Key findings for journalists
- The three types of social connections that were identified were: spending time with friends, neighbours and the community; interacting with family or providing childcare; and participation in religious groups
- All three social connection types were weakly heritable, indicating strong environmental influence.
- More frequent interaction with friends, neighbours and communities was linked to lower depressive symptoms, both immediately and over time.
Research from the Centre for Healthy Brain Ageing (CHeBA) at UNSW Sydney has found that social interactions in later life are largely shaped by life experiences - not genetics - and that staying connected with friends, neighbours and the community may help protect older adults against depression.
Using data from CHeBA’s Older Australian Twins Study (OATS), one of Australia’s most comprehensive ageing research projects, researchers analysed more than 560 twins aged 65 and over across six years to understand how social connections relate to mental and cognitive health.
Environment, not genetics, shapes social life in older age
The study, published in the British Journal of Psychiatry, found that social connections - including friendships, family interactions and involvement in community or religious groups - were only weakly influenced by genetic factors, meaning they are mostly shaped by each person’s individual experiences and environment.
The researchers say this is encouraging news.
“Because social connections are not strongly determined by genes, they are highly modifiable. This means programs and policies designed to boost social engagement can genuinely make a difference for older people,” said lead researcher and social health expert Dr Samtani.
More social interaction linked to fewer depressive symptoms
Importantly, the study found that older adults who interacted more frequently with friends, neighbours and community members experienced fewer symptoms of depression, both at the start of the study and six years later.
Even modest increases in social interaction had measurable benefits.
“These findings reinforce what many older people already know instinctively - that staying socially active helps support emotional wellbeing,” said Dr Samtani.
Co-author and Honorary Associate Lecturer at CHeBA, Dr Anne-Nicole Casey said the twin design of the study offered unique insights into what shapes social lives in later years.
“Looking at twins is particularly powerful because they share genetics and early environments, allowing us to see what is truly unique to individuals.
In this study, it became clear that it was people’s own life experiences that mattered most. Social connections are dynamic systems that change as we take on different roles across our lives, and our findings show that these varied relationships – with friends, family, neighbours or community groups - can all play meaningful and supportive roles in older age,” said Dr Casey.
While loneliness and social isolation are known risk factors for dementia, this study did not find strong evidence that social interactions predicted changes in cognitive function over the six-year period. Researchers note that larger studies and longer follow-up periods may be needed to detect subtle changes in cognitive ageing.
A rapidly ageing population
With Australia’s population ageing, understanding what supports healthy brain ageing is a national priority. Depression, anxiety and dementia are among the leading causes of disability worldwide, and social isolation is on the rise, particularly among middle-aged and older adults.
This new research strengthens the case for community programs, culturally informed social support, and clinical screening for isolation among older Australians.
Why this matters
Given that social engagement in older age is largely shaped by environment - not genetics - there is substantial opportunity to improve mental health through community design, social programs and health services that actively promote connection.
“Encouraging older adults to engage with local groups, stay connected to neighbours and participate in community life can be a powerful tool in supporting mental wellbeing,” said Dr Samtani.
