Table 1: Octo-Twin participant characteristics.

Year of testing
MeasureBaseline Year 2 Year 4Year 6Year 8
( 𝑛 = 5 7 2 )( 𝑛 = 4 7 0 )( 𝑛 = 3 6 1 )( 𝑛 = 2 7 4 )( 𝑛 = 1 9 4 )

Retention from previous testing (%)82.276.875.970.8
Age [M (SD)]83.3 (3.0)85.2 (2.8)86.9 (2.5)88.8 (2.5)90.7 (2.4)
Education [M (SD)]7.2 (2.4)7.3 (2.4)7.3 (2.3)7.2 (2.1)7.2 (2.3)
Sex, female [ 𝑛 (%)]369 (65)304 (65)235 (65)195 (71)144 (74)
Reasoning [M (SD)]11.5 (7.1)11.4 (7.2)11.4 (7.1)10.8 (7.2)10.3 (7.3)
Memory [M (SD)]9.6 (4.0)9.4 (4.2)9.2 (4.4)9.2 (4.7)9.0 (4.4)
Semantic knowledge [M (SD)]28.1 (11.1)28.6 (11.2)27.5 (12.4)26.7 (13.0)26.2 (11.4)
Cognitive activity [M (SD)]2.1 (1.7)1.7 (1.6)1.3 (1.4)1.2 (1.4)1.1 (1.3)
Activity change [M (SD)]−0.3 (1.3)−0.6 (1.3)−0.8 (1.5)−1.1 (1.6)

M: mean; SD: standard deviation. The theoretical ranges for each measure with a defined upper limit are as follows: reasoning = 0–42, Memory = 0–16, semantic knowledge = 0–44, and cognitive activity = 0–8.