National Geographic documentary and groundbreaking research highlight the vital role of social connection in protecting brain health
When National Geographic approached social health expert Dr Suraj Samtani to appear alongside Chris Hemsworth in a new documentary exploring dementia, memory and healthy ageing, it was an opportunity to bring science to millions.
Premiering 24 November 2025 on Disney+, Chris Hemsworth: A Road Trip to Remember follows Hemsworth as he confronts his family’s experience with dementia and learns how lifestyle and social factors can slow cognitive decline.
The release coincides with CHeBA’s latest findings, published in The Journals of Gerontology: Series B, which reveal that older adults experiencing social frailty - a lack of social connections, resources and support - are up to 50 per cent more likely to develop dementia.
For Dr Samtani, a Postdoctoral Research Fellow at UNSW’s Centre for Healthy Brain Ageing (CHeBA), the experience was both surreal and meaningful.
“As a scientist, it’s a dream come true to be part of a National Geographic documentary,” said Dr Samtani. “We’re lucky if a handful of people read our research articles. Having the global reach of Disney and Chris Hemsworth means we can share our dementia research with millions. It’s why I do this work - to help people. Science is not just about research; it’s meant to be shared.”
From the Lab to the Marvel Stadium
Dr Samtani filmed with Hemsworth at Marvel Stadium in Melbourne, where the two discussed the importance of mental wellbeing and connection.
“Chris is incredibly down-to-earth,” said Dr Samtani. “But what stayed with me was his sincerity. He genuinely wants to promote healthy ageing and reduce stigma around dementia.”
“When we spoke about his father and his own future, he was open and vulnerable. Seeing that side of him was inspiring. I hope it encourages men to talk more about their feelings and helps families speak more openly about dementia.”
In another memorable moment, the documentary team recreated Hemsworth’s childhood home on the outskirts of Melbourne to look exactly as it did in the 1990s.
“It felt like stepping into a time machine,” said Dr Samtani. “When Chris and his family walked in, it was incredibly emotional. His mum, Leonie, shared stories of the boys running around the house - it was a beautiful, nostalgic moment.”
Social Frailty: New CHeBA Research Connects Social Connection and Dementia Risk
The release of Chris Hemsworth: A Road Trip to Remember coincides with new findings from CHeBA that highlight why Dr Samtani’s message about connection matters more than ever.
Published in The Journals of Gerontology: Series B, CHeBA’s study of more than 850 Australians aged 70 and over found that older adults experiencing social frailty - a lack of social connections, resources and support to meet basic social needs - face a significantly higher risk of developing dementia.
Led by Dr Annabel Matison and Dr Suraj Samtani, the research followed participants in CHeBA’s Sydney Memory and Ageing Study for 12 years. It is the first study worldwide to directly compare multiple social frailty indices to determine which best predicts dementia risk.
Individuals identified as socially frail using specific screening tools were found to be up to 50 per cent more likely to develop dementia, even after accounting for physical and psychological frailty.
“Social frailty has been largely overlooked in dementia research,” said Dr Matison. “Our findings suggest it’s not only a key risk factor, but one we can identify early - and potentially change.”
Dr Samtani emphasised that early identification could transform prevention.
“We know staying socially connected is vital for brain health, but what’s missing is a simple, evidence-based checklist doctors can use,” he said. “Our research shows that the social frailty index has real potential to fill that gap - helping GPs identify people at higher risk and giving families a chance to act before dementia takes hold.”
He added that the next step is to make social prescribing - where doctors recommend meaningful social activities just as they prescribe medication - a routine part of dementia prevention.
So, what does social frailty look like in everyday life? According to Dr Samtani, it’s not the same as loneliness.
“Loneliness is a subjective feeling of disconnection - you can be surrounded by people and still feel lonely,” he explained. “Social frailty, on the other hand, may include loneliness but is broader than that. It is also about having limited opportunities for social contact and fewer people you can rely on. ”
For an older person, that might mean not seeing friends or family very often, no longer being involved in community or volunteer activities, or feeling dissatisfied with their relationships. “One of the things we found interesting was that low financial satisfaction was also a strong indicator,” said Dr Samtani. “It’s not about wanting to earn more but about lacking the financial freedom to do the things you want to do - the activities that give life meaning and connection.”
Dr Samtani noted that social frailty often goes unnoticed in medical settings. “We’ve long focused on physical health, and increasingly on mental and cognitive health, but social health tends to be ignored,” he said. “When we visit our GP, we’re asked about blood pressure or diabetes, but rarely if we feel connected to those around us. Yet we know that social isolation increases the risk of heart disease, dementia and even early mortality. People with strong social connections not only live longer - they also experience chronic conditions 10 to 15 years later and have a slower rate of cognitive decline.”
“Having a clear, evidence-based screening tool for social frailty will help GPs identify people at risk early,” said Dr Samtani. “Social isolation is the biggest modifiable risk factor for dementia in later life. By recognising social frailty as a clinical issue, we can intervene before cognitive decline takes hold.”
A Shared Message of Hope
Both the new research and Hemsworth’s documentary share a central message: there is hope.
“If you are living with dementia or caring for someone who is, you are not alone,” said Dr Samtani. “Over 55 million people worldwide live with dementia. But through awareness, social engagement and support, we can slow cognitive decline and help people live well.”
Dr Samtani also offered heartfelt thanks to Chris Hemsworth and his family for their openness.
“They’ve helped millions by being brave and honest about their journey. The documentary is beautiful and moving - it’s going to help people understand dementia and spark meaningful conversations in homes around the world.”
Chris Hemsworth: A Road Trip to Remember is produced by Protozoa, Nutopia and Wild State for National Geographic.
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