January 25, 2023
Spending time in green spaces may be good for the brain, according to a new report. The study found that older men and women who were admitted to the hospital were less likely to have Alzheimer’s disease if they lived in areas with lots of greenery compared to those who lived in less green neighborhoods. The findings expand on earlier evidence that greenery and nature are good for your health, including the health of the brain.
For the study, researchers at the Harvard T.H. Chan School of Public Health reviewed 16 years worth of medical records of more than 61 million men and women who were enrolled in Medicare, the government health plan for Americans 65 and older. The researchers also had access to the zip codes where they lived, along with databases that grouped them according to how much exposure to nature they typically had access to — including areas with lots of trees, grass, farmland or other vegetation; areas with a high density of parks; and homes near rivers, lakes, oceans and other bodies of water.
The researchers recorded when the Medicare recipients were admitted to the hospital for the first time, and whether a diagnosis of Alzheimer’s disease or other neurologic disease was noted during that hospital visit. They found that living in an area with just a bit more greenery than average was associated with a lower risk of having Alzheimer’s disease, as well as other neurologic illnesses like Parkinson’s disease. Areas with more greenery and vegetation had a bigger impact on Alzheimer’s risk than areas with lots of parks (which may be in urban or desert settings) or near water.
The authors say there may be several reasons why greenery may be especially beneficial for people with Alzheimer’s disease. Trees and other vegetation helps 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 could be lower levels of stress, increased physical activity (leading to greater heart and blood vessel health), and a greater level of social interactions, as people may be inclined to spend more time outdoors. Regular exercise and social interactions are known to reduce the risk of developing Alzheimer’s disease. Studies have also linked exposure 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 tended to score higher on tests of brain processing and attention, and 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 and other forms of dementia than those with little exposure to green spaces. Getting outside for a walk can be good both for those with Alzheimer’s and those who care for them as well, helping to allay stress and elevate mood and perhaps even boosting brain health.
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: Jochem O. Klompmaker, PhD; Francine Laden, ScD; Matthew H.E.M. Browning, PhD; et al: “Associations of Greenness, Parks, and Blue Space With Neurodegenerative Disease Hospitalizations Among Older US Adults.” JAMA Network Open, December 20, 2022