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Vol. LXIV, No. 23
November 9, 2012

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Mingling with Nature May Help the Depressed

Dr. Marc Berman
Dr. Marc Berman

Can a walk in the park help alleviate your trip “in the dark?” Your depression, that is? Recent NIH-supported findings suggest that interacting with nature may indeed be therapeutic.

Depression is a global burden, a condition that affects persons of all genders, races and ethnicities. According to the National Institute of Mental Health, clinical depression strikes about 20-25 percent of all adults at some point in their lives, while 9 percent of people are depressed at any one time.

A leading cause of disability and morbidity, the long-lasting malady can impair one’s ability to eat, sleep, work, think clearly, socialize and enjoy activities that would normally give pleasure.

While the disorder is often treatable through medication and most often, behavioral therapy, even the best treatments are not always fully effective. In some instances, patients may benefit from an additional measure to help regulate affected brain chemicals and chase away the blues. This is known as adjunct therapy.

NIMH-funded scientists led by Dr. Marc Berman at the Rotman Research Institute at Baycrest, in Toronto, compared the cognitive effects of walking through a park versus strolling through an urban setting for a small group of individuals diagnosed with major depressive disorder. During one session, each subject was asked to take a 50-minute nature walk through a park. In another instance, the same volunteer was asked to walk for 50 minutes down a traffic-heavy, urban street. After each activity, short-term memory and mood assessments were taken by the researchers.

Most people agree that walking is healthy—but even the experts aren’t entirely certain how much or where to walk, or why walking offers health benefits—which makes the current study even more provocative, as it applies to severely depressed adults.

“What we found was that interacting with nature [walking in a park] provided cognitive benefits to our subjects,” said Berman. “We noted about a 20 percent improvement in memory following walks in the park. Mood improved after both the nature and urban walk, but the mood improvements were larger after the nature walk.” The results were published in the Journal of Affective Disorders earlier this year.

Interestingly, the mood and memory effects were not correlated, suggesting that the memory improvements are not driven simply by putting individuals in better moods. Two separate effects seem to be taking place.

“Quite frankly, I was surprised that a fairly brief interaction with nature could produce such large improvements in memory,” noted Berman. At the start, he and his colleagues were uncertain as to whether the nature walk or any type of walking would benefit depressed patients, since walking alone could produce a constant preoccupation with negative thoughts (rumination), thereby worsening memory and mood. However, this did not occur. “In fact, the beneficial cognitive effects of walking in the park were 5 times greater for this population than in our previous studies with non-depressed individuals.”

The memory tests involved examination of working memory—a process that involves such mental manipulations as trying to remember a 7-digit number. The subjects heard digit sequences and were prompted to repeat them backwards. Berman explained that adequate working memory correlates largely with intelligence and self-control.

So, why would a stroll through the park confer some psychological, antidepressant effects while an urban walk did not? Berman explained that a walk in a quiet, tranquil setting such as a park is restorative. “But in the city, you have noise, traffic and you always have to be vigilant. That’s not to say that cities are bad. Instead, it suggests that we might enhance cities to make them less taxing and more restorative.”

Next in line for the investigators? Studies with a focus on such issues as uncovering the neural and physiological changes that accompany interacting with nature and exploring how prolonged exposure to neighborhoods that are rich in nature or lack nature relate to both mental and physical health. Doing so may enable the researchers to design environments in ways that will optimize their restorative quality and benefit those who need them most.

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