There are some special folks among us whose sharp minds defy their advanced years, their brains somehow resisting the slow march of time.

There are lots of possible reasons why, from genetics to personality. Now a Spanish study, one of the longest and largest of its kind, has pinpointed a few more traits that may explain how these so-called superagers retain their wit and memory.

"We are now closer to solving one of the biggest unanswered questions about superagers: whether they are truly resistant to age-related memory decline or they have coping mechanisms that help them overcome this decline better than their peers," says lead author Marta Garo-Pascual, a neuroscience graduate student at the Queen Sofia Foundation Alzheimer Centre in Madrid.

Superagers are a rare breed of elders aged 80 or older whose memory rivals those 20 or 30 years younger.

In this new study of 64 superagers and 55 typically healthy older adults, both groups averaging 82 years, Garo-Pascual and colleagues looked for differences in brain scans, mobility tests, clinical mental health assessments, lifestyle surveys, and blood samples.

If their findings are representative of superagers in other countries, the results suggest superagers' nimble minds might have something to do with their agile bodies.

Over six annual visits, the researchers tracked study participants' lifestyle factors, scanned their brains, sampled their blood, and put them through their paces on mobility tests – inputting the data into a machine learning model tasked with identifying factors associated with superagers.

In line with previous studies, MRI scans showed that superagers' brains shrank slower than their contemporaries' brains had over the 5-year study period in areas involved in memory and movement.

Superagers were generally more active in midlife, satisfied in their elder years with their sleep, had better mental health, and showed greater independence in their day-to-day living – likely enabled by their ability to move, balance, and remember things.

Superagers were also faster at standing up out of a chair, in a 'Timed Up and Go Test', and had better fine motor skills. Yet there was no discernible difference in the overall activity levels reported by superagers and typical older ported.

"Though superagers report similar activity levels to typical older people, it's possible they do more physically demanding activities like gardening or stair climbing," says neuroscientist Bryan Strange of the Polytechnic University of Madrid.

"It's also possible that having better brain health in the first place may be what's responsible for superagers having faster movement speed."

The study also found no differences in blood biomarkers of dementia, consistent with earlier studies that found superagers retain their memory function despite similar levels of Alzheimer's disease proteins in their brains.

"Our findings suggest superagers are resistant to these processes, though the precise reasons for this are still unclear," says Garo-Pascual.

Past research has revealed an abundance of spindle neurons, a rare type of neuron linked to memory capability, in superagers' brains. So their razor-sharp memories may partly be the product of a biological lottery as much as they are a reflection of their lifestyle choices, social connections, or outlook on life.

Genetics, too, likely plays a role, as the machine learning model used in this study to differentiate superagers from their peers could only do so correctly 66 percent of the time, based on 89 demographic, lifestyle, and clinical factors.

Further research involving superagers could, in time, reveal ways to help older people age well and preserve memory function, though there is a likely overlap with factors associated with dementia prevention, such as physical activity and low blood pressure.

Longer, larger studies on superagers might also provide more data to refine our understanding of what sets superagers apart.

The study has been published in The Lancet Healthy Longevity.