May 11, 2022
To help keep the mind and memory sharp, try taking in the trees and greenery in a local park. A new study found that middle-aged women who live near parks and other green spaces tended to score higher on tests of brain processing and attention, and had better overall thinking and memory skills.
The findings are important, because maintaining good cognitive skills in middle age is tied to a lower risk of Alzheimer’s disease and other forms of dementia in old age. Spending time in outdoor greenery may also have stress-relieving and mood-boosting benefits, which are also tied to a lower dementia risk.
“Some of the primary ways that nature may improve health is by helping people recover from psychological stress and by encouraging people to be outside socializing with friends, both of which boost mental health,” said study leader Dr. Marcia Pescador Jimenez, an assistant professor of epidemiology at the Boston University School of Public Health.
For this very large study, published in JAMA Network Open, researchers studied 13,594 American women who were part of the large Nurses’ Health Study, a group of studies that examined risk factors for chronic diseases. Their average age was 61.
Using satellite data, they assessed how much greenery, including areas with lots of trees and grass, was present near the women’s homes. The women also underwent tests of brain function, including processing speed and memory, as well as tests to indicate whether they showed signs of depression.
The researchers found that women who lived near areas where there were lots of trees and greenery tended to score higher on brain tests of speed and attention skills, and generally had higher cognitive function. The researchers estimated that women exposed to greenery had brains that were, on average, about 1.2 years “younger” than those of women who didn’t live near greenery. That is not a dramatic difference, but it could have an impact on the age at which the women eventually might develop dementia.
The researchers considered dementia risk factors like physical activity levels and exposure to air pollution, as well as socioeconomic status and education level. They found that the main risk factor that might contribute to better brain health was that the women living near greenery tended to have lower levels of depression, a risk factor for Alzheimer’s disease.
“We theorize that depression might be an important mechanism through which green space may slow down cognitive decline,” Dr. Pescador Jimenez said, “but our research is ongoing to better understand these mechanisms. Based on these results, clinicians and public health authorities should consider green space exposure as a potential factor to reduce depression, and thus, boost cognition.”
The findings add to growing evidence linking exposure to parks, community gardens and other greenery with improved mental health and a lower risk of dementia.
Another study of more than 3,000 men and women aged 75 and older living at four different locations in the United States, for example, found that those living in areas with moderate amounts of greenery had a 28 percent lower risk of developing Alzheimer’s disease and other forms of dementia than those with little exposure to green space.
A different study from Australia found that people living within a mile of green space tended to feel less lonely. The effect was especially pronounced among people who lived alone, perhaps because proximity to parks and outdoor spaces promote social interaction. Other studies have shown that feeling lonely is linked to a higher likelihood of developing Alzheimer’s disease, and that staying socially connected in old age can help ward off dementia.
And finally, a small British study found that people found it easier to exercise when they watched a video showing a rural setting bathed in green. They were also in a better mood afterward. Watching a video where red was the primary color, on the other hand, made them feel angrier.
So if you’re feeling stressed and overwhelmed, consider a walk in the neighborhood park. It may be good for your brain in more ways than one, and for your body too.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Marcia P. Jimenez, Elise G. Elliott, Nicole V. DeVille, et al: “Residential Green Space and Cognitive Function in a Large Cohort of Middle-Aged Women.” JAMA Network Open, April 27, 2022
