Is living near green areas beneficial to mental health? Results of the Pro-Saude Study

OBJECTIVE: To investigate the association between exposure to green areas in the surroundings of the residence and the presence of common mental disorders among adults, according to different income strata. METHODS: Cross-sectional study with 2,584 participants from the Pro-Saude Study (2006), residing in the city of Rio de Janeiro. Common Mental Disorders were measured using the General Health Questionnaire (GHQ-12) and exposure to green areas was measured using the normalized difference vegetation index, in buffers with radiuses between 100 and 1,500 meters around the residence. We used the mean and maximum normalized difference vegetation index categorized into quartiles. The study population was divided into three subgroups, according to the income: low, intermediate, and high. Odds ratios and their 95% confidence intervals were estimated with logistic regression models. The models were adjusted by sex and age, with and without inclusion of physical activity practice. RESULTS: The proportion of common mental disorders was 30% and 39% among men and women, respectively. The results of the adjusted models showed an inverse association between the presence of green areas in the surroundings of the residence and the occurrence of common mental disorders, in the buffer of 200 meters in the intermediate-income group and in the buffers of 400 and 1,500 meters in the low-income group. The odds ratio ranged from 0.52 (buffer of 1,500 meters) to 0.68 (buffer of 200 meters). The association found was independent of physical activity practice. CONCLUSIONS: The evidence found suggests the existence of a beneficial effect of urban green areas on the mental health of lower-income individuals. These findings can help in understanding how the urban environment can affect the mental health of the population.