Living around greenery may reduce depression & improve cognitive function; Study

By Arya M Nair, Official Reporter
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Image Courtesy; Max Andrey/ Pexels

Increasing greenspace in residential areas could help improve cognition function in middle-aged women which might result in reducing depression, which is a risk factor for dementia, according to a new study led by a Boston University School of Public Health (BUSPH).

The study, which was published in the journal JAMA Network Open, found that being exposed to greenspace can improve processing speed and attention, as well as improving general cognitive function.

The results also showed that lowered depression may help explain the association between greenspace and cognition, bolstering previous research that has linked exposure to parks, community gardens, and other greenery with improved mental health.

Marcia Pescador Jimenez
Marcia Pescador Jimenez
Assistant Professor

“Some of the primary ways that nature may improve health is by helping people recover from psychological stress and by encouraging people to be outside socializing with friends, both of which boost mental health. This study is among the few to provide evidence that greenspace may benefit cognitive function in older ages. Our findings suggest that greenspace should be investigated as a potential population-level approach to improve cognitive function.”

The study estimated residential greenspace with a satellite image-based metric called the Normalized Difference Vegetation Index (NDVI). Researchers measured psychomotor speed, attention, learning, and working memory among 13,594 women aged 61 on average and primarily White, from 2014 to 2016. The women were participants in the Nurses’ Health Study II, the second of three studies that are among the largest investigations into the risk factors for chronic diseases among US women.

In addition to depression, the researchers also examined the potential roles of air pollution and physical activity in explaining the association between greenspace and cognitive function, and they were surprised to only find evidence of depression as a mediating factor.

While the study shows evidence of this association, the greenspace metric does not differentiate between specific types of vegetation. In a new project, Dr. Pescador Jimenez will apply deep learning algorithms to Google Street View images to better understand which specific elements of greenery, such as trees or grass, could be the driving factors for health.

The researchers also hope that their study is replicated among other racial or ethnic populations and assesses associations with cognitive decline over longer periods of time.

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