Greater longevity tends to be accompanied by better late life health and a slower progression of measurable aspects of aging. Researchers are very interested in uncovering the genetic contribution to variations in the pace of aging in our species, but the harder they look, the more it appears that genetic differences provide only a small contribution at best. Variance in pace of aging must then largely result from better lifestyle choices and lesser exposure to damaging circumstances such as persistent infections. Even in the case of long-lived families, there is the argument that a slower pace of aging is far more a matter of culture, rather than of genetics.
The Long Life Family Study (LLFS) has enrolled over 5,000 participants from almost 600 families and has been following them for the past 15 years. The study is unique in that it enrolls individuals belonging to families with clusters of long-lived relatives. Since 2006, the LLFS has recruited participants belonging to two groups: the long-lived siblings (also called the proband generation) and their children. Since they share lifestyle and environmental factors, the spouses of these two groups have also been enrolled in the LLFS as a referent group.
To assess cognitive performance, the researchers administered a series of assessments to the study participants meant to test different domains of thinking, such as attention, executive function and memory, over two visits approximately eight years apart. This allowed researchers to ask whether individuals from families with longevity have better baseline cognitive performance than their spouses do and whether their cognition declines more slowly than does that of their spouses.
Individuals from long-lived families performed better than their spouses on two tests: a symbol coding test, which has participants match symbols to their corresponding numbers and provides insight into psychomotor processing speed, attention, and working memory, and a paragraph recall test, which asks participants to remember a short story and assesses episodic memory. Individuals in the younger generation (participants born after 1935) exhibited a slower rate of cognitive decline on the symbol coding test than did their spouses.
"This finding of a slower decline in processing speed is particularly remarkable because the younger generation is relatively young at an average age of 60 years and therefore these differences are unlikely to be due to neurodegenerative disease. Rather we are detecting differences in normal cognitive aging."