A major international research collaboration led by UNSW Sydney’s Centre for Healthy Brain Ageing (CHeBA), in partnership with an international consortium of six leading universities, has found that social health - how individuals interact with and are supported by their social environments - plays a critical role in maintaining cognitive function and building the brain’s resilience against dementia.
The findings come from the Social Health and Reserve in the Dementia Patient Journey (SHARED) Consortium, a global collaboration spanning more than 40 cohort studies and nearly 150,000 participants worldwide. The summary of the findings from the SHARED project was led by CHeBA social health expert Dr Suraj Samtani, Dr Jean Stafford from the University of Edinburgh, Dr Jane Maddock from University College London and Dr Anna Marseglia from Karolinska Institute in Sweden.
Published in Ageing Research Reviews, the research provides some of the most comprehensive evidence to date that social health is a key factor in cognitive ageing and dementia risk.
Dementia currently affects around 55 million people globally, with numbers projected to triple by 2050. As the economic and societal burden grows, identifying modifiable risk factors has become a priority. Social health - long overlooked compared to physical and mental health - is emerging as a crucial piece of the puzzle.
Beyond isolation: redefining social health
While social isolation has already been identified as a risk factor for dementia, SHARED researchers emphasise that it represents only one aspect of a much broader concept.
The consortium developed a comprehensive framework defining social health as a dynamic interaction between individuals and their social environments. This framework categorised existing indicators of social health such as social network size, loneliness and frequency of social interactions.
Qualitative research conducted across multiple countries also identified previously overlooked indicators, including reciprocity, dignity and emotional closeness.
Clear links to cognitive function and decline
Across global datasets, the SHARED Consortium found that better social health is associated with higher cognitive performance and individuals with stronger social connections experience slower cognitive decline. The researchers also found that positive social health markers are linked to a reduced risk of mild cognitive impairment and dementia.
However, results varied depending on the type of social factor, cultural context and stage of cognitive decline, highlighting the complexity of these relationships.
“Importantly, the research provides new insights into how social health may influence the brain,” said Dr Samtani.
Analyses showed that better social health is associated with markers of brain reserve - the brain’s structural capacity to withstand damage - such as greater total brain volume and healthier white matter microstructure.
“The findings suggest that social engagement and supportive relationships may help build or maintain the brain’s physical resilience, allowing individuals to better cope with age-related or disease-related changes,” said Dr Samtani.
Depressive symptoms were also found to partially mediate the relationship between social support and cognition, pointing to mental health as a key pathway linking social and cognitive outcomes.
A global effort
The SHARED Consortium brought together interdisciplinary experts across Europe, Australia, and Asia, and worked closely with major international collaborations. Professor Henry Brodaty from CHeBA led one of the teams on this collaborative project, focusing on exploring dementia risk in the Cohort Studies of Memory in an International Consortium (COSMIC). CHeBA’s involvement enabled harmonised analyses across diverse populations, strengthening the robustness and global relevance of the findings.
“Our findings show that social health is not just a ‘nice to have’ - it is a fundamental component of brain health. Strong, supportive social environments appear to help maintain cognitive function and may even enhance the brain’s resilience to damage,” said Dr Samtani.
“By moving beyond a narrow focus on social isolation or loneliness, we’ve shown that multiple aspects of social life - from relationship quality to social participation - play meaningful roles in shaping cognitive ageing.”
Implications for prevention and policy
The findings reinforce calls from global health bodies to address social factors in dementia prevention strategies. Reducing social isolation alone could potentially prevent or delay millions of dementia cases, but SHARED highlights the need for a broader, more nuanced approach.
The researchers emphasise the need for better measurement tools capturing the full spectrum of social health as well as further research into biological and psychological mechanisms, and consideration of life-course and cultural differences in social experiences.
While SHARED provides strong evidence linking social health to cognitive function and brain reserve, questions remain about the pathways from social health to brain reserve. Future research will aim to disentangle these pathways and explore how improving social health could be translated into effective, scalable interventions.
About SHARED
The Social Health and Reserve in the Dementia Patient Journey (SHARED) Consortium led by CHeBA is an international research collaboration funded by the EU Joint Programme – Neurodegenerative Disease Research (JPND). It brings together experts in epidemiology, neuroscience, psychology, and sociology to better understand how social factors influence cognitive ageing and dementia.
Contact details:
Heidi Douglass
(02) 9385 0410