2000), it appears likely that trait vulnerability is more malleable early in life, but significant life events can alter its trajectory even in old age. A depressive disorder is thought to emerge when personality liability crosses the threshold. Thus, individuals who are born with an elevated personality liability or those with a rapidly increasing trait trajectory would have a childhood onset of the disorder, whereas those with a more slowly increasing trait trajectory would not cross the threshold until much later, if ever. Moreover, a pathological trait trajectory may be checked or reversed by positive experiences (Ormel & de Jong 1999). In fact, personality generally tends to change in a more adaptive direction with age (Roberts et al. 2006), although this pattern is not universal (Johnson et al. 2007). This may help to explain why the probability of first-episode depression peaks in adolescence, as trait deviance is more common at that age.
