Study details and key findings

For the study, which was published in Lancet Healthy Longevity, researchers evaluated cognitively healthy adults ages 79.5 years and older who were recruited from  the Vallecas Project longitudinal cohort between October 2011 and January 2014.

Individuals were classified as superagers if they scored at or above the mean values for a 50- to 56-year-old in the Free and Cued Selective Reminding Test (FCSRT), as well as within one standard deviation of the mean or above for their age/education level for three non-memory tests. Those who scored within one standard deviation of the mean for their age/educational level on the FCSRT were classified as typical older adults.

Overall, the study included 64 superagers, with a mean age of 81.9 years and of which 59% were women. There were also 55 typical older adults, with a mean age of 82.4 years and of which 64% were women.

The researchers found that superagers had more gray matter volume in the medial temporal lobe, cholinergic forebrain, and motor thalamus than typical older adults. They had slower total gray matter atrophy over time.

However, there were no significant differences in amyloid-beta, APOE status, or other dementia biomarkers between the two groups. There was also no difference in how much each group exercised or self-reported sleep duration.

In an analysis of 89 clinical, lifestyle, and demographic variables using a machine learning model, researchers found that faster movement and better mental health may be key factors separating superagers from other older adults.

Compared to typical older adults, superagers performed better on the Timed Up and Go test, which measures mobility, and a finger-tapping test, which measures fine motor function. Superagers also had better self-reported scores on the Geriatric Depression Scale, as well as the State-Trait Anxiety Inventory.

In general, superagers were also more active in midlife and had a higher musical background compared to typical older adults. They were also more independent in their day-to-day living and had higher scores on reading tests.

According to the researchers, the machine learning model had a discrimination accuracy of 66.4%, suggesting that "further variables, possibly including genetic factors, are associated with the superaging phenotype."

Commentary

The study's findings suggest that some people may have an inherent resistance to age-related declines in memory, the researchers said.

"Our findings suggest superagers are resistant to these processes, though the precise reasons for this are still unclear," said Marta Garo-Pascual, a PhD candidate at the Universidad Autónoma de Madrid in Spain and one of the study's authors. "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."

"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," she added.

In an accompanying editorial, Alexandra Touroutoglou, from Harvard University, and colleagues, said that the findings are "consistent with reports of resilience to Alzheimer's disease in superaging, although the mechanisms underlying this resilience remain unknown."

"More efforts are needed to refine and harmonize definitions of superaging in multisite studies using large and diverse cohorts," the authors wrote. "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." (George, MedPage Today, 7/14; Touroutoglou, The Lancet Health Longevity, 7/13)

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