Most 'super agers' smoke, drink, gain weight, drink coffee, never retire and even have dementia tangles in their brains - but they have better brain function than people in their 50s.
Scientists are baffled by the paradox which has emerged from the famed 90+ study, analyzing people aged 80 to 100 who seem resilient to cognitive decline.
To their surprise, they found the people in this unique group do not have an over-expression of the APOE 22 gene, which was thought to be protective against dementia.
But they did all share a more positive outlook on life than their peers, they cared more about close relationships, they were very active - and diet seemed to have little to do with it.
New scans also reveal these super agers have a higher proportion in their brain of a rare neuron called von Economo, a 'social' neurons which tends to be dysfunctional in people with autism, schizophrenia and bipolar disorder.
Medical experts were stunned when they carried out research on 'super-agers', who despite having many symptoms associated with dementia, seemed not to be affected by the condition
Presenting the new findings on Sunday, Emily Rogalski, a professor of cognitive neurology at Northwestern University in Chicago, said lifestyle factors and outlook are increasingly being looked at as integral to maintaining cognitive function.
'The findings suggest that super agers have unique personality profiles,' she told the American Association for the Advancement of Science in Austin, Texas.
'Excellent memory capacity is biologically possible in late life and can be maintained for years even when there is significant neuropathologic burden.'
Selecting 10 super agers from the group of 74, Dr Rogalski's team followed them for 24 months then analyzed their brains after they died.
The scans showed the participants weren't void of the build-ups of tau protein that cause dementia, and yet they had none of the symptoms and were leading an active life unimaginable for most over 90.
The vast majority (71 percent) smoked or had smoked previously, and 83 percent still drink alcohol regularly.
The average retirement age is 68.5 years old, but Dr Rogalski said 18 percent of super agers never retire, and the rest tend to pick up another career later on, or at least are very active in the community.
There was no 'magic bullet' in terms of diet ('no, they don't eat more blueberries and some really like their hamburgers and French fries'), but they did tend to sleep at least eight hours a night.
Compared to their peers, they were also far more social - yet another sign that loneliness is a silent killer.
'This builds on the idea of negative consequences of loneliness and the positive consequences of positive relationships,' Dr Rogalski said.
It is not yet clear if this is a driving force, or a symptom, of having the von Economo neurons which were over-expressed in super agers.
These neurons are only found in the brains of large mammals and are believed to offer high-speed connections between different regions within the brain.
They are known to develop in the late stages of pregnancy and early childhood and could be down to luck.
Dr Rogalski's study could provide a breakthrough in dementia research.
In contrast to much of the dementia research carried out to date, it does not focus on trying to reverse the spread of amyloid and tau, deformed proteins that form lumps in the brains of people with dementia.
Dr Claudia Kawas, professor of neurology at the University of California, Irvine, said the findings are challenging everything she has ever known after decades in the field.
'I almost think we should stop doing research and just start using our bodies and brains more,' she quipped.
'These people are inspiring - they drink wine, drink coffee, gain weight, but they exercise and use their brains. Maybe that can tell us something.'