Where You Live Could Raise Your Risk of Cognitive Decline: Study

Living in a neighborhood with more green spaces could slow cognitive decline in older people, according to a study.

To investigate the potential link between being exposed to greenery and brain health, researchers based in Spain studied 6,500 people in the U.K. aged between 45 and 68 years old.

The participants, who were civil servants, were studied twice during a ten-year period from 1997 to 1999 and 2007 to 2009. During this time, they completed cognitive tests on three occasions, which measured factors including their short-term memory and their verbal and mathematical skills. Satellite images were used to calculate how much green space was in each individual's respective neighborhood.

Carmen de Keijzer, lead author of the study and predoctoral fellow at the Barcelona Institute for Global Health (ISGlobal), told Newsweek: "We found that participants living in neighborhoods with more vegetation had a slightly slower cognitive decline than those living in neighborhoods with less vegetation."

Pollution and sedentary lifestyles common in cities might contribute to cognitive decline, evidence suggests. Getty Images

So, should we try to spend as much time in green spaces as possible in order to keep our brains healthy? And should those with little access to such spaces be worried?

"This difference was small on an individual level; comparing the 25 percent of most green neighborhoods with the 25 percent of the least green neighborhoods, the decline was only 4.6 percent slower over a period of 10 years," Keijzer said.

"Therefore, on an individual level, this might be a less source of concern. Although we did not investigate whether the number of visits to green spaces have an association with cognitive function in this study, we could say that in general green spaces are beneficial for health and that visiting green spaces, in a safe and secure way, is recommendable."

Building an understanding of the causes of cognitive decline is vital if we are to swerve the doubling of dementia cases in the world between 2015 to 2050, as predicted by the World Health Organization. And the link to green spaces could be important as currently over half of the world's population lives in cities: a figure expected to rise two thirds by 2050, the authors noted.

"The results of this study could be useful for policy makers and urban planners, in our rapidly urbanizing world with aging population," Dr. Payam Dadvand, assistant research professor at ISGlobal and author of the study, told Newsweek.

Existing evidence indicates that being exposed to urban environmental factors like air pollution and noise, as well as living a stressful, sedentary lifestyle, could contribute to cognitive decline, said Keijzer.

But living near green spaces appears to have the opposite effect. That could be because people are more likely to exercise, reduce their stress levels and find social support. Green spaces also are generally less polluted by noise and fumes.

Read more: Skinny Fat Body Type Linked to Dementia Risk in Study

Dadvand acknowledged a limitation of the study was the fact it was based on measurements among civil servants, with only 30 percent of the participants being female and over 90 percent of the participants being white.

"The study should be repeated to see if the findings also apply in other settings, climates and cultures," he said. Further research is also needed to definitively confirm that green spaces cause a slowing of cognitive decline.