Living on Greener Blocks Can Decrease Incidence of Alzheimer’s Disease
Article Summary
- A recently published study linked neighborhood greenness with a reduced risk of Alzheimer’s disease for older adults.
- The “precision greenness” study compared older adults living in consistently high greenness blocks with those living in consistently low greenness blocks from 2011 to 2016.
- Dr. Scott Brown, the study’s senior author, said high levels of greenness can reduce the risk of developing Alzheimer’s disease by 16 percent over a five-year period.
Older adults living on green blocks in Miami-Dade County have a lower incidence of Alzheimer’s disease than those in less green surroundings, according to a new, collaborative study by public health researchers at the University of Miami Miller School of Medicine.
“We have coined the phrase ‘precision greenness’ to emphasize the importance of trees, shrubs and other ground cover on local blocks,” said Scott Brown, Ph.D., research associate professor of public health sciences at the Miller School. “This new study adds weight to our team’s prior research on the multiple health benefits of living in greener communities.”
Plant a Tree
Dr. Brown was senior author of the study, published recently in The Journal of Prevention of Alzheimer’s Disease.
“We found that a high level of greenness on the block where an older person lives can reduce the risk of developing Alzheimer’s disease by 16 percent over a five-year period,” he said. “It suggests that planting trees or other green interventions could reduce Alzheimer’s disease risk both at individual and population levels.”
Study co-author José Szapocznik, Ph.D., professor and chair emeritus of the Department of Public Health Sciences and director of the university’s Public Health Policy Lab, said the Miller School team has established greenness as a pathway to better health. Prior studies have shown that a higher level of neighborhood greenness can decrease the risk for 13 chronic conditions.
“Since we started these studies a decade ago, I have been stunned by the power of greenness in aging and chronic disease,” said Dr. Szapocznik. “If planting trees and preserving the existing canopy can reduce the incidence of Alzheimer’s disease, stroke, diabetes and other conditions, the payoff for communities around the world will be huge.”
Comparing Alzheimer’s Disease Risks
The precision greenness study of 230,738 U.S. Medicare beneficiaries compared older adults living in consistently high greenness Census blocks from 2011 to 2016 with those living in consistently low greenness blocks from 2011 to 2016.
Those living in the highest third of greenness had 16 percent lower odds of developing Alzheimer’s disease compared with those in the lowest third of greenness, adjusting for age, sex, race, ethnicity and neighborhood income.
Many cities around the world have tree-planting initiatives for climate change or beautification, and our team has shown there is a positive impact on public health as well.
— Dr. José Szapocznik
Dr. Brown said adults ages 65 to 74 benefited more from high greenness levels than those ages 75 and up.
“High greenness levels also had a greater impact on adults living in lower-income neighborhoods, suggesting that greenness may be particularly powerful for those most in need,” he said.
In addition to Dr. Brown and Dr. Szapocznik, University of Miami co-authors included:
Million Trees Initiative
Another contributor to the study was Maria I. Nardi, director of Miami-Dade Parks Recreation & Open Spaces. She said the Million Trees Miami-Dade County initiative is aiming for a 30 percent tree canopy and accelerating plantings in low-income neighborhoods through a $10 million U.S. Department of Agriculture Urban and Community Forestry grant.
“The benefits of greenness evident in this new study are consistent with the team’s findings on other conditions,” she said. “Based on these studies, we anticipate our work will enhance community health outcomes, mitigate extreme heat and contribute to resilience.”
Dr. Szapocznik said there are multiple reasons why greenness could improve health, including increased physical activity, greater social connectedness, improved sleep and a reduction in air pollution.
“When you look outside and see greenery, your stress levels are reduced, a particularly important consideration in lower-income neighborhoods, where residents are impacted by chronic stress,” he said.
Reflecting on the study, Dr. Szapocznik said, “Clearly, greenness is important for health, as well as for neighborhood beauty. Many cities around the world have tree-planting initiatives for climate change or beautification, and our team has shown there is a positive impact on public health as well.”
Tags: Alzheimer's disease, Department of Public Health Sciences, Dr. José Szapocznik, Dr. Scott Brown, greenness, neighborhood greenness, public health