Green mental health

| January 24, 2024

A new study intertwining nature with neuroscience has unveiled findings that could change the landscape of urban eldercare. The Washington State University researcher, published in Health & Place, affirms that parks, gardens, rivers, or lakes – also known as green and blue spaces – can be lifelines for the mental health of older adults.

The research, involving 42,980 seniors in urban Washington State, found that living near a city’s green and blue spaces can significantly reduce the risk of severe psychological distress.

“Our study showed that green spaces like parks, tree canopies, forest space, blue spaces, and length of trails are associated with better self-rated general health or reduced psycho-social distress,” first study author Adithya Vegaraju told ZME Science.

The research reveals that even a modest 10% increase in greenery or proximity to water bodies in one’s neighbourhood correlates with substantial improvements in mental and general health. As cities expand and green spaces shrink, the study raises the alarm about urbanisation’s unseen mental health costs. Studies of specific green areas have shown that the best results are obtained in environments of open woodland where people could see some distance into the treed area. It has been suggested that the reason is that when we lived in forests it was important that we could see approaching danger.

Slowing cognitive decline

Older people are especially vulnerable to mental health issues such as depression, which has been shown to increase the risk of cognitive decline and dementia. They are also less likely to receive treatment to manage their mental health conditions. If exposure to green or blue spaces could help prevent, delay or even treat poor mental health in older adults, Vegaraju said we need to look at that more closely as a way to improve mental health outcomes.

“It is thought that exposure to green and blue spaces could help slow cognitive decline,” Amiri stated in a WSU press release. “What we would like to know is if green and blue space exposure can influence dementia directly or whether it can do so by reducing mental health issues that may lead to cognitive decline.”

Studies have shown that spending short amounts of time in forests seems to benefit our immune systems. Specifically, one study found that elderly patients suffering from chronic obstructive pulmonary disease experienced decreases in perforin and granzyme B expressions, as well as decreased pro-inflammatory cytokines—all related to better immune function—after they visited forests rather than urban areas. Though it’s not clear exactly why this would be, a prior study suggests that trees may improve immunity thanks to certain aromatic compounds they release.

Trees also seem to help our heart health. In one study, participants walked in a forest one day and an urban environment another day, and researchers measured how the two walks impacted their bodies. In comparison to the urban environment, walking in trees lowered people’s blood pressure, cortisol levels, pulse rates, and sympathetic nervous system activity (related to stress), while increasing their parasympathetic nervous system activity (related to relaxation). All of these physiological markers are tied to better heart health, suggesting that walking in the woods improves cardiovascular function.

Trees in neighbourhoods lead to less crime

While some prior research has shown that green spaces reduce crime in urban settings, it may be that trees are even more effective.

In one study, researchers looked at crime data for the city of Chicago, computing a score for each census tract. Then, they compared that to the percentage of tree canopy cover and park space enclosed in each tract. They found that for every 10 percent increase in tree canopy cover, crime rates went down in several categories—11.3 percent for assaults, narcotics crimes, and robbery, and 10.3 percent for battery.

Maybe having a sea- or tree- change should be part of our retirement plan.