Neighbourhood blue space and mental health: A nationwide ecological study of antidepressant medication prescribed to older adults

As global populations age rapidly, older adult mental health is becoming an increasingly important public health issue. The consequences of poor mental health in later life are severe and include reduced physical and cognitive functioning and greater risk of dementia, morbidity and mortality. Neighbourhood and landscape characteristics, such as the presence of aquatic environments - or ‘blue spaces’ - can positively impact mental health. However, evidence supporting the potential of neighbourhood blue space to promote mental health among older adults remains tentative. This study used negative binomial regression modelling to quantify the association between multiple metrics of neighbourhood blue space availability - including neighbourhood freshwater coverage, distance to the coast and distance to large lakes - and antidepressant prescription prevalence among older adults. The study combined nationwide antidepressant prescription data for over two million older adults and geospatial data of blue and green space availability for over six thousand neighbourhoods across Scotland and adjusted for a range of demographic and socioeconomic covariates. The availability of both freshwater and coastal blue space was associated with lower prevalence of antidepressant medication among older adults in Scotland. Specifically, high neighbourhood freshwater coverage (>3%) (p<0.001) and residing in close proximity (<1 km) to the coast (p<0.001) and large freshwater lakes (p<0.05) was associated with lower antidepressant medication prevalence. Consequently, coastal and freshwater blue space merit greater consideration in public health and urban planning policy and in the design of landscapes that aim to promote mental health and healthy ageing.