A new study adds to increasing evidence that exposure to greenspace can help improve cognitive function.
Investigators believe that the association might be explained by a reduction in depression, which also is a risk factor for dementia, but they are continuing to study the possible connection. Previous research has linked exposure to parks, community gardens and other greenery with improved mental health.
“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 Marcia Pescador Jimenez, Ph.D., the study’s lead author, an assistant professor of epidemiology at the Boston University School of Public Health. “This study is among the few to provide evidence that greenspace may benefit cognitive function in older ages.”
Specifically, the study found that exposure to greenspace around one’s home and surrounding neighborhood could improve processing speed and attention, as well as boost overall cognitive function, in middle-aged women.
For the study, the researchers estimated residential greenspace with a satellite image-based metric called the Normalized Difference Vegetation Index. They measured psychomotor speed, attention, learning and working memory among 13,594 women aged 61, on average, from 2014 to 2016. The women were participants in the Nurses’ Health Study II, the second of three studies that are among the largest investigations into the risk factors for chronic diseases among U.S. women.
Adjusting for age, race and individual and neighborhood socioeconomic status, the researchers found that greenspace exposure was associated with psychomotor speed and attention, but not with learning or working memory.
Based on the study results, Pescador Jimenez said, clinicians and public health authorities should consider green space exposure as a potential factor to reduce depression, and thus, boost cognition. “Policymakers and urban planners should focus on adding more green space in everyday life to improve cognitive function,” she added.
The metric that the researchers used to measure greenspace exposure does not differentiate between specific types of vegetation, but they are working to better understand which specific elements of greenery, such as trees or grass, could be the driving factors for health. The researchers also hope that their study is replicated among other racial/ethnic populations and assesses associations with cognitive decline over longer periods of time.
The study, published in the journal JAMA Network Open, is one of several to find a connection between green spaces and health.
For instance, a 2018 study published in JAMDA: The Journal of Post-Acute and Long-Term Care Medicinefound that green spaces are good for the frailty status of older adults.
Spending time outdoors can improve one’s mind, body and spirit, reducing mobility issues, isolation, activities of daily living and physical therapy needs, depression and cognitive impairment, according to the authors of a 2016 literature review.
And another 2016 study found that women in the United States whose residences are surrounded by more vegetation appear to have a 12% lower overall mortality rate than those who live in areas with less vegetation.
