Bradford study of mothers finds no link between green space and mental health

Results of a study researching links between green space and common mental disorders in Bradford has found no association between mental health and residential greenness or living in proximity to major green spaces. Participants consisted of 4,737 mothers recruited to the Born in Bradford family birth cohort between 2007 and 2011, using data collected during a follow-up between 2017 and 2021.

 

The surprise findings complicate the current science showing proximity to green space can have a positive effect on mental health. However the green spaces were not assessed for their quality or maintenance. The researchers hypothesise that the results point to an interplay of multiple social factors – for example, whether those green spaces felt unsafe. 

 

“We did not find any statistically significant relationships between any measure of residential greenness and any mental health outcome,” the study, which was undertaken by a consortium of institutions and published in the journal for Urban Forestry & Urban Greening, concludes.

 

The study did, however, find a positive link between doorstep greenery (NVDI) and a risk of depression, which showed that increased greenness corresponded with a higher risk of depression. It also found people who did not like their local park showed increased anxiety based on their proximity to the green space. 

 

 

To explain the findings, the study questions whether the use of a sample composed solely by women affects the results – which differ to other studies which show green space is beneficial to mental health.

 

“In contrast to previous research, our results did not provide support for a positive association between greenness and mental health, adding to the uncertainty about it that have been found elsewhere.”

 

“Parks can be also a focus of antisocial behaviour and therefore a source of insecurity and distress for nearby, which has been already described in Bradford. This latter fact can indeed help to understand why living in the proximity of a green space was increasing anxiety symptoms for those participants who were unsatisfied with the quality of their local parks.

 

“It can be hypothesised that if insecurity is a problem in green spaces in a given area and one of the factors explaining dissatisfaction, living close to one of those could indeed have a negative impact on mental health due to increased stress or fear of crime.”

 

 

The study also posits whether the lack of green space in Bradford combined with its higher air pollution and noise levels could mask the positive effects of greenness. “Our findings suggest that for highly deprived populations, green space may be insufficient on its own as a tool to improve population health. A holistic approach to improving environments and reducing social stressors to improve the health of deprived communities is needed.”

 

“Future research in deprived areas should aim to understand how local environments are perceived by communities and how these perceptions interact with structural features to impact health.

 

For the study, residential greenness was assessed by two metrics: the Normalised Difference Vegetation Index (NDVI) which measures immediate residential or doorstep greenness, and a second metric which measures distance to major green spaces. Mental health outcomes were obtained from primary care records, prescription medication records and validated questionnaires, as well as self-reported depression and anxiety.

 

 

The study did not find a clear pattern of environmental inequality – participants living in more deprived areas, those of lower education levels and those belonging to South Asian and Black origin groups minorities “did live in less green areas but conversely had increased availability of green spaces”. These neighbourhoods had lower levels of doorstep greenery such as street trees, as measured by NDVI values.

 

“Despite being closer to major green spaces, South Asian and Black origin groups were less likely to report being frequent users,” the study noted.

 

South Asian and Black participants also showed better mental health across all the indicators considered in this study: “In contrast with previous research, participants of South Asian origin and Black origin reported better mental health. This could be explained by stronger social, cultural and family connections and support characteristics of these groups compared with deprived White British groups.”

 

The interpretation of the results concludes that the availability of green space alone “may not be enough to confer health benefits” for populations experiencing high rates of Common Mental Disorders (CMD) and “multiple environmental and social stressors”. 

 

Indeed, for those unsatisfied with their local park, living within 300m of a major green space increased risk of anxiety symptoms, but not other CMD indicators. “We re-fitted total effects models of green space availability, stratifying by park uses and park. We did not find any interaction by levels of park use and only found a significant effect when stratifying by park satisfaction. For those unsatisfied with their local parks, living within 300m of a park increased the likelihood of being at risk of anxiety as compared to those that did not live close.”

 

The researchers found 30% of participants had an indicator of CMD, which is higher than the estimated 17% national figure. Those most highly educated and those with the least education had higher levels of CMD.

 

Find out more: Read Social inequalities, residential greenness and common mental disorders in women: evidence from the Born in Bradford family cohort study