Land cover and air pollution are associated with asthma hospitalisations

International evidence suggests that green space has beneficial effects on general and mental health but little is known about how lifetime exposure to green space influences cognitive ageing. Employing a novel, longitudinal, life course approach, we examined the association between lifetime availability of public parks and cognitive ageing. Lifetime residential information was gathered from the participants of the Lothian Birth Cohort 1936 using a "life-grid" questionnaire at age 78 years. Parks information from 1949, 1969 and 2009 was used to determine a percentage of parks within a 1,500 m buffer zone surrounding residence for childhood, adulthood, and later adulthood periods. Linear regressions were undertaken to test for association with age-standardised, residualised change in cognitive function (Moray House Test score) from age 11 to 70 years, and from age 70 to 76. The most appropriate model was selected using the results of a partial F-test, and then stratified by demographic, genetic and socioeconomic factors. The local provision of park space in childhood and adulthood were both important in explaining the change in cognitive function in later life. The association between childhood and adulthood park availability and change in the Moray House Test Score from age 70 to 76 was strongest for women, those without an APOE e4 allele (a genetic risk factor), and those in the lowest socioeconomic groups. Greater neighbourhood provision of public parks from childhood through to adulthood may help to slow down the rate of cognitive decline in later life, recognising that such environmental associations are always sensitive to individual characteristics. Reviewer Comments Reviewer 3 1. To add a copyright statement onto Figure S3 to cover the use of postcode and census data. We agree that copyright information should be included and have added this to Figure S3. 2. To add the sample size N into the abstract, so readers are made aware of the size of the cohort at the beginning of the manuscript. We agree that it is important to display the sample size in the abstract; we have added this information to pg 1 line 11. Reviewer 4 1. “The authors have done a good job in addressing most of the comments. The manuscript looks improved now. However, I still have serious concerns regarding the interpretation of the findings. Even by ignoring that I would not agree with the authors saying that by having an interaction term in the model, the main effects are not meaningful, I still firmly believe that the findings do not support the conclusion of the manuscript. It is because from different models whose results are presented in Table 3, only one shows significant results, which could be a chance finding given the number of comparisons made (i.e. multiple comparison issue) and the inconsistent pattern of the associations for different models that show different strengths and direction of associations. Even if we believe that this is not a chance finding, still this association has lost its statistical significance after adjustment for the relevant covariates, meaning that it could be due to the confounding by these covariates rather than a genuine association between green space exposure and cognitive decline. Hence, based on these observations, it is quite unrealistic to conclude that "Greater neighbourhood provision of public parks in adulthood and particularly childhood may help to slow down the rate of cognitive decline in later life. " To me, these findings do not support such an association. ” Thank you for your comments regarding the interpretation of the results. The rationale behind testing multiple combinations of parks is to provide a formal comparison of several hypotheses, this is a method that has been utilised elsewhere, without correction for multiple testing. This is useful to stimulate discussion on the merits of the relationship. We think this is the right way to approach the question: “does public park availability affect cognitive ageing over life? ” because prior research is sparse for this relationship and we would be at risk of choosing the wrong exposure combination (i.e. increase in type 2-error rate). As Mishra et al., note picking a single exposure combination can “produce misleading or incomplete results that do little to help the understanding of how life course trajectories affect health”. On the question of the loss of statistical significance, we welcome the reviewer’s consideration of the effects presented in greater detail. Although we opted to present the interaction continuously, the association is mostly driven by the top end of adulthood park availability. To highlight this, we have conducted supplementary Response to Reviewers* (NO AUTHOR DETAILS)