Schnitker and Emmons (2007) found evidence for an inverse relationship between patience and negative affect and between patience and depression, but a positive relationship between patience and self-reports of certain negative health outcomes, including headaches, acne, and ulcers.
They found that trait stability increased from a correlation .31 in childhood to .54 during the college years, to .64 at age 30, and then it reached a plateau around .74 between the from age 50 until the age of 70. What we can infer from these results is that personality seems to stabilize with increasing age.
7 doctors agreed: Yes: for a personality disorder to be diagnosed in an individual younger than 18 years, the features must have been present for at least 1 year.The one exception to this is antisocial personality disorder, which cannot be diagnosed in individuals younger than 18 years. source: dsm-5 pages 647-648. ...Read more.