August 7, 2024
Living near green spaces may be good for the brain. A new study found that exposure to parks and trees in midlife slowed declines in thinking and memory skills. Brain benefits were especially pronounced in people who lived in poorer neighborhoods and in those who carried APOE-E4, a common gene variant that increases the risk of developing Alzheimer’s disease.
“Our results are important because they shed light into the cognitive benefits of increasing green space exposure at a population level, particularly among vulnerable subgroups of the population, such as carriers of the APOE-E4 gene,” said study author Dr. Marcia Pescador Jimenez, an assistant professor of epidemiology at the Boston University School of Public Health.
For the study, the researchers analyzed data from the Nurses’ Health Study, a long-running investigation into risk factors for various chronic diseases. The study began in 1976, enrolling hundreds of thousands of female nurses aged 30 to 55 who were living across the country.
The current research team focused on a subset of 16,962 nurses aged 70 and older who had completed up to four cognitive tests. The researchers also had detailed information about where these women had lived during their middle years, including satellite information about the density of green spaces in their home neighborhoods.
The researchers found that living in areas with greater concentrations of green space during midlife was associated with slower declines in thinking and memory skills later in life, equivalent to about eight months of age-related cognitive decline. The brain benefits of greenery were strongest in women of lower socioeconomic status who lived in densely populated neighborhoods, as well as in those who carried the APOE-E4 gene variant. The findings were published in the journal Environmental Health Perspectives.
Experts say there may be several reasons why greenery may be good for the brain. Trees and other vegetation help to filter the air and may lead to lower levels of air pollution, and several studies have linked poor air quality to brain shrinkage and other brain changes typical of Alzheimer’s disease. Living in areas with heavily polluted air may accelerate the onset of Alzheimer’s in people who may already be vulnerable to developing the disease.
Other potential benefits of living near green spaces and spending more time outdoors could be lower levels of stress, increased physical activity (leading to greater heart and blood vessel health), and enhanced social interactions, all of which may reduce the risk of developing Alzheimer’s disease. Studies have also linked exposure to green spaces to a lower risk of depression, which has likewise been identified as a risk factor for Alzheimer’s disease.
The findings add to growing evidence that spending time in nature can be good for the brain. One recent study found that middle-aged women who live near parks and other green spaces had better overall thinking and memory skills than their peers with less access to natural settings. Another study of more than 3,000 Americans aged 75 and older found that those living in areas with moderate amounts of greenery had a 28 percent lower risk of developing Alzheimer’s disease than those with little exposure to green spaces.
So get outside for a walk in the park when you get a chance. It can help to allay stress and elevate mood, and perhaps even boost brain health.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Sources: Marcia Pescador Jimenez, Maude Wagner, Francine Laden, et al: “Midlife Residential Greenness and Late-Life Cognitive Decline among Nurses’ Health Study Participants.” Environmental Health Perspectives, July 17, 2024
Li Xin Hu, Bo-Yi Yang: “Invited Perspective: More Greenspace, Less Cognitive Decline? Current Evidence and Future Directions.” Environmental Health Perspectives, July 14, 2024
