Successful leaders are at risk of developing exaggerated pride, contempt for others, and a diminished sense of reality. The ancient Greeks feared this syndrome and called it hubris. Although certain contemporaneous leaders show signs of hubris and pose a great danger, the hubris syndrome does not yet figure in our classification systems. The purpose of this paper is to examine several aspects of its validity, including clinical description, laboratory study, and exclusion of other disorders. Firstly, a substantial body of evidence indicates that the hubris syndrome may develop after a person has held substantial power for a considerable amount of time. Thus, the syndrome differs from a personality disorder with its characteristic onset in late adolescence or early adulthood. It is proposed, therefore, that the syndrome is a non-organic personality change after gaining substantial power or achieving overwhelming success, characterized by the emergence or marked increase of pathological personality traits within the domains of dissociality and disinhibition. Within the domain of dissociality, grandiosity is an obligatory trait. Secondly, with reference to laboratory study, recent evidence suggests that machine learning algorithms have the ability to differentiate hubristic from non-hubristic speech patterns. Thirdly, the exclusion of other disorders is difficult, because individuals with the hubris syndrome do not collaborate in any investigation. Some suggestions are made to overcome this problem. In conclusion, there is sufficient reason to further examine the validity of the hubris syndrome and to consider it for inclusion in our classification systems.

We argue that an advance directive (AD) is not invalidated by personality changes in dementia, as is claimed by Rebecca Dresser. The claim is that a new person results under such personality changes, and that the former person cannot write an AD for the new person. After stating the argument against ADs in cases of dementia, we provide a detailed examination of empirical studies of personality changes in dementia. This evidence, though not strong due mainly to low sample sizes and different notions of personal identity, does not support Dresser’s position. Given the weakness in the empirical evidence, we turn to a philosophical defense of ADs based on a social contract view supporting the current interests of those writing ADs. Additionally, we argue that personality change is not equivalent to change in personal identity, as would be required by the argument against ADs in cases of dementia.

We examined developmental trends and sources of stability and change in adolescent personality by using twin data collected from 1981 to 2010 (273 monozygotic (MZ) and 48 dizygotic (DZ) twin pairs) from a secondary school affiliated with the University of Tokyo. Phenotypic analyses showed high rank-order stability and substantial mean-level increases in neuroticism and declines in extraversion over the adolescent years. Longitudinal bivariate genetic analyses revealed that the best-fitting model for adolescent personality includes additive genetic and non-shared environmental influences. Heritability estimates ranged approximately from 0.30 to 0.60. Additionally, three-year stability in adolescent personality was influenced mainly by genetic factors, and there were both genetic and environmental innovations in mid-adolescence. Our findings suggest that both genetic and environmental effects have significant roles in the etiology of personality development across adolescence.