Use it or lose it: How cognitive skills change with age

It is commonly assumed that cognitive skills start to decline by age 30 if not earlier, which could pose major challenges for rapidly aging populations. But this assumption largely relies on cross-sectional data that cannot distinguish between aging patterns and cohort differences in skills. Using unique German longitudinal skill data, our analysis breaks the confounding of age and cohort patterns. We find that skills on average actually increase strongly into the forties before decreasing slightly in literacy and more strongly in numeracy. Furthermore, skills decline at older ages only for those with below-average skill usage.