Access to Natural Space Can Limit Hospital Stays With Parkinson’s

US study links accessible parks, water, and greenery to fewer hospitalizations

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Older adults with Parkinson’s disease who live in areas with more greenery, parks, or surface water are less likely to be hospitalized, according to an analysis of 16 years’ worth of U.S. data.

The study, “Associations of Greenness, Parks, and Blue Space With Neurodegenerative Disease Hospitalizations Among Older US Adults,” was published in JAMA Network Open.

Parks and other public natural spaces can have indirect health benefits for the people living nearby, providing a space for social gatherings and helping to ease stress.

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Study into role of environment on hospitalizations for Parkinson’s

In this study, a team led by researchers at Harvard T. H. Chan School of Public Health analyzed Medicare data from 2000 to 2016, assessing whether people with neurological diseases who live in areas with greater access to natural space were less likely to be hospitalized.

Medicare is the U.S. government-funded health insurance program for people 65 years or older, or those with certain disabilities.

In particular, they looked at the time from entry into the dataset to a first hospitalization among Medicare beneficiaries ages 65 and older. First hospitalization “can be interpreted as accelerated disease progression (exacerbation of symptoms),” the researchers wrote.

Their analysis included data, collected over those 16 years, covering 61.7 million people with Parkinson’s, and a nearly equal number of individuals with Alzheimer’s disease and related dementias. Alzheimer’s is an aging-related neurodegenerative disease that’s the most common cause of dementia.

In both groups, slightly more than half of the patients were women (55.2%), most were white (84.4%) and between the ages of 65 and 74 (76.6%). Most were also not eligible for Medicaid (87.6%), a government health insurance program for people with lower socioeconomic status, as indicated by income and assets.

Researchers identified more than one million first Parkinson’s hospitalizations and more than seven million first hospitalizations for Alzheimer’s and related dementias.

They then combined the data with patients’ zip codes, indicating residence, to determine access to features of the natural environment: green spaces, blue space cover, and parks.

Green space concerned an overall assessment of vegetation such as trees, crops, or grass in an area based on satellite imaging. Park cover referred to outdoor areas used for public recreation, and blue space cover to surface water.

After adjusting for potential influencing factors, results showed that Parkinson’s patients living in areas with higher values of any of these three natural environments were significantly less likely to be hospitalized.

For those with Alzheimer’s or related dementias, more green space significantly associated with fewer hospitalizations, but no statistically significant associations were detected for the other two types of natural space.

Some of these associations differed based on demographic factors, including socioeconomic status and ethnicity.

Protective associations for park cover or blue space with Parkinson’s patients were not statistically significant among Blacks, but this population showed the strongest link between more greenness and fewer hospitalizations.

The association between greater green spaces and fewer hospitalizations with both diseases was strongest among patients who were eligible for Medicaid. In the Parkinson’s group, the protective effects of green space were greatest in areas of mid- and high-socioeconomic status.

Greater green space, surface water also important for urban patients

In a separate analysis, the researchers looked only at urban areas, those with at least 1,000 people within each square mile. In these areas, greater green and blue spaces linked to significantly fewer hospitalizations for Parkinson’s patients.

There were also “protective associations of percentage park cover with [Parkinson’s disease] hospitalization for Medicaid-eligible individuals, individuals of unknown or other race or ethnicity, and individuals living in low-SES [socioeconomic status] neighborhoods,” the team wrote.

While parks had a protective effect among lower-income Parkinson’s patients in urban areas, more green and blue spaces did not. This lack could be due to the fact that these features “in higher-SES neighborhoods … represent higher qualities of natural environments than in low-SES neighborhoods (eg, greenness on vacant lots, blue space close to harbors/air pollution sources),” the researchers wrote.

It is also possible that “individuals from low-SES neighborhoods tend to use parks more often than other individuals,” they added.

Notably, observed links for all three environmental exposures generally weakened after statistical adjustments made to account for exposure to air pollution or meteorological indicators. Still, the associations generally remained statistically significant.

This suggests that factors beyond air pollution and weather, such as “stress reduction, attention restoration, increased physical activity, and social interactions,” may play a role in a natural environment’s protective effects, the researchers wrote.

While the Medicare dataset used represents “a fairly representative [group] of older adults in the US,” the team wrote, the analysis is limited by its population-level approach. While the researchers looked at green areas by zip code, they but could not zero in on specific access and utilization of these resources at the population-level.

“As we lacked information about the exact residential address of each beneficiary, we assessed zip code-level exposures, which likely resulted in measurement error,” they wrote.

Still, study findings add to accumulating data that public natural spaces can provide health benefits for people living nearby.

“As life expectancy increases globally, policy makers should consider interventions of natural environments” to help improve the health of people affected by Parkinson’s and other neurological diseases, the researchers concluded.

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