:http://dx.doi.org/10.3390/ijerph18105146