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Superagers -- people in their 80s who have the memory function of people 30 years younger -- had specific characteristics that set them apart, an observational study showed.

Superagers had more gray matter volume in the medial temporal lobe, cholinergic forebrain, and motor thalamus than typical older adults and slower total gray matter atrophy over time, reported Marta Garo-Pascual, MS, a PhD candidate at the Universidad Autónoma de Madrid in Spain, and co-authors.

There were no differences in amyloid-beta, APOE status, or other dementia biomarkers between superagers and typical older adults, the researchers reported in .

There also was no difference in the amount each group exercised. However, a model that assessed 89 clinical, lifestyle, and demographic variables indicated that faster movement and better mental health were key factors that differentiated superagers from others.

The findings may reflect an inherent resistance to age-related memory decline, the researchers noted.

"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," Garo-Pascual said in a statement.

"Our findings suggest superagers are resistant to these processes, though the precise reasons for this are still unclear," she observed. "By looking further into links between superaging and movement speed we may be able to gain important insights into the mechanisms behind the preservation of memory function deep into old age."

The results are "consistent with reports of resilience to Alzheimer's disease in superaging, although the mechanisms underlying this resilience remain unknown," noted Alexandra Touroutoglou, PhD, of Harvard University in Boston, and colleagues in an .

"More efforts are needed to refine and harmonize definitions of superaging in multisite studies using large and diverse cohorts." they added. "Large-scale studies will allow further exploration of resilience factors in superagers, which could lead to new insights in the prevention of age-related memory decline."

The study evaluated cognitively healthy older adults in the longitudinal cohort recruited between October 2011 and January 2014 who were 79.5 years or older. Participants were followed for up to 6 years, and the median number of follow-up visits was five.

Older adults were classified as superagers if they scored at or above the mean values for a 50 to 56-year-old in the (FCSRT) and within one standard deviation of the mean or above for their age and education level in three non-memory tests. If they scored within one standard deviation of the mean for their age and education level in the FCSRT, they were classified as typical older adults.

Overall, 64 superagers with a mean age of 81.9 (59% women) and 55 typical older adults with a mean age of 82.4 (64% women) were included.

Superagers performed better in the test (a gauge of mobility) and a finger-tapping test that assessed fine motor function, despite no group difference in self-reported exercise levels between superagers and typical older adults. They also had better self-reported scores on the State-Trait Anxiety Inventory assessment and on the Geriatric Depression Scale.

Superagers complained less often about not getting enough sleep than typical older adults, even though there was no difference in self-reported sleep duration between groups. They generally had more active lifestyles in midlife and had a higher musical background (formal or not) than typical older adults. They demonstrated greater independence in day-to-day living and scored higher in reading tests.

The machine learning model that analyzed the 89 variables to identify factors associated with superagers reached a discrimination accuracy of 66.4% (68.8% sensitivity and 63.6% specificity), indicating that "further variables, possibly including genetic factors, are associated with the superaging phenotype," the researchers acknowledged.

Causality can not be inferred from the study, and intervention trials, most likely implemented in midlife, may shed more light, they added.

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