Neuroticism is a personality trait that has been associated with several psychiatric disorders, and is considered one of the risk factors for the development of depression, anxiety disorders [1], [2], [3], [4] and dementia [5]. When measured by the Eysenk Personality Questionnaire (EPQ) [6], neuroticism has been shown to be relatively stable, with a stability of 0.62 over 20 years [7], although there is some evidence of a moderate decline in older ages [8], [9]. Neuroticism is consistently higher in females than males [10], [11], but it is unclear whether this is a direct effect of gender or a consequence of different environments experienced by males and females [8], [12]–[14]. The heritability of neuroticism has been estimated in the range 0.30 to 0.50, based on twin studies [7], [15]–[17] that also show a genetic covariance of neuroticism with anxiety and depression [10], [13], [18]–[22].
