A new study from the Centre for Healthy Brain Ageing (CHeBA) at UNSW Sydney has found that social interactions in older age are largely shaped by life experiences rather than genetics — and that staying connected with friends, neighbours and the community can help protect older adults from depression.
Published in the British Journal of Psychiatry, the research analysed data from more than 560 twins aged 65 and over who participated in CHeBA’s Older Australian Twins Study (OATS), one of the country’s most comprehensive ageing research projects. The participants were followed for six years to explore how social connections relate to mental and cognitive health.
Lead researcher and social health expert Dr Samtani said the findings show that social engagement is highly modifiable.
“Because social connections are not strongly determined by genes, they are highly modifiable,” Dr Samtani said. “This means programs and policies designed to boost social engagement can genuinely make a difference for older people.”
The study found that older adults who interacted more frequently with friends, neighbours and community members experienced fewer symptoms of depression, both at the beginning of the study and six years later. Even modest increases in social interaction were linked to measurable improvements in emotional wellbeing.
“These findings reinforce what many older people already know instinctively — that staying socially active helps support emotional wellbeing,” Dr Samtani said.
Co-author and Honorary Associate Lecturer at CHeBA, Dr Anne-Nicole Casey, said the twin design of the study provided 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,” Dr Casey said. “In this study, it became clear that it was people’s own life experiences that mattered most.”
While loneliness and social isolation are known risk factors for dementia, the study did not find strong evidence that social interactions predicted changes in cognitive function over the six-year period. Researchers noted that larger studies and longer follow-up periods may be needed to detect subtle changes in cognitive ageing.
With Australia’s population ageing rapidly, 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 increasing, particularly among middle-aged and older adults.
The researchers say the findings strengthen the case for community programs, culturally informed social support, and clinical screening for isolation among older Australians. “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,” Dr Samtani said.
