"Higher levels of green space were associated with lower symptoms of anxiety, depression and stress," said Dr Kristen Malecki, assistant professor of population health sciences at the University of Wisconsin School of Medicine and Public Health.
The study combines mental-health data from the Survey of the Health of Wisconsin (SHOW) and Landsat 5 satellite data from July 2009 that analysed how much vegetation was present in each of the SHOW census blocks.
About 2,500 Wisconsin residents from 229 neighbourhoods answered an assessment that asked them to rate their symptoms of depression, anxiety and stress.
They found that across all strata of society, people who lived in a neighbourhood with less than 10 per cent tree canopy were much more likely to report symptoms of depression, stress and anxiety.
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Malecki noted that the study gives credence to the "attention restoration theory," which holds that more time in nature restores the ability to concentrate and reduces mental fatigue.
"The greening of neighbourhoods could be a simple solution to reducing stress. If you want to feel better, go outside," said Malecki.