Agreeableness and Conscientiousness showed relatively gradual increases in absolute scores across the life span whereas Neuroticism showed relatively gradual decreases. ... Average levels of Neuroticism generally declined with age but increased slightly starting around age 80.

Which personality trait increases with age?

This results in increases in emotional stability, conscientiousness, and social dominance, which is a facet of extraversion. In older age, there are again comparatively strong changes in personality.

Which personality traits tend to become stronger between the ages of 20 and 40?

In fact, personality does change over long periods of time. For example, we tend to become more socially dominant, more conscientious (organized and dependable), and more emotionally stable between the ages of 20 and 40, whereas openness to new experiences tends to decline as we age.