Personality Traits: Stability and Change with Age
Individual differences in personality traits are generally stable during adulthood; where there are changes, they are generally in the direction of greater maturity. The trends are similar for men and women and across cultures. With advancing age, people generally become more emotionally stable, agreeable, and conscientious, with better impulse control, but less active and less open to new actions and values than younger individuals. Those trajectories provide several insights into adult development, challenging some negative stereotypes about older adults and serving as a reminder that enduring individual differences are more important than age in understanding personality.
Key words: personality traits, aging, cross-cultural, depression, Alzheimer’s disease.
Introduction
Personality traits are “dimensions of individual differences in tendencies to show consistent patterns of thoughts, feelings and actions.”1 These traits show universal trends as age advances, although people generally maintain their relative standing compared with their peers. This report briefly introduces the major personality factors, discusses the rank-order stability of individual differences and normative trends with aging in North America and around the world, and concludes with the relevance of personality traits for health and well-being.
The Five-Factor Model of Personality
Most personality psychologists today agree that five broad factors subsume most personality traits.2 These five factors are named neuroticism (N), the tendency to experience negative emotions, including anxiety, depression, and anger; extraversion (E), an interpersonal dimension that includes facets such as warmth, sociability, activity, and positive emotions; openness to experience (O), which includes active imagination, preference for variety, and intellectual curiosity; agreeableness (A), which includes altruism, trust, and modesty; and conscientiousness (C), a dimension defined by facets such as order, will to achieve, self-control, and persistence.1 Those traits can be assessed through personality questionnaires using either self-report or observer rating methods. Observer ratings are particularly useful in cases where the individual is unwilling or unable to complete the test, as, for example, in patients with advanced Alzheimer’s disease.3 Whatever the method used, personality traits are linked to important life outcomes, from health risk behaviours and well-being to academic achievement and political preferences.4 Personality traits have strong biological roots: twin studies indicate that about 50% of the variance in personality trait scores is accounted for by genetic factors,5 although lower estimates emerge from family studies.6 In the past decade, a large number of studies have tried to associate personality traits or mental disorders with several candidate genes, such as the serotonin transporter, but the results have been inconclusive so far. An alternative strategy for identifying trait-related genes is a genome wide scan of a large and genetically homogeneous sample, such as those from founder populations.6
Rank-Order Stability
A solid finding in the analysis of personality traits across time is the tendency of adults to maintain their relative standing compared with their age-group peers.1,7 In other words, a person who scores high on a given trait at the first time will tend to score high again at follow-up, even many years later. Indeed, longitudinal studies have repeatedly found correlations in the range of 0.70-0.80 with retest intervals of up to 10 years. Usually, the greater the time elapsed, the lower the correlation; but long-term longitudinal studies suggest that after the first 20-25 years, the correlation declines to an asymptote around