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Cognitive health decline in older Australians linked to neighbourhood environment

Lack of green space and air pollution in neighbourhoods play a pivotal role in shaping cognitive health - the ability to think, learn and remember clearly over time - and can contribute to developing conditions like dementia, new ACU research has found

Published in Environment International, the research found that where you live - well-planned, destination-rich neighbourhoods with good access to services and green spaces can reduce the risk of mild cognitive impairment.

Professor Ester Cerin, a world leading researcher on the environmental and psychosocial determinants of lifestyle behaviours and health across the lifespan, said the study showed neighbourhood characteristics can have a direct impact on developing severe cognitive conditions like dementia.

"This research is one of the few longitudinal studies to examine how the characteristics of our neighbourhood - including its design, availability to amenities, street network, access to nature and air pollution - may influence our cognitive health as we age," Professor Cerin said.

"These environments encourage physical activity and social interaction, both of which are known to support cognitive health.

Professor Cerin said the study is the first to identify how specific neighbourhood characteristics influence the transition from a healthy cognitive state to mild cognitive impairment, a precursor to more severe cognitive conditions like dementia.

It adds to the growing body of research linking the built environment to brain health in ageing populations.

The research drew on data which tracked a cohort of older Australians over 12 years as part of the ongoing PATH through life study.

"It suggests that the way our cities are built can make a substantial difference to our wellbeing and functionality as we age," she said.

"We need to balance the built environment with nature to ensure that we get opportunities to engage in stimulating activities as well as relax and breath in clean air. What's good for the planet - compact urban developments, greenery and low levels of emissions - is also good for our brain."

Professor Cerin said the long-term nature of the study offered valuable insights into how neighbourhood environments can influence cognitive health trajectories.

"We found that various aspects of neighbourhood walkability - such as street connectivity and access to a variety of services - were linked to better overall cognitive health and the ability to process information quickly in older adults," she said.

"Access to green spaces also emerged as a key factor in supporting cognitive function, especially memory, reinforcing the importance of natural environments in promoting mental wellbeing."

High levels of air pollution were found to negatively affect cognitive function over time, contributing to both cognitive decline and an increased risk of mild cognitive impairment.

"This underscores the urgent need for cleaner, healthier environments to ensure that older populations can maintain cognitive health as they age," she said.

"Interestingly, the study revealed a more complex relationship for those already diagnosed with mild cognitive impairment.

"For these individuals, the same features - dense neighbourhoods with rich access to destinations - were linked to a lower likelihood of reverting back to a healthy cognitive state. This highlights the need for tailored approaches when designing environments that support older adults at different stages of cognitive health."

Professor Cerin said the findings have important implications for urban planning, public health policy, and ageing populations as Australia deals with a growing number of older adults.

"The impact of this research extends beyond just understanding cognitive decline - it provides essential guidance for designing environments that can help preserve cognitive function and delay the onset of cognitive impairment," she said.

"By showing that well-planned, destination-rich neighbourhoods with good access to services and green spaces can reduce the risk of mild cognitive impairment, it suggests that health-oriented urban planning aiming to enhance features that promote cognitive health would yield vast and enduring public health benefits at a population level."

She has called on policymakers and urban planners to consider these findings when designing future communities, ensuring environments that promote physical and cognitive well-being.

Media Contact: Elisabeth Tarica, Australian Catholic University on 0418 756 941 or elisabeth.tarica@acu.edu.au